High-performance front-end electronics for frequency-modulated continuous-wave interferometers

A high-performance analog electronic circuit for processing the signal from an absolute distance meter based on a frequency-modulated continuous-wave (FMCW) interferometer is presented. The front-end electronics includes a derivative block followed by a the time-variant baseline restoration of the photodetector current. A high signal-to-noise ratio is ensured by avoiding the use of a resistive transimpedance preamplifier and subsequent voltage processing. The paper details the electrical scheme of the preprocessing chain as well as the experimental results from an actual prototype of a distance meter.