OPTICAL DISPLACEMENT MEASURING APPARATUS

摘要

PURPOSE: An optical displacement measuring apparatus is provided to detect a position by high resolution. CONSTITUTION: A pseudo-interference light is frost-deposited on a grid plane of a diffraction grid(1), a diffraction light(Lb) is frost-deposited on a light receiving plane of light receiving element(3), simultaneously. A plurality of lengths of the diffraction lights(Lb) passed via a opening scope of a second frost-deposing portion are the same. A frost-depositing position of the light receiving plane is not changed even if optic axis is crossed. A position detector compute a phase difference of two diffraction lights and detects a relative moving position of the diffraction grid.