Optical Lens Thickness And Refractive Index Measurement Based On Frequency Sweep Interference

The frequency sweep interferometry method is a kind of measurement method with excellent performance.Compared with other measurement methods,it has the advantages of high precision,no dead zone and ability to measure absolute distance and non-cooperative target.In the case of using a large swept bandwidth,this method can still obtain higher measurement accuracy even when the measurement target has a low return intensity,which makes it have the refractive index and thickness of the transparent optical component.A unique advantage.In this paper,the refractive index and thickness measurement techniques of optical components based on linear swept interferometry system are studied.Two measurement systems,single sweep frequency interference and double sweep frequency interference,are designed to measure the target refractive index and thickness,and theoretical analysis and simulation.The characteristics and feasibility of the two measurement schemes were verified.Finally,the refractive index and thickness measurement system for the target optical components was built,which proved that both systems can achieve the refractive index and thickness of the target components with high precision.measuring.In the theoretical analysis part,the basic principles of single-sweep interferometry and dual-sweep interferometry are analyzed,and the Doppler effect caused by laser frequency modulation nonlinearity,auxiliary interferometer fiber dispersion and target vibration is analyzed.The effects of the measurements of a swept interferometric measurement system and their respective characteristics give a way to eliminate them.According to the actual situation and the literature,the basic design of the measurement scheme of refractive index and thickness is carried out.In the measurement system setup and performance test sections,the single-sweep interferometry system and the dual-sweep interferometry system's ranging optical path were built and an automatic control program was programmed for fast measurement and focusing.Then test the ability of their cooperative and non-cooperative targets to be tested separately.Next,the multi-target measurement capabilities of the two systems were verified by simulation and experimentation.The accuracy analysis of the single-target and multi-target measurement capabilities of the two systems is then performed.Finally,based on the previous simulation and experiment,a measuring device for measuring the refractive index and thickness of the optical component was built.The reproducibility of the refractive index measurement of the single-sweep interferometry system was experimentally determined to be 4.32×10^-4?k=2?.,refractive index dimensionless)thickness measurement repeatability is 2.4?m?k=2?,double sweep interference.Measurement system refractive index measurement repeatability is6.80×10^-4?k=2?thickness measurement repeatability is 3.2?m?k=2?.Then,based on the previous precision analysis and experimental results,the formula for the relative accuracy of refractive index and thickness measurement is derived,which is verified to be consistent with the actual situation.