Absolute measurement method for optical non-uniformity of parallel flat crystals

Abstract

The invention discloses an absolute measurement method for the optical non-uniformity of parallel flat crystals. The steps are: perform an interferometric measurement on the working surface of the first transmission reference flat and the front surface of the parallel flat to be tested; place a reflection reference flat behind the parallel flat to be tested, and perform an interferometric measurement on the first transmission reference flat and the reflection reference flat An interferometric measurement is performed on the working surface; an interferometric measurement is performed on the first transmission reference flat crystal working surface and the back surface of the parallel flat crystal to be measured; a cavity interferometric measurement is performed on the first transmission reference flat crystal and the reflection reference flat crystal working surface; Replace the first transmission reference flat with the second transmission reference flat, and perform an interferometric measurement on the second transmission reference flat and the first transmission reference flat working surface; An interferometric measurement is carried out; the measurement results are integrated to obtain the optical non-uniformity of the parallel flat crystal to be measured. The invention is simple and easy to implement, accurate and efficient, and the measuring object is not limited by the parallelism of the front and rear surfaces.

Description

Technical field [0001] The invention belongs to the field of optical interference measurement, in particular to an absolute measurement method for the optical non-uniformity of parallel flat crystals. Background technique [0002] Optical transmission materials are an important part of optical materials. As an important index for evaluating the performance of optical transmission materials, optical non-uniformity reflects the inconsistency of refractive index within the same optical material. The inconsistency of the refractive index inside the optical material will directly lead to the change of the transmitted wavefront, thereby changing the wave aberration of the optical system. Normally, 10 -6 Optical non-uniformity of the order of magnitude will introduce wave aberrations of the order of wavelength, so it is of great significance for the high-precision detection of optical non-uniformity of optical elements. [0003] Experts at home and abroad have conducted a lot of research...

AI Technical Summary

Problems solved by technology

For the detection of optical non-uniformity by the sticking plate measurement method, it is necessary to add two glass flat crystals with the same refractive index as the measured piece as the sticking plate. The non-uniformity of the liquid will also affect the measurement accuracy; the four-step interferometry method for the detection of optical non-uniformity requires that the wedge angle of the glass plate to be tested be controlled between 2 and 66 angle minutes, and the parallelism of the front and rear surfaces cannot be very high. The parallel flat crystal is tested; the short coherence interferometry method solves the problem of flat plate optical non-uniformity with good surface parallelism before and after high-precision measurement, but the measurement accuracy is affected by the spectral width of the light source; the wavelength-tuned Fourier analysis measurement method The surface shape and material uniformity information of the front and rear surfaces of the parallel flat crystal can be obtained through two measurements, but the instrument must use a semiconductor laser that can precisely adjust the wavelength as the light source, and requires special processing software, which cannot be widely used

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