Single-pixel carrier-based approach for full-field laser interferometry using a CMOS-DSP camera

Abstract

This investigation describes the implementation of a Single Pixel Carrier Based Demodulation (SPCBD) approach on a digital CMOS-DSP camera for full-field heterodyne interferometry. A full-field vibration measurement system is presented as an alternative to a classical scanning Laser Doppler Vibrometer (LDV). The Heterodyne set-up, CMOS-DSP camera and the signal demodulation techniques adopted are described. Characterisation tests that describe the basic performance of the CMOS-DSP camera, in terms of acquisition rates and time response are presented. A simple experiment was performed to demonstrate the novel laser vibrometry system that consisted of determining the displacement of a point on the surface of a vibrating mirror. The measured velocity and displacement data were compared to the output from a commercial LDV. The integration of a CMOS sensor, DSP and a laser-doppler interferometer has lead to the development of a fully digital “functional” machine vision system that provides a flexible, compact and inexpensive tool for automated high-precision optical measurements.