01 – Introduction to Russ, Lasers and Fiber Laser Marking (58:33)

The Fiber Laser Learning Lab Series with Russ Sadler

In this Series, Lotus Laser have lent Russ a MOPA 20 watt fiber laser to “play with”. Although Russ has a moderate understanding of laser technology (his words) and how constant power glass tube systems work, pulsing fiber laser marking machines are shrouded in a deeper mystery than the glass tube machines.

They have been designed for high speed marking and the technology has been well tried and proven. There are limited “tricks” that the pulsing laser technology can perform. You enter predefined parameters for each marking “trick” you wish the machine to deliver , then stand back in amazement. Most correspondents tell Russ that they have bought their machine direct from China and received a machine and EZCAD software, preloaded with a few default parameters. No other instructions beyond the EZCAD manual are forthcoming.

Image of russ sadler with his loaned fiber laser marking machine
Image of Russ Sadler with his Loaned Fibre Laser Marking Machine

Russ states “I am neither a teacher or expert in this field so you join me in my learning adventure with the warning that I have a simple but inquisitive mind and will probably make mistakes on my way to discovering the truth. I WILL oversimplify and maybe distort the scientific detail in my quest to build a simple picture of why and how this technology works. I am not trying to reverse engineer anything, just to break through the seemingly impenetrable ‘techno cotton wool’ that surrounds this amazing piece of science.”

Contents

To be completed soon.

Previous VideoNext VideoSeries Menu

Video Resource Files

There are no more resource files associated with this video.

External Resource Links

Lotus Laser

MOPA 20 watt fiber laser

EZCAD

There are no more external resource links associated with this video.

Transcript for Introduction to Fiber Laser Marking

Click the “Show More” button to reveal the transcript, and use your browsers Find function to search for specific sections of interest.

1
00:00:01.61 –> 00:00:09.090
hi no my name’s Russ and I’d like to

2
00:00:06.089 –> 00:00:11.969
welcome you to this new series where I’m

3
00:00:09.09 –> 00:00:15.059
going to be exploring fiber laser

4
00:00:11.969 –> 00:00:17.070
marking machines well this one in

5
00:00:15.059 –> 00:00:19.830
particular we’ll talk about that in a

6
00:00:17.07 –> 00:00:20.340
second I think you could see I’m old I’m

7
00:00:19.83 –> 00:00:23.070
gray

8
00:00:20.34 –> 00:00:26.189
I’m Oakley I’m fat I’m also an ex

9
00:00:23.07 –> 00:00:28.019
engineer I’ve been involved in all

10
00:00:26.189 –> 00:00:32.759
aspects of engineering during my career

11
00:00:28.019 –> 00:00:34.860
and at one stage I own some co2 metal

12
00:00:32.759 –> 00:00:36.420
cutting laser machines so I thought I

13
00:00:34.86 –> 00:00:38.760
knew everything there was to know about

14
00:00:36.42 –> 00:00:40.680
nicer cutting until I got one of these

15
00:00:38.76 –> 00:00:42.780
Chinese machines and then all of a

16
00:00:40.68 –> 00:00:44.940
sudden I realized that I knew a lot

17
00:00:42.78 –> 00:00:48.030
about the machine and the way it’s

18
00:00:44.94 –> 00:00:49.890
rylynn the way it was maintained but

19
00:00:48.03 –> 00:00:53.280
nothing about the actual laser

20
00:00:49.89 –> 00:00:55.050
technology itself and so for the past

21
00:00:53.28 –> 00:00:58.680
four years I’ve been teaching myself

22
00:00:55.05 –> 00:01:01.340
very slowly but then again you’d expect

23
00:00:58.68 –> 00:01:04.799
that of somebody of my age wouldn’t you

24
00:01:01.34 –> 00:01:07.040
how these machines work what the

25
00:01:04.799 –> 00:01:09.510
technology is that makes them work

26
00:01:07.04 –> 00:01:11.189
successfully and I’ve been delving into

27
00:01:09.51 –> 00:01:13.619
some really dark corners that most

28
00:01:11.189 –> 00:01:16.530
people don’t bother to dig into these

29
00:01:13.619 –> 00:01:19.770
are hobby machines and lots of hobbyists

30
00:01:16.53 –> 00:01:22.860
just use them for small businesses or to

31
00:01:19.77 –> 00:01:25.590
play with yeah I play with mine as well

32
00:01:22.86 –> 00:01:28.049
but I specifically I’m an inquisitive

33
00:01:25.59 –> 00:01:31.829
person and I’d like to know how and why

34
00:01:28.049 –> 00:01:33.840
things work okay so I’m sitting here

35
00:01:31.829 –> 00:01:37.920
with my arm on a very nice

36
00:01:33.84 –> 00:01:40.350
fiber-optic laser marking machine why

37
00:01:37.92 –> 00:01:43.290
well we’re just about to start another

38
00:01:40.35 –> 00:01:47.550
learning journey into a different world

39
00:01:43.29 –> 00:01:51.409
of laces now the learning journey is

40
00:01:47.55 –> 00:01:53.340
mine maybe it’s yours as well but

41
00:01:51.409 –> 00:01:55.650
specifically I am the one that’s

42
00:01:53.34 –> 00:01:57.330
learning so always bear that in mind

43
00:01:55.65 –> 00:02:00.240
when you look at this when you watch

44
00:01:57.33 –> 00:02:02.220
these videos I can easily make mistakes

Transcript for Introduction to Fiber Laser Marking (Cont…)

45
00:02:00.24 –> 00:02:03.330
because there aren’t many people out

46
00:02:02.22 –> 00:02:05.400
there that can tell me a great deal

47
00:02:03.33 –> 00:02:07.740
about these machines they can tell me a

48
00:02:05.4 –> 00:02:09.420
lot about what they do and how they do

49
00:02:07.74 –> 00:02:12.989
it and the parameters that you need to

50
00:02:09.42 –> 00:02:14.610
set but that’s not what I’m after I want

51
00:02:12.989 –> 00:02:16.440
to dig into the dark corners and find

52
00:02:14.61 –> 00:02:18.630
out what this machine is really capable

53
00:02:16.44 –> 00:02:21.150
of let’s just give you a quick tour

54
00:02:18.63 –> 00:02:23.130
around the machine and then we’ll give

55
00:02:21.15 –> 00:02:24.510
you a quick demonstration first of all

56
00:02:23.13 –> 00:02:29.970
let’s take a look at the work area this

57
00:02:24.51 –> 00:02:32.610
is it no XY slides as you can see just a

58
00:02:29.97 –> 00:02:34.530
nice clean open work area with T slides

59
00:02:32.61 –> 00:02:37.110
in it so you can bolt down rotary unit

60
00:02:34.53 –> 00:02:40.200
if you want to this is a high-volume

61
00:02:37.11 –> 00:02:42.150
production marking machine now this is a

62
00:02:40.2 –> 00:02:45.450
product where the red anodized aluminium

63
00:02:42.15 –> 00:02:48.450
has been removed with a fiber laser you

64
00:02:45.45 –> 00:02:50.640
know every property three seconds go be

65
00:02:48.45 –> 00:02:54.450
another product offered in front of the

66
00:02:50.64 –> 00:02:56.850
laser this product is not flat the great

67
00:02:54.45 –> 00:03:00.630
advantage of this machine is it can mark

68
00:02:56.85 –> 00:03:04.620
non flat products because here’s the

69
00:03:00.63 –> 00:03:07.079
lens the lens is about 12 inches above

70
00:03:04.62 –> 00:03:09.989
the work surface and that means it’s an

71
00:03:07.079 –> 00:03:13.110
incredibly long focal length lens with

72
00:03:09.989 –> 00:03:15.150
quite a wide focal range on it so it can

73
00:03:13.11 –> 00:03:17.970
easily work over a curved surface like

74
00:03:15.15 –> 00:03:20.400
this now we can never get up inside the

75
00:03:17.97 –> 00:03:23.850
head to see what’s going on behind the

76
00:03:20.4 –> 00:03:27.720
lens so here’s the lens and that behind

77
00:03:23.85 –> 00:03:30.120
the lens we’ve got two mirrors one for x

78
00:03:27.72 –> 00:03:32.070
axis and one for y axis which is

79
00:03:30.12 –> 00:03:34.680
steering the beam that’s coming out of

80
00:03:32.07 –> 00:03:37.500
the laser machine now these are operated

81
00:03:34.68 –> 00:03:39.480
by two motors now these mirrors have got

82
00:03:37.5 –> 00:03:42.180
very very low mass and they can move

83
00:03:39.48 –> 00:03:44.070
incredibly quickly so the scanning speed

84
00:03:42.18 –> 00:03:45.750
of this machine I don’t know exactly

85
00:03:44.07 –> 00:03:48.069
what it is but I think it’s somewhere in

86
00:03:45.75 –> 00:03:51.219
the region about two meters a second

87
00:03:48.069 –> 00:03:54.060
which is incredibly fast but it’s all

88
00:03:51.219 –> 00:03:56.709
because of the low mass of these mirrors

89
00:03:54.06 –> 00:03:58.420
so that’s what’s hidden away up behind

90
00:03:56.709 –> 00:04:00.790
that lens there which I can’t get to

Transcript for Introduction to Fiber Laser Marking (Cont…)

91
00:03:58.42 –> 00:04:03.879
can’t just can’t do anything about it is

92
00:04:00.79 –> 00:04:06.579
what it is so the only thing that we can

93
00:04:03.879 –> 00:04:09.159
do to control this machine that’s assets

94
00:04:06.579 –> 00:04:11.379
and parameters that’s all I’ve got to

95
00:04:09.159 –> 00:04:12.939
play with now whether there are ways of

96
00:04:11.379 –> 00:04:15.189
defeating this software and going

97
00:04:12.939 –> 00:04:17.769
outside those limits I don’t know as yet

98
00:04:15.189 –> 00:04:19.599
I’ve got to investigate that but hey for

99
00:04:17.769 –> 00:04:22.800
the time being I think we’ll stay within

100
00:04:19.599 –> 00:04:26.229
the rules now at the back of the machine

101
00:04:22.8 –> 00:04:28.509
we’ve got a an extraction system and

102
00:04:26.229 –> 00:04:30.130
that’s what this cone is it’s an

103
00:04:28.509 –> 00:04:32.710
extraction system for pulling the fumes

104
00:04:30.13 –> 00:04:34.479
away from the engraving area now up in

105
00:04:32.71 –> 00:04:36.479
the machine there we’ve got a red box

106
00:04:34.479 –> 00:04:39.099
which is where all the clever

107
00:04:36.479 –> 00:04:41.830
fiber-optic work is being done or the

108
00:04:39.099 –> 00:04:44.889
electronic controls and here we’ve got

109
00:04:41.83 –> 00:04:47.349
the beam expanding system which takes

110
00:04:44.889 –> 00:04:50.280
the fiber-optic and opens the beam up

111
00:04:47.349 –> 00:04:52.509
ready to be processed by this lens here

112
00:04:50.28 –> 00:04:54.070
we’ve got a simple control panel at the

113
00:04:52.509 –> 00:04:57.340
front here with the emergency stop

114
00:04:54.07 –> 00:04:58.990
button and we’ve got a couple of key

115
00:04:57.34 –> 00:05:00.759
switches one which turns the machine on

116
00:04:58.99 –> 00:05:03.220
and off sorry this one turns the machine

117
00:05:00.759 –> 00:05:06.550
on and off and this one switches the

118
00:05:03.22 –> 00:05:08.259
interlocks on and off at the moment the

119
00:05:06.55 –> 00:05:10.419
interlock is on which means as soon as I

120
00:05:08.259 –> 00:05:13.030
press the start button this cover will

121
00:05:10.419 –> 00:05:16.570
come down and it will protect my eyes I

122
00:05:13.03 –> 00:05:19.449
can choose to operate it with the cover

123
00:05:16.57 –> 00:05:20.949
open like this which from time to time I

124
00:05:19.449 –> 00:05:22.780
should certainly be doing for you guys

125
00:05:20.949 –> 00:05:24.729
to show you what’s going on these were

126
00:05:22.78 –> 00:05:27.570
perfectly okay for protecting my eyes

127
00:05:24.729 –> 00:05:30.550
when I was working with the co2 laser

128
00:05:27.57 –> 00:05:33.099
but here we are on the fiber laser which

129
00:05:30.55 –> 00:05:34.930
is a different frequency of light I need

130
00:05:33.099 –> 00:05:38.229
to be a bit more careful with my eyes

131
00:05:34.93 –> 00:05:40.930
and when the guard is open I’m going to

132
00:05:38.229 –> 00:05:42.759
have to assume a Hollywood film star

133
00:05:40.93 –> 00:05:44.349
persona here we are on the co2 laser

134
00:05:42.759 –> 00:05:47.289
machine and we got to do a little teeny

135
00:05:44.349 –> 00:05:50.770
weeny bit of engraving and a speed and a

136
00:05:47.289 –> 00:05:54.389
power which is a close approximation to

137
00:05:50.77 –> 00:05:54.389
what we should be able to do on the

138
00:05:56.55 –> 00:06:03.870
now this is black anodized aluminium and

Transcript for Introduction to Fiber Laser Marking (Cont…)

139
00:06:01.11 –> 00:06:07.080
what we’re doing here we’re removing the

140
00:06:03.87 –> 00:06:09.930
black dye from the aluminium and leaving

141
00:06:07.08 –> 00:06:13.620
the aluminium oxide surface behind which

142
00:06:09.93 –> 00:06:16.349
is white okay now without changing

143
00:06:13.62 –> 00:06:19.379
anything I’m going to put a piece of

144
00:06:16.349 –> 00:06:29.970
glass over that then we’re going to

145
00:06:19.379 –> 00:06:31.979
repeat the same thing again so everybody

146
00:06:29.97 –> 00:06:33.870
with the co2 laser will recognize what

147
00:06:31.979 –> 00:06:37.560
I’ve done there I’ve been graved the

148
00:06:33.87 –> 00:06:39.659
surface of the glass and nothing no

149
00:06:37.56 –> 00:06:41.130
power at all has come through because

150
00:06:39.659 –> 00:06:44.880
the power has been a hundred percent

151
00:06:41.13 –> 00:06:47.370
absorbed by the glass okay so here we

152
00:06:44.88 –> 00:06:49.169
are on the fiber laser now I’m operating

153
00:06:47.37 –> 00:06:52.620
this machine at the moment with the

154
00:06:49.169 –> 00:06:59.310
guard open but I’ve got my film star

155
00:06:52.62 –> 00:07:01.229
goggles on and there’s a engraving that

156
00:06:59.31 –> 00:07:04.639
took place on the surface of the glass

157
00:07:01.229 –> 00:07:04.639
when we had it

158
00:07:04.719 –> 00:07:11.139
just there okay we’re now going to

159
00:07:08.439 –> 00:07:13.379
perform exactly the same trick on the

160
00:07:11.139 –> 00:07:13.379
favor

161
00:07:16.88 –> 00:07:21.330
so if I catch in the light right you can

162
00:07:19.38 –> 00:07:22.830
see that there is a mark on the back of

163
00:07:21.33 –> 00:07:25.800
the glass there it’s not on the front of

164
00:07:22.83 –> 00:07:27.810
the glass it’s a very very faint mark on

165
00:07:25.8 –> 00:07:30.630
the back of the glass there is a small

166
00:07:27.81 –> 00:07:31.860
amount of damage there to indicate it

167
00:07:30.63 –> 00:07:34.100
may well have done a little bit of

168
00:07:31.86 –> 00:07:36.540
engraving but it’s very very faint

169
00:07:34.1 –> 00:07:39.690
basically the glass has been completely

170
00:07:36.54 –> 00:07:42.960
transparent to infrared light at 1

171
00:07:39.69 –> 00:07:44.700
micron wavelength whereas at 10 point 6

172
00:07:42.96 –> 00:07:47.490
micron wavelengths the glass is

173
00:07:44.7 –> 00:07:49.800
completely opaque and the damage is

174
00:07:47.49 –> 00:07:51.870
taking place on the top surface here the

175
00:07:49.8 –> 00:07:53.970
energy is transferred right through the

176
00:07:51.87 –> 00:07:55.800
glass and it’s damaged the material

177
00:07:53.97 –> 00:07:57.420
underneath as though the glass wasn’t

178
00:07:55.8 –> 00:08:00.090
there look this was without the glass

Transcript for Introduction to Fiber Laser Marking (Cont…)

179
00:07:57.42 –> 00:08:03.510
and this was with the glass now after

180
00:08:00.09 –> 00:08:06.630
that little demonstration you may well

181
00:08:03.51 –> 00:08:08.820
now begin to understand that all lasers

182
00:08:06.63 –> 00:08:13.530
are not the same so I think we’ll start

183
00:08:08.82 –> 00:08:16.800
by explaining how a constant power co2

184
00:08:13.53 –> 00:08:20.490
laser works and then we’ll migrate from

185
00:08:16.8 –> 00:08:23.520
that into the fiber laser technology

186
00:08:20.49 –> 00:08:25.620
which is still a laser and the

187
00:08:23.52 –> 00:08:27.780
technology of lasing will still be the

188
00:08:25.62 –> 00:08:30.000
same and that’s what I think we must

189
00:08:27.78 –> 00:08:32.400
tackle before we even attempt to do

190
00:08:30.0 –> 00:08:35.039
anything with this machine I want to

191
00:08:32.4 –> 00:08:39.390
understand what it is that this machine

192
00:08:35.039 –> 00:08:42.450
is and can do I don’t even know what

193
00:08:39.39 –> 00:08:45.090
this machine is at the moment so how can

194
00:08:42.45 –> 00:08:48.060
I think about what it can do yet I could

195
00:08:45.09 –> 00:08:50.070
follow lots of YouTube clips and I could

196
00:08:48.06 –> 00:08:52.590
see lots of little parameter settings to

197
00:08:50.07 –> 00:08:54.150
make the machine do its tricks but

198
00:08:52.59 –> 00:08:57.090
that’s not what I’m about I want to

199
00:08:54.15 –> 00:08:59.910
understand why and how each one of those

200
00:08:57.09 –> 00:09:03.700
tricks can be done and how and why it

201
00:08:59.91 –> 00:09:05.890
takes place so

202
00:09:03.7 –> 00:09:07.540
this is not going to be an easy journey

203
00:09:05.89 –> 00:09:09.520
it’s going to be quite a technical

204
00:09:07.54 –> 00:09:11.380
journey but I am NOT a technical person

205
00:09:09.52 –> 00:09:13.420
I’m certainly not a physicist and I’m

206
00:09:11.38 –> 00:09:16.230
certainly not a chemist so anything that

207
00:09:13.42 –> 00:09:19.180
I described to you will be a very

208
00:09:16.23 –> 00:09:21.460
distilled and simplified version of the

209
00:09:19.18 –> 00:09:24.520
truth now before I get any further into

210
00:09:21.46 –> 00:09:28.360
this video I must just say a big thank

211
00:09:24.52 –> 00:09:30.640
you to the guys at Lotus laser systems

212
00:09:28.36 –> 00:09:33.970
they’ve taken the very brave step of

213
00:09:30.64 –> 00:09:36.700
entrusting this machine with me for one

214
00:09:33.97 –> 00:09:38.740
year they’ve lent it to me to play with

215
00:09:36.7 –> 00:09:42.310
as I’ve already started to tell you I

216
00:09:38.74 –> 00:09:46.180
know nothing about fiber laces so I’ve

217
00:09:42.31 –> 00:09:49.960
got this machine to just explore at my

218
00:09:46.18 –> 00:09:53.200
leisure now I have not in any way forced

219
00:09:49.96 –> 00:09:54.850
to make corporate videos Lotus laser

220
00:09:53.2 –> 00:09:58.320
system sounds like it should be a

221
00:09:54.85 –> 00:10:00.730
Chinese company these guys are only

Transcript for Introduction to Fiber Laser Marking (Cont…)

222
00:09:58.32 –> 00:10:03.820
probably about thirty miles up the road

223
00:10:00.73 –> 00:10:07.000
from me and they’re very easy to visit

224
00:10:03.82 –> 00:10:09.100
if I need to how much assistance have

225
00:10:07.0 –> 00:10:10.570
they given me with this machine the

226
00:10:09.1 –> 00:10:12.280
answer is very little at the moment

227
00:10:10.57 –> 00:10:13.900
they’ve installed it they’re showed me

228
00:10:12.28 –> 00:10:15.370
how to press all these buttons down at

229
00:10:13.9 –> 00:10:17.640
the bottom here they’re showing me

230
00:10:15.37 –> 00:10:20.890
roughly how the software works and

231
00:10:17.64 –> 00:10:23.110
they’ve given me a list of numbers and a

232
00:10:20.89 –> 00:10:25.720
little bit of paperwork that goes with

233
00:10:23.11 –> 00:10:28.300
the machine none of that paperwork tells

234
00:10:25.72 –> 00:10:30.550
me anything about how I make this

235
00:10:28.3 –> 00:10:33.880
machine perform the many tricks that it

236
00:10:30.55 –> 00:10:36.520
can perform but hey that’s going to be

237
00:10:33.88 –> 00:10:39.100
the fun of it ignorance is a great

238
00:10:36.52 –> 00:10:41.620
teacher too much knowledge gets in the

239
00:10:39.1 –> 00:10:43.390
way sometimes of digging into dark

240
00:10:41.62 –> 00:10:46.180
corners ignorance

241
00:10:43.39 –> 00:10:48.970
maybe allows me to dig into dark corners

242
00:10:46.18 –> 00:10:50.530
but I don’t even know a dark corners so

243
00:10:48.97 –> 00:10:53.260
we’ve got to build the foundations

244
00:10:50.53 –> 00:10:55.630
before we go anywhere near this machine

245
00:10:53.26 –> 00:10:58.900
now we’re going to start off with a very

246
00:10:55.63 –> 00:11:04.090
very simple atom got a small core or a

247
00:10:58.9 –> 00:11:06.520
nucleus and it’s got a charge a negative

248
00:11:04.09 –> 00:11:09.010
charge that Wizards around the outside

249
00:11:06.52 –> 00:11:10.780
of it in a little orbit just like a mini

250
00:11:09.01 –> 00:11:13.090
solar system the earth the moving

251
00:11:10.78 –> 00:11:15.720
running around the Earth now there are

252
00:11:13.09 –> 00:11:19.620
94 commonly found out

253
00:11:15.72 –> 00:11:22.439
months in this universe not just the

254
00:11:19.62 –> 00:11:26.759
world and each one of those elements has

255
00:11:22.439 –> 00:11:29.310
got a different mass in the centre and a

256
00:11:26.759 –> 00:11:31.709
different number of electrons floating

257
00:11:29.31 –> 00:11:35.189
in orbits around the outside of it now

258
00:11:31.709 –> 00:11:38.759
it’s very very usual for these atoms to

259
00:11:35.189 –> 00:11:41.519
not be on their own they like to exist

260
00:11:38.759 –> 00:11:43.560
with other atoms where they then become

261
00:11:41.519 –> 00:11:45.689
something called a molecule now

262
00:11:43.56 –> 00:11:48.060
molecules can either be two three four

263
00:11:45.689 –> 00:11:50.790
twenty atoms it depends on the

264
00:11:48.06 –> 00:11:53.069
complexity of what it is that you are

265
00:11:50.79 –> 00:11:56.279
looking at by whatever a material or a

266
00:11:53.069 –> 00:11:57.899
substance let’s forget about the larger

267
00:11:56.279 –> 00:12:00.029
picture and just come back to this very

Transcript for Introduction to Fiber Laser Marking (Cont…)

268
00:11:57.899 –> 00:12:04.199
simple atom because this is all we need

269
00:12:00.029 –> 00:12:08.670
to understand lasing when this charge

270
00:12:04.199 –> 00:12:12.120
this electron gets a little bump of

271
00:12:08.67 –> 00:12:16.370
energy from somewhere it can move from

272
00:12:12.12 –> 00:12:19.589
this orbit to the next orbit out and

273
00:12:16.37 –> 00:12:21.329
here it is it’s now happily whizzing

274
00:12:19.589 –> 00:12:24.809
around in this orbit here but it’s not

275
00:12:21.329 –> 00:12:28.889
happy to stay in that orbit its natural

276
00:12:24.809 –> 00:12:30.569
orbit as this one so within a short

277
00:12:28.889 –> 00:12:33.509
period of time that could be anything

278
00:12:30.569 –> 00:12:37.230
from a millionth to a thousandth of a

279
00:12:33.509 –> 00:12:40.050
second it will drop back to this lower

280
00:12:37.23 –> 00:12:42.870
orbit now when it drops back it loses

281
00:12:40.05 –> 00:12:44.759
the energy that it gained when it went

282
00:12:42.87 –> 00:12:46.649
out to that orbit and it loses their

283
00:12:44.759 –> 00:12:49.079
energy in the form of a strange little

284
00:12:46.649 –> 00:12:52.470
thing called a and I’m going to draw it

285
00:12:49.079 –> 00:12:55.709
like this a photon of light we’re going

286
00:12:52.47 –> 00:13:00.660
to start looking at lasing in this form

287
00:12:55.709 –> 00:13:04.050
here which is the co2 gas tube laser the

288
00:13:00.66 –> 00:13:07.829
outer tube contains a gas mixture and

289
00:13:04.05 –> 00:13:09.990
that gas mixture also can run right

290
00:13:07.829 –> 00:13:11.759
through to the middle of the tube as

291
00:13:09.99 –> 00:13:13.500
well there are three tubes in there the

292
00:13:11.759 –> 00:13:16.980
outer one and the inner one are joined

293
00:13:13.5 –> 00:13:19.740
together right but around the outside of

294
00:13:16.98 –> 00:13:23.009
the inner tube we’ve got another tube

295
00:13:19.74 –> 00:13:25.920
which is full of water and that water is

296
00:13:23.009 –> 00:13:27.780
used to carry the heat away from the

297
00:13:25.92 –> 00:13:30.600
central tube

298
00:13:27.78 –> 00:13:32.850
now within this outer tube and obviously

299
00:13:30.6 –> 00:13:34.310
the inner tube as well we’ve got a mix

300
00:13:32.85 –> 00:13:37.260
of gases

301
00:13:34.31 –> 00:13:41.150
now all gases are basically non

302
00:13:37.26 –> 00:13:43.410
conductors of electricity now if we put

303
00:13:41.15 –> 00:13:47.580
25,000 volts across the end of this

304
00:13:43.41 –> 00:13:50.700
central tube the gas mix inside which

305
00:13:47.58 –> 00:13:53.010
contains nitrogen the nitrogen element

306
00:13:50.7 –> 00:14:00.030
of that gas mix will start to break down

Transcript for Introduction to Fiber Laser Marking (Cont…)

307
00:13:53.01 –> 00:14:03.900
and release free electrons now these

308
00:14:00.03 –> 00:14:05.760
things here are electrons and what

309
00:14:03.9 –> 00:14:08.570
they’re basically doing is bursting free

310
00:14:05.76 –> 00:14:12.660
from their orbits and floating around

311
00:14:08.57 –> 00:14:15.330
and those free electrons are what are

312
00:14:12.66 –> 00:14:17.430
used to carry current through the tube

313
00:14:15.33 –> 00:14:19.650
electrical current through the tube so

314
00:14:17.43 –> 00:14:24.540
all of a sudden this nitrogen becomes a

315
00:14:19.65 –> 00:14:28.020
piece of almost resistance free wire it

316
00:14:24.54 –> 00:14:30.780
becomes conductive now we’re going to go

317
00:14:28.02 –> 00:14:32.520
to a real world tube now and I’m going

318
00:14:30.78 –> 00:14:35.280
to show you what happens when we put

319
00:14:32.52 –> 00:14:37.620
25,000 volts across the end the answer

320
00:14:35.28 –> 00:14:39.420
is nothing that you can see but then

321
00:14:37.62 –> 00:14:42.570
when we allow some current to flow

322
00:14:39.42 –> 00:14:46.589
through the nitrogen you’ll see that the

323
00:14:42.57 –> 00:14:49.650
colour or intensity of the glow in the

324
00:14:46.589 –> 00:14:51.900
tube is proportional to the amount of

325
00:14:49.65 –> 00:14:54.210
current that flows through the tube when

326
00:14:51.9 –> 00:14:58.980
you hear the little thing I’ve turned

327
00:14:54.21 –> 00:15:00.960
the 25,000 volts on now there was

328
00:14:58.98 –> 00:15:03.170
nothing happening when I turned to

329
00:15:00.96 –> 00:15:04.910
25,000 volts on

330
00:15:03.17 –> 00:15:06.859
okay so they’re now going to allow a

331
00:15:04.91 –> 00:15:10.579
very small amount of current to pass

332
00:15:06.859 –> 00:15:16.519
through the tube as well as the high

333
00:15:10.579 –> 00:15:18.290
voltage you can just about see a little

334
00:15:16.519 –> 00:15:21.769
bit of a pink glow at the end of the

335
00:15:18.29 –> 00:15:25.540
tube there I’m now going to allow more

336
00:15:21.769 –> 00:15:25.540
current to flow through the tube

337
00:15:26.62 –> 00:15:31.640
[Music]

338
00:15:29.42 –> 00:15:34.550
I’m now going to put the maximum

339
00:15:31.64 –> 00:15:39.900
allowable current through the tube

340
00:15:34.55 –> 00:15:42.390
[Music]

341
00:15:39.9 –> 00:15:46.200
I think you can see clearly the

342
00:15:42.39 –> 00:15:48.779
different intensity of light coming from

343
00:15:46.2 –> 00:15:50.160
the tube if I allow more than a certain

344
00:15:48.779 –> 00:15:51.870
amount of current to pass through the

345
00:15:50.16 –> 00:15:54.450
tube some very strange things happen

346
00:15:51.87 –> 00:15:56.940
okay so now you’ve seen this lovely pink

347
00:15:54.45 –> 00:15:59.220
glow that happens down the inside of the

Transcript for Introduction to Fiber Laser Marking (Cont…)

348
00:15:56.94 –> 00:16:01.279
tube basically this is lightning in a

349
00:15:59.22 –> 00:16:05.640
bottle the more current I put through it

350
00:16:01.279 –> 00:16:10.260
the more heat is being generated within

351
00:16:05.64 –> 00:16:14.089
the nitrogen itself and this element

352
00:16:10.26 –> 00:16:18.060
here the helium 80 percent of it is

353
00:16:14.089 –> 00:16:21.150
actually being used only as a means of

354
00:16:18.06 –> 00:16:23.339
transporting that heat out to the water

355
00:16:21.15 –> 00:16:25.070
jacket here where the heat is carried

356
00:16:23.339 –> 00:16:28.200
away and the whole system remains

357
00:16:25.07 –> 00:16:31.950
thermally stable now mixed in to this

358
00:16:28.2 –> 00:16:34.710
gas not only we got helium we’ve also

359
00:16:31.95 –> 00:16:37.440
got carbon dioxide a carbon dioxide

360
00:16:34.71 –> 00:16:41.790
molecule because it’s made up of carbon

361
00:16:37.44 –> 00:16:43.230
and two oxygen atoms bonded together so

362
00:16:41.79 –> 00:16:46.230
we’re now going to change away from our

363
00:16:43.23 –> 00:16:48.630
little orbital picture to just looking

364
00:16:46.23 –> 00:16:50.580
at the orbits themselves and what

365
00:16:48.63 –> 00:16:53.339
happens to these electrons it’s a much

366
00:16:50.58 –> 00:16:55.800
easier picture to understand here we’ve

367
00:16:53.339 –> 00:16:58.260
got the ground state where the electron

368
00:16:55.8 –> 00:17:00.600
starts then it goes up to its excited

369
00:16:58.26 –> 00:17:02.550
state which is the next orbit out then

370
00:17:00.6 –> 00:17:04.620
for a short period of time it may will

371
00:17:02.55 –> 00:17:06.270
drop down to this something called a

372
00:17:04.62 –> 00:17:07.920
metastable state which is an

373
00:17:06.27 –> 00:17:11.420
intermediate state and then it drops

374
00:17:07.92 –> 00:17:15.449
down all of the way and as it drops down

375
00:17:11.42 –> 00:17:16.650
it gives out this photon of light now

376
00:17:15.449 –> 00:17:19.890
I’m going to use this picture for two

377
00:17:16.65 –> 00:17:22.140
situations the first situation is where

378
00:17:19.89 –> 00:17:24.959
we put twenty-five thousand volts across

379
00:17:22.14 –> 00:17:27.199
the nitrogen column and what then

380
00:17:24.959 –> 00:17:29.309
happens is we shall knock some of these

381
00:17:27.199 –> 00:17:32.760
electrons out of their ground state

382
00:17:29.309 –> 00:17:34.890
completely into a free orbit so they’re

383
00:17:32.76 –> 00:17:36.570
floating around not all of them but just

384
00:17:34.89 –> 00:17:38.160
some of them and they’re there the

385
00:17:36.57 –> 00:17:40.410
electrons that will be carrying their

386
00:17:38.16 –> 00:17:42.330
current now as soon as we ask for

387
00:17:40.41 –> 00:17:45.000
current to flow those electrons they

388
00:17:42.33 –> 00:17:48.090
will rush towards the positive end which

389
00:17:45.0 –> 00:17:50.910
is the 25,000 volt end of the tube and

390
00:17:48.09 –> 00:17:52.950
as they rush along the tube so they will

391
00:17:50.91 –> 00:17:56.130
collide with other

392
00:17:52.95 –> 00:18:00.570
nitrogen electrons as they collide they

Transcript for Introduction to Fiber Laser Marking (Cont…)

393
00:17:56.13 –> 00:18:03.180
will promote those electrons up to an

394
00:18:00.57 –> 00:18:05.370
excited state now the action of

395
00:18:03.18 –> 00:18:08.220
promoting electrons up to an excited

396
00:18:05.37 –> 00:18:10.230
state is called pumping once they’ve

397
00:18:08.22 –> 00:18:12.330
been pumped up to their excited state

398
00:18:10.23 –> 00:18:14.070
they will stay there for a very short

399
00:18:12.33 –> 00:18:16.350
period of time now when they drop back

400
00:18:14.07 –> 00:18:18.180
to their ground state they will give up

401
00:18:16.35 –> 00:18:20.430
the energy that they acquired here in

402
00:18:18.18 –> 00:18:23.310
the form of a photon of light now the

403
00:18:20.43 –> 00:18:26.580
photon of light that they give up is

404
00:18:23.31 –> 00:18:29.460
pink that’s the action of the voltage

405
00:18:26.58 –> 00:18:34.020
and the current flowing through it which

406
00:18:29.46 –> 00:18:36.720
is pumping the nitrogen atoms up to a

407
00:18:34.02 –> 00:18:38.880
higher state and we’ve seen that pink go

408
00:18:36.72 –> 00:18:42.090
in action now in the tube it’s the

409
00:18:38.88 –> 00:18:43.710
collapse of excited nitrogen atoms going

410
00:18:42.09 –> 00:18:46.500
back to their ground state but the

411
00:18:43.71 –> 00:18:48.570
important thing here is this that we’ll

412
00:18:46.5 –> 00:18:53.190
think here which is the photon of light

413
00:18:48.57 –> 00:18:56.610
when they just drop back like this it’s

414
00:18:53.19 –> 00:18:58.860
a random action and that’s how you can

415
00:18:56.61 –> 00:19:00.330
see them because the pink is flying out

416
00:18:58.86 –> 00:19:02.010
the photons are flying out in all

417
00:19:00.33 –> 00:19:03.930
directions and some of them are

418
00:19:02.01 –> 00:19:07.110
finishing up at the back of your eye and

419
00:19:03.93 –> 00:19:11.010
you’re perceiving the pinkness of the

420
00:19:07.11 –> 00:19:14.040
photon it is the photon here this action

421
00:19:11.01 –> 00:19:17.550
of that photon which is going to then

422
00:19:14.04 –> 00:19:19.470
add energy to the carbon dioxide

423
00:19:17.55 –> 00:19:21.360
molecule and now we look at the same

424
00:19:19.47 –> 00:19:25.110
picture again so one of the electrons

425
00:19:21.36 –> 00:19:27.450
within the co2 molecule receives a

426
00:19:25.11 –> 00:19:31.320
little bit of pink energy from the

427
00:19:27.45 –> 00:19:33.690
nitrogen and that knocks the electron up

428
00:19:31.32 –> 00:19:35.790
to its excited state the next orbit

429
00:19:33.69 –> 00:19:38.430
where it stays for a short period of

430
00:19:35.79 –> 00:19:40.560
time drops down to its metastable state

431
00:19:38.43 –> 00:19:44.040
and then will just fall back to ground

432
00:19:40.56 –> 00:19:48.530
emitting an invisible ten point six

433
00:19:44.04 –> 00:19:50.900
micron wavelength of infrared light

434
00:19:48.53 –> 00:19:54.480
something that you can’t see but again

435
00:19:50.9 –> 00:19:57.090
look it will be totally random because

436
00:19:54.48 –> 00:19:59.520
there is nothing to say that it must go

Transcript for Introduction to Fiber Laser Marking (Cont…)

437
00:19:57.09 –> 00:20:01.410
in a particular direction you won’t be

438
00:19:59.52 –> 00:20:03.360
able to see it this time because it’s

439
00:20:01.41 –> 00:20:06.130
invisible but it’s still coming out of

440
00:20:03.36 –> 00:20:08.500
this tube it’s very very low

441
00:20:06.13 –> 00:20:13.710
random density so it’s not going to harm

442
00:20:08.5 –> 00:20:17.590
you now the word laser is acronym of

443
00:20:13.71 –> 00:20:20.320
light amplification by stimulated

444
00:20:17.59 –> 00:20:22.930
emission of radiation the important word

445
00:20:20.32 –> 00:20:26.680
here is stimulated what we’ve seen so

446
00:20:22.93 –> 00:20:28.630
far in both of these actions both the

447
00:20:26.68 –> 00:20:31.270
nitrogen and the carbon dioxide that

448
00:20:28.63 –> 00:20:36.130
we’ve mentioned so far has been random

449
00:20:31.27 –> 00:20:38.560
emission we get this light as the

450
00:20:36.13 –> 00:20:40.990
electron drops down from a high state to

451
00:20:38.56 –> 00:20:45.040
a ground state and we get this emission

452
00:20:40.99 –> 00:20:47.530
of radiation light and that’s what this

453
00:20:45.04 –> 00:20:51.100
is this is emission but it’s not

454
00:20:47.53 –> 00:20:54.010
stimulated it’s random so how do we get

455
00:20:51.1 –> 00:20:55.960
from random emission to stimulated

456
00:20:54.01 –> 00:20:58.810
emission but well here I’ve got a

457
00:20:55.96 –> 00:21:01.480
picture of a very simplified gas tube

458
00:20:58.81 –> 00:21:04.510
we’ve ignored the water and all we’ve

459
00:21:01.48 –> 00:21:07.960
done we’ve got the electrodes here and

460
00:21:04.51 –> 00:21:10.030
we’ve got our column of ionized gas down

461
00:21:07.96 –> 00:21:12.460
the center and we’ve got all the other

462
00:21:10.03 –> 00:21:15.280
gas around the outside but at the end of

463
00:21:12.46 –> 00:21:19.600
the tube we’ve got the mirror and a

464
00:21:15.28 –> 00:21:21.610
mirror now there’s just not one of these

465
00:21:19.6 –> 00:21:24.010
actions taking place we’ve got millions

466
00:21:21.61 –> 00:21:26.950
of this actions taking place at any

467
00:21:24.01 –> 00:21:30.820
given point in time and so just by

468
00:21:26.95 –> 00:21:34.690
chance one of these photons will finish

469
00:21:30.82 –> 00:21:36.760
up traveling in this direction rather

470
00:21:34.69 –> 00:21:40.690
than any of the other directions that

471
00:21:36.76 –> 00:21:43.450
I’ve mentioned there now if that photon

472
00:21:40.69 –> 00:21:46.120
travels in this direction it’s going to

473
00:21:43.45 –> 00:21:47.860
hit this mirror and as it hits this

474
00:21:46.12 –> 00:21:52.380
mirror it’s going to bounce back and

475
00:21:47.86 –> 00:21:54.310
pass through the tube to the other end

476
00:21:52.38 –> 00:21:57.280
where it’s going to bounce off that

477
00:21:54.31 –> 00:21:59.830
mirror and come back so let’s change

Transcript for Introduction to Fiber Laser Marking (Cont…)

478
00:21:57.28 –> 00:22:02.700
pictures again so here we’ve got our

479
00:21:59.83 –> 00:22:06.250
pink photon pumping the carbon dioxide

480
00:22:02.7 –> 00:22:08.080
electron up to its excited level it then

481
00:22:06.25 –> 00:22:09.640
drops down to its lowest state and then

482
00:22:08.08 –> 00:22:12.430
one of these random photon emissions

483
00:22:09.64 –> 00:22:15.250
hacks happens to accidentally bump into

484
00:22:12.43 –> 00:22:18.130
the mirror at an absolutely

485
00:22:15.25 –> 00:22:19.690
perpendicular plane and as it does so it

486
00:22:18.13 –> 00:22:24.130
will drive back down

487
00:22:19.69 –> 00:22:28.660
this way now as it passes one of these

488
00:22:24.13 –> 00:22:32.050
excited electrons it’s a bit like the

489
00:22:28.66 –> 00:22:34.060
Pied Piper saying come and join me it’s

490
00:22:32.05 –> 00:22:37.510
a very strange phenomenon that happens

491
00:22:34.06 –> 00:22:40.930
when any when a photon travelling in

492
00:22:37.51 –> 00:22:43.510
this direction can attract this to go

493
00:22:40.93 –> 00:22:46.680
down to its low level and emit a photon

494
00:22:43.51 –> 00:22:50.080
on the way that perfectly matches the

495
00:22:46.68 –> 00:22:52.150
one that’s travelling by it so as a

496
00:22:50.08 –> 00:22:54.280
consequence what you will get you’ll get

497
00:22:52.15 –> 00:22:57.160
these photons being collected and

498
00:22:54.28 –> 00:22:59.020
they’re completely synchronized as shown

499
00:22:57.16 –> 00:23:01.930
by this picture and they will be

500
00:22:59.02 –> 00:23:04.750
traveling in this direction until I hit

501
00:23:01.93 –> 00:23:06.850
the mirror at this end and then they

502
00:23:04.75 –> 00:23:08.320
will all come back now as they’re

503
00:23:06.85 –> 00:23:12.030
traveling this way they will be

504
00:23:08.32 –> 00:23:16.420
collecting more photons and causing

505
00:23:12.03 –> 00:23:18.490
stimulated emissions from the electrons

506
00:23:16.42 –> 00:23:21.520
that they are causing to drop down to

507
00:23:18.49 –> 00:23:25.900
their ground state and this action here

508
00:23:21.52 –> 00:23:29.020
of photons passing by excited electrons

509
00:23:25.9 –> 00:23:32.020
is the stimulated emission effect that

510
00:23:29.02 –> 00:23:35.620
you want that produces a laser now this

511
00:23:32.02 –> 00:23:38.140
is a laser beam everything is fully in

512
00:23:35.62 –> 00:23:41.950
phase it’s what they call a coherent

513
00:23:38.14 –> 00:23:44.380
beam and I suppose the best equivalent I

514
00:23:41.95 –> 00:23:47.170
can give to you of what this is the

515
00:23:44.38 –> 00:23:49.810
power that this has is you’re quite

516
00:23:47.17 –> 00:23:52.390
happy to stand out in the rain and have

517
00:23:49.81 –> 00:23:54.790
raindrops hit you but would you be happy

518
00:23:52.39 –> 00:23:57.460
to stand in front of a tsunami wave it’s

519
00:23:54.79 –> 00:24:00.010
the same stuff it’s water but it’s all

Transcript for Introduction to Fiber Laser Marking (Cont…)

520
00:23:57.46 –> 00:24:02.110
acting in harmony you can imagine the

521
00:24:00.01 –> 00:24:04.120
difference between rain and a tsunami

522
00:24:02.11 –> 00:24:06.240
wave now that’s not necessarily a

523
00:24:04.12 –> 00:24:08.980
perfect analogy but it gives the idea

524
00:24:06.24 –> 00:24:11.590
you know once you get things working in

525
00:24:08.98 –> 00:24:13.930
harmony they gain strength so we get

526
00:24:11.59 –> 00:24:16.450
this group of let’s call them soldiers

527
00:24:13.93 –> 00:24:18.730
all marching together down to this end

528
00:24:16.45 –> 00:24:20.050
they bounce off that mirror and of

529
00:24:18.73 –> 00:24:22.470
course by the time they bounce off that

530
00:24:20.05 –> 00:24:26.140
mirror not only have they collected more

531
00:24:22.47 –> 00:24:28.300
troops as they go down the road they hit

532
00:24:26.14 –> 00:24:30.730
the mirror and they come back now by the

533
00:24:28.3 –> 00:24:31.779
time they come back we’ve got more pink

534
00:24:30.73 –> 00:24:35.109
electrons

535
00:24:31.779 –> 00:24:37.869
promoted more carbon dioxide atoms up to

536
00:24:35.109 –> 00:24:40.239
their excited state and so as the army

537
00:24:37.869 –> 00:24:43.479
comes back it grows because it collects

538
00:24:40.239 –> 00:24:45.369
more soldiers all marching together and

539
00:24:43.479 –> 00:24:48.119
then it goes that wasn’t for words like

540
00:24:45.369 –> 00:24:51.729
this and this is the amplification of

541
00:24:48.119 –> 00:24:53.739
the light of the mirrors yes it’s no

542
00:24:51.729 –> 00:24:56.229
longer a random emission it’s a

543
00:24:53.739 –> 00:24:59.440
stimulated emission by virtue of other

544
00:24:56.229 –> 00:25:02.070
photons collecting photons so this is

545
00:24:59.44 –> 00:25:04.359
the strange action of how a laser works

546
00:25:02.07 –> 00:25:07.029
so back to our little picture here now

547
00:25:04.359 –> 00:25:09.669
and we can see this backwards and

548
00:25:07.029 –> 00:25:12.399
forwards motion up and down the tube the

549
00:25:09.669 –> 00:25:14.710
pink photons are contained within the

550
00:25:12.399 –> 00:25:16.119
tube but of course coming out the end of

551
00:25:14.71 –> 00:25:18.279
the tube here we’ve got invisible

552
00:25:16.119 –> 00:25:20.769
photons at ten point six microns

553
00:25:18.279 –> 00:25:22.749
infrared wavelength which are bouncing

554
00:25:20.769 –> 00:25:25.599
up and down inside the tube there the

555
00:25:22.749 –> 00:25:27.279
laser is the invisible army that’s

556
00:25:25.599 –> 00:25:29.649
marching up and down backwards and

557
00:25:27.279 –> 00:25:32.080
forwards here and when it gets to this

558
00:25:29.649 –> 00:25:34.359
end we don’t have a hundred percent

559
00:25:32.08 –> 00:25:36.879
mirror what we’ve got is a 90 percent

560
00:25:34.359 –> 00:25:38.469
mirror I say 90 percent because that’s

561
00:25:36.879 –> 00:25:40.809
just my guess I don’t know what the

562
00:25:38.469 –> 00:25:44.320
exact number is but the net result is

563
00:25:40.809 –> 00:25:48.249
that for example we get a 10% of the

564
00:25:44.32 –> 00:25:51.399
army escaping this is our laser beam

565
00:25:48.249 –> 00:25:53.399
that we are going to use okay now the

566
00:25:51.399 –> 00:25:57.549
rest of it is being sent back to

567
00:25:53.399 –> 00:26:02.080
regenerate more laser beam for us to use

Transcript for Introduction to Fiber Laser Marking (Cont…)

568
00:25:57.549 –> 00:26:05.080
and so this becomes a stable generation

569
00:26:02.08 –> 00:26:07.570
of a constant output laser beam within

570
00:26:05.08 –> 00:26:10.210
the hv power supply not only is it

571
00:26:07.57 –> 00:26:12.759
generating this 25,000 volts across the

572
00:26:10.21 –> 00:26:15.309
end here it’s also got a current

573
00:26:12.759 –> 00:26:17.409
limiting system in there and so when you

574
00:26:15.309 –> 00:26:19.570
specify that you want a certain power

575
00:26:17.409 –> 00:26:21.249
what you’re really specifying is you

576
00:26:19.57 –> 00:26:25.719
want to allow a certain amount of

577
00:26:21.249 –> 00:26:27.700
current to flow through the tube okay

578
00:26:25.719 –> 00:26:30.369
now as I’ve already described to you the

579
00:26:27.7 –> 00:26:32.710
current flowing through the tube is in

580
00:26:30.369 –> 00:26:33.969
fact causing a heating effect now I’m

581
00:26:32.71 –> 00:26:36.339
going to stop at this point in time

582
00:26:33.969 –> 00:26:39.700
because there is a very very important

583
00:26:36.339 –> 00:26:41.710
physics principle that I must explain to

584
00:26:39.7 –> 00:26:45.060
you now you all know what temperature is

585
00:26:41.71 –> 00:26:48.400
but how do you define temperature

586
00:26:45.06 –> 00:26:50.650
it’s hot it’s cold you measure it with a

587
00:26:48.4 –> 00:26:52.900
thermometer but there isn’t a definition

588
00:26:50.65 –> 00:26:57.820
of temperature let me try and explain in

589
00:26:52.9 –> 00:27:00.550
a very simple way there we go believe me

590
00:26:57.82 –> 00:27:04.510
that everything that you see every

591
00:27:00.55 –> 00:27:07.930
molecule every atom is busy doing this

592
00:27:04.51 –> 00:27:10.870
at room temperature it’s shaking it’s

593
00:27:07.93 –> 00:27:15.370
vibrating now as you lower the

594
00:27:10.87 –> 00:27:19.710
temperature to minus 273 degrees C what

595
00:27:15.37 –> 00:27:24.070
happens is all molecular motion ceases

596
00:27:19.71 –> 00:27:26.310
so therefore by default if we raise the

597
00:27:24.07 –> 00:27:28.660
temperature back up to room temperature

598
00:27:26.31 –> 00:27:32.680
everything all the molecules all the

599
00:27:28.66 –> 00:27:36.040
atoms start vibrating so the level of

600
00:27:32.68 –> 00:27:38.920
vibration in a molecule or atom is a

601
00:27:36.04 –> 00:27:42.010
definition of its temperature this power

602
00:27:38.92 –> 00:27:45.880
supply has got the ability to control

603
00:27:42.01 –> 00:27:48.700
the current through this tube but the

604
00:27:45.88 –> 00:27:51.880
power supply can actually supply a lot

605
00:27:48.7 –> 00:27:56.080
more current than the tube is allowed to

606
00:27:51.88 –> 00:27:59.530
carry now this is a strange property of

Transcript for Introduction to Fiber Laser Marking (Cont…)

607
00:27:56.08 –> 00:28:02.440
gas tubes which will not exist within

608
00:27:59.53 –> 00:28:04.300
the fiber laser but I need to explain it

609
00:28:02.44 –> 00:28:07.360
just briefly so that you understand the

610
00:28:04.3 –> 00:28:09.220
problem if we allow too much current to

611
00:28:07.36 –> 00:28:12.970
flow through the nitrogen the nitrogen

612
00:28:09.22 –> 00:28:17.500
becomes super excited because it becomes

613
00:28:12.97 –> 00:28:21.430
hotter remember hotter motion more

614
00:28:17.5 –> 00:28:24.910
motion hotter the energy of collision

615
00:28:21.43 –> 00:28:27.670
can actually break an oxygen away from

616
00:28:24.91 –> 00:28:30.580
the carbon dioxide molecule and turn it

617
00:28:27.67 –> 00:28:33.580
into carbon monoxide than oxygen this is

618
00:28:30.58 –> 00:28:37.210
a process called dissociation and this

619
00:28:33.58 –> 00:28:40.450
is what happens when you overdrive a gas

620
00:28:37.21 –> 00:28:41.710
tube you actually destroy the one thing

621
00:28:40.45 –> 00:28:44.590
that’s in there that gives you the

622
00:28:41.71 –> 00:28:48.160
lasing action which is carbon dioxide so

623
00:28:44.59 –> 00:28:51.970
you must never overdrive your carbon

624
00:28:48.16 –> 00:28:55.150
dioxide gas laser tube now this oxygen

625
00:28:51.97 –> 00:28:57.510
was floating around free in here it will

626
00:28:55.15 –> 00:28:59.790
possibly finish up floating around and

627
00:28:57.51 –> 00:29:03.240
and color and clogging up the cathode

628
00:28:59.79 –> 00:29:04.830
making it less efficient there are other

629
00:29:03.24 –> 00:29:07.290
mechanisms going on in there which I’m

630
00:29:04.83 –> 00:29:09.930
not going to explain but the net result

631
00:29:07.29 –> 00:29:11.840
is that you must be very careful when

632
00:29:09.93 –> 00:29:18.030
you’ve got a gas tube that you do not

633
00:29:11.84 –> 00:29:20.340
overdrive it now a typical gas 260 50

634
00:29:18.03 –> 00:29:24.510
Watts will be about a thousand

635
00:29:20.34 –> 00:29:26.910
millimeters long from end to end now the

636
00:29:24.51 –> 00:29:27.810
speed of light is such and we’ll talk

637
00:29:26.91 –> 00:29:31.290
about this later

638
00:29:27.81 –> 00:29:33.930
that it takes about three billions of a

639
00:29:31.29 –> 00:29:36.360
second for this action to take place

640
00:29:33.93 –> 00:29:38.190
backwards and forwards so three

641
00:29:36.36 –> 00:29:40.320
billionth of a second that way and three

642
00:29:38.19 –> 00:29:43.440
billionths of a second that way is all

643
00:29:40.32 –> 00:29:45.930
it takes for these photons to go so it’s

644
00:29:43.44 –> 00:29:47.400
virtually instantaneous okay so now

645
00:29:45.93 –> 00:29:50.040
you’re armed with all the information

646
00:29:47.4 –> 00:29:51.840
you need to understand how lacing works

647
00:29:50.04 –> 00:29:54.840
very quick summary

648
00:29:51.84 –> 00:29:57.210
you need a photon to bump into an

649
00:29:54.84 –> 00:29:58.710
electron which will promote the electron

650
00:29:57.21 –> 00:30:00.810
up to a higher energy level

Transcript for Introduction to Fiber Laser Marking (Cont…)

651
00:29:58.71 –> 00:30:02.400
something called the excited state where

652
00:30:00.81 –> 00:30:06.960
it could stay for a short period of time

653
00:30:02.4 –> 00:30:10.230
until a photon drifts by and encourages

654
00:30:06.96 –> 00:30:12.210
this excited state to drop down back to

655
00:30:10.23 –> 00:30:14.580
its ground state and as it drops back to

656
00:30:12.21 –> 00:30:17.400
its ground state it emits a photon of

657
00:30:14.58 –> 00:30:20.310
energy which matches the photon that

658
00:30:17.4 –> 00:30:23.970
encouraged the drop and then we need

659
00:30:20.31 –> 00:30:27.390
mirrors to encourage amplification those

660
00:30:23.97 –> 00:30:29.400
are the basics of a laser we’re now

661
00:30:27.39 –> 00:30:32.520
going to enter the amazing world of the

662
00:30:29.4 –> 00:30:36.210
fiber laser now as I said to you before

663
00:30:32.52 –> 00:30:37.770
a laser is a laser but there’s going to

664
00:30:36.21 –> 00:30:40.440
be a few differences here that we need

665
00:30:37.77 –> 00:30:41.970
to deal with it’s quite important that

666
00:30:40.44 –> 00:30:46.080
we understand a couple of things first

667
00:30:41.97 –> 00:30:48.990
of all the speed of light 186,000 miles

668
00:30:46.08 –> 00:30:50.850
per second in a vacuum let’s not get too

669
00:30:48.99 –> 00:30:53.820
picky about the vacuum surely let’s just

670
00:30:50.85 –> 00:30:57.510
assume that it’s also the same as 300

671
00:30:53.82 –> 00:30:59.640
million meters per second now this might

672
00:30:57.51 –> 00:31:01.620
seem a huge number but in fact it’s

673
00:30:59.64 –> 00:31:03.810
probably an easier number to work with

674
00:31:01.62 –> 00:31:05.850
let’s just move on to time everybody

675
00:31:03.81 –> 00:31:09.390
knows what one second is you can imagine

676
00:31:05.85 –> 00:31:10.840
that can you imagine what a millisecond

677
00:31:09.39 –> 00:31:13.740
is 1,000

678
00:31:10.84 –> 00:31:15.970
of a second how about when we go to a

679
00:31:13.74 –> 00:31:19.120
microsecond which is a millionth of a

680
00:31:15.97 –> 00:31:20.830
second I’m sure nobody can actually

681
00:31:19.12 –> 00:31:23.259
imagine what a millionth of a second

682
00:31:20.83 –> 00:31:25.929
feels like looks like or sounds like so

683
00:31:23.259 –> 00:31:28.779
we’re then go and times smaller than a

684
00:31:25.929 –> 00:31:32.070
microsecond and it’s called a nanosecond

685
00:31:28.779 –> 00:31:35.169
let’s relate the speed of light

686
00:31:32.07 –> 00:31:37.419
to time if we do some very simple maths

687
00:31:35.169 –> 00:31:41.139
like just just get rid of these notes

688
00:31:37.419 –> 00:31:42.789
here and we’ll get rid of those two

689
00:31:41.139 –> 00:31:46.119
notes there and two notes there

690
00:31:42.789 –> 00:31:50.350
what we find is that in one nanosecond

691
00:31:46.119 –> 00:31:51.850
we travel 0.3 of a meter so everybody

692
00:31:50.35 –> 00:31:55.570
can imagine what point three of a meter

693
00:31:51.85 –> 00:31:59.940
is it’s about a foot and that’s how far

Transcript for Introduction to Fiber Laser Marking (Cont…)

694
00:31:55.57 –> 00:32:03.340
light travels in a billionth of a second

695
00:31:59.94 –> 00:32:05.019
unimaginable numbers but they will

696
00:32:03.34 –> 00:32:07.659
become important to us as we start

697
00:32:05.019 –> 00:32:09.129
delving further into fiber optics we’ve

698
00:32:07.659 –> 00:32:11.470
now finished with the world of glass

699
00:32:09.129 –> 00:32:13.690
tubes and something that’s

700
00:32:11.47 –> 00:32:17.049
understandable and we’re going to move

701
00:32:13.69 –> 00:32:22.059
down into some atomically small world

702
00:32:17.049 –> 00:32:25.899
where things act very very strange I’ve

703
00:32:22.059 –> 00:32:30.549
drawn a picture here of a typical piece

704
00:32:25.899 –> 00:32:32.470
of fiber basically what we’ve got is two

705
00:32:30.549 –> 00:32:36.580
pieces of material here we’ve got this

706
00:32:32.47 –> 00:32:41.679
core in the center here which is shown

707
00:32:36.58 –> 00:32:45.129
as being either 8 microns diameter or 50

708
00:32:41.679 –> 00:32:47.139
microns diameter now eight microns

709
00:32:45.129 –> 00:32:49.659
diameter is only major and really small

710
00:32:47.139 –> 00:32:53.320
you may or may not be able to see just

711
00:32:49.659 –> 00:32:55.960
here two hairs this is a gray hair of my

712
00:32:53.32 –> 00:33:02.289
head and that is probably three times

713
00:32:55.96 –> 00:33:05.259
thicker than that 8 micron core the 50

714
00:33:02.289 –> 00:33:07.840
microns which here is probably much

715
00:33:05.259 –> 00:33:09.570
closer to this hair here which is a

716
00:33:07.84 –> 00:33:12.970
remnant of one of my ex-girlfriends

717
00:33:09.57 –> 00:33:15.429
this is the sort of magnitude that we’re

718
00:33:12.97 –> 00:33:17.889
talking about to be able to get ten or

719
00:33:15.429 –> 00:33:21.869
twelve kilowatts of energy out of

720
00:33:17.889 –> 00:33:23.750
something that diameter is unimaginable

721
00:33:21.869 –> 00:33:25.730
but it happens

722
00:33:23.75 –> 00:33:27.980
now the way in which the last laser tube

723
00:33:25.73 –> 00:33:30.980
was working was very simple we were

724
00:33:27.98 –> 00:33:35.510
creating pink light energy in this

725
00:33:30.98 –> 00:33:38.260
central tube and in here also was carbon

726
00:33:35.51 –> 00:33:42.050
dioxide and that was the carbon dioxide

727
00:33:38.26 –> 00:33:44.540
that was being stimulated to create a

728
00:33:42.05 –> 00:33:46.220
laser output we had a mirror at each end

729
00:33:44.54 –> 00:33:48.470
and the whole thing was bouncing

730
00:33:46.22 –> 00:33:50.210
backwards and forwards this being a 90%

731
00:33:48.47 –> 00:33:54.830
mirror and we were getting output from

732
00:33:50.21 –> 00:33:57.760
here so with the fiber laser what we do

733
00:33:54.83 –> 00:34:01.880
we inject the light from the outside

Transcript for Introduction to Fiber Laser Marking (Cont…)

734
00:33:57.76 –> 00:34:04.730
into this outside core this blue outer

735
00:34:01.88 –> 00:34:07.340
cladding as they call it okay now as

736
00:34:04.73 –> 00:34:11.389
that light bounces around it crosses

737
00:34:07.34 –> 00:34:14.600
over and interferes with this red core

738
00:34:11.389 –> 00:34:16.810
down the center now the red core down

739
00:34:14.6 –> 00:34:20.510
the center is a rather special material

740
00:34:16.81 –> 00:34:23.629
it’s a core made of silica glass doped

741
00:34:20.51 –> 00:34:25.909
with a rare earth called ytterbium now I

742
00:34:23.629 –> 00:34:29.330
know it says why there to begin to start

743
00:34:25.909 –> 00:34:33.080
with but why has actually said I so it’s

744
00:34:29.33 –> 00:34:36.260
ytterbium doped basically means it’s got

745
00:34:33.08 –> 00:34:37.570
a high percentage of ytterbium included

746
00:34:36.26 –> 00:34:40.490
in the glass

747
00:34:37.57 –> 00:34:42.980
whereas this outer sheath with a

748
00:34:40.49 –> 00:34:47.750
different refractive index I’m not going

749
00:34:42.98 –> 00:34:50.240
to explain that is just ordinary silica

750
00:34:47.75 –> 00:34:52.550
glass and it’s the difference in the

751
00:34:50.24 –> 00:34:55.639
refractive index of these two materials

752
00:34:52.55 –> 00:34:59.210
that causes the strange phenomena called

753
00:34:55.639 –> 00:35:02.360
total internal reflection and as you can

754
00:34:59.21 –> 00:35:06.080
see here we’ve got a red beam which is

755
00:35:02.36 –> 00:35:09.830
our power beam and it’s keeping to its

756
00:35:06.08 –> 00:35:14.210
own motorway which is the thin core down

757
00:35:09.83 –> 00:35:16.490
the center now this material in here

758
00:35:14.21 –> 00:35:18.070
called ytterbium has got some very

759
00:35:16.49 –> 00:35:22.820
interesting properties

760
00:35:18.07 –> 00:35:25.310
whereas with our co2 and a nitrogen we

761
00:35:22.82 –> 00:35:30.470
had something called an excited state

762
00:35:25.31 –> 00:35:33.350
and a a saw semi permanent state which

763
00:35:30.47 –> 00:35:34.750
is called a metastable state where it

764
00:35:33.35 –> 00:35:37.590
dropped down from there

765
00:35:34.75 –> 00:35:41.110
metastable state to the ground state

766
00:35:37.59 –> 00:35:44.410
with ytterbium we only have two states

767
00:35:41.11 –> 00:35:46.330
we’ve got a ground state and an excited

768
00:35:44.41 –> 00:35:48.840
state and relatively speaking this

769
00:35:46.33 –> 00:35:51.280
excited state can last quite a long time

770
00:35:48.84 –> 00:35:54.250
so we have no difference in the

771
00:35:51.28 –> 00:35:55.990
principle of lacing we’re just using a

772
00:35:54.25 –> 00:35:57.610
different material we’re using a solid

773
00:35:55.99 –> 00:36:01.240
material as opposed to a gas

Transcript for Introduction to Fiber Laser Marking (Cont…)

774
00:35:57.61 –> 00:36:03.250
so we pump light in and as you can see

775
00:36:01.24 –> 00:36:05.410
the light as gradually decreasing as we

776
00:36:03.25 –> 00:36:08.380
go along the fiber because we are

777
00:36:05.41 –> 00:36:12.150
gradually converting more and more of

778
00:36:08.38 –> 00:36:15.550
these ytterbium into high energy state

779
00:36:12.15 –> 00:36:17.530
which are then being released as the

780
00:36:15.55 –> 00:36:19.390
light bounces backwards and forwards of

781
00:36:17.53 –> 00:36:20.740
these two mirrors on the end here now

782
00:36:19.39 –> 00:36:22.720
although this is a general

783
00:36:20.74 –> 00:36:25.840
representation to give you the idea of

784
00:36:22.72 –> 00:36:28.060
how a fiber optic laser works it doesn’t

785
00:36:25.84 –> 00:36:30.070
actually work like this in reality at

786
00:36:28.06 –> 00:36:32.140
all now I’m not gonna go too far away

787
00:36:30.07 –> 00:36:34.390
from my diagram here but I am going to

788
00:36:32.14 –> 00:36:38.520
say that we don’t have real mirrors on

789
00:36:34.39 –> 00:36:41.890
the end of the fiber they manipulate the

790
00:36:38.52 –> 00:36:44.650
diameter of this central core in such a

791
00:36:41.89 –> 00:36:46.660
way it’s something called a brake

792
00:36:44.65 –> 00:36:48.850
grating which you can look that up and

793
00:36:46.66 –> 00:36:52.690
find out more about it which either

794
00:36:48.85 –> 00:36:55.300
causes complete reflection or partial

795
00:36:52.69 –> 00:36:58.240
reflection so we have the same effect as

796
00:36:55.3 –> 00:37:02.230
mirrors but without mirrors I’ve shown

797
00:36:58.24 –> 00:37:05.950
this is a very short section of fiber in

798
00:37:02.23 –> 00:37:09.490
reality this could be one two three six

799
00:37:05.95 –> 00:37:12.250
meters long it really depends on how

800
00:37:09.49 –> 00:37:14.410
much energy you want to store in the

801
00:37:12.25 –> 00:37:18.190
system okay now a few moments ago we

802
00:37:14.41 –> 00:37:21.040
talked about huge power capability out

803
00:37:18.19 –> 00:37:23.350
of these lasers but in reality it’s not

804
00:37:21.04 –> 00:37:25.780
quite as phenomenal as you might imagine

805
00:37:23.35 –> 00:37:28.690
we’re not talking about 12 kilowatts of

806
00:37:25.78 –> 00:37:31.960
continuous power we’re talking about the

807
00:37:28.69 –> 00:37:34.090
very very short duration pulse so in

808
00:37:31.96 –> 00:37:36.190
this world of fiber lasers marking

809
00:37:34.09 –> 00:37:38.770
machines which will come across two

810
00:37:36.19 –> 00:37:40.420
types of laser the most common type of

811
00:37:38.77 –> 00:37:42.820
laser is something called a q-switched

812
00:37:40.42 –> 00:37:44.710
laser now they’re generally the cheaper

813
00:37:42.82 –> 00:37:46.630
type of laser that doesn’t mean to say

814
00:37:44.71 –> 00:37:47.099
that bad it just means to say there have

815
00:37:46.63 –> 00:37:49.019
got

816
00:37:47.099 –> 00:37:52.349
a certain amount of limitation on their

817
00:37:49.019 –> 00:37:53.999
capabilities but first of all let’s take

818
00:37:52.349 –> 00:37:57.769
a look at the q-switch laser because

Transcript for Introduction to Fiber Laser Marking (Cont…)

819
00:37:53.999 –> 00:38:01.890
this is a fairly simple jump from a

820
00:37:57.769 –> 00:38:02.880
continuous wave laser to explain how

821
00:38:01.89 –> 00:38:05.609
this one works

822
00:38:02.88 –> 00:38:07.979
now as you can see I’ve modified the

823
00:38:05.609 –> 00:38:10.170
drawing very slightly and I’ve included

824
00:38:07.979 –> 00:38:12.269
this thing in here called a cue switch

825
00:38:10.17 –> 00:38:14.459
so I’m not going to explain how a cue

826
00:38:12.269 –> 00:38:16.109
switch works you can go and befuddle

827
00:38:14.459 –> 00:38:18.059
your own brain if you want I’m just

828
00:38:16.109 –> 00:38:20.400
going to regard this as being a piece of

829
00:38:18.059 –> 00:38:23.940
electronic cotton wool for the purpose

830
00:38:20.4 –> 00:38:26.519
of my very simple mental model basically

831
00:38:23.94 –> 00:38:28.920
it stops anything from reaching this

832
00:38:26.519 –> 00:38:31.289
mirror here and bear in mind these are

833
00:38:28.92 –> 00:38:33.390
not real mirrors these are things called

834
00:38:31.289 –> 00:38:35.459
Bragg gratings but I’ve shown them as

835
00:38:33.39 –> 00:38:38.430
mirrors because that’s what the net

836
00:38:35.459 –> 00:38:41.940
effect is so here we’ve got a cue switch

837
00:38:38.43 –> 00:38:44.910
and here we’ve got our blue pumping

838
00:38:41.94 –> 00:38:49.109
laser and remember what pumping is

839
00:38:44.91 –> 00:38:51.989
pumping is pushing all the electrons

840
00:38:49.109 –> 00:38:54.930
that are in here up to a higher excited

841
00:38:51.989 –> 00:38:56.969
state if we turn our electronic cotton

842
00:38:54.93 –> 00:38:59.459
wall on and prevent anything from

843
00:38:56.969 –> 00:39:01.229
reaching this mirror the only thing

844
00:38:59.459 –> 00:39:03.119
that’s going to happen is we’re going to

845
00:39:01.229 –> 00:39:03.660
pump all these electrons that are in

846
00:39:03.119 –> 00:39:06.569
here

847
00:39:03.66 –> 00:39:08.479
up to there excited state we’re

848
00:39:06.569 –> 00:39:12.989
effectively going to be storing energy

849
00:39:08.479 –> 00:39:14.670
in this piece of fiber-optic material so

850
00:39:12.989 –> 00:39:17.099
we’ve stored as much in as with energy

851
00:39:14.67 –> 00:39:18.809
as we can in here and now we’ll turn out

852
00:39:17.099 –> 00:39:22.949
a piece of electronic cotton wall off

853
00:39:18.809 –> 00:39:24.509
and some photons will escape and come

854
00:39:22.949 –> 00:39:26.969
through here and bounce off this mirror

855
00:39:24.509 –> 00:39:29.249
now as soon as a photon bounces off this

856
00:39:26.969 –> 00:39:31.019
mirror and runs back we know what the

857
00:39:29.249 –> 00:39:33.989
effect is going to be it’s going to

858
00:39:31.019 –> 00:39:36.539
trigger a cascade effect as it travels

859
00:39:33.989 –> 00:39:39.209
back to this mirror and so here we go

860
00:39:36.539 –> 00:39:41.999
this is the same basic principle that

861
00:39:39.209 –> 00:39:44.459
we’ve already discussed so there’s

862
00:39:41.999 –> 00:39:46.380
nothing new here except that we’ve put

863
00:39:44.459 –> 00:39:48.479
this switch in the way what is the

864
00:39:46.38 –> 00:39:51.779
effect of this switch now it’s much

865
00:39:48.479 –> 00:39:54.989
easier to show you this in a

866
00:39:51.779 –> 00:39:58.140
diagrammatic form here we’ve got the

867
00:39:54.989 –> 00:39:59.700
blue section over time and we’re busy

868
00:39:58.14 –> 00:40:02.490
pumping

Transcript for Introduction to Fiber Laser Marking (Cont…)

869
00:39:59.7 –> 00:40:05.069
electrons up to their high energy state

870
00:40:02.49 –> 00:40:06.900
they’re excited state and here we’ve got

871
00:40:05.069 –> 00:40:10.309
a green line which shows the general

872
00:40:06.9 –> 00:40:12.900
progression over time of the amount of

873
00:40:10.309 –> 00:40:15.150
excited electrons they get more and more

874
00:40:12.9 –> 00:40:16.710
and more and more until we reach a point

875
00:40:15.15 –> 00:40:18.960
where there are no more electrons to

876
00:40:16.71 –> 00:40:21.240
excite and so consequently this line

877
00:40:18.96 –> 00:40:23.910
would then level out once we’ve reached

878
00:40:21.24 –> 00:40:26.760
this maximum point here where we cannot

879
00:40:23.91 –> 00:40:29.130
actually excite any more electrons up to

880
00:40:26.76 –> 00:40:31.380
there excited state Mars will turn off

881
00:40:29.13 –> 00:40:33.809
the cue switch we remove the cotton wool

882
00:40:31.38 –> 00:40:36.000
and will allow the photons to pass

883
00:40:33.809 –> 00:40:38.309
through and hit the mirror now it’ll be

884
00:40:36.0 –> 00:40:40.530
initially there’ll be one or two photons

885
00:40:38.309 –> 00:40:42.119
a few photons that hit then they’ll

886
00:40:40.53 –> 00:40:43.650
start bouncing backwards and forwards

887
00:40:42.119 –> 00:40:45.299
and as they bounce backwards and

888
00:40:43.65 –> 00:40:47.790
forwards we’ll get this amplification

889
00:40:45.299 –> 00:40:49.530
effect well it takes a little bit of

890
00:40:47.79 –> 00:40:51.750
time for the amplification effect to

891
00:40:49.53 –> 00:40:53.880
build up but once the amplification

892
00:40:51.75 –> 00:40:56.760
effect builds up we get this cascade

893
00:40:53.88 –> 00:41:00.420
that happens where we get a tremendous

894
00:40:56.76 –> 00:41:02.730
rush a conversion rate of electrons and

895
00:41:00.42 –> 00:41:05.490
they start dropping down producing

896
00:41:02.73 –> 00:41:07.380
photons huge numbers of photons and of

897
00:41:05.49 –> 00:41:09.839
course as we’ve seen what we’re really

898
00:41:07.38 –> 00:41:12.809
producing here is that photon tsunami

899
00:41:09.839 –> 00:41:15.420
wave you know all these all the photons

900
00:41:12.809 –> 00:41:17.819
working together and they will produce a

901
00:41:15.42 –> 00:41:19.829
very huge peak but of course as soon as

902
00:41:17.819 –> 00:41:23.430
we start to get this peak which will

903
00:41:19.829 –> 00:41:27.720
reach a crossover point where the number

904
00:41:23.43 –> 00:41:29.819
of electrons available to rush out into

905
00:41:27.72 –> 00:41:32.400
the real world starts dropping rapidly

906
00:41:29.819 –> 00:41:35.130
so all of a sudden we’ll reach this peak

907
00:41:32.4 –> 00:41:37.740
and we will drop off just as quickly as

908
00:41:35.13 –> 00:41:40.290
we started this is only a 20 watt laser

909
00:41:37.74 –> 00:41:44.790
so let’s just see what would happen if

910
00:41:40.29 –> 00:41:48.720
this was a continuous 20 watt laser as

911
00:41:44.79 –> 00:41:52.200
opposed to a pulsed 20 watt laser so

912
00:41:48.72 –> 00:41:55.079
here we are we’re pumping and here we

913
00:41:52.2 –> 00:41:57.930
are pumping but this time because it’s a

914
00:41:55.079 –> 00:42:01.380
continuous output we’ve also got this

Transcript for Introduction to Fiber Laser Marking (Cont…)

915
00:41:57.93 –> 00:42:03.299
leakage here and so we won’t in this

916
00:42:01.38 –> 00:42:07.559
particular instance of a continuous wave

917
00:42:03.299 –> 00:42:10.400
ever reach saturation what what happen

918
00:42:07.559 –> 00:42:12.960
is we shall pump and we shall get the

919
00:42:10.4 –> 00:42:16.560
which will get the excited it

920
00:42:12.96 –> 00:42:20.070
runs up to a certain amount let’s call

921
00:42:16.56 –> 00:42:23.490
it that amount okay and it will be

922
00:42:20.07 –> 00:42:26.070
stable because as we’re pumping

923
00:42:23.49 –> 00:42:30.690
electrons up to this higher level so

924
00:42:26.07 –> 00:42:33.780
they’re leaking away and here we’ve got

925
00:42:30.69 –> 00:42:34.830
our 20 watt output okay now to try and

926
00:42:33.78 –> 00:42:36.630
make this a little bit more

927
00:42:34.83 –> 00:42:39.119
understandable what I’d like you to do

928
00:42:36.63 –> 00:42:40.710
is imagine a bath now if the water

929
00:42:39.119 –> 00:42:43.859
running into the bath is slightly

930
00:42:40.71 –> 00:42:46.290
greater than the oil will go at the plug

931
00:42:43.859 –> 00:42:48.119
hole there will be a balance that will

932
00:42:46.29 –> 00:42:50.369
be achieved we’ll get a certain level of

933
00:42:48.119 –> 00:42:52.380
water in the bath such that the water

934
00:42:50.369 –> 00:42:55.310
can disappear out the plug hole at the

935
00:42:52.38 –> 00:42:58.500
same rate that it comes in from the tap

936
00:42:55.31 –> 00:43:01.830
and that’s the stability that’s shown in

937
00:42:58.5 –> 00:43:04.140
this situation here now when we talk

938
00:43:01.83 –> 00:43:07.349
about a cue switch what we’re really

939
00:43:04.14 –> 00:43:09.750
doing is we’re putting the plug in so we

940
00:43:07.349 –> 00:43:13.500
put the plug in the bath and the bath no

941
00:43:09.75 –> 00:43:15.330
fills up to overflowing and then we

942
00:43:13.5 –> 00:43:18.089
remove the plug and as we remove the

943
00:43:15.33 –> 00:43:20.460
plug look we get a rush of water back to

944
00:43:18.089 –> 00:43:23.130
the plug hole so that’s how we can

945
00:43:20.46 –> 00:43:26.220
produce very high power out of a very

946
00:43:23.13 –> 00:43:27.540
low power input we can store it up for a

947
00:43:26.22 –> 00:43:34.589
period of time and then release it

948
00:43:27.54 –> 00:43:38.040
instantly instantly hmm remember we

949
00:43:34.589 –> 00:43:40.490
talked about the speed of light how far

950
00:43:38.04 –> 00:43:44.730
things travel in one nanosecond

951
00:43:40.49 –> 00:43:49.980
well these pulses here we’re talking

952
00:43:44.73 –> 00:43:52.589
about maybe maybe as little as 5 to 10

953
00:43:49.98 –> 00:43:55.170
nanoseconds let’s just say 10

954
00:43:52.589 –> 00:43:57.210
nanoseconds so that means look we’ve

955
00:43:55.17 –> 00:44:01.260
also got another 10 nanoseconds here

Transcript for Introduction to Fiber Laser Marking (Cont…)

956
00:43:57.21 –> 00:44:06.890
which is to build up time so it’s taking

957
00:44:01.26 –> 00:44:11.099
10 nanoseconds to get our system running

958
00:44:06.89 –> 00:44:14.010
so if this system is only one meter long

959
00:44:11.099 –> 00:44:16.859
for example and we know that it takes

960
00:44:14.01 –> 00:44:20.040
roughly 3 nanoseconds to travel a meter

961
00:44:16.859 –> 00:44:22.200
and if this is a 10 or 12 nanoseconds

962
00:44:20.04 –> 00:44:23.520
here it means we’re going to have Rea

963
00:44:22.2 –> 00:44:27.780
maybe

964
00:44:23.52 –> 00:44:30.960
two round-trips of a photon to build up

965
00:44:27.78 –> 00:44:32.490
to this critical level so that’s why

966
00:44:30.96 –> 00:44:35.820
we’ve got a delay here we can’t

967
00:44:32.49 –> 00:44:38.340
instantly get power out of the switch

968
00:44:35.82 –> 00:44:42.360
there is a delay after you switch on

969
00:44:38.34 –> 00:44:44.580
before things happen because the speed

970
00:44:42.36 –> 00:44:47.190
of light is actually now getting in the

971
00:44:44.58 –> 00:44:48.600
way of the pulse generation and then the

972
00:44:47.19 –> 00:44:51.870
width of the pulse is basically

973
00:44:48.6 –> 00:44:54.540
determined by the speed at which you

974
00:44:51.87 –> 00:44:57.030
could convert excited electrons into

975
00:44:54.54 –> 00:44:58.650
photons and that again is determined by

976
00:44:57.03 –> 00:45:00.270
the speed of light traveling up and down

977
00:44:58.65 –> 00:45:02.610
the fiber so there are certain physical

978
00:45:00.27 –> 00:45:06.690
limitations as to what can happen with

979
00:45:02.61 –> 00:45:08.940
this pulse now we could reduce the

980
00:45:06.69 –> 00:45:10.380
amount of pumping time in other words we

981
00:45:08.94 –> 00:45:13.260
could we could make the cue switch

982
00:45:10.38 –> 00:45:15.780
switch earlier and if we make the cue

983
00:45:13.26 –> 00:45:17.910
switch switch earlier then what it means

984
00:45:15.78 –> 00:45:19.470
is that we shan’t produce as much of a

985
00:45:17.91 –> 00:45:24.050
pulse which will produce a smaller pulse

986
00:45:19.47 –> 00:45:27.930
like this but it will still be a pulse

987
00:45:24.05 –> 00:45:31.020
but at a much lower peak power so that’s

988
00:45:27.93 –> 00:45:33.420
one variable that they could use to play

989
00:45:31.02 –> 00:45:41.490
with a cue switch the second variable is

990
00:45:33.42 –> 00:45:44.520
the repeat interval here of the pulse it

991
00:45:41.49 –> 00:45:47.220
really depends on how how long the fiber

992
00:45:44.52 –> 00:45:49.950
is and how quickly it takes to reach

993
00:45:47.22 –> 00:45:52.860
this saturation point so that’s the

994
00:45:49.95 –> 00:45:54.330
principle of q-switch laser ok so

995
00:45:52.86 –> 00:45:56.250
eventually we get on to the most

996
00:45:54.33 –> 00:45:58.230
difficult part of my quest which is

997
00:45:56.25 –> 00:46:01.110
trying to understand how a moped laser

Transcript for Introduction to Fiber Laser Marking (Cont…)

998
00:45:58.23 –> 00:46:04.250
works it’s not the same there’s any

999
00:46:01.11 –> 00:46:08.390
other laser that we’ve talked about yes

1000
00:46:04.25 –> 00:46:14.820
it’s got core yes it’s got a cladding

1001
00:46:08.39 –> 00:46:17.130
but it has no mirrors so that was a big

1002
00:46:14.82 –> 00:46:20.480
problem I had to start with with no

1003
00:46:17.13 –> 00:46:24.960
mirrors but then I realized something

1004
00:46:20.48 –> 00:46:27.840
significantly different this one has an

1005
00:46:24.96 –> 00:46:31.440
injection of a signal down into the core

1006
00:46:27.84 –> 00:46:34.280
itself not just a pump signal but

1007
00:46:31.44 –> 00:46:37.730
actually a signal which runs through

1008
00:46:34.28 –> 00:46:41.600
both laces and comes out this end in a

1009
00:46:37.73 –> 00:46:43.970
fully amplified laser format how does

1010
00:46:41.6 –> 00:46:46.850
this actually work it’s quite

1011
00:46:43.97 –> 00:46:50.750
complicated optically but in principle

1012
00:46:46.85 –> 00:46:53.000
it’s very simple for me to explain now

1013
00:46:50.75 –> 00:46:55.010
bear in mind this explanation that I’ve

1014
00:46:53.0 –> 00:46:57.230
given you as the explanation that I’m

1015
00:46:55.01 –> 00:47:00.260
giving myself this is how I’ve

1016
00:46:57.23 –> 00:47:03.950
interpreted after many hours of reading

1017
00:47:00.26 –> 00:47:06.530
and research into mopus nobody has told

1018
00:47:03.95 –> 00:47:08.930
me exactly how this thing works what I’m

1019
00:47:06.53 –> 00:47:13.400
just about to tell you fits all the

1020
00:47:08.93 –> 00:47:16.100
facts that I have we energize the core

1021
00:47:13.4 –> 00:47:18.740
in here up to its fullest extent with

1022
00:47:16.1 –> 00:47:21.200
these pumping lasers and this is a

1023
00:47:18.74 –> 00:47:23.930
signal input something they call a seed

1024
00:47:21.2 –> 00:47:25.670
laser more about this in a second so

1025
00:47:23.93 –> 00:47:28.930
once you’ve got the population in here

1026
00:47:25.67 –> 00:47:32.510
fully saturated inverted and saturated

1027
00:47:28.93 –> 00:47:35.440
at the same in this one we’ve got the

1028
00:47:32.51 –> 00:47:38.420
pump laser which is busy pumping all the

1029
00:47:35.44 –> 00:47:41.300
electrons in this core up to their

1030
00:47:38.42 –> 00:47:43.550
saturation high energy level we can then

1031
00:47:41.3 –> 00:47:47.680
inject a signal into this end

1032
00:47:43.55 –> 00:47:53.000
so this photodiode sends a powerful beam

1033
00:47:47.68 –> 00:47:55.040
into the end here and it then runs right

1034
00:47:53.0 –> 00:47:58.040
the way through here collecting photons

1035
00:47:55.04 –> 00:48:01.120
as it goes and comes out the other end

Transcript for Introduction to Fiber Laser Marking (Cont…)

1036
00:47:58.04 –> 00:48:04.300
with more photons than it went in with

1037
00:48:01.12 –> 00:48:08.090
but then it transfers across to another

1038
00:48:04.3 –> 00:48:10.370
much bigger and wider beam with more

1039
00:48:08.09 –> 00:48:13.490
pumping this secondary fine but then

1040
00:48:10.37 –> 00:48:16.190
actually amplifies the signal this first

1041
00:48:13.49 –> 00:48:19.690
fiber is signal conditioning that it’s

1042
00:48:16.19 –> 00:48:22.640
generating the pulse shape that we want

1043
00:48:19.69 –> 00:48:24.380
but this one amplifies the pol shake

1044
00:48:22.64 –> 00:48:26.600
there is a small amount of pulse change

1045
00:48:24.38 –> 00:48:28.640
shaping taking place in here as well but

1046
00:48:26.6 –> 00:48:31.850
most of the shaping takes place in here

1047
00:48:28.64 –> 00:48:34.610
now it’s not necessarily from what I

1048
00:48:31.85 –> 00:48:36.620
understand conscious shaping it’s

1049
00:48:34.61 –> 00:48:39.320
something that happens because of the

1050
00:48:36.62 –> 00:48:41.270
natural properties of the fiber this is

1051
00:48:39.32 –> 00:48:43.160
how I’ve explained it to myself so we’ve

1052
00:48:41.27 –> 00:48:46.160
got full population inversion in the

1053
00:48:43.16 –> 00:48:49.099
center core there we then inject a small

1054
00:48:46.16 –> 00:48:52.640
million from this red laser and that

1055
00:48:49.099 –> 00:48:56.530
signal might look like that and that

1056
00:48:52.64 –> 00:49:00.619
might be say one and then a second white

1057
00:48:56.53 –> 00:49:03.770
now this here could be for instance four

1058
00:49:00.619 –> 00:49:05.680
meters long and this cable here might be

1059
00:49:03.77 –> 00:49:08.599
six meters long

1060
00:49:05.68 –> 00:49:11.480
they’re quite long these fiber-optic

1061
00:49:08.599 –> 00:49:15.319
cables now we already know that one

1062
00:49:11.48 –> 00:49:20.390
nanosecond equals roughly 300

1063
00:49:15.319 –> 00:49:22.309
millimeters so four meters it’s going to

1064
00:49:20.39 –> 00:49:24.020
take thirteen or fourteen nanoseconds to

1065
00:49:22.309 –> 00:49:26.599
travel down there but what we’ve got to

1066
00:49:24.02 –> 00:49:29.450
imagine is this once we inject the

1067
00:49:26.599 –> 00:49:32.539
signal and the signal goes in and it is

1068
00:49:29.45 –> 00:49:34.460
300 millimetres long so there we are

1069
00:49:32.539 –> 00:49:35.750
we’ve got have 300 millimetre long

1070
00:49:34.46 –> 00:49:38.180
signal going in there

1071
00:49:35.75 –> 00:49:40.700
and it’s going to travel along and

1072
00:49:38.18 –> 00:49:43.400
remain 300 millimeters all the way along

1073
00:49:40.7 –> 00:49:44.900
there and then it’s going to do the same

1074
00:49:43.4 –> 00:49:48.680
all the way through here it’s going to

1075
00:49:44.9 –> 00:49:50.690
be a 300 millimetre long signal and it’s

1076
00:49:48.68 –> 00:49:53.089
got to pass right through the system as

1077
00:49:50.69 –> 00:49:55.400
this signal passes along here the

1078
00:49:53.089 –> 00:49:58.670
leading edge of this signal is going to

Transcript for Introduction to Fiber Laser Marking (Cont…)

1079
00:49:55.4 –> 00:50:02.119
encounter the most number of excited

1080
00:49:58.67 –> 00:50:05.720
electrons ready to drop down and produce

1081
00:50:02.119 –> 00:50:08.089
a photon which will join this army so

1082
00:50:05.72 –> 00:50:11.779
the leading edge of this signal will

1083
00:50:08.089 –> 00:50:13.460
collect the most number of photons so

1084
00:50:11.779 –> 00:50:15.289
but the time this signal gets to the

1085
00:50:13.46 –> 00:50:17.059
other end here the signal is going to

1086
00:50:15.289 –> 00:50:23.809
come out the other end is likely to look

1087
00:50:17.059 –> 00:50:27.410
something like this it’s still one

1088
00:50:23.809 –> 00:50:29.750
nanosecond wide but the leading edge has

1089
00:50:27.41 –> 00:50:31.970
collected more photons than the trailing

1090
00:50:29.75 –> 00:50:34.309
edge of the signal and so that is how

1091
00:50:31.97 –> 00:50:36.710
that signal goes into here

1092
00:50:34.309 –> 00:50:37.940
and the chances are that what it’s going

1093
00:50:36.71 –> 00:50:40.099
to do is kind of come out the other end

1094
00:50:37.94 –> 00:50:42.200
very similar to that but maybe with a

1095
00:50:40.099 –> 00:50:45.289
little bit more trailing edge Distortion

1096
00:50:42.2 –> 00:50:47.869
here is the chart that I was given which

1097
00:50:45.289 –> 00:50:51.829
made no sense to me when I received it I

1098
00:50:47.869 –> 00:50:54.470
was told that hey if you run at 850

1099
00:50:51.829 –> 00:50:55.940
kilohertz with a 2 nanosecond signal

1100
00:50:54.47 –> 00:50:59.020
that’s when you’re going to develop

1101
00:50:55.94 –> 00:50:59.020
print our

1102
00:50:59.4 –> 00:51:05.109
so when I look at the other end of the

1103
00:51:01.779 –> 00:51:09.940
scale here which is 350 nanosecond

1104
00:51:05.109 –> 00:51:12.970
signal pulse that seems quite staggering

1105
00:51:09.94 –> 00:51:18.160
because when we started putting real

1106
00:51:12.97 –> 00:51:21.339
numbers to that 350 nanoseconds and we

1107
00:51:18.16 –> 00:51:24.369
know the speed of light causes 0.3 of a

1108
00:51:21.339 –> 00:51:26.859
meter per nanosecond that means that

1109
00:51:24.369 –> 00:51:30.700
signal is actually a hundred and five

1110
00:51:26.859 –> 00:51:33.460
meters long in other words I start the

1111
00:51:30.7 –> 00:51:36.670
signal off here and it’s actually coming

1112
00:51:33.46 –> 00:51:38.829
out and burning on the job before I’ve

1113
00:51:36.67 –> 00:51:41.470
actually finished the signal coming into

1114
00:51:38.829 –> 00:51:44.079
the end here because this is only 10

1115
00:51:41.47 –> 00:51:45.970
meters long now if I’ve got the physics

1116
00:51:44.079 –> 00:51:47.739
of that wrong perhaps somebody will tell

1117
00:51:45.97 –> 00:51:50.829
me but that’s the way that it looks to

1118
00:51:47.739 –> 00:51:52.869
me that’s how we can get these really

1119
00:51:50.829 –> 00:51:55.960
weird shaped pulses because the leading

1120
00:51:52.869 –> 00:51:58.059
edge passes through here so I’ve only

Transcript for Introduction to Fiber Laser Marking (Cont…)

1121
00:51:55.96 –> 00:52:05.140
got a signal which is sits which sits

1122
00:51:58.059 –> 00:52:08.109
there for 350 nanoseconds like this it’s

1123
00:52:05.14 –> 00:52:10.269
now a very long pulse but the trailing

1124
00:52:08.109 –> 00:52:16.359
edge of their pulse is going to look

1125
00:52:10.269 –> 00:52:18.269
like this because the tail end of the

1126
00:52:16.359 –> 00:52:22.680
pulse is going to collect a lot less

1127
00:52:18.269 –> 00:52:25.930
photons than the leading edge because I

1128
00:52:22.68 –> 00:52:28.269
presume that the path blazer is not

1129
00:52:25.93 –> 00:52:31.809
going to be working while the signals

1130
00:52:28.269 –> 00:52:34.119
working I don’t know I don’t know what

1131
00:52:31.809 –> 00:52:36.400
the mechanism is but this clearly

1132
00:52:34.119 –> 00:52:38.380
describes to me a mechanism by which we

1133
00:52:36.4 –> 00:52:41.410
can generate these strange-looking

1134
00:52:38.38 –> 00:52:45.039
pulses that come out of this signal

1135
00:52:41.41 –> 00:52:48.309
element here now I suspect that this

1136
00:52:45.039 –> 00:52:49.630
will be energized all the time but they

1137
00:52:48.309 –> 00:52:51.430
don’t know whether these will be in the

1138
00:52:49.63 –> 00:52:54.130
Joseph these are the sort of facts that

1139
00:52:51.43 –> 00:52:55.839
I can’t find anything about nobody out

1140
00:52:54.13 –> 00:52:57.910
there is telling me how this thing works

1141
00:52:55.839 –> 00:53:01.029
so I’m having to try and work it out

1142
00:52:57.91 –> 00:53:02.920
from yourself now maybe know that

1143
00:53:01.029 –> 00:53:04.359
somebody’s seen me struggling they might

1144
00:53:02.92 –> 00:53:06.400
be able to enlighten me and give me a

1145
00:53:04.359 –> 00:53:09.549
very very simple explanation as to how

1146
00:53:06.4 –> 00:53:10.750
this works but in the absence of anybody

1147
00:53:09.549 –> 00:53:13.210
else’s explanation

1148
00:53:10.75 –> 00:53:15.070
I’m happy to work with this as a model

1149
00:53:13.21 –> 00:53:16.780
the only thing that I can absolutely be

1150
00:53:15.07 –> 00:53:18.820
sure is I’m going to get a leading edge

1151
00:53:16.78 –> 00:53:22.800
pulse which is a lot higher than the

1152
00:53:18.82 –> 00:53:25.570
trailing edge pulse and that agrees with

1153
00:53:22.8 –> 00:53:28.599
several facts that I’ve already got this

1154
00:53:25.57 –> 00:53:30.820
is the 350 milliseconds which looks like

1155
00:53:28.599 –> 00:53:33.460
this it’s got a very long trailing edge

1156
00:53:30.82 –> 00:53:35.770
whereas in fact the tune in the second

1157
00:53:33.46 –> 00:53:38.619
pulse which is this one here has got a

1158
00:53:35.77 –> 00:53:40.869
very very short trailing edge when we

1159
00:53:38.619 –> 00:53:44.200
look across this graph typically we’re

1160
00:53:40.869 –> 00:53:46.960
talking about 12 kilowatts peak power

1161
00:53:44.2 –> 00:53:49.240
for most of these pulses and then we get

1162
00:53:46.96 –> 00:53:52.300
to this lower range which are about 8

1163
00:53:49.24 –> 00:53:54.520
kilowatts but over a much wider period

1164
00:53:52.3 –> 00:53:58.030
so one has to assume that we can

1165
00:53:54.52 –> 00:54:01.240
actually do more sustained damage with

Transcript for Introduction to Fiber Laser Marking (Cont…)

1166
00:53:58.03 –> 00:54:03.490
this range of pulses that we can with

1167
00:54:01.24 –> 00:54:07.030
these these are going to produce very

1168
00:54:03.49 –> 00:54:08.710
sharp deep pulses can I say there’s not

1169
00:54:07.03 –> 00:54:11.650
very much energy and there’s a lot of

1170
00:54:08.71 –> 00:54:13.240
power but not very much sustained energy

1171
00:54:11.65 –> 00:54:15.460
in there to do damage to the material

1172
00:54:13.24 –> 00:54:17.500
but that’s one of the subjects I’m going

1173
00:54:15.46 –> 00:54:19.480
to have to investigate how much damage

1174
00:54:17.5 –> 00:54:21.490
can I do to the material with each one

1175
00:54:19.48 –> 00:54:24.869
of these pulses now that I’ve begun to

1176
00:54:21.49 –> 00:54:27.880
understand this my list of numbers here

1177
00:54:24.869 –> 00:54:29.230
begins to make a little bit of sense so

1178
00:54:27.88 –> 00:54:32.740
let’s take a quick look at this 2

1179
00:54:29.23 –> 00:54:35.470
nanosecond pulse here what it means is

1180
00:54:32.74 –> 00:54:37.570
that inter if I’ve got 2 nanoseconds and

1181
00:54:35.47 –> 00:54:40.960
I’ve got an eight hundred and fifty

1182
00:54:37.57 –> 00:54:44.200
kilohertz maximum allowable frequency

1183
00:54:40.96 –> 00:54:50.520
that I can run at approximately that’s

1184
00:54:44.2 –> 00:54:53.740
roughly one microsecond for every cycle

1185
00:54:50.52 –> 00:54:56.589
approximately so that means that I’ve

1186
00:54:53.74 –> 00:55:00.010
got roughly a ratio of two nanoseconds

1187
00:54:56.589 –> 00:55:03.130
to a thousand nanoseconds which is

1188
00:55:00.01 –> 00:55:05.440
roughly 500 to 1 or in real terms let’s

1189
00:55:03.13 –> 00:55:07.930
go back to here and say that if I put a

1190
00:55:05.44 –> 00:55:11.740
two nanosecond pulse in there that means

1191
00:55:07.93 –> 00:55:14.710
I’ve got 998 nanoseconds in which to

1192
00:55:11.74 –> 00:55:17.380
recharge or rien vert the population in

1193
00:55:14.71 –> 00:55:18.609
here to make it fully charged again so

1194
00:55:17.38 –> 00:55:21.820
that I can understand

1195
00:55:18.609 –> 00:55:23.150
alright that’s why I must make sure that

1196
00:55:21.82 –> 00:55:27.210
I don’t exceed

1197
00:55:23.15 –> 00:55:30.090
850 kilohertz not it runs slower because

1198
00:55:27.21 –> 00:55:33.540
if I run at 500 kilohertz then there’s

1199
00:55:30.09 –> 00:55:35.160
even more time for the light to invert

1200
00:55:33.54 –> 00:55:38.010
that population and get full saturation

1201
00:55:35.16 –> 00:55:40.650
in there ready for the next pulse so I

1202
00:55:38.01 –> 00:55:43.080
can always run these numbers at smaller

1203
00:55:40.65 –> 00:55:45.780
values but I mustn’t run these numbers

1204
00:55:43.08 –> 00:55:48.090
at larger frequencies now in Lotus

1205
00:55:45.78 –> 00:55:49.980
installed the machine for me they

1206
00:55:48.09 –> 00:55:54.180
provided me with this very useful piece

1207
00:55:49.98 –> 00:55:56.940
of support documentation which basically

1208
00:55:54.18 –> 00:55:59.160
tells me understanding the differences

1209
00:55:56.94 –> 00:56:01.800
between q-switched and micro lases which

Transcript for Introduction to Fiber Laser Marking (Cont…)

1210
00:55:59.16 –> 00:56:03.960
is hopefully can be very interesting and

1211
00:56:01.8 –> 00:56:07.910
on the front page they give me this

1212
00:56:03.96 –> 00:56:11.250
diner if I had a physics doctor in

1213
00:56:07.91 –> 00:56:14.430
optoelectronics I might be able to

1214
00:56:11.25 –> 00:56:18.930
understand this but this is pretty

1215
00:56:14.43 –> 00:56:25.980
meaningless too I think most people meet

1216
00:56:18.93 –> 00:56:28.260
the wording used here hf f BG ydf these

1217
00:56:25.98 –> 00:56:30.510
are all acronyms which mean absolutely

1218
00:56:28.26 –> 00:56:33.540
nothing to me I mean I know that this

1219
00:56:30.51 –> 00:56:41.040
happens to be a a hyper ramen scattering

1220
00:56:33.54 –> 00:56:44.040
fiber Bragg grating Wow fantastic what

1221
00:56:41.04 –> 00:56:46.670
is it what does it mean we’ve got the

1222
00:56:44.04 –> 00:56:51.030
same thing here hello Raman scattering

1223
00:56:46.67 –> 00:56:53.430
fiber Bragg grating well technically

1224
00:56:51.03 –> 00:56:55.470
these two things here are the mirrors I

1225
00:56:53.43 –> 00:56:57.540
think I’ve described to you the break

1226
00:56:55.47 –> 00:56:59.030
grating well you need to go and have a

1227
00:56:57.54 –> 00:57:03.240
look up and see what that is

1228
00:56:59.03 –> 00:57:08.310
these are this Y D F stands for

1229
00:57:03.24 –> 00:57:13.650
ytterbium doped fiber okay it’s easy

1230
00:57:08.31 –> 00:57:17.490
when you know and this a o M it’s an

1231
00:57:13.65 –> 00:57:19.230
acoustic octo modulator what’s that well

1232
00:57:17.49 –> 00:57:23.450
that’s my piece of electronic cotton

1233
00:57:19.23 –> 00:57:26.880
wool my simplified drawings are that

1234
00:57:23.45 –> 00:57:28.770
exactly without all the frigging bits in

1235
00:57:26.88 –> 00:57:32.580
the same way that look this is a motor

1236
00:57:28.77 –> 00:57:35.610
system as described by presumably jpt

1237
00:57:32.58 –> 00:57:36.390
originally it there’s a lot more stuff

1238
00:57:35.61 –> 00:57:39.809
in here

1239
00:57:36.39 –> 00:57:41.460
deleting my simple diagram it’s called a

1240
00:57:39.809 –> 00:57:44.999
YB doped

1241
00:57:41.46 –> 00:57:47.369
DCF net what’s a DCF well it’s a

1242
00:57:44.999 –> 00:57:51.380
diffusion corrected fiber there’s a very

1243
00:57:47.369 –> 00:57:54.119
good site on on the web called photonics

1244
00:57:51.38 –> 00:57:56.880
encyclopedia you’ll find a lot of this

1245
00:57:54.119 –> 00:57:58.920
stuff defined in there but the problem

1246
00:57:56.88 –> 00:58:00.869
is you won’t understand most of the

Transcript for Introduction to Fiber Laser Marking (Cont…)

1247
00:57:58.92 –> 00:58:03.329
stuff that’s in there because it’s

1248
00:58:00.869 –> 00:58:05.789
written in Klingon for people that read

1249
00:58:03.329 –> 00:58:08.910
Klingon and I’m afraid I’m just a very

1250
00:58:05.789 –> 00:58:10.799
humble old-school engineer and most of

1251
00:58:08.91 –> 00:58:13.319
this stuff means nothing to me so I like

1252
00:58:10.799 –> 00:58:15.749
to reduce it back to the very basic

1253
00:58:13.319 –> 00:58:17.670
elements that I can understand and I

1254
00:58:15.749 –> 00:58:20.160
hope I’ve done the same thing for you

1255
00:58:17.67 –> 00:58:23.489
jpt claim all sorts of things for their

1256
00:58:20.16 –> 00:58:25.079
little bit of kit for the next phase I’m

1257
00:58:23.489 –> 00:58:27.359
going to be working with the machine to

1258
00:58:25.079 –> 00:58:30.329
see just how close I can get to some of

1259
00:58:27.359 –> 00:58:32.279
this stuff so I look forward to seeing

1260
00:58:30.329 –> 00:58:34.880
you in the next session thank you very

1261
00:58:32.279 –> 00:58:34.880
much for your time

Transcript for Introduction to Fiber Laser Marking

What Next?

Did you enjoy this post? Why not check out some of our other posts:

Disclaimer

Last updated August 26, 2021

WEBSITE DISCLAIMER

The information provided by n-Deavor Limited, trading as Laseruser.com (“we,” “us” , or “our”) on (the “Site”) is for general informational purposes only. All information on the Site is provided in good faith, however we make no representation or warranty of any kind, express or implied, regarding the accuracy, adequacy, validity, reliability, availability or completeness of any information on the Site.

UNDER NO CIRCUMSTANCE SHALL WE HAVE ANY LIABILITY TO YOU FOR ANY LOSS OR DAMAGE OF ANY KIND INCURRED AS A RESULT OF THE USE OF THE SITE OR RELIANCE ON ANY INFORMATION PROVIDED ON THE SITE. YOUR USE OF THE SITE AND YOUR RELIANCE ON ANY INFORMATION ON THE SITE IS SOLELY AT YOUR OWN RISK.

The Site may contain (or you may be sent through the Site) links to other websites or content belonging to or originating from third parties or links to websites and features in banners or other advertising. Such external links are not investigated, monitored, or checked for accuracy, adequacy, validity, reliability, availability or completeness by us.

WE DO NOT WARRANT, ENDORSE, GUARANTEE, OR ASSUME RESPONSIBILITY FOR THE ACCURACY OR RELIABILITY OF ANY INFORMATION OFFERED BY THIRD-PARTY WEBSITES LINKED THROUGH THE SITE OR ANY WEBSITE OR FEATURE LINKED IN ANY BANNER OR OTHER ADVERTISING.
WE WILL NOT BE A PARTY TO OR IN ANY WAY BE RESPONSIBLE FOR MONITORING ANY TRANSACTION BETWEEN YOU AND THIRD-PARTY PROVIDERS OF PRODUCTS OR SERVICES.


AFFILIATES DISCLAIMER

The Site may contain links to affiliate websites, and we receive an affiliate commission for any purchases made by you on the affiliate website using such links. Our affiliates include the following:

  • makeCNC who provide Downloadable Patterns, Software, Hardware and other content for Laser Cutters, CNC Routers, Plasma, WaterJets, CNC Milling Machines, and other Robotic Tools. They also provide Pattern Files in PDF format for Scroll Saw Users. They are known for their Friendly and Efficient Customer Service and have a comprehensive back catalogue as well as continually providing New Patterns and Content.
  • Cloudray Laser: a world-leading laser parts and solutions provider, has established a whole series of laser product lines, range from CO2 engraving & cutting machine parts, fiber cutting machine parts and laser marking machine parts.
DMCA.com Protection Status Follow @laseruser_com