Posts tagged Nonlinear crystal innovation
Interferometry - Fringes and Phases

Before light sources with considerable coherence length were available (think lasers), opticians formed fringe patterns using a test plate, also known as an optical flat.  Spherical test plates also exist, to check the surface of lenses, or curved mirrors.  These test plates could be placed in close proximity to each other, so common light sources could be used.

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