LASER DIODE DISTANCE MEASUREMENT

摘要

2121902 9311448 PCTABS00022 A laser diode distance measurement device includes a laser diode (10) which emits light (20) to a lens (22) which provides focussed light (24) incident on a target (26). The light (24) is reflected from the target (26) back to the laser diode (10) which causes the laser diode (10) to emit a light (28) which exhibits intensity pulses (due to coherent interference) related to the distance (L) to the target (26). A photodetector (30) provides a feedback signal indicative of the intensity of the light (28) to a distance measurement circuit (18). The laser diode (10) is driven by an up-ramp signal that reduces electronic processing and at a frequency that reduces speckle noise. The distance measurement circuit (18) blanks out a portion of the feedback signal during discontinuities of the laser diode drive signal to minimize associated noise from distorting the distance measurement.