Automatic Timing & Controls, Inc.

John D Rogers

Steven H Mersch

A laser diode (,) emits laser light which is collimated into parallel rays with collimating lens (,). The collimated beams travels as much as 50 meters or more before being reflected back to a photoreceiver (,). A ball lens (,) focuses the reflected light onto the photoreceiver. The photoreceiver, preferably, is a synchronous detector which issues control pulses to a laser drive circuit (,) for causing the laser diode to emit intermittent bursts of laser light. The synchronous detector then compares the timing of received light with the timing of the control pulses to the laser diode to distinguish between true reflected light and stray light. An intensity adjustment (,) adjusts the intensity of the laser light in accordance with a distance between the laser diode/photoreceiver and a reflector. In this manner, distances of 1-70 meters can be accommodated with no lens modification. A reference voltage (,) proportional to the intensity of the laser light is used in a gated feedback (,) for faster response times.

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Coatesville, PA, United States of America

John D Rogers