Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1988-08-26
1990-06-05
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
25022718, 2502311, G01J 350
Patent
active
049316362
ABSTRACT:
A sensor for determining the value of a measurand, such as the rotational position of a shaft (32). The sensor includes a wavelength sensitive beamsplitter (44), an encoder (30), and a wavelength sensitive modulator (48). A beamsplitter receives an optic input signal (60) having first (80) and second (82) wavelength bands, and forms the input signal into first (62) and second (64) beams corresponding to the wavelength bands. The encoder includes a track (36). The modulator preferentially modulates the intensity of light in the first wavelength band in comparison to light in the second wavelength band. The first beam is modulated by the encoder to form a modulated first beam (66), and the second beam is modulated by the modulator to form a modulated second beam (68). A differential embodiment is also provided in which the encoder comprises a pair of mechanically coupled tracks, one track modulating each beam.
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Nelms David C.
The Boeing Company
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