Real-time Calculation of Distance and Displacement by FTT Signal Analysis with Optical Frequency Sweeping

Abstract

We describe the configuration of a system that employs the Fourier Transform Technique (FTT) to calculate an analysis signal from a time domain interference signal in real-time by using optical frequency sweeping and demonstrate that this system is capable of measuring the distance of multiple targets. Although minute vibrations of the target create a problematic Doppler effect for distance measurement using optical frequency sweeping, that problem can be reduced at the same time by averaging the values during the times of optical frequency increase and decrease. We then show that the velocity and displacement of the measured object can both be measured every 12.5 ms by measuring the velocity using the Doppler component and summing the velocities to measure the displacement. This system can be used for simultaneous measurement of distance and displacement for multiple targets.