Abstract: Two types of optical liquid level sensor are disclosed. In the first refractive-type (20,65), light is selectively refracted by the particular fluid(s) in a plug recess between primary and secondary detectors (D.sub.1,D.sub.2). The output signal from either detector indicates whether the sensor is above or below the liquid level. The signals of the respective detectors are cross-compared and used to corroborate one another. In the second absorptive-type (100), light at a particular wavelength is passed through a body chamber (86'), which is exposed to the liquid whose level is to be sensed. Such light is selectively absorbed by the liquid. A detector (D) is arranged to measure the intensity of such light as has passed through the chamber, and to indicate the level of liquid in said chamber.

Abstract: An optical liquid level sensor has an optically-transmissive body (28) provided with a frusto-conical tip end portion (32). When the tip end portion is exposed to air, the angle of incidence (.theta..sub.i) of light at each of three points of reflection (b,c,d) is less than the critical angle (.theta..sub.c) such that substantially all light transmitted through the body will be reflected internally. However, when the tip end portion is exposed to a liquid, light is refracted, and the intensity of the reflected light is reduced. The intensity of the reflected light is used to indicate whether the sensor is above or below the surface of the liquid.

Abstract: An optical apparatus for measuring physical quantities, comprising an optical transducer (33) for sensing position, outgoing and return optical fibers (20,23), and an electronic control module (43). Light is generated at the control module and is transmitted by the outgoing optical fiber (20) to the optical transducer (33), which simultaneously varies the relative intensities of two different colors in a dissimilar manner in response to location of a positionable device (34,35) in the optical transducer. The modified intensity is transmitted back to the control module via the return optical fiber (23). The control module (43) measures the intensities of the two returning colors, and then outputs an electrical signal proportional to the intensity ratio for analog applications, or, alternatively, tests the intensity ratio against preselected constants and outputs discrete signals for digital application.

Abstract: A temperature measuring device comprises an optical temperature probe (20) and a control module (21). Thermal emission from a recess (28a, 28b) in the tip end portion (23) of an optical fiber (22) is transmitted to the remote end (26) of the fiber for detection by the control module. The recess provides improved sensor capability with regard to maintaining constant emissivity and rapid response time. The recess is suitable for both single crystal optical fiber and optical fiber with a core-and-cladding construction.

Abstract: A metal-encased light conductor having a continuous pressure boundary seal capable of use to transmit light signals in an environment having a pressure up to about 5000 psi based on a sealing length of a minimum of 6 inches and a temperature falling in the range of from about -40.degree. C. to about 250.degree. C., and comprising a core/clad optical fiber, coated with polyimide, surrounded by a jacket of thermoplastic resin on which there is a cured film of epoxy resin, and compressed by a surrounding mechanically reduced ductile metal sheath.

Abstract: A connector for sealingly joining the ends of a pair of electrical cables which provides a reusable quick-disconnect metal-to-metal sealing joint. Without the use of elastomeric seals. The connector has a male housing encircling the marginal end portion of one cable, has a female housing encircling the marginal end portion of the other cable, and has a coupling for selectively drawing the two housings into sealing engagement with one another. Each housing is sealed to the outer surface of the associated cable. An insert, provided with a flexible tab, is snapped into each housing to maintain the spacing of the conductors from one another and from the housing.

Abstract: A way of terminating an optical fiber is provided by collet-chuck type means which do not involve stripping, crimping or cementing.

Abstract: A fiber optic feedthrough module which comprises a metal sleeve, a fiber optic element extending through the sleeve relation thereto, and a tandem series of centrally-apertured mating annular sealant bodies of thermoplastic material surrounding the fiber optic element and compressed between it and the sleeve. The module is made by first providing a loose sub-assembly of a plurality of individual but interfitting sealant bodies on the fiber optic element and then inserting this subassembly into a metal sleeve, followed by swaging the whole assembly which eliminates clearances and provides sealed interfaces between the various contacting components.