Pre-biasing technique for a transistor based avalanche circuit in a laser based distance measurement and ranging instrument

摘要

A pre-biasing technique for a transistor-based avalanche circuit which improves the initial rate of rise in the current applied through a laser diode or other light emitting device in a laser based distance measurement and ranging instrument and, therefore, the sharpness of the leading edge of the laser pulse produced. Since the timing of the flight time of a laser pulse to a target and back to the ranging instrument is determined with reference to the leading edge of the emitted laser pulse, the inherent precision obtainable is enhanced by the production of a sharper leading edge pulse. Through the use of the pre- biasing technique disclosed, the very rapid rise time pulse which may be achieved also allows for the substitution of a much cheaper light emitting diode in lieu of a conventional laser diode in an alternative implementation of a light pulsed-based distance measuring and ranging instrument.