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OMFG! "Cancer ray"!!!!

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Curiously_Coherent said:
Not sure about the cancer risk but I have personally "sunburned" my skin quite badly with a 26W SW UV lamp that I photograph fluorescent minerals with.

Cheers, CC
:eek: How long did that take? Was it just a flash?
 

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Guest
Hey, so you are the dude that got the rest of these lasers

I have 6 of them one had a very low output (about 1mw), one the main tec is damaged and it won't come out of 'temp stabilization' mode, one is doing about 45mw of 355nm at 6khz rep rate, and 3 of them are in the mail :)  I have pictures of the low output one up at my website at krazerlasers.com/images/355nm/ in case you are curious as to what is in each of these oh so carefully sealed boxes.  Also, the initial diagram posted s not quite right, the module closest to the power connector is an 808nm pump source (consisting of 2 9mm can 808nm laser diodes co-colimated with a pbs cube) which is then fed into the middle module which has the 1064nm cavity optics, the AOM q-switch, and a small (roughly 3x3x3mm) yag or very low doped vandate crystal.  This outputs nanosecond ~.1mj pulses of 1064nm which then is converted to 1064+532nm, by a long (2x2x6mm) nonliner crystal (ktp?) and then converted to 355nm by an even longer (2x2x12mm bibo?) crystal.  The resulting mix of 1064 532 and 355 (and probably a tiny bit of 266 and 808) is sent through a few dicros to separate out the 355 in that assembly closes to the front.


In any case, the easiest way to get this laser to run is to plug in the interlock defeater (you lucky bastard, you have no idea how long it took me to figure out which pins I needed to ground to get it to lase), feed it with 24v (it will suck up to 3A so you need a pretty decent supply), and while you wait for the 5-10 minute warmup period grab a ne555 and build an oscillator that will go from about .1-10khz  The key with getting these lasers to run is that the rise time of the trigger needs to be <100ns, so crappy function generators or slow logic won't work.  If the timer you have is to slow, run the output through a logic gate of some kind (preferably one with hysteresis) which will clean up the signal and keep everyone happy.  When the laser switches over to double yellow flashes (the difference between yellow/green is subtle, but if you watch for it quite noticeable).  Then you can hook a 1khz trigger into the trigger in, and in a few seconds the light will go to solid orange, then solid green, and within a minute you will have a nice UV dot on the (preferably florescent) target you set up.    After you get it lasing turn up the frequency, I found the power will increase up to a sweet spot at about 5khz, and then slowly die off after that when the pumps can't keep up with the reprates.  Running at 5.6khz I was able to to burn through electrical tape quite effectively, the q-switching makes it quite a fun burner!

Good luck getting yours running, they are awesome little beasts!  I plan to convert the low output one to 1064nm, I expect about 100-300mw of IR based on the 50mw of 355nm and comparing data sheets.

BTW if you haven't found them yet, the manuals are at
laser-export.com/prod/garnet.html  (it took me forever to figue out that the oem system manual was on that page, not the page that mentions the DTL-374QT part number)
 
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Thanks for load of info! The exact model is DTL-374QT, not the garnet model. These appear to use the garnet PSU but these are just standard OEM PSUs for laser export lasers. I have spoken to Laser Export and these units were meant to be integrated into mass spectrometers made by "Lifetechnologies" AKA "appliedbiosystems"

As for the interlock connector, I built it from the data sheets ;) I'm gonna have a full interlock remote rigged up in a few weeks when I get a chance. The TEC is a standard 136W, you can probably replace it with a generic one.

The front end is not a dicro, it is a harmonic separator. It "filters" out the excess 1064 and 532 allowing only 355nm to pass...
 
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Guest
Glad you figured out the manual situation, I also have a hard copy of the manual I got from teamlaserplus that is different altogether (it looks like the one from the garnet series, but was customized for one laser sold to some company (I forget the exact details)


BTW, the optic at the front serves as a harmonic separator, but it is made out of a dichroic mirror, which reflects 1064/532 and transmits 355

UPDATE: Turns out the optic at the front of the laser is just a prism, and all that is needed to get a green beam out of the beast is to remove the beam stop at the end of the laser!  It is the anodized piece of aluminum closest to the output end of the laser, just take out the 2 flat head screws holding it in (they are glued, but will turn with a little bit of force)  After you remove it the green beam will come out of the main aperture at a slight angle.  I won't have time to get out the power meter until next week, but in this mode I am estimating 50mw of 355 and 100mw of 532 (at the same time) being emitted.  Also, in this mode if you pull off the front apeture (just remove the 2 3/32" hex screws from the front of the laser and it will drop right off, it will put out a fair bit of 1064nm (there appears to be more 1064 than there was 532, but the uv has more burning power than either of the 532/1064.   One neat thing about the 1064 is that normal lenses will focus it, and if you do a decent job focusing it you can hear each of the small explosions (1 per pulse) so the resulting plasma ball will buzz and the frequency you are triggering the laser at!  Also because it is q-switched it works amazingly well for etching anodized aluminum, you can burn strait through the anodisation about as fast as you can keep the part in focus  :D On that note, this laser is most definitely not eye-safe, even when running at 'low' powers it is capable of literally vaporizing things, bits of skin and eyeballs included. Even the unfocused beam will slowly turn white paper yellow as it burns the die :eek:

 I haven't got the courage to open up my half power one (it still has a sealed sticker over the cover, so removing it is a big step) but I would expect that putting an optic coated to reflect 532nm (green dicro or the likes) would let you extract about 50-100mw of green without reducing the UV output significantly.  By opening up the tripler box and unbolting the second crystal you should be able to up the 532nm output to something on the order of 200mw, but that would obviously kill the uv output.  Lucky because it is doubled outside the laser cavity the alignment of the doubler/tripler crystals isn't critical so it should be fairly easy to mess with them.

As to the tec, I am hoping the tec itself is fine (have you ever seen a tec actually go bad?  unless you physically crack it they are generally quite robust) but that the problem lies in the controlling circuitry somewhere.  I only had about 20 minutes to look at it before I had to head back to school, but I did not observe any blatantly obvious blown parts or disconnected wires which is leading me to think there is an issue with control loop. I know that it is trying because it will draw a little over an amp (compared to about 2.5a for my working head) during the warm up period, but I am pretty sure that is only running the crystal tec and q-switch driver. Lucky they are fairly simple buck converters based on the oh so famous tl494 pwm controller, so it should be fairly easy to figure out where the issue is.  Oh well, I hope to get it running over spring break (which starts tomorow!) along with the other 3 Bob is supposed to be mailing me.  One the bright side if this laser was indeed scrapped because it had a damaged tec it might very well do full power *hopes* when I get it working.

UPDATE - on a hunch I tried plugging the bad-tec head into a known-good power supply, and sure enough the tec worked just fine and it started lasing (and putting out a ton of power to boot, possibly slightly more than I was getting from the half power head).  I am not sure why they mention that you need to match supplies, it looks like they set the temps in the laser head (the pots by the main input connector) and looking at the psus I have I don't see any real reason why you would need to match them.  I am thinking it may be that that qswitch is tuned for each supply, or that some of the rework done in older supplies is not compatable with the newer head designs (for those that haven't looked in one of these power supplies, there is a pretty good amount parts that are obviously hand reworked, diodes rigged to find in the pads for a resistor little circuits rigged etc).  

Good luck with your project!  One thing I will say about the interlocks is that it takes a while for the laser to realize it has been put back into armed mode, and personally I would just use the signal running the q-switch as the interlock.  If it doesn't have a <200hz signal it will go into standby (double yellow flash) mode, until you give it a valid trigger, and it only takes about 30s to get a beam out and another minute for it to stabilize after that.  
 
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Do not connect a PSU to a head with a different serial! You will probably end up burning something out... There are some pots inside the PSU and Laser head that will need adjustment before running the laser on a modified PSU or vice versa...
 

iewed

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Niko said:
In soviet russia, laser makes YOU!!
This is by far the most meaningful and informative post in this thread. I commend you good sir on your expansive knowledge on the geography of the world and lasers. :cool:
 
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Guest
Ok in my last hours at home I took some numbers, and am quite pleased with these lasers!  Best $120 (times 6 lasers you do the math) I have spent in a long time.
DTL-374QT Mods
Stock power (355/532/1064nm) = 71mw/0mw/0mw (running for max power, not max pulse energy, about 5khz for these lasers)

Stage 1 - easily reversible:
*remove knife edge to allow 532nm green beam to exit laser head = 71mw/93mw/0mw
*remove front apeture from laser to allow 1064nm beam to exit (it doesn't quite make it through the hole) 71mw/93mw/122mw

Stage 2 - can be undone but requires rough alignment
*remove the harmonic separator assembly off the end of the laser, leaving one beam that is about 250mw mixed 355/532/1064nm (presumably the ballance is about the same as the stage 1 mod, I was running the same frequency)  You can safely ignore and/or unplug the photodiode that it sends power into, it only us used to generate the sync out pulse (to the best of my knowledge)
*With tweaking to maximize total power, 291mw

Stage 3 - (will require moderately complex alignment to undo)
*remove the power tap from the harmonic generator module (you can safely unplug it, the supply seems to only monitor it for the power output pin on the db9 on the supply) by removing the 2 screws - didn't measure power
*remove the longer of the 2 crystals (presumably the 532+1064=355nm crystal), power = 0mw/80mw/458mw(!!).  Note, to get the green power I used a hr@1064nm mirror, and I would say 10-30% of the green did not make it to the power meter.  
*remove the shorter (presumably 1064+1064=532nm) crystal, power = 560mw (presumably all 1064 at this point)

Stage 4? - (will require realigning the pump diode on the 1064nm generation module, fairly tricky)
not yet tried, but I have a laser that I think needs realignment, so I may get to it when summer comes
*remove the entire 1064nm generation module, expected power about 2-10w of 808nm multimode.

So to recap, this laser will put out over 1/2watt of single mode, q-switched 1064nm power!  And the higher the frequency the more power you get, my craptastic 555 timer counter system toped out about 10khz and I didn't have time to rig something better, but I bet you can get more total power with a higher running frequiency.  However, average power is not always what you are looking for, and running at 1khz giving only 1/4watt can be much more destructive than the 1/2watt of low pulse energy stuff (see further results)


That said, it was time to burn things!  I focused the output with an asphere lens (5mm focal length, ar coated) and decided that these lasers were born to vaporise.  Whenever you hold something that is even moderately absorptive at 1064nm, you will get a nice plasma plume about 1mm long, that buzzes at the frequency you are running at.  It will burn through electrical tape in seconds, and if you go slow you can vaporise out a complete line across the tape so that the cut piece will simply fall off the end.  Furthermore, if you turn the rep rate down to to the 1-3khz region you can burn through aluminum foil.  Just make sure you are focusing well, and go about 1" per minute, and it will leave a piece that can be removed just by blowing on it.  

Cheers, enjoy your laser!
 
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... said:
Best $120 (times 6 lasers you do the math) I have spent in a long time.
Wow, you got jipped... I got both my lasers for $120(excluding shipping) from another seller(Not Teamlaserplus) ;D BTW, would you happen to have a spare working PSU you can sell/trade me? My other laser's PSU is fried...
 
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Guest
Hmm, I think that $120 for a working laser beats $60 for a broken one ;)

In any case, I have several working power supplies (and one that mostly works, but doesn't power the main tec, still need to look into that), but I am somewhat attached to them. PM me with offers, looking for something in the $150 range for the working one and $50 for the somewhat working one.
 
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UPDATE: I finally got the working laser running today... Unfortunately, the pictures are a bit overexposed so dot appears much brighter than it actually is. The dot is actually a very faint white colour; if it's not fluorescing stuff. Also, the small vertical "line" beside the dot is the green "line" leaking through. Another thing worth mentioning is the crappy divergence; 4 inch dot at 10 feet, 1mm dot at 4 inches :D

Anyways, enjoy the pics

On paper:




On paper(closeup):




In the dark:




The real "colour" of the laser:

 

Cyparagon

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it's nearly impossible to not encounter fluorescence with a wavelength that low. Hold a diffraction grating to your eye and you'll see colors.
 
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Actually, I'm surprised at how much stuff does not fluoresce, I would have thought a short wavelength like this would fluoresce all white/neon coloured objects... Anyone have any recommendations for a focusing lens? Apparently, glass blocks out a fair bit of UV and plastic degrades when exposed to UV...
 

.3lite

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Remember, by removing third harmonic generation's crystal you would propably get about 1 WATT OF 532nm which is better deal ;)
 

diachi

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not 1W of green, 100-200mW pulsed ( each pulse would be several kW )
 

GooeyGus

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not 1W of green, 100-200mW pulsed ( each pulse would be several kW )

Exactly.

Not anywhere close to 1W average power, but you will have several kW's peak power (it still doesn't look very bright...) 100mW average power is more like it.

I also have one of these units, they are pretty fun to play with!











Mine is only running 200Hz right now, 20uJ with a 4-7ns pulse (do the math for peak power). I'll have to build a driver to modulate it a bit higher.
 




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