Sampling in Optics
Illuminate an object with laser light and look at it through a diffraction grating. You will see a set of mutually displaced copies of the object. If the lateral extent of the object is small enough, the various copies do not overlap. You can easily devise a method for selecting a single copy of the object. For example, you can replace your own optical system, i.e., your eye, by a converging lens and let the multiple images that were impressing your retina be produced on a screen. Then, a hole on the screen will suffice to isolate a single image. You can even dispense with the laser light and repeat the observation in a more domestic environment by looking at a distant street lamp through a piece of fine fabric. In this case, all of the object copies except the central one will appear iridescent, but the basic phenomena will be the same.
KeywordsEntropy Attenuation Hexagonal Retina Coherence
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