The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 26, 1987
Filed:
Jun. 13, 1983
Richard F Cahill, El Toro, CA (US);
McDonnell Douglas Corporation, Long Beach, CA (US);
Abstract
The demodulator system includes a source of light, and a beamsplitter which produces mutually coherent sensor and reference beams through sensor and reference fibers respectively, the sensor fiber being exposed to the effect to be sensed while the reference fiber is isolated therefrom. A ferrule maintains the output ends of the sensor and reference fibers in fixed positions with respect to a combiner lens which collimates the sensor and reference beams to form an interference pattern on a quad detector through a quad grating. The quad grating has four quadrants lined with the spacing of the interference pattern produced by mixing of the sensor and reference beams but positioned 0.degree., +90.degree., -90.degree., and 180.degree. apart in phase, .phi.. Therefore the quad detector produces outputs which contain +sine .phi., -sine .phi., +cosine .phi., and -cosine .phi. of the phase change between the sensor and reference beams due to changes in the effective optical path length difference between the reference and sensor fibers. These signals are then electronically converted into an electrical output which linearly represents the phase of the signal originally impressed on the sensor fiber.