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DLP as SLM

Lorenzo Ferrara
Prodigy 30 points

Good day!

We're using a DLP system for projection. We want to address the light from a laser/lamp source to a few hundreds of different photodetectors, randomly distributed,  at a certain distance from the source. The throw ratio of the optical system has to be enough to cover an area of 4 m2 at 4m of distance, where the panel with the photodetectors will be located.

Beacuse of the requirements in term of beam expansion and photodetector active area, the projection of a single mirror of the DMDs array will be enough to cover the area of one photodetector. 

So, the problem we are facing is that we will need just a few hundreds of mirrors respect to the half/milion mirrors in a DMD array. So we lose a lot of power. 

I wonder if it's possible to apply an interferferometric approach to the DMD projection in order to focus almost all the incoming light in a few spots, like a SLM. 

Regarding this question, i would also know something more about the experiment shown in the paper, "Dynamic holographic 3-D image projection" (M. Huebschman et al. , OPTICS EXPRESS, v11, n5, 2003). Is it possible to use the DMD array as a phase mask with low power losses from higher diffraction orders? 

Thank you a lot for your feedback.

Best

Lorenzo Ferrara

  • TI__Mastermind 48310 points

    Hello Lorenzo,

    First, welcome to the DLP section of the TI-E2E Community.  We are glad you are here.

    Using a DMD in ordinary projection mode will result in the low power you describe.

    You may be able to use the DMD at the Fourier transform plane rather than the image plane.  Assuming you are using coherent light, this would mean forming the inversere tranform on the surface of the DMD.  However,  I do not know if you will be able to distrubute the light in a arbitrary (i.e. truly random) pattern and almost certainly will not be able to deliver equal amounts of light to each point in question.

    You may want to contact the author of the paper you mention, since he would the right party to provide you with more information about his experiment.

    Fizix

     

  • in reply to Fizix
    Prodigy 30 points

    Hello Fizix, 

    thank you very much for your quick answer and the information.

    I'll try to contact the authors for more insight.

    Best

    Lorenzo