Optical sensor arrangement using dual mode devices

Details Optical sensor arrangement using dual mode devices Optical sensor arrangement using dual mode devices

1994-02-09

1995-03-21

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Optical or pre-photocell system

324 96, H01J 516

Patent

active

053998537

ABSTRACT:
A proximity detector apparatus that uses the Faraday Effect to detect position changes of a target. The proximity detector includes a permanent magnet having a magnetic field that changes as the target moves to or from a predetermined position. A self-referencing optical sensor is provided that detects the changed magnetic field. The optical sensor includes a magneto-optic material positioned near a node of the magnet. Means are provided to transmit polarized interrogation light along an optical path that includes the magneto-optic material. The optical path is bi-directionally addressed and is non-reciprocal. The optical sensor transduces the changed magnetic field into a modulation of the interrogation light's intensity. Means are provided to detect variations in the interrogation light intensity and to determine a ratio such as the difference over the sum ratio for two interrogation light samples that traveled the optic path in opposite directions.

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