Connect with us

Laser Diode Data Sheets ?

Discussion in 'Electronic Design' started by Steve Kavanagh, Nov 22, 2005.

  1. Can anyone direct me to a data sheet for the type of laser diode (or
    laser diode module) used in the really cheap laser pointers (the ones
    with < 1 mW output, no fancy current regulator or power output
    feedback...just a series current limiting resistor) ? My search
    efforts have not managed to find one.

    Steve
     
  2. John  Larkin

    John Larkin Guest

    You might try Lasermate, motto "The Friend of Laser."

    John
     
  3. Thanks, John. I wasn't aware of that company....but still, as far as I
    can tell, their lowest power diode is 5 mW and their modules all use
    feedback power control.

    Steve
     
  4. Fred Bloggs

    Fred Bloggs Guest

    Can anyone direct me to a data sheet for the type of laser diode (or
    I direct you to this:
    http://www.photonic-products.com/products/laserdiodes_visible/sanyo_visible_ds/dl-3148-025.pdf
    Hmmm- hopefully your application skills are better...if the output
    monitor scares you, then maybe you should take up stamp collecting or
    something.
     
  5. Yes, I have found many like this...but the type of module I am asking
    about does not use the power monitor for feedback.
    Actually it is more the lack of the use of the output monitor that
    scares me ! I am trying to understand how the manufacturers of such
    laser pointers get away with it, what the temperature constraints might
    be, etc.

    It has just occurred to me that the cheap pointers may just be LABELLED
    as "< 1 mW" for the purpose of fooling customers and customs inspectors
    but may actually contain 5 mW diodes running at some unknown power that
    may or may not be under a milliwatt depending on temperature, state of
    batteries, etc. If this is the case then perhaps a typical 5 mW diode
    data sheet could be instructive.

    Steve
     
  6. John  Larkin

    John Larkin Guest

    Give them a call. They can usually find what you need.

    John
     
  7. John  Larkin

    John Larkin Guest

    We use VCSEL lasers, about 1 mW fiber-coupled, with constant-current
    drive, and they work fine. We switch them on/off in a few hundred
    picoseconds, and leave them on/off for indefinite times, so feedback
    isn't feasible for us.

    John
     
  8. You can do this because with VCSELs the threshold current tends to be
    a much smaller fraction of the operating current. With visible laser
    diodes (VLDs) this is not generally the case. E.g. the threshold at
    25'C might be 20mA, with 30mA destroying the device. But the threshold
    at 70'C might be 50mA...
     
  9. John  Larkin

    John Larkin Guest


    Do the cheap laser pointers use photodiode feedback? They seem to work
    fine.

    John
     
  10. Apparently not, according to Steve.

    The VLD's I have used increase the threshold current with
    temperature. So if you set the current to give the nominal output at
    20'C, then they would just get dim or go out at high temperatures (or
    as they self-heat). But if it got too cold, then you might be in
    trouble!
     
  11. One model (which I acquired for the princely sum of CDN $1.95) consists
    of just three 1.5V cells, a switch, a 68 ohm resistor and a laser diode
    (all in series of course), as far as I can tell. I have wondered about
    holding in my hand for a few minutes and seeing if it goes out and then
    leaving it outside for an hour and seeing if it goes out....permanently
    ! Or has someone in China figured out how to make a
    less-temperature-sensitive diode ?

    Steve
     
  12. One model (which I acquired for the princely sum of CDN $1.95) consists
    of just three 1.5V cells, a switch, a 68 ohm resistor and a laser diode
    (all in series of course), as far as I can tell. I have wondered about
    holding in my hand for a few minutes and seeing if it goes out and then
    leaving it outside for an hour and seeing if it goes out....permanently
    ! Or has someone in China figured out how to make a
    less-temperature-sensitive diode ?

    Steve
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-