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DLPLCR67EVM: DLP products forum

?? ?
Prodigy 10 points
Part Number: DLPLCR67EVM


Tool/software:

Hello!

As shown in the figure, the optical power of the two brightest spots in the vertical direction is almost the same. Changing the incident angle can only concentrate the beam energy in a vertical column, but it cannot focus the beam into a single spot. The beam utilization rate is only 30%. Could you please advise on how to adjust the setup to improve the beam utilization rate?

Thank you!

  • 0
    TI__Guru 54705 points

    Hello User,

    Please tell me about your illumination path.  This device is intended to be illuminated from the bottom edge of the device.  What input illumination angle are you using.  Judging from the color it looks like you are using a 532 nm laser or near that.

    If you are illuminating from the bottom edge, then moving the illumination angle horizontally will not move the energy distribution of the orders.  Moving the illumination angle vertically should change the distribution of energy in the orders.

    FIzix

  • 0 in reply to Fizix
    Prodigy 10 points

    This is our illumination path. We are using a 532 nm laser beam that is nearly parallel to the horizontal plane to illuminate the DMD. We primarily adjust the horizontal angle, and during testing, the image loaded on the DMD is completely black. When we slightly change the vertical angle by adjusting the tilt of the mirror, the energy distribution does not show significant changes. If, as you mentioned, the illumination needs to be from the bottom edge, could you please advise what the approximate vertical angle should be? Thank you!

  • 0 in reply to Fizix
    Prodigy 10 points

    Thank you very much for sharing this tool—it has been incredibly helpful. I do have a question regarding my calculations: for a laser with a wavelength of 532 nm and a beam waist of 1 mm, I obtained an f/# value exceeding 1000. At this f/#, the calculated diffraction efficiency appears to be nearly zero. Could you kindly advise if this result is expected, or if there might be something I am overlooking?

  • 0 in reply to ?? ?
    TI__Guru 54705 points

    Hello User,

    Please allow a day or two to consult with the Optical team that wrote this tool.

    Fizix

  • 0 in reply to Fizix
    TI__Guru 54705 points

    Hello again User,

    This model looks at the output in the direction normal to the DMD array (window).  Unless an order exists along the normal within the f# you specify then you will get very little energy.  Energy is only allowed where an order exists.  You may need to adjust your incident angle.  Try one direction then the other to see which direction moves the energy in the orders.  

    One direction only shifts the pattern.  The other should also shift the energy distribution in the orders.

    Fizix

  • 0 in reply to Fizix
    Prodigy 10 points

    Hello! We are using a 515 nm laser with a beam waist of 1 mm to test diffraction efficiency by varying the incident angle. We found that when the laser is incident at 50° relative to the normal of the DMD array, the maximum diffraction efficiency measured is 40%. Could you please confirm if it is acceptable to use a 50° incident angle, and whether a maximum diffraction efficiency of 40% is reasonable under these conditions?

  • 0 in reply to ?? ?
    TI__Expert 6830 points

    Hi E2E User,

    Please give us another couple of days to discuss with the optics team about this. Thank you!

    Regards,
    Michael Ly

  • 0 in reply to ?? ?
    TI__Guru 54705 points

    Hello User,

    It appears my response  on yesterday did not post correctly.  

    It is acceptable to use the 50° incident angle, but at that angle the AR coatings are not as efficient, so I am not surprised by the 40% efficiency. Also given the small NA you are using.

    Fizix