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Questions for structured illumination application

qiyuan song
Prodigy 230 points
Other Parts Discussed in Thread: DLPC350
We ordered the LightCraft 4500 Evaluation Module for a research purpose to make structured illumination pattern sequences and synchronize the pattern with our CMOS. In general, we use our laser as light source and do not use the LEDs. Now we are checking if this module can realize our application. I would like to ask some questions here. I hope anyone can help me.

1. If LED is not connected with the module and only DMD is connected, can this module work?

2. In the guide, it mentions that this module will spatio-temporal interleave color frames for displaying, will this happens in Pattern Sequences mode? 
3. For DMD, when it display a 1-bit  gray-level pattern in Pattern Sequence mode, will all mirrors move simultaneously or one-by-one?
  • 0
    TI__Expert 4720 points

    Hello Qiyuan,

    Here are my responses to your questions:

    1. Yes, the module will work correctly
    2. The spatio-temporal interleave for color frames is only in video mode and not pattern sequence mode
    3. The mirrors move simultaneously

    Hope this helps! If you are using lasers with your application you may find one of our application notes helpful. Using Laser with DLP DMD Technology (DLPA037)

    Best regards,

    Blair

  • 0 in reply to Blair Conner
    Prodigy 230 points

    Hi Blair, 

    Thanks for your answer. I get additional question. When the DMD works at sequential mode, will each mirror always oscillate slowly? In other words, how long can each mirror be kept still before next frame?

  • 0 in reply to qiyuan song
    TI__Expert 4720 points

    Hello Qiyuan,

    The controller will oscillate the mirrors to ensure reliability and lifetime of the device, but these oscillations are not noticeable in most applications and do not change the binary mirror position. I actually don't know the absolute maximum frame exposure on the LightCrafter 4500, but have tested binary patterns which are exposed for well over ten minutes in the past.

    Best regards,

    Blair

  • 0 in reply to Blair Conner
    Prodigy 230 points
    Dear Blair,

    I additional questions here to bother you.

    1. On the interface of the software, DLP LightCrafter 4500 Control Software 2.0.0, there is only option 'internal/external', how does the software know I am using internal or external trigger? And how does the software know I am using Trig_IN_1 or Trig_IN_2?

    2. The chip has internal memory buffer to rotate two 24 bit planes. I am a little bit confusing here. Does it mean that there is no loading time if my pattern sequence size is less than 24bit or 48bit?

    3. Once I set the pattern sequence, could I save it? It seems I have to manually set this every time when I re-start the software.

    4. If I want to use VSYNC signal for synchronization, is it able to use on pattern sequence mode?
  • 0 in reply to Blair Conner
    Prodigy 230 points
    Dear Blair,

    I have two more question.

    1.
    Let's suppose the simplest case. If I set a 1-bit pattern sequence. And it is triggered by Trig_IN_1 or Trig_IN_2. Once a trigger pulse arrives, how long does it take for the DMD move the mirror from the off state to be ready for displaying? Is it 230 us or 78.3 us? What does the system do during this time?

    2.
    For Trig_IN_2, the default setting is that rising edge for start and falling edge for stop, isn't it? Could I set it reversely as falling edge for stop and rising edge for stop?
  • 0 in reply to qiyuan song
    TI__Expert 4720 points

    Hello Qiyuan,

    Here are my responses:

    1. On the interface of the software, DLP LightCrafter 4500 Control Software 2.0.0, there is only option 'internal/external', how does the software know I am using internal or external trigger? And how does the software know I am using Trig_IN_1 or Trig_IN_2?

    When creating a pattern sequence you must specify the trigger mode and each pattern needs its trigger set as well. Please reference the section 3.3.1 "Sequence Settings" in the LightCrafter 4500 User's Guide for details to do this with the GUI and section 2.4.3 "Pattern Display Commands" DLPC350 Programmer's Guide if you are writing your own application.

    2. The chip has internal memory buffer to rotate two 24 bit planes. I am a little bit confusing here. Does it mean that there is no loading time if my pattern sequence size is less than 24bit or 48bit?

    Correct. If the sequence needs 48 bitplanes or less both buffers are preloaded before the sequence starts.

    3. Once I set the pattern sequence, could I save it? It seems I have to manually set this every time when I re-start the software.

    You need to attach a custom solution file to a firmware file along with the image data. Please reference sections 3.6 "Storing Images in Flash Memory" and chapter 5 "Saving Solutions" in the the LightCrafter 4500 User's Guide.

    4. If I want to use VSYNC signal for synchronization, is it able to use on pattern sequence mode?

    Yes, plase reference the sections I mentioned in question 1 above.

    And the responses to your second set of questions:

    1. Let's suppose the simplest case. If I set a 1-bit pattern sequence. And it is triggered by Trig_IN_1 or Trig_IN_2. Once a trigger pulse arrives, how long does it take for the DMD move the mirror from the off state to be ready for displaying? Is it 230 us or 78.3 us? What does the system do during this time?

    I do not know the answer to this question, but will find out. 

    2. For Trig_IN_2, the default setting is that rising edge for start and falling edge for stop, isn't it? Could I set it reversely as falling edge for stop and rising edge for stop?

    That is not a supported configuration.

    Please let me know if you have any other questions!

    Best regards,

    Blair

     

  • 0 in reply to Blair Conner
    TI__Expert 4720 points
    Hello Qiyuan,

    The delay between a trigger signal and the mirrors updating is 230us. During this time the DLPC350 is transferring the data from frame buffer to the DMD CMOS memory.

    Best regards,
    Blair