A precision measurement device and method for the refractive index of optical materials

Abstract

The invention provides precision measurement device and method for an optical material refractive index. By adopting the device and the method, combination of a wide spectrum analysis method and a Fabry-Perot interference method can be achieved, accurate optical material thickness and refractive index are obtained by global residual analysis, and spectral analysis is carried out through a wide spectrum method Fabry-Perot interference system, so as to obtain a refractive index dispersion curve of the optical material under a continuous wave band. By adopting the device and the method, the measurement accuracy of the refractive index is improved, a stable interference cavity is formed by using parallel plate structures of most of optical materials, effects on the stability of an interference signal caused by air agitation are reduced, the optimal material is prevented from being processed into a special shape, and nondestructive measurement of the optical material is achieved.

Description

technical field [0001] The invention relates to the technical field of measuring the refractive index of optical materials, in particular to a precision measuring device and method for the refractive index of optical materials. Background technique [0002] Refractive index is a basic physical property for evaluating optical materials. There are generally three types of measurement methods for the refractive index of optical materials: one is to measure the refractive index of optical materials by using the refraction of light in the optical material to be tested with a specific shape, such as the minimum deflection angle method and the self-collimation method; the other is to use total reflection Phenomena to measure the refractive index of optical materials, such as the critical angle method (also known as the Abbe refraction method); the third is to use the interference principle to measure the refractive index of optical materials, such as Michelson interferometry, Fabry...

AI Technical Summary

Problems solved by technology

However, both the minimum deflection angle method and the self-collimation method have a disadvantage, that is, the optical material to be tested must be processed into a specific shape (such as a wedge) before it can be measured, and the processing accuracy of the specific shape directly affects the measurement accuracy of the refractive index. At the same time, it is impossible to realize the non-destructive online measurement of the optical material to be tested

In the second type of method, the critical angle method is mostly used to measure the refractive index of liquid and gas optical materials. When measuring solid optical materials, due to the different processing states of the surface roughness and flatness of the optical materials to be tested, the optical material to be tested is different from the measuring prism. Not in close contact, so there is a difference in the critical angle, which creates an error in the index of refraction

In the third type of method, although the shape of the optical material to be tested is not particularly restricted, the optical path in the interference arm of the Michelson interferometry and the Mach-Zehnder interferometry is exposed to the air and will be affected by air disturbance and the environment. Vibration affects the stability of the interference signal

Although this type of method reduces the influence of environmental factors, due to the limitation of the accuracy of material thickness d, the accuracy of the obtained refractive index is not high, and can only reach 10 -3

Moreover, the refractive index obtained by the above method is only for a single incident light of a specific wavelength, and the application field is very narrow.

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