A novel opto-electronics interface-circuit design for sensingapplications

摘要

A new and practical opto-electronic sensor interface is presented.It consists of a transmitter and a receiver for sensors measuringoptical attenuation. Emphasis is given to commonly-neglectedbackground-noise-interference and dynamic-range-limitation problems. Thedesign of the electronic circuitry allows sensors to operate inmanufacturing environments. A modulated laser-diode, together withoptical and electrical filtering, reduces the optical noise to less thana measurable level, even in extremely bright“light-infested” surroundings. In addition, a novel approachis introduced which substantially increases the sensor's dynamic range.The power of the light-source is monitored in a dynamicintensity-control loop designed to perform “floating-point”measurements according to the attenuation in the optical path. Thesensor acquires the combined dynamic ranges of the detector andlight-source circuits