Medium range laser telemeter: A unique tool for instrumentation and process control

It has been demonstrated, through theoretical analysis and experimental results, that fast accurate range measurement is possible with a hazardless low-power laser telemeter, for medium ranges well suited to instrumentation and process control. The high frequency modulation of this double-modulation telemeter guarantees the measurement accuracy, while the low frequency modulation enables the full measuring range without phase ambiguity. The performance achieved makes this telemeter a true instrumentation device (relative precision 0.5×10^-4), with reasonable dimensions and a high measurement rate ability (maximum 50 kHz). Its coaxial design makes scanning an easier task than for triangulation type devices. The authors have developed a set of processing tools intended to achieve an optimal use of specific information supplied by this kind of sensor and give an example of an original, accurate, and robust localization algorithm from a partially occulted contour