公开(公告)号：US3708229A

公开(公告)日：1973-01-02

申请号：US3708229D

申请日：1970-12-29

Applicant: THOMSON CSF

Inventor： PIRCHER G

IPC: G01B9/02 ,  G01B11/06

CPC classification number: G01B11/0675 ,  G01B9/02028

Abstract: The invention relates to systems for the measurement of optical path length utilizing coherent light interferometry. The system according to the invention comprises a differential interferometer wherein the two systems of fringes associated with each of the two faces of the layer whose optical path length is measured, are detected by a single optical-electrical detector to which they are alternately supplied by an optical chopper arrangement. The data produced by said detector, undergoes synchronous detection for controlling a phase-shift optical element inserted in one of the two optical paths reflected from the above mentioned faces. By way of example such systems can be employed to measure either the thickness or the refractive index of the thin films used in integrated circuitry.

Abstract translation: 本发明涉及利用相干光干涉测量法测量光路长度的系统。