High-precision fiber-optic position sensing using diode laser radar techniques

Publisher Website
Google Scholar
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 Cram‰r-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 SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This publication has 0 references indexed in Scilit: