Theoretical analysis of the affecting factors on the contrast of broadband optical interference signals in frequency domain

The signal contrast of broadband optical interferometry system is affected by many parameters. In order to accurately guide the parameter design of broadband optical interferometry system and predict the contrast degradation law of interference signal, a mathematical model of broadband optical interferometry is established in this paper from the perspective of two-beam interferometry. The modulation effects of key parameters such as spectral resolution, optical path difference, tilt coefficient of test surface and surface reflectivity on the contrast of interference signals in frequency domain are analyzed. On this basis, the correlation simulation and practical frequency domain interference distance sensing experiments are carried out. When the contrast of the interference signal is reduced below 0.1 and the interference signal in the frequency domain can be solved, the constructed frequency domain interferometry system can measure the surface reflectance R=13.6%, the maximum optical path difference can be measured as 150 μm, and the tilt angle of the test surface can reach 0.0168°. The results show that the mathematical model of interference intensity in broadband optical frequency domain can effectively analyze the modulation rule of different parameters on the interference signal contrast.