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DLPLIGHTCRAFTER4500: Trigger pattern by line-scan camera

Timo Eckhard
Prodigy 20 points

Part Number: DLPLIGHTCRAFTER4500

Hi,

I want to use a LightCrafter 4500 in combination with a line-scan camera.

The line-scan camera is supposed to trigger a pattern change at every line that is acquired, such that each acquired line corresponds to a distinct pattern. After the maximum number of pattern that can be stored on the LightCrafter, I would like to repeat the sequence from the first pattern.

The patterns I am using are bitplane pattern stored on the device. For triggering I want to use the input trigger connector pins, and I have a signal from the camera available that is output with every acquired image line. However, there is no other signals available, for start or stop.

For testing, I am using the GUI software. However, I am not clear how to setup the pattern sequence. What I tried is:

  • Use pattern sequence  (fixed exposure)
  • Add my bitplanes, each with external trigger
  • Set pattern exposure to the same value as the camera expousre time per line
  • Set trigger mode internal/external
  • Set paatern source to flash


Now I am not having clear the following things:

  • How can I start the pattern sequencing automatically, once my trigger signals for changing pattern arrive?
  • If I manually start the sequence, it does not seem to wait for the trigger. Should it, or did I miss something?

Help would be greatly appreciated.

Thanks in advance!

  • 0
    TI__Mastermind 30600 points
    Timo,

    Welcome to the DLP forums and thank you for your question. What you are trying to accomplish should definitely be possible and it sounds like you have the right set-up idea.

    For your first question, are you wondering if you can get the Lightcrafter to enter your pattern sequence right on start-up? If you could clarify this question for me, I would appreciate it. In general, once the pattern sequence is set, it should advance the patterns in response to the external triggers.

    When you manually start the sequence, does it go through the patterns but they are out of sync with the lines? Or the patterns don't show at all? One issue could be that your triggering voltage isn't correct or that you need to select different jumpers on the board for proper I/O voltage levels.

    A couple things that would help me further debug your issue:
    * Screenshots of your GUI with pattern setup
    * Descriptions of the symptoms

    Thanks,
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 20 points

    Dear Paul,

    thanks for the quick reply. I think I understand much more in the meantime, haveing the chance to trigger the DLP with a singal generator, and measuring the output pattern in high frequency using a photodiode and oscilloscope.

    Regarding my first question, I would not only like to enter pattern sequence at start, but also do the action equivalent to pressing the "Play" button in the GUI automatically. This is, because I only have one input triggger (Trigger 1), which I use to trigger next pattern. In my application, I do not want to use the GUI, but have the device ready to display the pattern once Trigger 1 is active.

    Regarding my second question, I think I solved it myself. It seemed to be related to the trigger generation, so didn't have to do anything with the LightCrafter module.

    However, one other quesiton came up. Using the oscilloscope, I found a time delay of approximately 340µs between the input trigger and the LED current to rise to display the pattern. I do not use the Trigger 1 delay or the LED delay parameter. Is this normal? Can it be reduced?

    I guess the delay for switching mirrors is shorter than the delay for switching lights (eg. switching two pattern with green LED on is faster than switching a pattern with red and a pattern with green LED). Is that correct?

    Thanks!

    Timo

  • 0 in reply to Timo Eckhard
    TI__Mastermind 30600 points

    Hi Timo,

    You are correct that the mirrors can switch much faster than the LEDs. I'm not sure exactly what the delay is between input trigger and LED reaction, we've never sat down and tested that. My initial reaction is that amount of time seems approximately correct - there is a fairly large circuit network for the triggers to go through. I'm not sure that there is anything you'd be able to do about on the EVM, with custom hardware you might be able to get that time lower.

    -Paul