Related Experiment Video
Updated: Jul 6, 2026

A Random-displacement Measurement by Combining a Magnetic Scale and Two Fiber Bragg Gratings
Published on: September 30, 2019
Measurement of absolute displacement by a double-modulation technique based on a Michelson interferometer
L W Chang1, P Y Chien, C T Lee
1Institute of Optical Sciences, National Central University, Chung-Li, Taiwan.
Abstract:
A novel method is presented for of measuring absolute displacement with a synthesized wavelength interferometer. The optical phase of the interferometer is simultaneously modulated with a frequency-modulated laser diode and optical path-length difference. The error signal originating from the intensity modulation of the source is eliminated by a signal processing circuit. In addition, a lock-in technique is used to demodulate the envelope of the interferometric signal. The displacement signal is derived by the self-mixing technique.
Related Concept Videos
Electronic Distance Measuring Instruments
Distance Problem
Design Example: Measuring Distance Between Two Points with Obstructions
Uncertainty in Measurement: Reading Instruments
Characteristics of Simple Harmonic Motion
Distance Measurements by Taping
