EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: PartialDischarge on December 08, 2016, 07:50:51 pm
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I got a solid state laser that was used in a laser ranging system. Also, I've got the main control board that includes 2 HV modules to power the laser, the power supplies are functional but the control is not. My intention is to power it up but I'm not sure how should I trigger the lamp.
Does anyone know what kind of laser is this? wavelength? What frequency should I apply to the trigger of the HV lamp pulses?
Attached is the datasheet of the step up transformer used in the design, and the typical diagram also matches the one in the circuit.
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You should find out what crystal is in it and ensure you have suitable goggles for this.
This thing will not fuck around. The reflection from the reflection off a white wall will still be enough to damage your eye sight... I really can't stress this enough.
https://www.photonlexicon.com/forums/showthread.php/25595-Repair-and-Redesign-of-a-110W-surgical-laser-unit-to-operational-functionality?p=329522#post329522 (https://www.photonlexicon.com/forums/showthread.php/25595-Repair-and-Redesign-of-a-110W-surgical-laser-unit-to-operational-functionality?p=329522#post329522)
This is a post from a laser forum of a laser I own. I haven't even plugged it in yet in favor of working my way up.
Your laser, while much less powerful in continuous mode, it's peak light output will be in excess of several 1000 Watts if it is Q-Switched YAG
I'd suggest making a thread at the forum I linked, if anyone can help you it's them.
BE CAREFUL, YOU ONLY HAVE ONE SET OF EYES!
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Thanks. I didnt go into safety issues but Im aware of its danger. It was used in a tank to measure targets probably up to 10kms away. Half of the metal brick is used to measure the reflected light from the objective.
If at least I knew if its visible or not...
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I would imagine its a Nd:YAG crystal so will most likely be 1064nm - IR. I don't think any military range finders used visible light as.. well, that would give the game away, especially given the power they used.
A quick google and these came up:
http://mi-lasers.com/product/ssy-1-nd-yag-laser-head/ (http://mi-lasers.com/product/ssy-1-nd-yag-laser-head/)
http://www.repairfaq.org/sam/laserscl.htm#sclsy1 (http://www.repairfaq.org/sam/laserscl.htm#sclsy1)
Nd:YAGs, in my very limited experience, can have quite low lasing thresholds, so you might be able to start off with relatively low power (10J?) discharge cap for testing. As mentioned, whilst I doubt its designed for continuous operation (which can arguably be more dangerous with regard to burns, but also obviously require continuous large power input) the pulses can be so brief the peak power can be enormous, so reflections off almost anything can cause serious eye damage.
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That is a tank range finder laser at 1064 nm, ND:YAG lasing medium. Its lamp needs a large cap and a series inductor. It received a informal name of SSY ONE as Sam Goldwasser who writes the Laser FAQ named his example that. The real nomenclature is a AN/VVG-3. You have one made under contract by Kigre with a internal passive Q-Switch.
Let me be VERY clear about this. A direct or diffuse reflection from that laser will damage your eye, your mom's eye or your pet dog's eye. I know I can't stop you from hooking it up and trying it. However you need to totally enclose the beam in thick metal during use, or wear a pair of professionally made Laser Safety Glasses with an Optical Density rating of 6, or preferably 7. ie OD6 or OD7. NO, you cannot make your own laser safety glasses. Something like these are the minimum:
https://www.thorlabs.com/thorproduct.cfm?partnumber=LG1 (https://www.thorlabs.com/thorproduct.cfm?partnumber=LG1)
The laser is rated for a few pulses per minute.
I CANNOT STRESS ENOUGH THAT THIS LASER WILL EASILY RUIN OR DESTROY YOUR VISION FOR LIFE. IN LESS THEN 20 NANOSECONDS.
This laser uses a pulse compression scheme called Q-Switching. It will take the green, violet, and IR light from the flashlamp pulse, saturate the laser rod after about 256 microseconds of flashlamp energy, store it in the lasing rod till the dye in the Q switch module bleaches clear from energy saturation, and dump all that power out in a pulse between 20 nanoseconds and 100 nanoseconds in length, and may dump more then one pulse per flash.
In a previous job I serviced ND:YAG lasers for a living. Of all the lasers I've ever worked with, Pulsed Neodymium in Yttrium Aluminum Garnet scares me more then any other kind. You cant see it, its energetic, and you only need make one mistake.
If I could, I'd take that away from you until you've worked with other simpler types of lasers for six months. It is not a toy. You cannot see that wavelength, and a bare black and white CCD or CMOS camera chip will barely detect such a short pulse. In fact, without care, you can damage the camera faster then your eye.
Steve
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Blueskull, your right, about the pulse compression. This can easily reach 10 milli-Joules to 50 milli Joules. Off the back of the hand calculation, that would be a Peak power of say 100 Kilowatts or more at the low end and nearing a Megawatt at the high end. I've seen 10-20 mJ focused pulses create a plasma in a solid glass block, cracking the glass at the focal spot.
If you remove the Q-Switch and drive this rod near the flashlamp implosion energy, this laser rod will reach say 500 mJ before the rod cracks or the lamp implodes. It is NOT a toy. If used incorrectly, a nominal ocular hazard range for this class of laser is measured in Kilometers.
Steve
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Thanks. I could easily put the setup inside a big nato ammo box. That laser faq gives lots of information and setup tips, however given the short pulse I see no practical use for me of this laser at this point :P
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So, if this thing is for range finding (which certainly looks the part) it is indeed most likely in the infrared spectrum. Wouldn't want charlie to know where you are, now would you?
And indeed it generates very short pulses, but because you need to constantly update the range measurement, these things are made to also generate those short pulses quite a few times per seconds (can't remember the exact value right now)
I've worked on testing the HV power supplies for some military grade range finders and, though they're not all that complicated (a thyristor, a transformer and a big ass capacitor), they do employ some sort of energy management i.e. they do not fire the xenon lamp at full power. This helps with the mentioned method of pulsing this thing some cycles per second.
Unfortunately, I can not directly post a schematic of the HV power supply, for obvious reason (military stuff, remember ?) but I could take the HV PSU schematic and "translate" it in Altium if you really want to put that puppy to work. Mind you, that it would be a military grade version, so some things are over-engineered and quite complex. Just PM me if you want, and we can sort things out.
Oh, and just so you know... the voltage pulse for the lamp would be somewhere from 400V to about 1.2 KV, depending on the lamp's specs (at least the models I dealt with had the voltage output somewhere in that range) but also on the transformer used (N1/N2 ratio and what not)
PS: Congrats on the nice find. You can use that thing for quite a lot of things (range finding, laser experiments, popping balloons, Raman spectroscopy ? :popcorn:)
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I didn't post them at first but here are the modules to power up the laser, one supplies up to 1000V and the other 800V from 12-18V if I remember correctly.
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Analog Modules is in Florida, USA....
analogmodules.com
Steve