Patent ID: 6831750
Filing Date: 2004-12-14
Classification: G01B

Abstract:
A method for measuring a tilt angle of a micromirror array, the method comprising:activating a pattern of micromirrors on the micromirror array, the pattern corresponding to a function having uniform power spectral density; applying a coherent light beam to the micromirror array wherein the coherent light beam passes through an aperture in a screen before reaching the surface of the micromirror array; wherein the activated pattern of micromirrors generates a reflected pattern on the screen, the reflected pattern comprising: a first spot corresponding to a beam of light that has been reflected from the surface of the micromirror array at an angle equal to the angle of incidence of the coherent light beam; a series of second spots arranged along a line passing through the first spot wherein each of the second spots corresponds to a respective diffraction order; and a pair of reflected shapes arranged along the line; measuring a distance from a first spot to the center of one of the reflected shapes; determining a diffraction order number corresponding to the measured distance from the first spot to one of the reflected shapes; and calculating the tilt angle of the micromirror array by applying the diffraction order number to a trigonometric equation.