Hughes Aircraft Company

Other

Patrick C Brownrigg

Victor Vali

David B Chang

Slava A Pollack

Bruce R Youmans

A system adapted for attachment to a device that undergoes changes in temperature and pressure, and for detecting changes in temperature and pressure in the device comprises a mechanism for attaching the system to the device and an optic device that includes pressure-responsive, temperature-responsive optical fibers that produce signals representative of temperature changes over a first optical frequency band, and of pressure changes over a second, distinctly different optical frequency band, or two or more optic devices, at least one including a pressure-responsive optical fiber, and at least one including a temperature-responsive optical fiber.

System for accurately detecting changes in temperature and pressure

A fiber optic fuel or liquid level gauge is disclosed which determines the liquid level by measuring the amount of light loss due to evanescent transfer to the fuel or liquid. An optical fiber is supported in the fuel or liquid tank, with a first end adjacent the highest possible liquid level to be measured with a reflector at the first end. The optical fiber extends downwardly through the tank, and its second end is connected to a light source for injecting light into the fiber. The intensity of the input light is compared to the intensity of light reflected from the first fiber end, and the liquid level is calculated from the light loss. The gauge has very high reliability since it has no moving mechanical parts.

Fiber optic fuel and liquid gauge having an open rigid 'J' shaped tube

A shaft rotation rate sensor for turbine engines. A reflective radial grating on the surface of the turbine shaft is employed in conjunction with an electromagnetic wave source and beam combining elements to mix two beams of frequency f and f.+-..DELTA.f, where .DELTA.f is proportional to the rotation rate of the grating. The source energy is reflected off the grating, and the zero-th and first order transmission from the grating are mixed to give the beat frequency proportional to the rotation rate. The sensor has no moving parts.

Shaft rotation rate sensor with a diffraction grating producing a

A speed sensor for a moving vehicle. A transmissive grating is used in conjunction with an electromagnetic wave source and beam combining waveguide to mix two beams of frequency f and f+.DELTA.f, where .DELTA.f is proportional to the speed of the grating relative to the ground. The source energy is reflected off the road to the grating. The zeroth and first order transmission from the grating are mixed to give the beat frequency .DELTA.f proportional to the ground speed. The sensor has no moving parts, and is independent of any gear ratios.

True ground speed sensor

Latent fingerprints are detected by upconverting infrared radiation provided by a special dusting powder and digitally imaging the upconverted radiation. In accordance with the principles of the present invention, a real time image of latent fingerprints is obtained by first 'dusting' the print with a powdered upconversion material. The print is then illuminated with 1.55 .mu.m infrared radiation using a fiber optic bundle in the form of a probe. The 1.55 .mu.m infrared radiation is converted into several reradiated wavelength bands by the powdered upconversion material. A charge coupled device or diode matrix detector array converts the image of the fingerprint to digital format for real time display and/or transmission over airwaves. The system is a portable latent fingerprint acquisition system that permits rapid fingerprint evaluation and comparison. A method of detecting fingerprints is also disclosed.

Acquisition and testing of latent fingerprints using upconversion

Liquid gauge having an optical fiber with flexible membrane enclosure

A precision liquid leak detector 10 free of mechanical moving parts is disclosed herein. The liquid leak detector 10 of the present invention is disposed to measure the rate of change of the volume of a liquid within a container 14. The leak detector 10 includes a light guide 16, implemented as an optical fiber, which is disposed within the container 14 and at least partially immersed in the liquid. The optical fiber 16 includes a fiber core circumscribed by a fiber cladding selected such that evanescent wave loss occurs as a result of immersion of the cladding within the liquid. The optical fiber 16 is positioned in optical alignment with a laser source 26, which injects optical energy therein. The leak detector 10 of the present invention further includes an arrangement 24 for measuring the decrease in the intensity of the injected optical energy occurring over a length of the fiber 16 immersed in the liquid. The measuring arrangement 24 then generates an intensity loss signal indicative of this intensity decrease. The inventive leak detector 10 also includes a network 36 and 38 for measuring the rate of change of the intensity loss signal and for calculating the rate of change of the liquid volume on the basis of the change in the intesity loss signal.

Fiber optic liquid leak detector

An optical fiber is constructed by selecting a first material for a core of the optical fiber. The first material has a known coefficient of thermal expansion, .alpha..sub.1, and a known temperature dependent rate of change, dn/dT, of an index of refraction, n. A second material (cladding) has a predetermined coefficient of thermal expansion, .alpha..sub.2, and a radius, R.sub.2, about the axis of the fiber. The radius, R.sub.2, of the cladding is determined such that an effective coefficient of thermal expansion for the fiber is substantially equal to the negative of the product of the reciprocal of the index of refraction of the first material and the temperature dependent rate of change of the index of refraction of the first material, i.e. .alpha.=(-1/n)dn/dT.

Method for eliminating the temperature sensitivity of an optical fiber

A fiber-optic interferometric chemical sensor for detecting chemical vapors in the air. The chemical sensor 10 includes a light source 12 which outputs an optical signal to a first beam splitter 14. The first beam splitter 14 splits the optical signal into first and second components and transfers the optical signal over sensor and reference optical fibers 20 and 22 respectively. The optical fibers 20 and 22 are bonded to the sensor and reference magnetostrictive substrates 24 and 26, which oscillate in response to an oscillating electromagnetic field generated by a coil 28 circumscribing the substrates 24 and 26. The sensor substrate 24 is further coated with a substance to facilitate collection thereon of molecules associated with the chemical vapor being detected. The optical outputs of the optical fibers bonded to the substrates 24 and 26 are then output to second and third beam splitters 16 and 18 respectively, and first and second beam combiners 32 and 34 respectively. The beam splitters 16 and 18 and beam combiners 32 and 34 operate cooperatively to provide an interferogram which is output to a signal processing circuit 44. The signal processing circuit provides an electrical signal indicative of the collection on sensor substrate 24 of molecules of the chemical vapor being detected, and outputs the signal to a display system 46.

Growing community of inventors

Long Beach, CA, United States of America

Patrick C Brownrigg