DLP4500: Trigger in and out in turns

Thank you!

I have been able to set it up to trigger the camera. DLP currently sends a trigger signal after every 2 frames.

How do I set it to trigger the camera for every change in frame?

Thanks a lot!
Rashmi

Hello Rashmi,

What mode are you using? Are you using an external video input or patterns from the flash?

Thanks,
Kyle

Hi,

I am using patterns from the flash. Two images 8bit depth, of which one with fringes and another without pattern(plain white).

Thanks!

Rashmi

To add details to this,

Currently an external source triggers DLP every 500ms. For every triggering, dlp projects two images with pattern exposure time=230000 us and pattern period=230000 us

There is no trigger-in between two patterns 1st pattern is the fringe image and the other one without fringe. Like shown in the pattern sequence in the image attached

In this case for every input trigger, dlp projects both images continuously for 230000 us and goes off before repeating from the first image. During this, camera captures an image of the projection without fringes(i.e,the second image in the pattern sequence) and another image during the off period ( before repeating the first image in the pattern sequence). Whereas , camera should capture projection of  two images in the pattern sequence and not when the projection is off.

Please let me know the external trigger settings that could rectify the problem. 

Thanks a lot!

Rashmi

Hello Rashmi,

My guess is that with your current setup you are producing a waveform something like shown below (the yellow wave is the external trigger in and the blue wave is the external trigger out to the camera).

The trigger out drops very quickly as the DMD is clearing to project the next image. My guess is the camera does not properly pick this up. To remedy this I suggest lowering the pattern exposure time (perhaps try something like 180,000us). The pattern period will be the same time. You should then produce waveforms that look something like this: 

Notice how the output trigger 1 (blue wave) doesn't stay high when the pattern is not being exposed (even the the period is not yet over). Let me know if that properly triggers your camera. 

Thanks,

Kyle

Hello Kyle,

Thanks for the response.

I tried changing the exposure time but that is showing no change in the behaviour of the camera. 

I tried to add a few more patterns in the pattern sequence. The camera is triggered to capture every pattern in the sequence leaving only the first one. i.e, the change from first pattern to the second is triggering the camera to capture the second pattern . Change from second to third pattern is triggering the camera to capture the third pattern and so on. 

How can I make it to trigger to capture the first pattern also before capturing the next ones?

Thanks!

Rashmi

Hello Rashmi,

Can you try inverting the trigger 1 output? This can be found under "Trigger Controls" in the "Pattern Sequence" tab. Let me know if that works.

Thanks,
Kyle