0:00welcome to another fiber laser Learning lab
0:02today I’ve just been left in the
0:07sweet shop and I can have the pick of
0:09any sweets I like Wow well here we are
0:15we’ve pimped up my 40 year old
0:18stereomicroscope with a rather modern 41
0:22megapixel camera and they’re
0:25specifically designed for working on the
0:26eyepiece of a microscope and we’ve also
0:29put a nice LED lighting ring around it
0:32now the problem with the LED lighting
0:35ring is that of course it throws a light
0:36straight down now we’re looking for
0:39colors that are probably going to be
0:40seen from incident light and I don’t
0:43know how well this is going to work this
0:46is stage one and it does enable me to
0:49show you some of the things that I have
0:51seen so one of the first things I saw
0:54through here ever was these lines that
0:56I’ve edged onto this piece of stainless
0:59steel it’s a little bit out of focus at
1:01the moment and probably let’s put it
1:02back onto the center of the screen and
1:04one of the problems with this magic with
1:06this microscope is that first of all it
1:08isn’t mm super responsive it’s a little
1:13bit laggy and of course the focus that
1:19I’ve got on this stereoscope is not
1:21super fine it’s fairly coarse so let me
1:25just bring it into focus about there if
1:30I took a stick and dragged it through
1:33the sand I would finish up producing not
1:38only a groove but also a pile of sand on
1:42either side of my stick let’s remember
1:46that this groove that’s in here has been
1:49created with a laser beam a beam of
1:52light it has no solidity so how can it
1:55do that and force material out the side
1:58of the beam the only thing I can think
2:00of is that as it heats up and melts the
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
2:04melt material is it’s actually boiling
2:07so hard that it actually bubbles out
2:10onto the sides and as it bubbles out
2:12onto the sides we’ve got this little
2:14raised section here this is the basis
2:16upon which I started to muse that we may
2:20well be able to put another line right
2:22beside it if if I was to work this way
2:25what I would do I’d be finishing it
2:27finish up with a series of these little
2:30ridges moving behind so I would finish
2:33up with something that looked a bit like
2:35a plowed field you know nice even ridges
2:39a pattern a uniform pattern all the way
2:41across the material now that was the
2:43basis upon which I started to consider
2:44this butterfly wing approach by which
2:47we’ve got a uniform pattern or regular
2:49pattern running across the surface that
2:52reflects the light both by a combination
2:54of thin film interference and if you’re
2:58like interference patterns between the
3:03thin film interference patterns so we
3:06produce these colors by a complex
3:08arrangement of physics now whether or
3:10not that actually happens we’re going to
3:14try and discover but that’s that’s the
3:16thought process behind how I think these
3:18colors actually come into existence
3:20because their colors that go beyond this
3:23flat surface thin film interference
3:25effect what happens when we start
3:28looking at some of these colored
3:29patterns that’s the thing that really
3:31interested me and to be honest when I
3:35started looking at some of them and
3:37let’s just pull one across for a minute
3:38now the problem that I’m having with
3:40this camera is that this is a sort of
3:45emerald green when you catch it in the
3:47right light we can’t see enough detail
3:50in here to see what’s going on with the
3:52surface texture this is the still and so
3:57you can see the steel is sort of gray
3:59this looks as though it might even be
4:01black but as I said it’s basically an
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
4:05emerald green hue when you look at it in
4:08daylight so we get no idea what color is
4:14with this system so as I mentioned to
4:16you previously when I wanted to kit up
4:18to look at this we
4:20can’t do it with the standard
4:22stereomicroscope because there is just
4:25not enough magnification to see what’s
4:27going on down at the crystalline
4:29structure level on the surface of the
4:31material we’ve got probably around about
4:3340 maybe 45 magnification here and
4:37that’s about as much as we’ve got yeah I
4:40could spend time on the screen there
4:44setting the color balance up right but
4:47I’d have to do that every single time I
4:49switch the camera on I’ve been to visit
4:52a company down near Swindon they
4:54specialize in scientific microscopes now
4:57they’re not top of the range Zeiss or
5:00something like that microscopes they are
5:03basically from China but they have been
5:06specifically designed for a guy who
5:09understands scientific microscopes he
5:12has spent his life working with them I
5:15went down to visit the guy with one of
5:16the sample colour swatches he’s not an
5:19engineer he used to be a botanist so as
5:22soon as he he understood what I was
5:24trying to do which is the look for
5:25butterfly wing patterns he was
5:28absolutely in his element another guy in
5:30a sweet shop so he was able to
5:34completely out of this whole roomful of
5:37probably about four or five hundred
5:40different microscopes that he had there
5:42and he’s if you like demonstration
5:43laboratory he guided me towards
5:46something that I’ve got in the office
5:49we’re going to look at my even newer toy
5:52or big bag of sweets I’m such a happy
5:56guy so my other camera has got very good
6:01resolution and it’s K could take us a
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
6:04good quality video the problem is
6:07without a brain it’s kind of
6:10faithfulness leaves a lot to be desired
6:13whereas this one has got some
6:15intelligence automatically built into it
6:17and when I went to see the guy at Brunel
6:20microscopes where I’d bought this from
6:22he demonstrated this and he demonstrated
6:24the sort of camera that I’ve got and
6:27there is no competition so despite the
6:31fact that this was painful
6:33I felt I had to have it to be able to
6:36show you guys what is actually happening
6:39under there now what I’m going to do for
6:42the last part of this is to look at some
6:44of the things that I’ve been talking
6:46about previously and said Wow look at
6:48this look at that sorry you can’t let me
6:51just zoom in on this a little bit
6:52several things about this camera it’s a
6:54lot it’s a lot Mysteria I don’t have to
6:56move the the sample around because on
6:58the side here this has got a proper
7:01microscope stage for moving backwards
7:04and forwards or left and right and I can
7:07do that down here so I get a nice steady
7:09movement under the camera the second
7:12thing it’s got it’s got a very very fine
7:14and calibrated focus so each one of
7:21these divisions on here is 2 microns so
7:24I can determine to the nearest micron
7:26the depth of focus and trust me when you
7:31get to high magnifications you can do
7:33some great vertical measurements with
7:35this system as I will demonstrate to you
7:37in a few moments now the other thing
7:40that it’s got this weird system at the
7:42back here now
7:44this is a normal halogen lamp in here
7:47because I mentioned to you before
7:49halogen lamp is a closed replication of
7:52sunlight there’s a wide spectral color
7:55range within the light whereas with LED
7:58lights it’s a very suppressed color
8:01range this light comes through here it
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
8:04passes through some filters if I need
8:06them and then it goes down here and it
8:08appears through the lens down onto the
8:11surface that I’m looking at the problem
8:14that we have with the work that we’re
8:16going to be looking at is that we need
8:18probably incident light from the side
8:22because that’s how this phenomenon works
8:25in some instances I’m not sure it
8:28happens like that in every instance
8:29because some of these colors you could
8:31look at from all angles and they remain
8:34fairly stable but some of them you have
8:38to hold them just the right position to
8:40the light to see the color so in
8:43addition to this
8:44through the lens light which I can turn
8:48off or regulate up and down we’ve also
8:51got these separate LED side lights which
8:56allows us to put incident light onto the
9:00subject every possible combination that
9:02we need is built into this microscope I
9:05think we’ve got 50 times hundred times
9:11200 times and 400 magnification now I
9:19could have had 600 and a thousand but
9:22from the from the work that we did in
9:26his little experimental demonstration
9:28room it looks as though we don’t need to
9:30go more than 400 times because I will
9:33show you what 400 times looks like on
9:36the screen with some of these samples
9:37right so you’re know looking at the
9:39Canon software that’s available on my
9:42screen here let’s take a look at that
9:44green sample that we looked at before
9:46so there we go you can almost see the
9:50intelligence of the brain working there
9:54when it’s got just green on the screen
9:58it adopts a slightly different color to
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
10:04when it’s got some other color on the
10:06screen to do comparison with but I don’t
10:08think got any doubt that that is a green
10:10an emerald e-type green and then we’ve
10:14got a pale blue here can’t make up his
10:17mind about that one can it and we turn
10:19the main light off I mean there’s the
10:23silver color of the stainless steel and
10:27we can see this yellow burning here and
10:32we can see the pale blue now sort of a
10:35gray slate blue which is approximately
10:37what I’m seeing here this one is more of
10:40a coppery color
10:47so that’s the main central light turned
10:51on and I don’t think there’s any doubt
10:53that you could say that we’ve got when
10:55we’ve got a full spectrum light and we
10:56can turn the side lights off now and you
11:00don’t even notice that the side lights
11:02have turned on or off so it does depend
11:06on the texture of the surface and the
11:09color that we’re producing as to whether
11:12or not side lighting is required
11:14incident lighting is required or not
11:16let’s take a look and see what it looks
11:18like at a hundred times we need to
11:21refocus again it’s got some interesting
11:26imperfections in the surface there let’s
11:30go to 200 times and how you were getting
11:34all sorts of very very small details
11:36coming in now will come into focus if
11:39you look particularly just there as I
11:41play with that look you can see in the
11:43bottom there’s a little there’s a little
11:45shadow here which comes in there to
11:48focus well that comes in and out of
11:51focus there at and let me tell you on
11:53the knob 41 microns and yet if I bring
11:58it up to the surface which is there
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
12:05that’s 46 microns so there’s five micron
12:11difference in the depth between the top
12:15and the bottom of that pattern now that
12:18might sound just a number but I think
12:21that that number is very important to
12:24the effects that we’re going to find
12:26when we start looking at the texture of
12:28these surfaces so let’s go one
12:31amplification more which is to 400 and
12:34look now you can see as I fiddle around
12:37with the focus how certain parts of up
12:39are in focus and certain parts are out
12:43of focus to red bits on the top are the
12:47bits that are giving the coppery effect
12:49and there’s it mixing the bottom there
12:52with the yellow so it’s the mix of those
12:55two colors that look as though they’re
12:57producing our copper if
12:59so let me turn the side lights on and
13:03I’ll turn the lights off again no
13:09different
13:10I could also turn this main light off
13:14and put the side lights on now you can
13:18see that you know there isn’t the color
13:21spectrum available on that white light
13:24to give us the whole range that we’re
13:26looking for okay let’s take a look at
13:29that green what’s the difference between
13:31the copper and the green I wonder
13:34look at the texture difference it’s
13:36completely different texture what about
13:39the difference in the height between the
13:41blue and the green background let’s just
13:45have a look can I get anything they’re
13:49almost the same I don’t think there’s
13:51very much difference I’m trying to find
13:53a piece of clear
13:58maybe maybe here let’s have a look so
14:00what we can do here we’ll bring this
Transcript for Fiber Laser Engraver: We are no longer Flying Blind(Cont…)
14:03this black is obviously hiding down a
14:06crack somewhere
14:07we’ll get that little black mark there
14:09spot-on focus and we’re at about 85
14:14microns and let me see if I could focus
14:17up on some of the blue somewhere that’s
14:20about 83 at the most close to 84 so
14:27there’s only about a one or one 1/2
14:29micron difference in the texture on that
14:33surface now that’s the sort of thing
14:36that are convinced we’re going to be
14:37looking for to get different colors
14:40different types of texture on the
14:42surface now we can’t say in this light
14:45but just there the colors that I’ve been
14:47looking at are fairly why I call solid
14:50colors they’re not these speckly colors
14:53now when I look at this pattern here
14:56I’ve got several pinks and moves which
15:01are nice and and greens of pale blues
15:04which are nice and sparkly so let’s use
15:07this pinky color here to look at to
15:10start with
15:12get the idea now we’ve got a completely
15:14different surface texture completely
15:17let’s just look at the tops of the
15:19texture in fact what we’re doing at the
15:22moment we coming in at the bottom look
15:23at these because these little blue spots
15:25here then you’ll see that as I bring
15:27them into focus just about probably
15:32about there we are showing up as -6
15:39microns and now we’ll take it up to the
15:43top so we start looking at things like
15:50this yellow spot here as being on the
15:54top you can just see the tops coming in
15:59and that’s about minus 10 so that’s
Transcript for Fiber Laser Engraver: We are no longer Flying Blind (Cont…)
16:06about a 4 micron difference but that’s a
16:10completely different pattern for a
16:13different color if we change this back
16:15to 200 now we can probably get more of
16:18it in focus and I don’t think there’s
16:20any doubt you can see the underlying
16:21pink that’s in there the movi pink
16:24that’s halogen light directly on the
16:27surface and that’s white light from the
16:30side now the reason that they’re showing
16:32that pattern like that is because this
16:34white light is fairly concentrated at
16:38the blue end of the spectrum it’s not
16:41down at the red end of the spectrum
16:42whereas in fact the halogen light has
16:48got a much wider spectral range and
16:50we’re more likely to see what’s going on
16:53now the other thing that’s interesting
16:55apart from colors is as I said the
16:59amount of damage that we’re doing now
17:01there is one of my grid lines there’s
17:06the little pile of sand that I was
17:07telling you about that’s that’s piled up
17:10on either side of the groove and that is
17:12at a height of 62 microns let’s find out
17:18where the surface of the material is I
17:20would say the surface of the material
17:22focus is about
17:23they’re so 62 that ones 42 so that pile
17:33of sand on either side of the crew was
17:3420 microns tall okay so let’s now go
17:40down to the bottom of the groove and at
17:42the moment where as I said we’re reading
17:4442 let’s go down to the bottom of the
17:47groove and find out what depth the cut
17:50is look at it isn’t it amazing you can
17:54see every little ripple of the pulsing
17:58action does taking place 25 so that’s 15
Transcript for Fiber Laser Engraver: We are no longer Flying Blind (Cont…)
18:05that 17 microns deep that groove now how
18:10did that get 17 microns deep below the
18:13surface is it just the explosive energy
18:16with which the melting takes place
18:19because it’s cast it up onto the surface
18:22and it hasn’t run back so it must have
18:26cast it up onto the surface and
18:27instantly cools leaving that channel
18:31down in the middle I mean that’s
18:33fascinating isn’t it
18:34okay let’s just I’m loving this plane
18:37let’s just pop that off and pop that on
18:41just because I can and we can still see
18:45down into that groove from the reflected
18:47light it’s not quite as clear when we
18:50were messing around with the focus I
18:52generated this little pattern so that
18:54was with the focus on the surface and
18:57then we went point to five up point five
19:01point seven five and one millimeter we
19:04lifted the focus up by one millimeter
19:06above the surface and then we went all
19:08the way down to three four five six
19:19millimeters above the surface and at six
19:22millimeters above the surface you could
19:24begin to see there’s a change taking
19:26place here at just after five at five
19:28point two five five point five look
19:31we’ve got lines going along the side
19:36and then we’ve got this breakup okay as
19:44we’re running out of power this one has
19:46done at a different power where you can
19:51see much clearer what’s going on now you
19:54may remember when we talked about focus
19:56how I was trying to describe to how the
19:59focus was not that the beam diameter was
Transcript for Fiber Laser Engraver: We are no longer Flying Blind (Cont…)
20:02not going to change until we got to the
20:06very tip of the power of the beam I’ve
20:11used strange words there but I think my
20:13pictures really described what I’m
20:15talking about and if we look down here
20:17as we start raising the focus we still
20:20got power we’ve still got the same width
20:22beam we’re still doing the same amount
20:24of damage at two millimeters above the
20:26surface three millimeters above the
20:28surface okay we’re getting a slight
20:30change in the pattern now of the debris
20:33on the side of the groove four
20:35millimeters but we still got power there
20:38now we’ve got some color coming into the
20:40bottom of the groove now you’ll notice
20:41but now look at number five we’ve
20:44started to get a distinct thinning of
20:47the line itself and there we go look
20:52we’re now starting to lose power and
20:54lose line thickness now this is the
20:56effect that we achieved with the
20:59 co2 laser as we went faster and faster and
21:01faster we were painting with a thinner
21:03and thinner part of the Gaussian beam
21:08here we’ve got exactly the same effect
21:10but of course we’re not running faster
21:13and faster we’re running at the same
21:14speed what we’re doing is lifting the
21:16Gaussian beam up above the surface so
21:19the thinner and thinner power part of
21:22the beam is now taking over and we’re
21:24getting less and less power and now
21:27we’re just about to run out of power and
21:29now all you can see in the background is
21:32the ghosting effect of if you like the
21:35out-of-focus beam that was really there
21:38around the outside of this central core
21:40let’s just go and have a look at high
21:43magnification
21:47in that groove sounds I focus in on
21:50there I think you could see a lot of the
21:52tempering colors that we had seen
21:54earlier
21:55additionally there are some other colors
21:58in there like there’s a green in there
22:00which is not one of the natural
Transcript for Fiber Laser Engraver: We are no longer Flying Blind (Cont…)
22:01tempering colors so my shear material is
22:04obviously not flat because it’s going at
22:06a focus oh look at that when I change
22:09the focus I get the red and when I
22:13change the focus again the blue comes
22:15into focus so there’s different depths
22:18there along that colored line well I
22:22think we’re in no doubt now that we’re
22:24on the right track these colors come
22:26from surface textures and what we have
22:29to do is to develop the technique for
22:32finding the right texture for the right
22:33color now there won’t be a single answer
22:38to this question because some colored
22:40suspect colors as you’ve seen and some
22:43colors are solid colors so there’s going
22:46to be lots of different ranges of
22:48textures but the question is how can we
22:51define a range of settings for the
22:54machine to access these range of
22:57different colors and textures that’s a
23:01lot of work for the future but hey we’ve
23:04now got the tools to do the job
23:05I’m getting a bit over dosed on all this
23:07sugar and I’m a bit hyper so I think
23:10we’d better stop there now and I’ll come
23:12down to ground thanks for your time and
23:14I’ll catch up with you in the next
23:15session
