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DLPLIGHTCRAFTER: Diffraction

Jack H
Prodigy 60 points

Part Number: DLPLIGHTCRAFTER

I am interested in using the DLP Lightcrafter to image patterned light onto a brain. My intention is to remove the light drive and incident the DMD chip with a laser (473nm 300mW) that has been expanded. The laser beam will once again be expanded before targeting the brain.

I understand that coherent light sources are subject to diffraction which can augment the actual image projected.

1) If the DMD chip is incident with a laser will diffraction cause the image patterned to be different then the intended pattern?

2) If so, what are some low cost methods around this issue? 

  • 0
    TI__Guru 54480 points

    Jack,

    Do you intend to re-image the surface of the DMD onto the target or do you plan to work in collimated space? 

    • If you plan to re-image the surface of the DMD as you would in a typical projection system then within the effective Depth of Field the image should re-converge in a usable way. 
    • If you plan to work in collimated space at the target, then one way would be to put your final expander collection optics far enough away from the DMD that the orders diverge and only collect the brightest order.  This assumes that the illumination has a small enough NA that the outbound order cones do not overlap.

    I hope this makes sense.

    Fizix

  • 0 in reply to Fizix
    Prodigy 60 points
    Fizix,

    We do plan on re imaging the surface of the DMD.

    Do you know what the effective Depth of Field is for the DLP3000: 0.3-inch WVGA chip used in the Lightcrafter?

    Furthermore, how much diffraction can we expect?

    Thanks
  • 0 in reply to Jack H
    TI__Guru 54480 points

    Hello Jack,

    The effective Depth of Field (DOF) will be the same as for any other ordinary optical system, so it will depend on the lenses and apertures you choose to make your system.

    I am not sure how to answer the second question - I don't know how to quantify the diffraction.  What wavelength are you going to use?

    Fizix