Optically-Powered Transducer With Optical-Fiber Data Link

Abstract

A novel transducer with optical-fiber data link -- to provide electrical isolation and immunity from electromagnetic noise -- has been developed. A pulse-position (or pulse-frequency) modulated optical signal is transmitted by optical fiber from a remote converter to mainframe. Light of a different wavelength is transmitted via the same optical fiber from a laser in the mainframe to a photocell battery in the remote converter, to power it. Signal and "power" light beams are separated by dichroic mirrors. A practical thermocouple converter is described; it consumes only 84 μW, and is powered by light from a 5 mW semiconductor laser in the mainframe.