ABSTRACT
In order to improve both the measurement accuracy of glass thickness and the signal processing speed of operation, this paper proposes a novel method of second harmonic measurement of multi-beam laser heterodyne to obtain the glass thickness, which is based on the combination of Doppler effect and heterodyne technology, loading the information of the glass thickness to the frequency difference of second harmonic of the multi-beam laser heterodyne signal by frequency modulation of the oscillating mirror, which is in the light path. Heterodyne signal frequency can be obtained by fast Fourier transform, and values of the glass thickness can be accurately obtained after the multi-beam laser heterodyne signal demodulation. This novel method is used to simulate measurement for thickness of glass by MATLAB. The obtained result shows that the relative measurement error of this method is just 0.08%.
