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DLPD4X00KIT: Illumination light

Qiang Li58
Intellectual 420 points

Part Number: DLPD4X00KIT

Hello,

I have a problem with the illumination light.

I used the collimated LED light (MCWHL5-C2, www.thorlabs.com/NewGroupPage9.cfm as the incidence, although the collimation can't be perfect.

The test checkerboard pattern was displayed on the DMD.

When checking the reflected light from the DMD, I found that the reflected image was blurred, without clear checkerboard boundaries. The reflected image was clear when the image screen was very close to the DMD.

Thus it seems that the divergence of the incident light is the problem.

Does anyone have a similar experience? What kind of light source do you usually use?

Any suggestions or comments would be highly appreciated.

Thanks,

Qiang

  • 0
    TI__Guru 54705 points
    Hello Qiang,

    The source you are using has a fairly wide spectrum (a medium wide but tall peak near 435 nm and wide lower peak near 550 nm. Since the DMD is a periodic array of mirrors, you will get diffraction orders for these peaks and they will diverge spatially the further from the DMD.

    You can either get far enough away to pick off one order of one of the peaks, but I suspect that you want all of the light.

    The other way is to use an ordinary lens to re-image the surface of the DMD at the screen at the distance you want. A fairly slow lens will give you a good working distance, but may require a big lens. This lens will converge all the orders into an image.

    The other possibility is to use a very narrow band light source, and work far enough away from the DMD that you isolate the brightest order and it should be collimated also.

    Fizxix