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Vertical polarization laser illuminate on dlp3000

user4470081
Prodigy 40 points

While I use 780nm polarized laser illuminate on dlp3000 Lightcraft , output pattern will become flat.

I want to figure out this problem, and the experimental result is below. I'm considering the problem might be the cause by DLP-3000 window.

Could you offer any solutions to the problem or any products(DMD) for 780nm polarized laser?

Thanks.

Stark Yeh.

  • 0
    TI__Guru 54725 points

    Hello Stark,

    Welcome to the DLP Advanced Light Control section of the TI E2E community.

    The AR coating should still be reasonably good even at 780 nm.  If you rotate the polarization 90 degrees (i.e. horizontal), does it still have this effect? 

    What is the incident angle of the laser and what state are the DMD µ-mirrors in?  (are they in the "off" or "on" position or unpowered?)

  • 0
    Prodigy 40 points
    Thanks for your answer.
    Whatever the incident angle of the laser, it always result in the same.
    The DMD mirrors in "on" state.

    I saw a related topic .

    e2e.ti.com/.../147317

    I think it can overcome this problem by use wafer-level type (WLP) DMD package.

    But I can't research the information on TI website.
  • 0 in reply to user4470081
    Prodigy 40 points
    Sorry, I just know the package of DLP3000.

    I think the question should not be derived by birefringence.

    I can't test horizontal polarization . Because our lase is linear and s-polarized laser.
    I directly use of laser light illuminate on DLP3000. The DMD mirrors are all in the "on" state.
    Output beam will initially be circular, but gradually become a line.
    Do you know how to fix this problem ?
    I'm very confused now.
    Thanks.
    Stark Yeh.
  • 0 in reply to user4470081
    TI__Guru 54725 points

    Hello again Stark,

    You should be able to use the following methods:

    • A 1/2 wave plate in the path of the laser - this will rotate the polarization 90° (if oriented correctly)
    • A couple of mirrors in the path at 45° and perpendicular to each other.  --> holowiki.org/.../File:PolarizRotateWMirrors.jpg

    Otherwise I wonder if anyone else has experienced this issue.  If so we would welcome other input.