A NOVEL OPTOELECTRONIC INTERFACE-CIRCUIT DESIGN FOR SENSING APPLICATIONS

A novel and commercially viable optoelectronic interface is proposed f or sensors measuring optical attenuation, Emphasis is given to commonl y neglected background-noise-interference and dynamic-range-limitation problems. A modulated laser-diode, together with optical and electric al filtering, reduces the optical noise to less than a measurable leve l, even in extremely bright ''light-infested'' surroundings, In additi on, an effective approach is introduced for substantially increasing t he sensor's dynamic range, The power of the light-source is monitored in a dynamic intensity-control loop designed to perform ''floating-poi nt'' measurements according to the attenuation in the optical path, Th e sensor acquires the combined dynamic ranges of the detector and ligh t-source circuits.