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Thread: Melles Griot / Laser Power RS232 protocol?

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    Default Melles Griot / Laser Power RS232 protocol?

    Ended up with two Laser Power branded DPSS lasers. They're similar in form and shape to the Melles Griot, as MG bought the company out.

    Just read the laser faq on these.

    They spin up but no output, emission indicator goes red and PSU seems happy. Haven't tested actual diode or TEC DC output yet.

    I hooked up a db9 serial cable to the unit and ran the Melles Griot software, but it never connects to the units. I've tried all baud rates.

    My serial cable is nulled, so I've tried it both with the cable and with the USB dongle plugged straight into the unit (providing a non-null cable.) Neither work.

    Opened PuTTY in serial mode, shorted pins 2 and 3 on the DB9 RS232 to USB dongle and loopback is working.

    Does anyone know if the Laser Power branded (early era) units work with the Melles Griot Windows software?

    The laser FAQ stated that some units didn't have RS232, but the port is on the front and there is a MAX chip inside.

    Any hints appreciated! Such sexy lasers.

  2. #2
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    Be really darn careful running those without full spectrum goggles (1064, 808, 532) with the lid off. Lots of HOT stray IR.

    Really no place to stick a power meter between the special fiber optic array that evens out the pump 808 and the vandate.

    Wait a while before opening the hood. Bad idea without knowing what your going into.

    They are not so tolerant of being opened. You own a clean room or a laminar flow hood? (I'm not kidding!)

    They have a HEPA vent filter on the head and in some cases a dessicant for a reason!

    Just your luck I'm out of town setting in a lab with a dead one. I might get a pic tonight of the innards.

    Actually call Sam G. who runs the FAQ or Talk to Fred at One Stop (rebuilds them) before cracking the hood. Also make sure the PSU serial matches the head or it wont work.

    You may need ACTUAL RS232 handshacking. Founder of the company/chief designer passed away last year.

    Steve
    Last edited by mixedgas; 09-28-2014 at 18:37.
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    The factory warranty seal is still intact and no plans to open them yet. The serials though, no way to match.

    Mainly curious if the MG tools should work with the unit over rs232 or not. Was hoping the information that comes back from that is from actual measurements.

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    This one head has a 8 pin chip for the serial on the daughterboard. Marking is ground off. No level shifters or anything but what might be a reset line. Its a Melles. Pictures are taken, posting in the morning. I have to do the work that pays for the trip first.

    The pump diode array has to line up to a carefully spaced block of fibers that are then metalized and soldered into a bundle to feed the YAG/Vanadate. The fiber bundle is then clamped into a block
    and the block is epoxied in position to aligned the fibers with the rest of the laser. If you take the block out the laser is effectivley junk. The reason being you need a 5 axis fixture or jig to reposition the block while the zero expansion, zero relaxation epoxy hardens.

    So pretty much custom diode array feeds very custom fiber bundle. One temp sensor per tec, two tecs. Nothing inside to adjust. Optics are aligned and glued in place. No mirrors to adjust. Doubling crystal has a slight angle adjustment. However you would have to really, really skilled to adjust it.

    This one got submerged in Hurricane Sandy, so I was allowed to crack it open and take pics. As well as remove the fiber beam conditioning for a photo.

    Pump diodes have a finite life and change in wavelength as they age. Especially these early generation

    Steve
    Last edited by mixedgas; 09-29-2014 at 04:31.
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    Opened the Pre Melles Laser Power Corporation Laser Head. NO serial number eprom or serial number wiring. Unlike the Melles head that has the serial number chip.
    Also flood damaged.

    Steve
    Last edited by mixedgas; 09-29-2014 at 04:40.
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    Aren't those heads supposed to be water proof? I have an old laser power laser which could use a new head...

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    These have a tiny HEPA filter vent and a massive oring seal. They have dessicant packs gluded inside the head. Water worked its way into the HEPA and got up to the TECs which are about 1 mm above the baseplate. Water vapoer and salt fog did the rest.

    Steve
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    Pics of one of the two rigs:

    https://www.flickr.com/photos/ethano...57648219096941

    Tried the serial stuff again. With putty on com2/9600bps (RS232 to USB) no activity seen when powering it on in terminal application.

    Melles Griot app normally says it's not working.

    Going to check to see if diodes are shorted next.

  9. #9
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    It's been a while (I round robin projects and it can take a while.) These things sitting in kitchen are too tempting.

    So I actually found good spot to grab the diode voltage in the power supply and measured it, the PSU is pushing out 1.8VDC give or take. So that's not a good sign.

    Diode check on the meter doesn't read a short in either direction of the diode.

    Laser FAQ didn't have a voltage listed (did have a current, 18 amps, yowsers) and I don't want to run that through my radio shack multimeter for current check.

    The PSU has a daughter card right near the RS232 and interlock ports. There is room for a quad sided through hole IC/socket, which isn't populated on the daughter card. Anyone know if this is populated on the MG lasers? Perhaps the MCU that handles RS232.

    More higher quality pics of inside the power supply:

    https://www.flickr.com/photos/ethano...7648275490813/

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    What is the status of the LED's on the front panel?
    It doesn't look right to me, but I can't make it fully out.
    - There is no such word as "can't" -
    - 60% of the time it works every time -

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