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Thread: Lightwave Halfnote Green Laser Questions

  1. #21
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    May 2007
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    Default Half-note

    Hey Simon,

    Did you build a controller for the original analog board, or did you just build a complete new power supply? I have 3 of these lasers but only one test fixture to power them up. Curious what you did.

    -George

  2. #22
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    Quote Originally Posted by hologeek View Post
    Hey Simon,

    Did you build a controller for the original analog board, or did you just build a complete new power supply? I have 3 of these lasers but only one test fixture to power them up. Curious what you did.

    -George
    Hello George

    I built two complete new power supplies, new cooling controllers and even put new tecs and heatsinks on the laser modules themselves..
    The goal was to make something that would fit into a mac250 moving head fixture, which it just barely did after i was finished..

    The psus are based on some vicor flatpacks, with a switching current regulator attached, an omron temp controller for the base (diode) temperature and a lightwave electronics htc controller for the sensitive ktp temperature..

    are all 3 of your laser heads working ?

    would you be interested in a trade - one head for one psu ?

    Regards, Simon

  3. #23
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    Jan 2007
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    Cupertino, California
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    Default

    Simon,

    Would you be willing to provide information on the controller you built? Otherwise, I might be interested in getting one from you.
    CLICKY!!!

    Admin: In the immortal words of Captain Planet: YOU HAVE THE POWER
    Admin: (To quit being a bitch)

  4. #24
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    Jan 2007
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    Quote Originally Posted by Showlaser.dk View Post
    Other than that this is a very nice laser - its beam divergence is a bit high - it could probably be improved by some optics, but i have not yet found something that works well without being quite complicated and expensive.. also, i dont think you can get more than around 2.2W out of them - i would recommend setting them to 2W to not stress them too much..
    Kevin gave me a 1 meter focal length lens when I bought the laser from him which was able to cut the divergence to very slightly converging. It's amazingly tiny! Then again, when I realigned the cavity. I found that any tweak to the end mirrors made a huge difference in beam profile and divergence. It was nearly 1.5mRad without the lens once I aligned it correctly and better then then -0.5mRad with the lens.
    CLICKY!!!

    Admin: In the immortal words of Captain Planet: YOU HAVE THE POWER
    Admin: (To quit being a bitch)

  5. #25
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    Sep 2008
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    Denmark, Europe
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    Hi Ben

    Thanks for the info on the 1 metre lens - i will try that.. allthough i would like to have it just barely diverging rather than converging.. having a beam waist somewhere out in the audience is not good maybe a slightly shorter focal lenght lense will do the job (you can tell that i know absolutely nada about optics, right?)

    I can make a list of the parts i have used for making the psu.. but it is not the cheapest way to do it..

    If you want to go for simple (and cheap), and dont need direct modulation of the diode, all you really need is an adjustable constant current source of up to 30A - that can be done with a vicor 3.3V flatpac module and an opamp and a couple of simple components.. then you need to keep the base plate at around 20 degrees C - that can be done with some simple ready made temp controller, from omron for example, or you can build something yourself from plans that can be found on the web.. it just needs to have a big FET or SS-relay to drive the large 12V TEC. Then you need to control the temperature of the KTP, which is the most critical part.. I would reccomend the HTC1500 from wavelength electronics - it is stable to a fraction of a degree if set up correctly.. A shorting relay for the diode is also a good thing to avoid static discharge damage when the laser is powered off..
    The main thing to remember is to make everything run good with simulated loads before connecting the real laser, so you minimize the risk of blowing something inside the laser..

    Like i wrote in one of my earlier posts, i have one of the original halfnote psus with the test board, that i would like to trade for a good working laser head..

    Regards, Simon

  6. #26
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    Sep 2008
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    Denmark, Europe
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    Default

    Here's a few links to the parts that went into making the psus i made.. but this may be overly complex since i wanted direct modulation of the diodes.. so the OEC controller could be left out and replaced with a simple opamp circuit or a batmod current addon..

    http://www.ia.omron.com/product/fami...index_fea.html
    omron temp controller for the baseplate tec.

    http://www.teamwavelength.com/produc...ler.asp?part=5
    Precision temp controller for the KTP doubler crystal

    http://www.oec-gmbh.com/index.php?op...281&Itemid=535
    modulable effícient switching current regulator for the diode (option)

    http://www.vicorpower.com/products/c...sscode=flatpac
    Very stable power supplies for diode (and for tec 12V)

    I will post some pics of my project building these systems tomorrow.. its almost 2 in the morning local time, and i have to be up again at 6:30, so i better hit the bed..

    Regards, Simon

  7. #27
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    May 2007
    Location
    Minnesota
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    Default Half-note

    Hey Simon,

    Appreciate the offer but I'm determined to figure out the control signals for the analog board. I will keep your offer in mind though. It would be such a shame to not use the analog board + power supplies, especially considering there is not much to the control signals. I think the problem I'm having is related to the two 'enable' signals, the -enable and enable.
    All three work. One is basically new in the Lightwave box. One has a problem with the 40amp switching -3.3v supply, so when I tested that one I had to switch the supply with another, but that one still does >2W. I did pick up a replacement supply but its bigger and won't fit into the stock sheet metal chassis. The third one does somewhere around 2 watts.

    The divergence can be controlled by a lens but I haven't really experimented much past my basement, LOL. The 1m focal length lenses cut the divergence greatly, but I'm not sure if you'll have a focal point somwhere out in the distance which would be pretty bad. My plan with these lasers is to figure out the control signals first, then work on the divergence problem later before I do anything with them. It's just hard finding time with a kid and multiple lasers projects. I'm sure you know..well at least with the multiple laser projects.

    I attached a pic I took of one of the lasers running with the lightwave test controller.

    -George
    Attached Thumbnails Attached Thumbnails photo.jpg  


  8. #28
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    Sep 2008
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    Denmark, Europe
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    Default

    Hello George

    Nice pic !

    So you have the psus for all three lasers, just not the analog test boards ?
    -i misunderstood you before, then - i thought you only had 2 laser heads and then one complete laser..

    then getting it to work shouldnt be so hard.. do you have the service manual ? - i think i have it in pdf somewhere..

    Regards, Simon

  9. #29
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    Jan 2007
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    Cupertino, California
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    Hey Simon,

    I actually posted a bunch of pictures of both the insides of the cavity as well as my experience aligning the cavity from scratch.

    http://www.photonlexicon.com/forums/...ead.php?t=7695

    I did find that the analogue controller with the interface I have on loan from George has some screwed up signals. Many of the digital signals are floating (~2V) and the potential between digital and analogue ground is ~5V.

    Do you have a picture of the units in your projector? Also, how much power are you putting into your TEC to keep it cool? I am putting nearly 10A in this one just to get it to temp so I think the TEC is dead, 120W to move ~15W of heat

    Additionally, did you figure out what the thermistor values for the oven and head temps are? I moved the sensor inside the head for the diode temp to right next to the diode instead of the other side of the cavity. It provides faster response on the controller, but with the TEC damages, it still stays at a high temp.

    I am going to clean the optics on the cavity this week when I get a chance and see what kind of power increase I can get from it. The appear to be clean, but after learning to clean optics the correct way, I think I am going to try again.

    Aligning this was not very difficult. I used a Coherent Sapphire and got it set up to go collinear with the Nd: YAG rod then readjusted every mirror from scratch to place the reflected beam right on the centers of the next mirror. I didn't count on any of the mirrors being aligned, so I just did all of them. I also repositioned the KTP to an area where the beam was not as focused so there is less chance of damage, and increased power. Once I got all of the other optics aligned, the final end mirror behind the Nd: YAG rod was tweaked with the diode running. I got a bright flash of green, and then slowly got it into a place where i could tighten the screws a tiny bit and just barely treak the mirror. I think now it is still a tiny ways from optomized, but it's way better then not working at all .

    I did find that any change to the end mirror made an enourmous change in the divergence and output beam shape. It was actually easy to tweak for optimal power by running the laser and chaning the position until the beam on the wall several meters away was as small as possible.

    Every bit of alignment was done without a stage or any precision instrument besides my fingers.

    I actually found it was WAY easier to align this laser then to align the SP Millinneas we have at work. They are a pain in the ass, and they even have adjustable kinematic mounts inside the cavity! I have one putting out a tiny bit of green and the other missing one mirror which should be easy to replace once we get a replacement.

    George,

    I was gonna call you today, I just didn't get a chance, I'll give you a call tomorrow.
    CLICKY!!!

    Admin: In the immortal words of Captain Planet: YOU HAVE THE POWER
    Admin: (To quit being a bitch)

  10. #30
    Join Date
    May 2007
    Location
    Minnesota
    Posts
    162

    Default Half-note

    Hi Simon,

    All three lasers are complete with psu's and what lightwave calls the 'analog pcb'. Its just that I have only one 'test fixture' in order to supply the correct signals to the analog pcb board. That's my problem, along with a lack of electronic digital design savy I have a copy of the Alcon service manual from Kevin, which has been very useful.
    In order to turn the laser on I have boiled down to what I think is needed (from the manual),to a few signals: enable, -enable, wd, Dio_Cur, and reset. However when I apply the signals to the 50 pin connector on the analog pcb, the main ssr relay does not turn on and thus no lasing. So right now I'm not sure what's going on. I know Ben and Heroic noticed that on the schematics, there's a mislabeling related to the input/output pins to the PAL chip. I let Ben borrow the test controller so maybe he has some input. I have a couple other ideas, but its now pretty late here and the alarm clock is now imminent.

    -George

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