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Alaskan

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Please help with Lumenis Vasculight Laser Head Nd:YAG 1064nm

Lumenis Vasculight Laser Head Nd:YAG 1064nm

I bought a NOS 1064nm ND:YAG laser head without the power supply or control circuitry. Trying to find specs on the flash lamp and coolant flow required for this head as well as anything else that can be found about it. The manufacturer isn't helpful, tried already, they just want to sell me the newer version of this unit. The unit is capable of up to 50 joules of power, that's many thousands of watts of peak power.

 
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Are you sure that that is the complete laser?!! I think that's way too small for what you said no way getting a 50J pulse out of that! :whistle:
Looks like a fibre coupled handheld
can you please post a pic of the cable connections:beer:
 

Sigurthr

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The voltage depends on the capacitor used and flashlamp length and bore diameter. Typically values between 400V and 800V are common. YAGs also require a pulse formation network (PFN), and whether or not that was contained in the head or the power supply is not immediately obvious. There's no pulse cap in the head, that's for sure, so you could theoretically match a power supply to a pulse cap you find, as long as the (electrical) pulse energy is within the flashlamp's rated range. Likewise, flashlamps require a trigger voltage, usually in the tens of kilovolts, to initiate the discharge. There are two methods; external (parallel) and internal (series) triggering. A simple piezoelectric butane ignitor unit can suffice. Finally, you need to know if it is passively or active Q switched. If it is passive then that is the easiest to get going. Active q switching requires precision high speed electronics design.
 

Sigurthr

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I invite you to initiate a conversation with Hemlock_Mike. He has done wonders getting old Nd:YAG units to run beautifully off of nothing more than disposable camera flash circuits. Make sure to let him know about your experience with high energy and high voltage electronics as well as your understanding of laser safety, else he may not divulge much info (as I wouldn't either!).
 

LSRFAQ

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I've sent Sam Goldwasser at the Laser FAQ a spreadsheet for calculating lamps.
I'd start with having him help you reverse engineer the xenon flashlamp parameters.
I'm up to my ears with projects right now, but Sam is retired.

For good Yag operation, one likes a higher voltage and smaller capacitor on a flashlamp pumped system like that. I used to service a similar product line used in labs, not for medical.

You need a cap charger, a cap, a series inductor of between 20-40 uH etc. You'll need a series injection trigger transformer, the whole lamp current flows through the trigger transformer. Due to the wet cavity, an external spark will not do.

If you can find a big Russian diode, you can also simmer and injection trigger the lamp. Coherent will have probably simmered the lamp, which is running a 30-60 mA current at DC through the lamp and dumping the cap into the lamp via a high DI/DT SCR or IGBT and a blocking diode..

However the classical external trigger will not work.

The good news is you can wind the inductor easily enough out of #10.

Coherent's Medical Partnership (Aka Lumenis) (and nearly every one else) flows partially deionized, filtered water through the cavity. Just a few litres per minute, at low rep rates like that. You need water at about 8 Megohms, not fully De-Ionized water. Fully deionized 18 Meg water will corrode the cavity. This is achieved by connecting a very small deionizer cartridge across the tubes to the laser head with tiny *********; sized tubing. The DI cart thus never sees enough flow to fully de-ionize the water. Without water, you run a strong chance of imploding the lamp.

The goal for running the small YAG laser is a critically damped flashlamp circuit. Otherwise you get horribly short lamp life. Running a mix of low voltage caps will not be such a good idea. The critically damped circuit gives you a higher peak power in the rod, which is desirable.

That has enough connectors on it that I believe it will have a Electro-Optic Q Switch on it.

SAM's page in the FAQ on the SSY-1 will give you a good start.

EG&G / Perkin Elmer have flashlamp guidebooks that are on the net at multiple locations.

You'll need to open the cavity up and see if there is a Q-switch crystal in there. May be, May not. Your pulse length spec is too vague for me to decide.

Pulse times in Nanoseconds indicate a Q-switched Laser. Pulse times in 100s of nanoseconds or a few microseconds indicate a free running laser.

YAG Pulse times in milliseconds mean the laser is probably Quasi-CW. Quasi CW means the lamp is simmered and a long DC pulse is dumped into the lamp for a few tens/hundreds of milliseconds using a switching power supply. (very rare)

50J/CM^2 at what spot size? That is not a 50 Joule head, by any means. (50 Joule per pulse Yags are massively huge)

READ: http://www.google.com/url?sa=t&rct=...=mh0qiCHJondR2-WjH927wQ&bvm=bv.75097201,d.aWw


I've emailed my medical YAG friend, I'll see if he knows about that one.... It looks like a small IR "Versapulse" cavity.

Oh, and did I mention you need laser safety glasses of at least Optical Density 6 or OD7....

Lumenis reuses model names like crazy, you'll have a hard time finding data.


Steve
 
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Hemlock_Mike

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Chris --
I have an SSY-1 plus a couple little brothers made in Israel, both
using low duty cycles for range finding. Mine have Q switch cells
which self trigger and give a shorter pulse.
As stated above, I started with good sized camera strobe power
supplies but you need to find out the wiring for triggering as noted
above. Mine are not water cooled because they are low duty cycle
and no flash tube simmer current.

It appears that there are others here familiar with your device. I
hope they can help on this specific device. USE GOGGLES....

HM
 

Hemlock_Mike

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Alaskan --- I know this is an old thread but I have new info.
A friend of mine in TX got one similar to this and from the specs, it appears that the "flash" tubes
are high pressure CW Krypton tubes with the liquid cooling. They use a three stage power source
and are series triggered with the first ignition stage.
Don't try to flash these like a Xenon tube. They do POP and you will get cut (trust me!)!
HM
 




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