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DMD (DLP3000) question on micromirror lateral position accuracy

Fedor Inochkin
Prodigy 40 points

Hello,

we are using DLP LightCrafter EVM with DLP3000 in a scientific application for the purpose of optics calibration. Our partial interest is the micromirror's lateral position accuracy - whether it is specified or not, some "worst case" estimations etc.?

The only reference for the accuracy we can find in datasheets is the size of active array, especially amount of digits after a decimal point (we can see 4 digits, so the estimate would be 100nm), but this is not stated clearly, as well as other geometrical characheristics (adjacent mirrors accuracy, field distortion, dimension calibration accuracy). 

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Thanks for any information,

Fedor Inochkin

  • 0
    TI__Mastermind 30600 points
    Fedor,

    Welcome to the DLP forums!! Can you describe a little further what you mean by lateral position accuracy? I'm not sure that I follow what you're after. The DMD's mirrors are fixed on the substrate, so I'm not sure what accuracy comes into play in the lateral direction.

    Thanks,
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 40 points
    Hello, Paul, thanks for your reply,
    and what I mean by the term "lateral position accuracy" is the manufacturing accuracy of the micromirrors positions on the substrate.
    Subdividing the question into smaller parts, I can rewrite this as:
    1) I expect that the DLP3000 array size has to be 6571,8 x 3699,0 um as stated in datasheet. But what are the tolerances for these dimensions (1/10/100nm/1um...) ?
    2) Micromirror pitch size variation over the entire array ("distortion").
    Correct me if I'm not right, but It's quite common for the manufacturing process to have a small distortion over the field, so we believe that these process-induced distortions are reflected onto the DMD structure, slightly (but smoothly) varying the actual pixel pitch over the array.
    3) Adjacent mirrors misplacement, or a random error in micromirrors positions.

    Of course, all of these values should be really small (leading from the CMOS process itself), but the numerical estimates for any of them are greately appreciated in scentific applications.
  • 0 in reply to Fedor Inochkin
    TI__Mastermind 30600 points
    Fedor,

    Thank you for your clarification. Let me ask some colleagues and see if I can find that information and get it to you. You are correct that there will be small distortions.

    Give me a few days and I'll get back to you on whether TI can share this information (or even if we have it).

    Thanks,
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 40 points
    OK, got it.
    Thanks,
    Fedor
  • 0 in reply to Fedor Inochkin
    TI__Mastermind 30600 points
    Hi Fedor,

    The values you're looking for aren't what we specify and therefore we have no way to guarantee that a particular device will meet a given specification. That being said, your estimate of +/- 100nm on the overall array size is probably a good one.

    I would point you to the data sheet for this device and have you look at table 6.12: www.ti.com/.../dlp3000.pdf
    That table has tilt angle variation and orientation variation would should cover all the different distortions that you're asking about. If your optical and illumination designs can tolerate those variations as specified, you should not see any other effects.

    Thanks,
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 40 points
    Paul, thanks,
    BTW - do you plan to specify that in the future?
    Fedor
  • 0 in reply to Fedor Inochkin
    TI__Mastermind 30600 points
    Fedor,

    Not at this point.

    Thanks,
    Paul