Page 9 of 9 FirstFirst ... 56789
Results 81 to 86 of 86

Thread: Info on scan fail systems

  1. #81
    Join Date
    Oct 2009
    Location
    sweden
    Posts
    116

    Default

    can i place a lens on the output of my spectra physics 168
    to get a higher divergence?

    for us who donīt like silicone

  2. #82
    Join Date
    Oct 2009
    Location
    sweden
    Posts
    116

    Default

    i mean can i put the lens before the scanners instead of after the scanners
    is there any product (lenses) to recomend?

  3. #83
    Join Date
    Oct 2009
    Location
    sweden
    Posts
    116

    Default

    what about this?
    http://www.dragonlasers.com/product....cat=285&page=1

    feels strange to combine a spectra physics with some laser pointer thingy

  4. #84
    Join Date
    Nov 2010
    Location
    Ilchester Somerset UK
    Posts
    58

    Default

    Hi everyone,
    Is this thread still live?
    I have a few ideas for practical circuits that I can share.
    Thanks, Si Bond.

  5. #85
    Join Date
    Mar 2007
    Location
    Rotorua New Zealand
    Posts
    528

    Default

    Hi
    I'm always interested in good ideas
    Thanks
    Ray

  6. #86
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,801

    Cool Hooray for grave digging!

    Wow - this *is* an old thread!

    Sometime after this thread died down I started a project with Mo (Daedal) to build a digital scan-fail device based around the Arduino. The idea was to store the X/Y coordinates (sampled from the position feedback signal on the amp) in a large array and then compare the current value to the last 500 values in the array. If you got a hit, it tripped the scan-fail for 1 second - which would crowbar all the modulation lines to ground. (Why 500 values? Because that worked out to no more than 6 pulses per second in the same location, which made the MPE math easier.)

    We weren't sure if it would be a hobbyist product or a commercial product at the time, so we just banged away at it to see what we could accomplish. Very quickly we discovered that the Arduino wasn't fast enough, so we switched to a different processor (forget exactly which one, but I'm thinking it was the Beagleboard). Note that this was well before the Raspberry Pi was released. Mo finally got the code working at 10-bit resolution, which seemed OK at the time, but we soon ran into lots of other problems.

    Truthfully, the concept was fraught with conceptual errors, compromises, and performance issues from the very beginning, and in the end it would not have been robust enough to guarantee safety, so we abandoned it. Spoke with Casey Stack about the effort sometime later (after I had completed my LSO course) and he said that lots of people who design scan-fail systems try the digital approach at some point, but they usually drop it in favor of an all-analog one because they're more reliable. Tellingly, the gold standard for audience-scanning scan-fail systems (PASS) is all-analog.

    The idea of scan-fail is pretty simple. But implementing it in a truly fail-safe manner is more complicated than you might imagine. You've got to account for some really edge-case scenarios (including highly unlikely things like a single-rail failure on a dual-rail power supply!), and in the end I would always be worried about the liability issue if I were designing a commercial product.

    All that being said, if the PL community wanted to collectively work on something that was open-source, I think that would be cool. And so long as there is a disclaimer that it comes with no guarantees as to performance, I think it would be fine for hobbyist use. If a company decided to use it commercially - well, that puts the legal onus on them.

    Adam

Posting Permissions

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