Abstract: An optical sensing system for sensing the temperature at a first location, including: electro-optical unit for producing a modulated optical signal and a light guide unit for receiving and transmitting the modulated optical signal along an optical path. The optical system further includes temperature sensing fiber which receives and guides the modulated optical signal along a temperature sensing optical path. One portion of the modulated optical signal serves as a reference optical signal and another portion of the modulated optical signal serves as a target optical signal. The optical sensor system also has a transducing unit, which receives the reference optical signal, the target optical signal having first and second time delays with respect to a chirped rf signal from the electro-optical unit. The transducing unit produces a multi-frequency electrical signal which includes a first frequency corresponding to the first time delay a second frequency corresponding to the second time delay.

Abstract: A three-phase angular position sensor is described in which three beams of light having polarization directions rotated 60.degree. to each other are passed through a polarizer, the rotational position of the polarizer representing an angle to be measured. The intensities of the beams transmitted through the polarizer uniquely encode its angle over a 180.degree. range. This range may be doubled, for example, by including a binary track. A two-phase angular position sensor is also described in which two beams have polarization directions oriented 45.degree. with respect to one another.

Abstract: An optical sensing system with a rotation sensor head for sensing the rotation of a rotatable object while simultaneously sensing the position of a displaceable object with a position sensor head. An electro-optical unit outputs a modulated optical signal and a chirped rf signal. The envelope of the modulated optical signal has a phase that has a known relation to the phase of the chirped rf signal. The electro-optical unit is coupled to a light guide element and receives and transmits the modulated optical signal along an optical path for reflection off a disk secured to the rotatable object in order to provide a rotation sensing optical signal. A transducing unit receives the rf signal at one input and has another input optically coupled to receive the rotation sensing optical signal while simultaneously receiving position sensing optical signals from the position sensor heads.

Abstract: A sensor that comprises an encoder that includes three or more tracks extending along a sensing axis. Each track i has a modulus m.sub.i, and a property that varies along the sensing axis such that the property can have one of m.sub.i distinguishable levels. The moduli m.sub.i of the tracks are all pairwise relatively prime. The tracks are formed such that a value is associated with each position along the sensing axis, the level of each track i at a given position being equal to the residue of the value at that position to modulus m.sub.i. The detector detects the levels of the tracks at a detection position along the sensing axis, and produces output signals corresponding to such levels. The track with the largest modulus comprises a redundant track that provides error detection capability.