SINGLE-BEAM DIODE-LASER TECHNIQUE FOR OPTICAL PATH-LENGTH MEASUREMENTS

A simple single-beam technique employing radio-frequency modulation of a tunable diode laser with homodyne demodulation is demonstrated as a means of measuring optical path lengths. This technique offers a stra ightforward method for determining path lengths traversed through opti cal multipass cells or performing optical range-finding over short (i. e., tens of meters) standoff distances. The radiofrequency phase-sensi tive nature of the technique permits narrow-band detection and high si gnal-to-noise ratios, even when range-finding measurements are made wi th range resolutions of <<1 m. This compares favorably with traditiona l short-pulse, wide-bandwidth optical range finders. (C) 1996 Optical Society of America