1 May 1990 High-precision fiber-optic position sensing using diode laser radar techniques
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Abstract
The analysis, design, and testing of a high-precision linear position sensor using diode laser radar techniques and fiber-optic signal distribution is described. A frequency-chirped, intensity-modulated semiconductor diode laser is used as the transmitter. Each sensor head consists of two reflectors -one moving and one fixed -in a differential ranging mode to cancel apparent range changes caused by temperature induced fiber length variations. The returned (round trip delayed) chirps are direct detected by a photodiode and then are mixed with the original (undelayed) chirp to produce a sum of beat frequencies, each proportional to the range of a reflector. Several sensors heads, located at different fiber distances, can be optically multiplexed by a single laser transmitter using a reflective or transmissive network. The performance of the laser radar position sensor is anal,rzed by first calculating the return signal-to-noise ratio (SNR). A Cramér-Rao lower bound is derived to relate the SNR, chirp bandwidth, and chirp duration to the root-mean-square (RMS) range error. The theoretical optimum performance of the experimental sensor system is determined. An experimental system was built that achieved 58 pm RMS range error using a 1 ms chirp duration with a processing time of 50 ps.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gregory L. Abbas, Gregory L. Abbas, W. Randall Babbitt, W. Randall Babbitt, Michael de la Chapelle, Michael de la Chapelle, Mark L. Fleshner, Mark L. Fleshner, James Doyle McClure, James Doyle McClure, Edward J. Vertatschitsch, Edward J. Vertatschitsch, } "High-precision fiber-optic position sensing using diode laser radar techniques", Proc. SPIE 1219, Laser Diode Technology and Applications II, (1 May 1990); doi: 10.1117/12.18285; https://doi.org/10.1117/12.18285
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