Apparatus and method for performing two-frequency interferometry
The present apparatus includes a two-frequency, Zeeman-effect laser and matched, doubly refracting crystals in the construction of an accurate interferometer. Unlike other interferometric devices, the subject invention exhibits excellent phase stability owing to the use of single piece means for producing parallel interferometer arms, making the interferometer relatively insensitive to thermal and mechanical instabilities. Interferometers respond to differences in optical path length between their two arms. Unlike many interferometric techniques, which require the measurement of the location of interference fringes in a brightly illuminated background, the present invention permits the determination of the optical path length difference by measuring the phase of an electronic sine wave. The present apparatus is demonstrated as a differential thermooptic spectrometer for measuring differential optical absorption simply and accurately which is but one of many applications therefor. The relative intensities of the heating beams along each arm of the interferometer can be easily adjusted by observing a zero phase difference with identical samples when this condition is obtained.
- Inventors:
-
[1]
- (Los Alamos, NM)
- Issue Date:
- OSTI Identifier:
- 867288
- Assignee:
- United States of America as represented by United States (Washington, DC) LANL
- Patent Number(s):
- US 4906095
- Contract Number:
- W-7405-ENG-36
- Research Org:
- Los Alamos National Laboratory (LANL), Los Alamos, NM
- Country of Publication:
- United States
- Language:
- English
- Subject:
- apparatus; method; performing; two-frequency; interferometry; zeeman-effect; laser; matched; doubly; refracting; crystals; construction; accurate; interferometer; unlike; interferometric; devices; subject; exhibits; excellent; phase; stability; single; piece; means; producing; parallel; arms; relatively; insensitive; thermal; mechanical; instabilities; interferometers; respond; differences; optical; path; length; techniques; require; measurement; location; interference; fringes; brightly; illuminated; background; permits; determination; difference; measuring; electronic; sine; wave; demonstrated; differential; thermooptic; spectrometer; absorption; simply; accurately; applications; relative; intensities; heating; beams; arm; easily; adjusted; observing; zero; identical; samples; condition; obtained; phase stability; heating beam; single piece; optical absorption; phase difference; path length; optical path; sine wave; relatively insensitive; interference fringes; interference fringe; exhibits excellent; length difference; /356/
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