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DLPLCR6500EVM: How to synchronize the Pulsed laser and the DLPLCR6500

Part Number: DLPLCR6500EVM

Hi TI team, 

I try to implement single-pixel imaging using DLP6500  and single-pixel detectors. For that, I use a 532 nm pulsed laser to illuminate the DMD mirrors with modulated patterns. To get measurements corresponds to each pattern the DMD and laser should be synchronized. The laser I use has the following specifications
Lser - 532nm
Pulse energy - upto 1mj
pulse width @2khz  -<1.5ns
Repetition rate - single shot 2kHz
Power- 1W
  • Hi Anumol,

    You can use the output trigger option where you can trigger the pulse generator the laser is connected to. The output trigger sends a trigger pulse while displaying the patterns on DMD. One triggers during dark time and the other triggers at the beginning of displaying image.

    While you load patterns in Pre-stored pattern or Pattern-on-the-fly mode in TI provided DLP Lightcrafter tool, please make sure to check the output trigger option. You can get these signals out of J24 in the TI provided EVM

    Please let me know if you need any additional information

    Thanks

    Sachin

  • Thank you for the prompt response. could you please let me know how this triggering is performed?

    Are there any devices should be connected to the trigger input?

    if so what kind of devices? 

    Could you please guide me in resolving this problem ?

  • Hi Anumol,

    Considering your laser input to be driven @ 2Khz @1.5ns pulse width, you cannot directly connect the trigger output to your laser as the minimum pulse width of the output trigger 2 is 20us. You can either opt for a laser with 20us pulse input or use a 555 timer in monostable mode with output trigger pulse as trigger input.Below is the circuit.

    where pulse width t = ln(3).R.C

    You need to select the values of R and C such that t<1.5ns.

    You can use TI provided 555 timer .

    For 2Khz input, you can set the (exposure time + darktime) around 500us

    Hope this helps.

    Thanks

    Sachin

  • Hi Sachin,

    Can I have an integrated product from TI that can directly use? I am not good at implementing circuit boards. 

    if I get such a product how it can be utilized to synchronize. 

    Thanks    

  • Hi Anumol,

    Could you let me know how you are planning to source your pulsated laser according to its specification? You can use the trigger signal as enable to the source instead. It would be a much simpler solution (without the use of any convoluted circuitry) if you already have a source. 

    Thanks

    Sachin

  • Hi Sachin,

    Attached are the specifications of the pulsed laser I have. I need to synchronize both light source and DMD  in such a way that both should project light for one second at the same time. thus, I would get measurements corresponding to each pattern from the DMD from the single-pixel detector, 

    Thanks 

     
    WEDGE HB 532.pdf

  • Hi Anumol,

    I have contacted the RPMC engineers for suggesting a product for sourcing the laser. Usually , we require special sources for driving such lasers and cannot be driven directly from DLPC900. I will come back to you with the product and a simple design for your requirement soon after I get reply from them

    Thank you for your patience

    Regards

    Sachin

  • Anumol

    What peak energy from your laser source and what portion of the DMDs active array are planning on exposing?

    At 1.5 ns  1 mJ the peak output power is in the order of 660 kW.

    That level of peak optical power could easily damage the DMD. 

    Please read our application note on using Laser Power Handling for DMDs

    DLPA027 www.ti.com/.../dlpa027.pdf

  • Hi Carey Ritchey,

    Thank you for your valuable comments.

    The total 1080*1920 mirrors will be exposing with 1- 10W power

    Thanks 

  • Thanks for the clarification

  • Hi Sachin,

    Have you got response from RPMC engineers?

  • Hi Anumol,

    I received their reply. They are asking me about the type of application you are using so that they can suggest a Laser and its source. To make the communication better and faster, It will be better for you to directly contact them.

    You can go to 

    http://www.rpmclasers.com/ and raise a request in their website for getting suggestions on the type of lasers and their source for your application.

    Once you have decided the source after contacting your laser manufacturer, you can reply to this thread if you have any further queries.

    Thanks

    Sachin