Page 3 of 3 FirstFirst 123
Results 21 to 25 of 25

Thread: Laserwave 1W 520nm green diode module - part 2 - powering up and measuring

  1. #21
    Join Date
    Nov 2008
    Location
    Cleveland Ohio
    Posts
    2,599

    Default

    gentleman and ladies that is what a bias voltage is all about. It moves zero up to the point that the laser starts emitting as a laser. Problem is it makes the laser an led/laser and makes a dot on the wall. This is why people like beam suppression that starts the beam at the bias voltage but when no signal is seen drops the bias to zero. Since diodes react so fast this works. This essentially compresses the modulation signal. What would be more appropriate would be to do the bias voltage and compress the 0-5v signal in to the lower range 1.28-5v or 3.72V. if you have 8 bits that is 0.0145V per step as apposed to the 0.0195V per step for the 5V modulation signal. Since you are rescaling the signal from 5v to 3.72v it makes no difference in pallet because the steps are made smaller when the signal is rescaled.
    Nobody seems to do this though and just accepts the compression. The only device I know that does this the eyemagic iris system.

    I envision simply using a voltage divider ie pot and then adding the bias voltage to the result would do the job fine without any active electronics. Could also be done with an opamp and act as a buffer at the same time. Negative gain opamps work same as gain opamps. That seems overly built though and I'd just do the passives.

  2. #22
    Join Date
    Nov 2009
    Location
    Whanganui New Zealand
    Posts
    312

    Default

    oh.............

  3. #23
    Join Date
    Nov 2007
    Location
    Southampton, UK
    Posts
    458

    Default

    Sorry about the lack of recent updates to this thread, I recently had the misfortune to break my leg and will be out of action for a while. More in due course...

  4. #24
    Join Date
    Dec 2006
    Location
    Scotland
    Posts
    1,408

    Default

    Hey , will it be half a decade before your back like last time :-)
    good to see ya back , wonder if banthai will pop up next :-)
    In the beginning there was none. Then came the light - #1 UKLEM - 2007
    BUY UK LEGAL LASER POINTER :: NEW - Blue 460nm Laser Pointers

  5. #25
    Join Date
    Sep 2012
    Location
    Crawley, UK
    Posts
    82

    Default

    Quote Originally Posted by greenalien View Post
    I don't know why you're expecting 1mrad divergence - Laserwave quote < 2 mrad on their website, and my tests confirm that this is the case.
    When I've finished installing the new module in my projector, I'll do a side-by-side comparison of the new green against a Kvant red (array of 638nm) and a Kvant blue (Single Nichia 445 nm, from when they cost loadsa money, before people started harvesting video projectors...). One thing I can say - compared with my Viasho DPSS green 1W that's just come out of the projector, the new diode green is significantly brighter.
    I'm quite interested in those results, but it is fair to mention that we have moved forward quite a bit since then.
    At present our 1W 520nm and 445nm modules have pretty much the same beam profile and divergence of 3x3mm and 0.7/0.3mrad (half angle).
    Martin Pelikan
    KVANT Laser Systems UK
    www.kvantlasers.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
  •