Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1988-01-25
1990-03-06
McGraw, Vincent P.
Optics: measuring and testing
By particle light scattering
With photocell detection
356361, G01B 902
Patent
active
049060953
ABSTRACT:
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.
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Freund Samuel M.
Gaetjens Paul D.
Koren Matthew W.
McGraw Vincent P.
Moser William R.
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