Laser heterodyne surface profiler
Abstract
A method and apparatus is disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference. The beam also is split into its two components with the separate components directed onto spaced apart points onthe face of the object to be tested for smoothness. The object is rotated on an axis coincident with one component which is directed to the face of the object at the center which constitutes a virtual fixed point. This component also is used as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length which is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center.
- Inventors:
-
- Livermore, CA
- Issue Date:
- Research Org.:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- OSTI Identifier:
- 864361
- Patent Number(s):
- 4353650
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Classifications (CPCs):
-
G - PHYSICS G01 - MEASURING G01B - MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS
G - PHYSICS G01 - MEASURING G01J - MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED, VISIBLE OR ULTRA-VIOLET LIGHT
- DOE Contract Number:
- W-7405-ENG-48
- Resource Type:
- Patent
- Country of Publication:
- United States
- Language:
- English
- Subject:
- laser; heterodyne; surface; profiler; method; apparatus; disclosed; testing; deviation; flat; smooth; beam; coherent; light; plane-polarized; components; frequency; constantly; fixed; amount; produce; difference; constant; phase; reference; split; separate; directed; spaced; apart; onthe; tested; smoothness; rotated; axis; coincident; component; center; constitutes; virtual; follows; circular; track; recombined; reflection; reflected; proportional; path; length; compared; signal; height; respect; separate components; circular track; laser heterodyne; surface profile; signal proportional; smooth surface; path length; spaced apart; difference frequency; coherent light; surface profiler; flat smooth; heterodyne surface; separate component; plane-polarized components; /356/
Citation Formats
Sommargren, Gary E. Laser heterodyne surface profiler. United States: N. p., 1982.
Web.
Sommargren, Gary E. Laser heterodyne surface profiler. United States.
Sommargren, Gary E. Fri .
"Laser heterodyne surface profiler". United States. https://www.osti.gov/servlets/purl/864361.
@article{osti_864361,
title = {Laser heterodyne surface profiler},
author = {Sommargren, Gary E},
abstractNote = {A method and apparatus is disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference. The beam also is split into its two components with the separate components directed onto spaced apart points onthe face of the object to be tested for smoothness. The object is rotated on an axis coincident with one component which is directed to the face of the object at the center which constitutes a virtual fixed point. This component also is used as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length which is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 1982},
month = {Fri Jan 01 00:00:00 EST 1982}
}