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Thread: Repair and Redesign of a 110W surgical laser unit to operational functionality.

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    Laser Warning Repair and Redesign of a 110W surgical laser unit to operational functionality.

    Hello All, I was recommended over here from the LPF as I'm dealing with a unit a tad out of their usual size range.

    I come to you today with my first laser (beyond those 5mW toy lasers)
    I figured if I will go anywhere, I might as well go big so I purchases a second hand greenlight medical laser system. It employs a 100W (110W?) flash pumped laser.

    The unit I purchased had it's screen smashed, leaving me to suspect the rest of it could well be ok!

    Before you start worrying or having concerns about a 'newbie' with such a laser. I have read quite a lot of the safety pointers here and I have 2 pairs of greenlight glasses that game with the unit for eye protection (though I'd still treat the laser as if I didn't have them in terms of safety) I have already had the safety discussion on LPF, however I would be very welcome for any information for safe operation / working!

    I have yet to fix the cooling system up however I ran the unit on startup and it seems to fault out on the self-test for the flash lamp....

    Having opened up the unit, I have attached pictures of the lot, including the flash bulb. (Don't worry. I have not touched it, just held it by the plastic holder. To me the tube looks fine? al-bit the connectors on each end are a little corroded....

    It does have a Q-Switch and some very fancy looking water cooled optics under the black cover (that I probibly shouldn't have removed?)


    Judging by the electronics. I have a feeling I will need to work out exactly how this whole thing works and redesign the control board as there is a lot of complex functions on it that I can't / won't use. (broken display unit etc.)

    I'm rather excited to get this I hope I can fix it but all is not lost if I can't (it was 'only' 260) I wonder if I could Diode pump it if all goes wrong with the flash pumping circuit.

    I'm fairly understanding of safety precautions in general, my other main 'hobby' is high voltage, I have a 70kV x-ray transformer plus a few others including a potential transformer.
    I am somewhat of a collector of 'cool things' Well, I have a few projects I'm gradually saving up components for (Ion mill, fusor, SLS printer, laser cutter)


    Some background to establish who I am on this and what experiences I have:

    I'm 19Yrs, I work for a company as an Electronic / Applications Engineer and do a fair bit of electronics / CAD work there including motor design, drive design, demo design, microcontroller programming etc.

    I have good experience with power electronics (500J+ capacitors, 70kV transformers, heavy duty switching power stages)

    I'm currently doing an HNC in EE.

    I have access to plenty of power supplies, oscilloscopes etc.

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  2. #2
    mixedgas's Avatar
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    The lamp must be submerged in flowing, non-conducting DI water. You need to email NEOS and see if "Giant Pulse Suppression" is enabled / integrated on the Q-switch driver.
    !
    I'm not so sure that is a flashlamp. I think I'm looking at a CW krypton arc lamp.
    !
    As that appears to have an integrated "BUCK" mode switching lamp driver, you have a long way to go as lamps are finicky and easily can explode. You have to figure out how to start the lamp, shut off the start boost voltage, and regulate the lamp current. Some where in there will be a series injection ignition transformer with greater then 160 VDC at 20-30 amps coming out of the secondary. When it fires, it will typically produce 20-40 KV riding on top of the DC coming from the buck switcher. The lamp is a current controlled device, while it has a slightly positive delta on its voltage/current curve, it is a device that must be current limited or it will run away. At the same time you have to have flow and water quality/tank level monitored.
    !
    To give you an idea, we usually let water flow thru the de-ionizer cartridge for four to eight hours before starting the lamp. Any serious conductivity in the water and the power supply, lamp, and rod usually die in a few hundred microseconds. Little details like that matter.
    !
    Diode pumping is out of the parameters for that rod size and doping.
    !
    Your calling it a 110 Watt, I see something more like sixty based on the lamp size...
    !
    If it all possible, using the existing controller is a must. Are you sure there is a not a big box with a separate lamp supply in it?
    !
    Q-Switched 1064 and 532 nanometer laser light is, IMHO, one of the most dangerous things on the planet, especially for a beginner. You need certified and tested safety goggles at these power levels and a safe beam stop. If you have never worked with sixty to two hundred watts of laser light, you HAVE NO IDEA what a safe stop is, and how dangerous the scattered light is. THIS IS NOT A TOY. Telling me not to give you the safety advice, that you heard it all on LPF, is about the quickest thing you can do to make me NOT want to help you. Less then 0.15% of the LPF population has ever been anywhere close to something like this. There are probably less then 10 people participating on LPF that could tell you how to work on one of these.
    !
    Looking at the device cooling, it appears to be a low duty cycle laser, I'm not seeing a large cooling system there.
    Steve

    - - - Updated - - -

    The lamp must be submerged in flowing, non-conducting DI water. You need to email NEOS and see if "Giant Pulse Suppression" is enabled / integrated on the Q-switch driver.
    As that appears to have an integrated "BUCK" mode switching lamp driver, you have a long way to go as lamps are finicky and easily can explode. You have to figure out how to enable the psu, set the current, turn on the boost voltage start the lamp, shut off the start boost voltage, and regulate the lamp current. Some where in there will be a series injection ignition transformer with greater then 160 VDC at 20-30 amps coming out of the secondary. When it fires, it will typically produce 20-40 KV riding on top of the DC coming from the buck switcher. The lamp is a current controlled device, while it has a slightly positive delta on its voltage/current curve, it is a device that must be current limited or it will run away. At the same time you have to have flow and water quality/tank level monitored.
    !
    To give you an idea, we usually let water flow thru the de-ionizer cartridge for four to eight hours before starting the lamp. Any serious conductivity in the water and the power supply, lamp, and rod usually die in a few hundred microseconds.
    !
    Diode pumping is out of the parameters for that rod size and doping.
    !
    Your calling it a 110 Watt, I see something more like twenty to sixty based on the lamp size...
    !
    If it all possible, using the existing controller is a must.
    !
    Q-Switched 1064 nanometer laser light is, IMHO, one of the most dangerous things on the planet, especially for a beginner. You need certified and tested safety goggles at these power levels and a safe beam stop. If you have never worked with sixty to two hundred watts of laser light, you HAVE NO IDEA what a safe stop is, and how dangerous the scattered light is. THIS IS NOT A TOY. Telling me not to give you the safety advice, that you heard it all on LPF, is about the quickest thing you can do to make me NOT want to help you. Less then 0.15% of the LPF population has ever been anywhere close to something like this.
    !
    Looking at the device cooling, it appears to be a low duty cycle laser, I'm not seeing a large cooling system there.
    !
    Are you sure there is not a separate lamp psu box inside the unit that I am not seeing in your pictures?
    Steve
    Last edited by mixedgas; 07-28-2016 at 13:09.
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    You mentioned pound sterling which leads me to think you may be in the UK. If so... be certain to look up Daniel Briggs on this forum and if at all possible, pay him to come look at it before getting too far along. It's absolutely not something to try and fire up without someone experienced WITH you. Reading stuff on the internet is good but fail able. You WANT someone standing alongside you willing to accept the risks associated with lighting it up.
    PM Sent...

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    Quote Originally Posted by mixedgas View Post
    The lamp must be submerged in flowing, non-conducting DI water. You need to email NEOS and see if "Giant Pulse Suppression" is enabled / integrated on the Q-switch driver.
    As that appears to have an integrated "BUCK" mode switching lamp driver, you have a long way to go as lamps are finicky and easily can explode. You have to figure out how to start the lamp, shut off the start boost voltage, and regulate the lamp current. Some where in there will be a series injection ignition transformer with greater then 160 VDC at 20-30 amps coming out of the secondary. When it fires, it will typically produce 20-40 KV riding on top of the DC coming from the buck switcher. The lamp is a current controlled device, while it has a slightly positive delta on its voltage/current curve, it is a device that must be current limited or it will run away. At the same time you have to have flow and water quality/tank level monitored.
    A lot of really interesting information there, I'll take some time to digest it.

    Quote Originally Posted by mixedgas View Post
    To give you an idea, we usually let water flow thru the de-ionizer cartridge for four to eight hours before starting the lamp. Any serious conductivity in the water and the power supply, lamp, and rod usually die in a few hundred microseconds.
    I will note that down. I intend to do a full teardown and check everything out, replace all water and flush it a few times.

    Quote Originally Posted by mixedgas View Post
    Diode pumping is out of the parameters for that rod size and doping.
    A pity, but I already have a near complete system here, I suppose there is no point rebuilding it to a different style.

    Quote Originally Posted by mixedgas View Post
    Your calling it a 110 Watt, I see something more like sixty based on the lamp size...
    Well, 110W is what I read on the 'factory test' paper stuck to it.

    Quote Originally Posted by mixedgas View Post
    If it all possible, using the existing controller is a must.
    I see where you are coming from. I believe I could replace it with sufficient intel and research with some assistance.
    I think the current design won't be plausible due to the fact it is controlled by a touch screen which is broken and really has far too much to it to be convenient to use for laser cutting / interesting experiments.

    Quote Originally Posted by mixedgas View Post
    Q-Switched 1064 nanometer laser light is, IMHO, one of the most dangerous things on the planet, especially for a beginner.
    I'd be interested in hearing about this more.

    Quote Originally Posted by mixedgas View Post
    You need certified and tested safety goggles at these power levels and a safe beam stop.
    I am looking into a beamstop now, as for the goggles. Would you agree the goggles that came with the unit (likely from the center that used it) are suitable?
    Or do they need to be checked every so often (do they degrade over time? :/)


    Quote Originally Posted by mixedgas View Post
    If you have never worked with sixty to two hundred watts of laser light, you HAVE NO IDEA what a safe stop is, and how dangerous the scattered light is.
    Well, there are two ways to learn, research it (as I am doing now) or find out the hard way and work with it, possibly blinding yourself (something I have no interest in doing)

    Quote Originally Posted by mixedgas View Post
    THIS IS NOT A TOY. Telling me not to give you the safety advice, that you heard it all on LPF, is about the quickest thing you can do to make me NOT want to help you. Less then 0.15% of the LPF population has ever been anywhere close to something like this. Less then 0.05% would know how to teach about getting one of these working.
    !
    Steve
    Sorry if it sounded that way. I think a better way to read it would be 'I have already had some safety discussions on LPF (enough to cause some concern / scare my balls off) and I'm interested in any other further safety information that can be provided!) That's what I said read back to me like. I have no interest in loss of eyesight. It's rather important for my life as you might have guessed.

    I really appreciate your input and would be very grateful for all information you could share with me. I'm not even thinking of turning on the laser / enabling the output (if I can) without someone telling me to go ahead with it.

    EDIT:


    Regarding Duty Cycle, I'm not too sure, I think it can be used for longer considering there is 2 ports on the back for coolant water to be put through a big heat exchange I'm betting. All of that there is a tank and a diaphragm pump.

  5. #5
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    I think you have entered the Briggs Zone...
    First thing to do is replace the DI filter with a new reliable DI cartridge, else you'll see more lamp faults followed by a lamp explosion or dead lamp power supply.
    Even the indirect scatter from your beam stop is hazardous with one of these. So is the intracavity scattered light when any of the covers are off.
    You need a way of viewing IR while not taking off your glasses. You need total control of the room you are in. And so forth.
    !
    Then you need to read Walter Kochner's book on YAG lasers before starting. It spells everything out in plain terms, except for how to operate safely.
    !
    As this unit has been removed from medical service, you have no idea if its missing beam handling parts. Some of them are quite critical to your safety.

    Steve
    Last edited by mixedgas; 07-28-2016 at 13:18.
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  6. #6
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    Jumping from 5 mW to 110 Watts without some training and a local mentor is a bad move.
    You need some time around the few watts level before you make the jump.

    Kind Regards,

    Steve
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    Quote Originally Posted by mixedgas View Post
    I think you have entered the Briggs Zone...
    I don't get the reference. Hint?

    Quote Originally Posted by mixedgas View Post
    First thing to do is replace the DI filter with a new reliable DI cartridge, else you'll see more lamp faults followed by a lamp explosion or dead lamp power supply.
    Right, I'll look into it.

    Quote Originally Posted by mixedgas View Post
    Even the indirect scatter from your beam stop is hazardous with one of these. So is the intracavity scattered light when any of the covers are off.
    Note Taken

    Quote Originally Posted by mixedgas View Post
    You need a way of viewing IR while not taking off your glasses. You need total control of the room you are in. And so forth.
    What would you suggest.... room control is a problem but I suppose I should have forseen this.
    This might shelf the project 'testing' phase for a while as the unit is in the companies workshop and there is a massive window to the side which employees occasionally walk past, even though the beam is below the desk level, Best not to take any chances at all.


    Quote Originally Posted by mixedgas View Post
    Then you need to read Walter Kochner's book on YAG lasers before starting. It spells everything out in plain terms, except for how to operate safely.

    Quote Originally Posted by mixedgas View Post
    As this unit has been removed from medical service, you have no idea if its missing beam handling parts. Some of them are quite critical to your safety.
    I have the unit shown, no fiber cables etc. Unfortunately.

    How do I find out?

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    Quote Originally Posted by mixedgas View Post
    Jumping from 5 mW to 110 Watts without some training and a local mentor is a bad move.
    You need some time around the few watts level before you make the jump.

    Kind Regards,

    Steve
    Well, at one point it was nearly 5mW to 400 Watts / 5kW....

  9. #9
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    As Brad mentioned, Daniel Briggs is a UK Laserist with experience in the high power yag laser arena. You very much need his help. He is a PL member.
    Otherwise you need an industrial laser tech, a hospital biomedical engineer with surgical yag experience, or a laser show person with the YAG skill set such as Mr. Briggs.
    You'll have to convince them that you can use this safely.
    !
    I'm not so sure I'd do this at my workplace, well, unless I owned the company or was paid to do it. I work in academic laser labs for a living.
    !
    Your at the level of laser power where your high quality beam stop needs to be water cooled and the beam spread before impacting it.
    !
    Again, little details that are only known to those skilled in the art. I'm supposed to write that you should scrap this and move on to another project at this point, because this is a IR Class IV system.
    !
    I don't know you well enough to continue helping you, and I state that not as a personal insult, but based on past experience with the wrong person getting their hands on one of these and abusing it in public. I have a friend with a 15 mm hole thru the palm of his hand from a YAG psu arcing. That laid him up in bed for something like four months. I have a local competitor with brain damage from leaning his head against the laser and touching the anode of a cap bank. Hence the next question. Why do you want one of these?
    !

    Steve
    Last edited by mixedgas; 07-28-2016 at 13:47.
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    Quote Originally Posted by mixedgas View Post
    As Brad mentioned, Daniel Briggs is a UK Laserist with experience in the high power yag laser arena. You very much need his help. He is a PL member.
    Otherwise you need an industrial laser tech, a hospital biomedical engineer with surgical yag experience, or a laser show person with the YAG skill set such as Mr. Briggs.
    Alright then, I will have to have send him a message, I'm not sure where to find the rest of those people...

    Quote Originally Posted by mixedgas View Post
    I'm not so sure I'd do this at my workplace, well, unless I owned the company or was paid to do it. I work in academic laser labs for a living.
    I'd rather avoid it too but the alternative is taking it back to my parent's house, which means I either have to put it in my bedroom or a cellar workshop that has a river flowing through it during rainy days.
    I hate the idea of just sitting on it, too many of my projects are in that phase.

    Quote Originally Posted by mixedgas View Post
    Your at the level of laser power where your high quality beam stop needs to be water cooled and the beam spread before impacting it.
    I'm looking for one right now, depending on the cost I may build one myself.


    Quote Originally Posted by mixedgas View Post
    Again, little details that are only known to those skilled in the art. I'm supposed to write that you should scrap this and move on to another project at this point.
    Well... there is only one way to learn those details. (get Taught e.g. here / Mr. Briggs should he be willing) or teach myself which... honestly makes no sense and I would sooner dump the project and what I have invested in it so far, which would be a pity as there are quite a number of interesting projects I could do here and the restoration itself would be interesting.


    Quote Originally Posted by mixedgas View Post
    I don't know you well enough to continue helping you, and I state that not as a personal insult, but based on past experience with the wrong person getting their hands on one of these and abusing it. I have a friend with a 15 mm hole thru the palm of his hand from a YAG psu arcing. That laid him up in bed for something like four months. I have a local competitor with brain damage from leaning his head against the laser and touching the anode of a cap bank. Hence the next question. Why do you want one of these?
    There are a few projects I had in mind for this:

    Laser Cutter
    Laser Cooking (considering it's surgical uses, I wonder if you could cut slices of chicken so thin, cooking it at the same time... a curiosity at best.)
    DIY SLS printer.
    Investigating high voltage discharge controlled by lasers. (I need to look more into that one, Is this laser suitable to ionize air / gasses?)


    I would argue that all those injuries you listed there come down to high voltage / stored energy, something I am already familiar with. I have a 70kV x-ray transformer here along with a few 4kJ+ capacitor banks.
    as an electronics engineer I know how to handle electrical systems safely. It is lasers I would have doubts about.




    EDIT:

    based on past experience with the wrong person getting their hands on one of these and abusing it in public


    I seriously lack the imagination to even work out how one could abuse such a thing in public, let alone the motive to abuse it in public.
    I have no interest in chaos, I'm a techie!
    Last edited by TCWilliamson; 07-28-2016 at 14:10.

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