Square Wave Driver for Laser Diode

Discussion in 'The Projects Forum' started by CAP87, Sep 17, 2013.

  1. CAP87

    Thread Starter New Member

    Sep 17, 2013
    3
    0
    I am trying to build a driver for a SPL PL90 Laser Diode. I have done a lot of searching on square wave generators/oscillators and found a lot of different plans but can not find any information on how to build something to the specifications I need.

    Power Output: 25W

    Forward Current : 40A

    Threshold Current: 1A

    Operating Voltage : 4.3V

    Rise/Fall Time: 1ns

    Duty Cycle: .1%

    Pulse Width: < 100ns

    Frequency: I would like to use the highest constant frequency possible without causing damage to the LD. From what I understand around 1kHz is possible but anything over 10Hz should work.

    Power Source: I'm using is a car battery charging off of an alternator so it will be about 13.5V. I know this wont be the most stable source but I think will be converting it down to 4.5V.

    Most of the designs seem very similar to the example in the link below but I need to know the specific parts list to make mine work properly with that design or let me know if I completely wrong with my assumptions so far. I don't mind spending a little extra to get quality components but I don't waste any money on the wrong pieces.

    I have completed 2 years of undergrad engineering course work (3 Physics, 3 Calculus, etc) before I decided to switch paths to medicine. So I have some understanding of the basics but I'm stuck with this project at the moment so any help would be greatly appreciated.

    Data Sheet:
    http://catalog.osram-os.com/catalog...=downloadFile&favOid=020000020000a905000100b6)

    Application Note:
    http://catalog.osram-os.com/media/_en/Graphics/00018297_0.pdf

    Example Plan:
    http://www.electronicdesignworks.com/basic_electronics/555_timer/555_timer.htm
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,033
    I don't pretend to understand the Terms of Service around here, but I cannot imagine that a 25W laser is something allowed for discussion. The safety issues are substantial.
     
  3. CAP87

    Thread Starter New Member

    Sep 17, 2013
    3
    0
    I'm only trying to make my own cheap laser "jammer". I know that they are legal to use in my home state.

    I have seen the safety warnings on the packaging but the police point these same lasers into traffic so I assumed it was acceptable for this purpose. You can also purchase professional products without any issues.

    I believe the potential concerns are for being continuously exposed at a very close range. My application for this device would not involve continuous exposure or close range (Appox. +100m distances).
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,033
    I understand that might be your intention, but doo doo happens. Anyway it's not my call.

    Are you hoping to produce pulses <100ns? That's not trivial.
     
  5. CAP87

    Thread Starter New Member

    Sep 17, 2013
    3
    0
    I understand and appreciate your concern. I'm certainly not an expert on laser radiation and I will be researching this issue further before attempting to use any device.

    The pulse width does not really matter to me but 100ns is the maximum listed on the data sheet for that particular LD.
     
  6. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    Even if it's legal and safe, it's not easy. You would start with a 5 megahertz (or higher) square wave and try to get one half cycle (either positive or negative) to throw 40 amps into a laser diode at a ramp speed of 1/2 gigahertz.

    Beyond the abilities of 99% of the people that would even know how, and completely impossible to do without hands-on design work. This circuit is not googlable.
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,033
  8. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    632
    Its a sure bet that the police aren't pointing 25W lasers at cars! Lidars use milliwatts. Best to known what you are doing before you become like these guys:

    [​IMG]
     
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