Abstract

A device for angular position sensing is fabricated with the help of a source/detector assembly and by utilizing the total internal reflection at the glass-air interface of the rotating prism. A collimated beam from a high intensity LED source is incident on the 45 prism assembly, which is rotated about the axis of the incident beam. The emergent beam is focused on to the P-I-N photodiode detector assemblies placed at different spatial angular points along the circumference of the rotating emergent beam. The prototype model of the sensor is tested in the laboratory, and the variations in pulse amplitude with the variations of photodiode-focusing optics distance are observed in the oscilloscope. The resolution of the system can be greatly enhanced for precision measurements by incorporating the focusing optics within the rotating prism assembly and by using optical fibers as light collectors. The system can also be used as precision rotating speed sensor and optical time space demultiplexer.

© 1992 Optical Society of America