Optical fiber angle position sensor

Claim 1

Apparatus for determining the position of a first element relative to a second element, one of said first and second elements being rotationally movable relative the other, comprising: a source of electromagnetic radiation, the source being adapted to be fixedly secured to said first element; and an optical fiber cable including first and second elongated portions in coaxial alignment and closely axially fixed relative to one another; the first cable portion being fixedly secured to said source and adapted to receive and transmit therethrough radiation from said source; the second cable portion being adapted to be fixedly secured to said second element; one of said first and second cable portions being rotatable about its longitudinal axis relative to the other as a function of rotational movement of the element to which it is secured; the respective cable portions having interface surfaces with face angles of approximately equivalent magnitude; whereby, when the interface surfaces are parallel, a major portion of the radiation transmitted through and exiting the first cable portion will be received by and transmitted through the second cable portion, and when the interface surfaces are non-parallel, radiation exiting the first cable portion will be reflected at the interface surface of the second cable portion in varying amounts as a function of angular displacement from parallel of the interface surface of the second cable portion with respect to the interface surface of the first cable portion, maximal reflection occurring when the interface surfaces are rotated 180° from the true parallel position, thereby resulting in attenuation of radiation being transmitted through the cable.