Tilt (optics)

In optics, the term tilt simply refers to a deviation in the direction a beam of light propagates. Tilt quantizes the average slope in both the X and Y directions of a wavefront or phase profile across the pupil of an optical system. In conjunction with Piston (the first Zernike polynomial term), X and Y tilt can be modeled using the second and third Zernike polynomials: X-Tilt:
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