title: Flatness measurement by a grazing Ronchi test.
abstract: The Ronchi test with a LCD amplitude sinusoidal grating is used for testing nominally flat surfaces. We prove that it is possible to measure flat surfaces without using a reference element by modifying the common optical Ronchi set up. The Ronchi rulings are computer generated and displayed on the LCD. By displaying various phase-shifted rulings and capturing the corresponding images, the phase is obtained with the conventional phase-shifting algorithms. Theoretical and experimental results are shown.
authors.forename: Noé
authors.initials: N
authors.lastname: Ochoa
authors.forename: Miguel
authors.initials: M
authors.lastname: Mora-González
authors.forename: Fernando
authors.initials: F
authors.lastname: Santoyo