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Title: Phase shifting diffraction interferometer

An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.
Inventors:
 [1]
  1. (Santa Cruz, CA)
Issue Date:
OSTI Identifier:
870577
Assignee:
Regents of University of California (Oakland, CA) LLNL
Patent Number(s):
US 5548403
Contract Number:
W-7405-ENG-48
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Country of Publication:
United States
Language:
English
Subject:
phase; shifting; diffraction; interferometer; capability; measuring; optical; elements; systems; accuracy; lambda; 1000; wavelength; visible; light; current; interferometers; employ; reference; surface; inherently; limits; measurement; 50; essentially; perfect; spherical; wavefront; generated; fundamental; process; adjustable; unity; fringe; visibility; maximizes; signal-to-noise; means; introduce; controlled; prescribed; relative; shift; optics; permits; analysis; interference; pattern; standard; extraction; algorithms; measuring optical; reference surface; relative phase; diffraction interferometer; phase shifting; phase shift; optical element; optical elements; visible light; fringe pattern; spherical reference; reference wavefront; reference wave; interference fringe; essentially perfect; shifting diffraction; phase extraction; current interferometers; interferometers employ; /356/

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