0:00well welcome to another fiber laser learning lab we’re going to continue our pursuit of colors today and I say colors
0:08because I really probably mean color I mean we’ve got a lot to learn because as
0:18we can see from this color here depending on how I move that in the light I get a completely different color
0:25and I think the last time we established why that might be happening and that’s
0:31because of the surface texture and the way in which the light is reflecting off that surface texture now that’s I
0:39suppose what we would naturally call an iridescent color alright but when we
0:46look at some of these other colors here okay there’s a slight change as we move
0:52around in the light but they’re relatively stable you know these sort of
0:57lovely little sort of a pale J green and pale blue and then we move to the the
1:04most the lilacs and then the Pink’s then these crimson colors and finally here
1:10we’ve got gold which is a pretty stable color even if we catch those in the
1:16light right you can see that there’s they’ve got iridescent features as well right but gold is one of those colors
1:25which is produced I believe by low-temperature heating of the surface
1:31to manipulate the surface texture here we’ve got our old favorite oxide marks
1:36and as you can see the outer or lower temperature range of colors is the
1:43yellow color and the blue is the much higher temperature range in the middle
1:48okay so I’m claiming that the gold is old to do with low temperature because
1:54this is where we’re finding it on the low temperature region around about 170 to 200 degrees C something like that so
2:02I could really care for what we discovered last time we found that this heating to cooling ratio here is very
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
2:11important we could get 5,000 pulses per millimeter if we ran at 100 millimeters a second
2:17but we were getting only 250 pulses per millimeter if we were running it two
2:23thousand millimeters a second so the amount hate that we are putting into the product was directly proportional to the
2:29speed the overlap between the dots was one of the control features that we
2:35realized we could play with last time because this is heating and cooling effect meant the the less distance you
2:42traveled between each pulse the more heating you could put into a single spot and the hotter you could make that spot
2:49now the second feature that we found was that if we could overlap these lines we
2:56could increase that heating effect as well although we previously talked about
3:01all sorts of other ways of controlling power on this machine using higher or lower frequency above and below the
3:09optimum peak power frequency although focuses there as a feature for us to
3:14play with it’s not the most reliable and accurate form of control there are three
3:20features that will allow us to play with the heating effect on a particular spot
3:26one of them is speed as we’ve just mentioned here one of them is line
3:34spacing let’s call it pitch and the
3:40third one is percent power now these are
3:47all predictable and easily controllable features so from what I learnt last time
3:53I hope I’ve got sufficient mastery of these parameters that I might be able to
4:01go hunting for gold just one color let’s not get too
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
4:09ambitious we need to walk before we can run so during today’s session i hope
4:15that i should be able to prove to myself what i believed all the way along that there is no single formula for gold gold
4:23will depend on different mixes of these parameters there will be all sorts of
4:29parameter mixers that will give me gold now some will be dark gold some will be
4:34light gold if I start raising the temperature of the surface too much I’m very very confident I should be getting
4:40into this red zone here which is the next temperature zone up from gold and
4:46therefore if I mix red with gold I should probably finish up with a coppery color so when I got to a coppery
4:54color I know that I’ve pushed the boundary too far and what we saw last time was that the color that’s actually
5:00on the surface of the material is not necessarily the color that we perceive with our eyes it is a mix of all those
5:08colors that are on the surface so there is a very complex relationship between these features here what happens on the
5:17surface of the material and what we perceive with our eye now whether that
5:23is actually controllable and predictable is what we’re going to try and find out
5:28with our hunt for colors over the next few sessions my starting point is gold because that’s probably the easiest of
5:35the colors to work with we will then start probably increasing things like
5:40the pulse width to see if we can find more colors as we increase the
5:46temperature let’s start off with our four nanosecond pulse at 500 kilohertz
5:52I’m going to go for 50% power to start with and a speed which it 1500 is sort
5:59of okay that should give us a reasonable gold from previous experience
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
6:06okay now forget back the black clump there I’m reusing an old plate here so there’s our initial gold I’ve got
6:14another little lump there which I shall stay around as well but after that everything gets clear if I increase the speed
6:20I should be reducing the number of pulses per millimeter which will make it
6:27run cooler it might drop off the bottom of the scale or it might make a slightly
6:33paler gold let’s try 2000 and leave everything else
6:39the same but it’s still a very pale greeny gold so that prediction was
6:44correct so we’ve got a bit cool now so how do we increase the power
6:51we’ll leave the speed the same at 2000 and this time we want to increase the
6:56power so we can increase the power by probably lowering the pitch of it so
7:03from say 10 microns let’s go down to 8 microns so for number 3 we’re going to
7:08do 8 microns that was 10 microns just for clarity we’ve gone back to our a
7:15slightly darker gold it’s not quite as green as that one so we go another
7:21couple of microns and make it a little bit hotter you can see we’ve gone too much because we’ve got a hint of red in
7:27there now see it’s a slightly movi color so we’ve actually put too much heat into
7:32the gold now and we’ve driven it back towards red so when we look at the hand of the microscope will probably find
7:38we’ve got quite a lot of red sitting under there we will go and check these under the microscope so let’s go back
7:44and we’ll try 7 microns and yes we’ve
7:49got our gold back again it’s a slightly darker but gold it’s um it’s it’s not
7:56copper colored it’s actually quite a nice colored gold and it’s not dissimilar to the one that we had at the
8:03top here let’s move on from this one and see what we can change here to still
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
8:08keep gold so if I drop back down to 1500
8:14which we haven’t had before with 7 microns
8:21what will that do for us we’re putting more heat into the job therefore it probably might send us
8:28towards the ring again we might get a copper color who knows Wow so 1500 with a 7 micron
8:37pitch there’s but just putting too much heat into it because it’s turning it blue what else have we got we can play
8:44with the power so we’ll reduce the power to 30% and sure enough we’ve got a bit
8:49of a gold back again to pile gold maybe 20% let’s try 30 percent well we’ve got so
8:57little power on there now that we can’t even see it so it is a very very very
9:04pale gold in this light but it’s it’s almost invisible so we need to put the
9:11power back up so we could decrease the pitch to get the power back up so we take that down to six or five microns
9:18let’s go down to five microns it’s darker but we’ve overdone the power
9:23decrease I think so we’ve either got to decrease the speed to get the power back
9:28up why don’t we try that instead of 1,500 let’s go down to a thousand that
9:37was 20% hasn’t really given us a great deal of advantage we haven’t got our
9:43gold back it’s it’s goldish but it’s extremely faint in the background so
9:49let’s gradually creep up on the power again so go up to 30% see if we can get
9:55our gold back we’re almost into a blue here the same as we were here so the
10:03biggest difference between most of these colors is this pitch I’ve closed the
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
10:09picture so let’s change from 30% power five
10:17microns let’s go back up to seven microns so I haven’t done that before I buy 37 now I’ve done a 57 but not a 37
10:27and we’re down a thousand millimeters a second now whereas we were two thousand
10:32here when we were doing seven before
10:41and yes of beginning to get our gold back more spacing let’s try eight
10:47microns yeah we’ve still got our gold it’s it’s
10:56not bad it’s a little bit lighter let’s try now I might promise
11:02I might crawl the still works they’re
11:07all pretty similar we’ll go back to ten microns they’re still gold I think
11:19you’ll see they’re all much of a muchness those Gold’s there it’s getting a little bit pale
11:25but then again look at the difference ten microns at a thousand millimeters a
11:33second and ten millimeter and ten microns at fifteen hundred or even ten
11:39microns at two thousand look so here’s ten microns at two thousand slightly
11:46blue and then we’ve got ten microns at a thousand so that’s a huge range in which
11:53we’ve got a sort of a Goldy color I mean for to build us that 10 microns that at
11:59two thousand is one of the brighter Gold’s it is a nice bright gold these have got a slightly duller hue to them
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
12:06that one is definitely a nice although in this light it looks slightly green when you catch it in the light that
12:12aren’t seeing it most of the time that looks like the brightest gold of the lot so if I put the power up we’re probably
12:21going to force it towards a darker color again but let’s try that shall we let’s
12:27go ten a thousand which is hot ten which
12:33is cool because we’ve opened the spacing up and now we’ll put some power into it
12:38as well so let’s go from 30% to 40%
12:43it’s got a slightly blue cast to it we
12:49won’t know until we look at under the microscope what the colors are within that gold surface so we push it up a
12:57little bit more we’ll go out to 50% and
13:03then we shall have a comparison between 50% as a thousand and fifty percent at
13:101,500 and 2,000 and yet now we’ve done it we’ve pushed it over and we’ve gone
13:16to blue so we’ve gone too hot now 50% at
13:23a thousand it’s too hot we could leave it at 50% and we can increase the
13:30picture gain to say 12 microns that should cool it down so now we’re calling
13:40it down it’s no longer a bright blue we’re getting back towards more like one of these colors here so we could
13:47probably go a little bit wider on the spacing say 14 microns so now we’re bringing our gold back into play again
13:55by calling it down opening up the spacing can I not the spacing a bit more
14:0216 microns the answer is yes I can and
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
14:07it’s becoming an even better gold so we’ve gone from a blue to a slightly
14:13blue hue that gold air looks almost as good as number three or number one a
14:19convenient point to stop maybe and take a look at these first set of results now oK we’ve got all these other Gold’s in
14:25between slightly different colors but the two that seem to match for these b3 sorry a3 and b10
14:33now this may actually be more significant than I thought when I first
14:38picked it up in the previous session and dismissed it so b10 is done at a thousand millimeters a second with 50%
14:45power and 16 micron pitch a3 is two
14:53thousand millimeters a second with 50% but this time with an 8 micron pitch let
15:01me just remind you of that little picture which I talked about in the
15:09previous session if we look at 83 we’ve got 125 lines in a millimeter and
15:14we’ve got 250 pulses in a millimeter that’s a total number of pulses of 30
15:211250 and if we check the same thing for b10 we find that we’ve got 62 and a half
15:28lines per millimeter with 500 pulses per
15:33millimeter which again comes out to the same number of pulses per square millimeter so this might be worth
15:39investigating just a little bit further to see if this is just just a coincident set of data because it could well be
15:47that the there is a relationship between the lines per millimeter and the pulses
15:54per millimeter so taking that to a conclusion I wonder what happens if we
15:59decide to put in 32 microns that’s mm that’s really pushing it
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
16:07because the beam is supposed to be 60 to 65 microns that means we’ve basically
16:13got around about three lines three and a half lines overlapping here maybe we’ll
16:18go to 20 and we’ll see what happens at 20 microns that will give us three lines of overlap it means we’re going to get
16:2550 lines per millimeter and 50 lines per millimeter divided into three one two
16:32five Oh gives us 625 pulses per millimeter and then when I take a look
16:39at my chart here 625 pulses per millimeter as a speed of 800 millimeters
16:47a second so that defines for us 800
16:53millimeters a second with the 20 micron spicy let’s test that should we well I
17:02would actually say that that and that and that you can’t see in this light but
17:12they certainly all look the same what else can we predict I think if I
17:17stretched this much further I should be in trouble we could try 25 that gives us
17:24a running speed of about 650 millimetres a second still leaving everything else
17:32the same well that’s still a perfect match we might be on to something here
17:3810 microns well that looks like another
17:49success big difference in the settings no difference in the color the maximum
17:56speed we can go to is 2,000 so let’s
18:01leave mm 50% and work out what the micron spacing should be it’s going to
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
18:07be 8 because we’ve done it already we did it for number 3 so so we’ve gone
18:14from 852 mm 20 microns to 8 microns we
18:23will do it again just so that we’ve got it in comparison and there it is again
18:28four in a row all exactly the same 800 650 1600 mm 20 microns 25 microns 10 and
18:388 phenomenal change of parameters but all arriving at the same result so we go
18:44to repeat these four results here but with 100% power rather than 50% power
18:50normally when you throw a hundred percent power at something you get the
18:57sparkly crinkly surface especially with these small posters where you tend to
19:02dig in quite a lot I’m not sure that we’re going to get too much color change
19:08I am moderately confident that these are all going to be sparkly gold sparkly yes
19:18just a lighter shade yes still a gold I
19:25would say erring towards the silver but
19:31definitely got a gold here in there when we look at that carefully we may well find it there’s some blue in there but
19:38we’ll carry on and we’ll see how had the others match up to that particular platen it’s still a light gold very
19:46light now it’s a similar color to the one beside it but when you turn them to
19:54the light they’ve got different reflective characteristics let’s go for
20:00the last one which is 2008 Mike Ross
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
20:07well that’s another success now I’m going to jump off a cliff I’ve got no
20:14idea what color I’m going to get but let’s try exactly the same test let’s
20:21double the the false density so here’s my next test we’re going to use exactly
20:27the same speeds with a hundred percent power the same which gave us golds
20:33everything here remains the same the only thing is we’re going to have the pitch between the lines for each one of
20:41these now whatever color that one comes out I would expect that that and that to
20:47match that’s if we were onto something interesting here now on the basis of our
20:54a3 test which is what we did at some stage it’s hinting towards maybe somewhere
21:05down here in the bluey emerald green region pale blue pale green we left the
21:16wait-and-see silver for the hint of mmm silver with a hint of bluey green in
21:24it let’s try the 651 well all I can say
21:29is there’s another matching one silver ish with a hint of possible hint of
21:35cream now we’ve got a pale blue a
21:40sparkly pale blue well that’s a perfect match it’s a very nice pale blue now
21:51just as I’ve gone to change those settings I’ve realized I made a slight mistake last time and this one should
21:57have been 5 microns and that is 5 microns so there’s a very slight color
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
22:03difference in the blue when I went to 5 microns as opposed to 4 microns so 4 & 5
22:09microns beside each other there
22:23you know they’re very nice golds perhaps I ought to sit down and work out what the what the pixel density is in these
22:31and see if we can replicate these because these are very nice golds the
22:37others are fairly weak in comparison you can see when I even as I move those
22:44around in the light they really don’t change a great deal all the others have gone dark but those are actually showing
22:50their true colors and that’s because they’ve got a disrupted surface finish
22:55they’re reflecting all over the place
23:02particularly these last two here which the 1600 and 2000 at two and two and a
23:09half microns so I’ve chosen a range of
23:14pictures here from threat from 2.5 up to
23:2012 microns and I’ve calculated the appropriate speed which will generate a
23:28hundred thousand pulses per square millimeter so the three four and five
23:33micron tests come out more or less the same as the standard two and a half that
23:39we started off with which is that one so we’ve done the same test again but we’ll
23:44use the copper this time and see whether or not the copper gold in this last row
23:50replicates reasonably well as well or whether it can extend down further than
23:55this as I said these are all gold but some of them are fairly weak and pathetic and they’ve got a shiny surface
24:01on them which means that they can only be viewed in one direction so we’re
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
24:09definitely after these speckled colors because these are the colors that are going to if you like survive in almost
24:16any light so we’ve now chosen the coppery gold and matched up the speeds so that they come
24:24out two hundred fifty six thousand five hundred pulses per square millimeter and we run ten more results off and see what
24:31we get now these first three at one point six two and three microns are all very very
24:39good now all that lovely coppery gold color now these others are also pretty good
24:47coppery gold you see they run all the way down as a gold and in fact they are
24:53a slightly coppery gold more coppery gold than the ones beside it so and
24:58clearly see on here those that enjoy playing with the light and those that
25:04are not very happy with it but I think the case is now proved that there is a
25:10whole range of speeds and pictures which
25:15provided you set the other parameters correct you can vary quite a lot if you
25:21stick to a certain rule and the rule is polish density per square millimeter now
25:27although we found all sorts of Gold’s on there and I’ve been very successful with my gold mining today we can see the ones
25:35that are obviously standing out these are the speckled ones so they’re
25:41slightly deeper and they tend to be the finer pitch ones that you can see in
25:47this light which is great because it means they’re no longer particularly
25:53sensitive to light direction they pick up the light from all directions and that really is what my total aim will be
26:00to try and produce a palette of colors that are virtually impervious to the
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
26:06direction of the light didn’t have a look through two or three of the samples under the microscope just to show you
26:12those textures that are created by the different parameters all these samples that I’m going to show you had done with
26:17hundred percent power this first one is six microns pitch six hundred and fifty
26:24millimeters a second I think you could probably guess from that forney look that it may well be a gold you can only
26:31see that it’s gold in one direction in another direction when you can turn the light across it it’s it’s black you
26:37wouldn’t know that from looking at that because that looks as though it’s a pretty good gold let’s take a look at it in high magnification well I can tell
26:44you that that surface there is basically high disturbing the surface of the material
26:50we’ve got all these marks here which are the like the oxidization marks that
26:58you’ve seen on my flat metal sample we’re not actually burrowing into the or disturbing the surface of the material
27:03very much maybe just in one or two places where the power is high in the center of the beam we might just be
27:11breaking through the oxide film so it’s not a uniform film that we’re seeing it’s an effect a color effect from a
27:19variable a continuously variable film now this was done at three times the
27:24speed almost 1600 and but this is done with a two micron step there’s some
27:31definite sand yellowy cream in there that is virtually the same color as the
27:38one next to it except that this one is glittery let’s see what the what’s
27:44caused the glitter when we look at the high magnification what we’ve got there are blobs and pits the green pieces
27:53which I’m bringing into focus now and look particularly at something like this one up here which has got particularly
28:00I’ve got a lot of depth because you could see that from the way I’m bringing the colors in those color bands can you
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
28:06see all those color bands just around there I mean they are variable degrees
28:12of oxide thickness within a pit and then
28:19if I change the focus and bring it up to the surface put all these lovely heat
28:27patterns these colors that we’ve seen on my oxide film look the Blues the Browns
28:35the yellows which are in the background I mean it’s a right mixture of color
28:43here at the surface does it look as though it’s going to come out gold now
28:50there’s a predominance of yellowy stuff there I suppose that’s definitely surface disruption and that has
28:56caused a sparkly color now here’s another sparkly one more or less the
29:02same color I would say that on the surface of it this looks as though it might be a lighter color this was two
29:08and a half micron interval with a two thousand millimeter but second speed not
29:14a huge difference for the previous one so we haven’t got very much yellow in this one we’ve got our large changes in
29:22depth we’ve got probably three or four microns there I suspect if I was to
29:27measure it we’ve got this sort of pale yellow which looks as though it’s on the surface and then we’ve got these pixie
29:34which look as though they’re buried into the surface we’ve got a few bits of this orange and red but we saw on the
29:42previous one but at this high magnification the colors are nothing
29:48like the previous one and yet stand of side by side and they look virtually the
29:54same to the naked eye this again to the naked eye it’s not quite a sparkly gold
30:01and it’s not a flat gold but then again the parameters for this are totally
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
30:06different than those that we’ve just seen now I’m going to move it up you can see the line across the top there which
30:12is the line that created this pattern but this unlike the others has done slow
30:19at 800 millimeters a second with a huge pitch of 20 microns and 100% power the
30:29same as the others now you’d ask yourself the question why isn’t that a
30:35blue because there’s a greater predominance of blue in that pattern then there is gold nope it comes out to
30:44the naked eye as a slightly non flat gold it’s not polished gold again it
30:53does lose its color when you turn it away in certain types of light well I
31:00could spend hours looking at this stuff because it’s absolutely fascinating well it’s very difficult to catch my test
31:06plate in the right light to show you all the possible is that happening I mean these are all
31:12most of these are golds as it happens these came out quite well you can see that they’re all gold up here they look
31:18white but in fact these are nice sparkly golds but what you can see on these
31:24pictures is that these are sparkly and the ones that we’ve just looked at on the screen in high magnification this
31:31one here which is a flat gold this one here which is a sparkly gold and this one here which is a semi sparkly gold so
31:38you’ve got this fairly crude image as a reference starting point and then what
31:44I’ve done I’ve taken images of each one of my tests this one is a one at
31:5250-times magnification this one’s a one at 400 times magnification so you’ve got
31:58low and high resolution for each one of those test squares okay
Transcript for Fiber Laser Engraving Metal – Various Achievable Colours (Cont…)
32:04you’ve actually got the test square picture here and beside that what we’ve
32:10got is a record in the form of a spreadsheet with all the parameters and
32:17two quick thumbnails of 50 times and 400 times between each result so if you
32:25really are interested in seeing these images in high resolution then I’m happy
32:30to send them to you what you need to do is to add your email address a disguised
32:35email address write it out in words john dot smith at yahoo.com all is one great
32:45big long string i will send you a link to my dropbox where you’ll be able to download all these onto your own pc and
32:52study them if you wish to now these these pictures good as they are they
32:58still are only probably about 80% of the quality that I can see directly into the
33:05microscope the microscope gives a much clearer image of what’s going on but these are very good representations and
33:12will give you a feel there is no depth all I can do is find an optimum focus
33:18when I take the picture so I think we’ll conclude at that point and
33:23next time we might go searching for some different colors now we’ve got a little bit of an understanding of how it all
33:29works thank you very much for your time and I’ll catch you in the next session
