Optical Testing

  • Shack-Hartmann Wave Sensor

    - Used in adaptive optics and optometry, uses a lens array to measure aberrations.
  • The Moire Effect

    - The formation of interference fringes due to the overlap of similar gratings. The fringes produced are greatly magnified in comparison to the size of the actual grating spacing, so minute variations in one grating result in large changes in the moire fringes made with a second grating. Moire fringes are extremely useful in comparing a set of fringes that has been misaligned in some way (projected onto the surface of a mirror to find aberrations, or a specimen for contouring) with a reference grating. Used to monitor small displacements, also used to measure deviations into and out of a reference plane (topographical imaging, contouring, 3D imaging, etc). The moire effect creates a readily observable pattern that changes as the alignment of the gratings is altered.
    Moire demo - Fringes (the thick black and white bands) are created by overlapping spherical patterns and change greatly with respect to the motion of the smaller sphere.

Assorted Stuff

  • Schlieren Links

    Andrew Davidhazy-Articles and photos for high speed, Schlieren, stroboscopic photography, etc.
    Schlieren Demo - Basic Schlieren setup, cool pictures.

Scott Huang
June 2006
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Laser Teaching Center