Patent ID: 8659761
Filing Date: 2014-02-25
Classification: G01B,G03F

Abstract:
1. A method of measuring a displacement of an object to be inspected, comprising the steps of: irradiating a grid polarizer with a first polarized light beam and a second polarized light beam, said grid polarizer being configured to transmit the first polarized light beam through the grid polarizer, said first polarized light beam having a polarized component directed in a different direction from a longitudinal direction of the grid polarizer, and said grid polarizer being further configured to cause a first reflection of the second polarized light beam back toward a direction in which the second polarized light beam was irradiated in, said second polarized light having a polarized component directed in the longitudinal direction of the grid polarizer; allowing the first polarized light beam transmitted through the grid polarizer and reflected by the object to be inspected disposed facing the grid polarizer to interfere with the second polarized light beam, reflected by the grid polarizer, to generate an interference light; wherein an optical path of the second polarized light beam after the first reflection thereof from the grid polarizer is substantially the same as an optical path of the first polarized light beam after it is reflected by the object to be inspected; and extracting displacement information of the object to be inspected from information included in the interference light.