Quadratic light Sensors

Discussion in 'Homework Help' started by bondissement, Dec 3, 2008.

  1. bondissement

    Thread Starter New Member

    Nov 6, 2008
    Hi.. i need to know about types of quadratic light sensors could u pls help me thank you
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Could you expand on that? Light sensors exist in several varieties, but quadratic is new to me.
  3. Wendy


    Mar 24, 2008
    I'm not sure if it's the same thing, but I've run into glass slides that have two sets of stripes next to each other (chromium on glass). As you slide one over the other they alternately block and let light through, in what looks like a sine wave looking at the output of the photodetector.

    The other side is 90° off, with a separate photo detector, so now you have a sin/cosine function. Put them on a lasou(sp?) pattern on a oscope and you get a circle. I've had to calibrate several X Y tables that used this technique.

    The advantage is you get 4X the resolution than the glass slide actually has, Looking at the phase angle of the voltage you get a very precision measurement.

    Is this what you're asking about?