Optics: measuring and testing – By polarized light examination
Patent
1996-05-29
1998-12-08
Font, Frank G.
Optics: measuring and testing
By polarized light examination
356366, 356367, 356368, G01J 400
Patent
active
058478310
ABSTRACT:
A liquid crystal (LC) polarization modulator segment (216, 218) includes a monitoring device (220). The monitoring device (220) includes a polarized reference light source (222), located at an LC polarization monitor input, and polarized light detector (224), located at an LC polarization monitor output. If the reference light having the correct polarization is received at the detector (224), an indication of the switch state is provided. Alternatively, if the polarized detector (224) includes orthogonal polarizers (230A, 230B) provided for two separate light detectors (232A, 232B) both the desired polarization, and the opposite polarization, may be monitored to determine whether a failure exists in the segment. If the reference light is detected having the opposite polarization (instead of or in addition to the correct polarization) or no light is detected, the segment (or the monitor) is not operating correctly.
REFERENCES:
patent: 5414540 (1995-05-01), Patel et al.
patent: 5414541 (1995-05-01), Patel et al.
Patel et al., "Liquid Crystal and Grating-Based Multiple-Wavelength Cross-Connect Switch", IEEE Photonics Technology Letters, vol. 7, No. 5, pp. 514-516, May 1995.
Tomlinson, III W. John
Wagner Richard E.
Bell Communcations Research, Inc.
Falk James W.
Font Frank G.
Giordano Joseph
Stafira Michael P.
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