US 4,732,481 AGranted

Polarization interferometer

AssigneeHitachi, Ltd.

InventorsShigeru Matsui, Masaru Inoue

Life of this patent

Estimating the term…

Loading patent…

Abstract

A polarization interferometer includes a light source to be measured, a Wollaston prism, a pair of polarizers arranged in such a manner that the Wollaston prism is interposed between the polarizers and the plane of polarization of each polarizer is inclined at 45.degree. to each of two crystallographic axes of the Wollaston prism, a photodetector for detecting an interference fringe which is spatially formed by two light beams separated by the Wollaston prism, changeover means for causing one of the polarizers to changeover from one of polarizing and non-polarizing states to the other state, memory means for storing a first output signal which is delivered from the photodetector in a state that one polarizer is kept at the non-polarizing state, and means for dividing a second output signal which is delivered from the photodetector in a state that one polarizer is kept at the polarizing state, by the first output signal stored in the memory means.

Claims8

Dependent claims

A polarization interferometer comprising:

a light source to be measured;
a Wollaston prism for splitting light from said light source into two light beams;
a pair of polarizers disposed before and behind said Wollaston prism in the traveling direction of the light from said light source, the plane of polarization of each polarizer being inclined at 45.degree. to each of two crystallographic axes of said Wollaston prism;
means for spatially forming an interference fringe by said two light beams from said Wollaston prism;
detection means for detecting said interference fringe formed by said interference-fringe forming means;
changeover means for putting one of said polarizers in a non-polarizing state;
memory means for storing a first detection signal which is obtained from said detection means in a state that said one polarizer is put in the non-polarizing state by said changeover means;
and
means for dividing a second detection signal which is obtained from said detection means in a state that said one polarizer is put in a polarizing state by said changeover means, by the first detection signal stored in said memory means, and for outputting the result of the division.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/042,244Filed 24 Apr 1987
Priority: JP 61-9452825 Apr 1986
Granted: 22 Mar 1988
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01B 9/02024
Characterised by the beam path configuration: measuring in transmission, i.e. light traverses the object
G01B 9/02057
Passive reduction of errors: by using common path configuration, i.e. reference and object path almost entirely overlapping
G01J 3/4537
By correlation of the amplitudes: devices with refractive scan
G01B 2290/70
Aspects of interferometers not specifically covered by any group under G01B9/02: using polarization in the interferometer