Measuring refractive index device and method thereof

Abstract

The present invention discloses a measuring refractive index device and a method thereof, which belongs to the field of optical detection. The device comprises a plurality of short coherent light sources with different wavelengths, a wavelength division multiplexer, an optical fiber coupler, two optical fiber collimators, a movable reflector, a reflector, a transparent slab, a wavelength-division multiplexer, a plurality of photoelectric receivers, and multistage optical fibers, and all components form a reference optical path and a measuring optical path. Through the cooperation of the reference optical path and the measuring optical path, the location of the cavity formed by the upper and lower surfaces of the tested transparent objects on the reflector and the transparent slab is measured, and with the distance between the reflector and the transparent slab, the thickness of the tested transparent object is obtained. The refractive index of the tested objective is obtained by comparing the optical path difference before and after the tested object is put in as well as the thickness of the tested transparent object. The measuring device provided by the invention is of simple structure, high measuring precision, able to conveniently measure the refractive index of planes and spherical mirrors and dispersion coefficient online with high precision.

Description

technical field [0001] The invention relates to the field of optical detection, in particular to a high-precision refractive index measuring device and method. Background technique [0002] In high-precision precision optical instruments, in order to ensure that the optical system has a good imaging quality, it is necessary to accurately measure the refractive index of optical materials. At present, the high-precision measurement of the refractive index of optical glass materials is carried out by the minimum deflection angle method. The minimum deflection angle method has high precision, wide wavelength range, and is an absolute measurement. Most high-precision optical glass material refractive index measuring instruments at home and abroad generally use the minimum deflection angle method. The measurement accuracy is generally about 10^-5. If necessary The measurement accuracy of the refractive index reaches 10^-6, and it needs to be measured with a large precision goniome...

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Problems solved by technology

[0004] The premise of the above minimum deflection angles is that a prism needs to be made for light refraction, and the angle of the prism needs to be accurately tested. Such a prism is very troublesome to make and requires a long period of time.

[0005] In addition, this method cannot test flat optical elements. It is more suitable for testing the refractive index samples of the same batch of glass used by glass manufacturers, and is not suitable for online high-precision testing of actual lens materials. Due to the refraction in the same batch of glass There may be a large difference in the refractive index (above 10^-5), so there may be a large difference between the refractive index of the sample and the refractive index of the actual lens

And in some special applications, when the material grade of the optical element is not known, it is necessary to determine the grade of the glass through the refractive index test without destroying the element, but the current detection equipment and methods are not very good. Measurement

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