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Re: [diy_3d_printing_and_fabrication] Re: Projector Calibration/ Lens Distortion

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  • Jon Elson
    ... Yes, you really only want blue illumination, that is what cures the resin. Either that, or put a deep blue filter in front of the photodiode. ... I m not
    Message 1 of 39 , May 22, 2013
      Graham Stabler wrote:
      >
      >
      > Also if we are correcting for the optics perhaps using a single colour
      > would work OK?
      >
      >
      Yes, you really only want blue illumination, that is what cures the resin.
      Either that, or put a deep blue filter in front of the photodiode.
      > A big advantage of a PD is that you can get it really close to the
      > image plane.
      >
      I'm not sure that is critical for this zone correction, but it can't hurt.

      Jon
    • Graham Stabler
      ... The reason I suggested a diffuser is because I was talking about converting a camera into a sensor so the image you get is actually an average of the
      Message 39 of 39 , May 23, 2013

        On Wed, May 22, 2013 at 11:32 PM, Bhatt Himanshu <bhatthimanshu@...> wrote:

        @Graham
        I read about ND filters and i think i can get it from local camera shop. Do i need diffuser if i use ND filter/filters properly. 

        The reason I suggested a diffuser is because I was talking about converting a camera into a sensor so the "image" you get is actually an average of the light hitting the sensor. The idea of an ND filter is just to reduce the light levels though as I mention on another thread you can do this by projecting darker images anyway I think. 

        I want to make it clear that I am not suggesting trying to measure the output of a specific pixel on the projector but rather to get the average intensity over a fairly small area (because crappy webcam sensors are tiny) and then use a grid of these measurements to produce a correction which should be fairly smooth if the aberration is only caused by the optics.

        Cheers,

        Graham
         
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