Page 5 of 5 FirstFirst 12345
Results 41 to 48 of 48

Thread: Home made blue dpss laser

  1. #41
    Join Date
    Apr 2006
    Location
    Wirral, UK
    Posts
    191

    Default

    Behave - I haven’t shafted it yet ;-)

    I diode 2.5A, Pout 180mW
    This is strongly non linear. A little more pump power gives a lot more output.
    I need to plot this. Job for tomorrow.
    Lasers and beer don't mix. After 2 beers I lose coherence.

  2. #42
    Join Date
    Jan 2007
    Location
    Sheepsville, Wales, UK
    Posts
    3,406

    Default

    Robin - I would post circuit diagram but I know you are an elctrohead so didnt think it was needed - but will if you want.
    As for that diode current - hmmmmm do I feel brave? Probably not at this time of night

    another day perhaps

    Rob
    If you need to ask the question 'whats so good about a laser' - you won't understand the answer.
    -----------------------------------------------------------------------------------------------
    Laserists do it by the nanometre.

    Stanwax Laser is a Corporate Member of Ilda

    Stanwax Laser main distributor of First Contact in UK - like us on Facebook http://www.facebook.com/FirstContactPolymerCleaner
    www.photoniccleaning.co.uk

  3. #43
    Join Date
    Apr 2006
    Location
    Wirral, UK
    Posts
    191

    Default

    Rob,

    It was my 'couldn't be arsed' kicking in.
    I looked at tracing it out but at the time I could not be bothered to take the transistors off the heatsink in order to lift the board.

    I will do the drive plots tomorrow & sketch out later. I will do the TEC time constant mods though - should help the power stability - you can see the TEC hunting on the power meter.

    Robin
    Lasers and beer don't mix. After 2 beers I lose coherence.

  4. #44
    Join Date
    Jan 2007
    Location
    Sheepsville, Wales, UK
    Posts
    3,406

    Default

    its not just you that is lazy - I did the tec mod to one drive ages ago and only did the other on sunday! I also was gonna try a lower value maybe 1uF and see what happend but I will prob get round to the next Xmas

    Rob
    If you need to ask the question 'whats so good about a laser' - you won't understand the answer.
    -----------------------------------------------------------------------------------------------
    Laserists do it by the nanometre.

    Stanwax Laser is a Corporate Member of Ilda

    Stanwax Laser main distributor of First Contact in UK - like us on Facebook http://www.facebook.com/FirstContactPolymerCleaner
    www.photoniccleaning.co.uk

  5. #45
    Join Date
    Apr 2006
    Location
    Wirral, UK
    Posts
    191

    Default

    I prefer to think of it as prioritizing away from the task at hand.
    Spending a couple of hours tracing out a circuit = dull
    Building a dual red with a brand new PBS cube = fun

    Anyhoo... I attach a graph of Pout vs I diode for my *ahem* 20mW 473.

    The diode current with the pot at max was 2.54A (just a nadge under the max current for a 2W diode)

    Power stability was +/- 10mW at >150mW out.
    Don't know if it was mode hopping or the hunting of the TEC.

    After doing the plots I fine tuned the TECs. I diode was 2.2A
    Before tuning Pout=115mW, after tuning Pout 150 to 160mW
    Interestingly at these TEC settings Pout would not increase above 170mW.
    If this is due to temperature of the crystals the only thing I can think of is that there must be a significant thermal resistance between the crystals and the TEC controlled bit of the crystal mount.
    This would mean that the optimum TEC setting would be Pout dependant. For analogue or TTL modulation the best performance might be achieved by mixing a small amount of the modulation signal into the TEC setpoint.
    I know the time constant of the TEC would mean that the correct temp will lag drive by several seconds but it would be better than nothing.

    Right - off to finish the dual red then revisit the TEC.

    Robin
    Attached Thumbnails Attached Thumbnails drive.jpg  

    Lasers and beer don't mix. After 2 beers I lose coherence.

  6. #46
    Join Date
    Oct 2007
    Posts
    52

    Default

    I happen to have a CNI blue that looks just like that.

    Controller is a bit diffrent though.

  7. #47
    Join Date
    Dec 2007
    Location
    Texas
    Posts
    98

    Default

    Isn't YAG always pulsed while YVO4 always CW?

    Quote Originally Posted by stanwax View Post
    Laserads
    You are along the right lines - nearly

    The 808 diode as with all dpss will pump a crystal of YAG or more likely in a small laser vandate (ND:YV04).
    Rob

  8. #48
    Join Date
    Jan 2007
    Location
    Sheepsville, Wales, UK
    Posts
    3,406

    Default

    Its more true to say that YAG is used in higher power lasers which are often pulsed - but not exclusivley. Yv04 is more common in lower power lasers.

    Rob
    If you need to ask the question 'whats so good about a laser' - you won't understand the answer.
    -----------------------------------------------------------------------------------------------
    Laserists do it by the nanometre.

    Stanwax Laser is a Corporate Member of Ilda

    Stanwax Laser main distributor of First Contact in UK - like us on Facebook http://www.facebook.com/FirstContactPolymerCleaner
    www.photoniccleaning.co.uk

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •