Measurement Method of Refractive Index of Bilateral Displacement Differential Confocal Lens

Abstract

The invention belongs to the technical field of optical precision measurement, and relates to a method of measuring lens refractive index based on a bilateral misalignment differential confocal technology. In a confocal measurement system, the method comprises steps of setting large and small virtual pinhole detection areas on an Ellie spot image detected by a CCD by using software and performingsubtraction on two detected confocal characteristic curves so as to sharpen the confocal characteristic curves, then performing bilateral misalignment differential subtraction on the sharpened confocal characteristic curves so as to obtain an axial highly sensitive differential confocal characteristic curve, then conducting high-precision fixed-focus locating on the vertex of a tested lens by using a characteristic of precise alignment of a zero point of the bilateral misalignment differential confocal characteristic curve and a focal point of the confocal measurement system, and finally obtaining accurate lens refractive index through ray tracing compensation calculation, so as to realize high-precision measurement of the lens refractive index. Compared with existing lens refractive indexmeasurement method, the method has advantages of high measurement precision, strong environment interference resistance, and simple structure, thereby having a prospect of being widely used in the field of optical precision measurement technology.

Description

technical field [0001] The invention relates to a method for measuring the refractive index of a bilateral dislocation differential confocal lens, in particular to a non-contact high-precision measurement method for the refractive index of a lens, and belongs to the technical field of optical precision measurement. Background technique [0002] Spherical lenses are one of the most important components in an optical system. The refractive index of a spherical lens is its basic parameter, which directly determines the performance parameters such as the focal length and the position of the main plane of the lens. Therefore, the measurement of the refractive index of a spherical lens has always been the most basic problem in optical measurement. At present, the main methods for measuring the refractive index of glass are: V prism method and right angle irradiation method. The measurement accuracy of these two methods is very high, but the lens material needs to be processed int...

AI Technical Summary

Problems solved by technology

However, two detectors must be used, and the position of the two detectors must be equal to the defocus amount. The system structure and the installation and adjustment process are more complicated, and the error introduced by inaccurate installation and adjustment may be large; after replacing the mirror under test, The amount of defocus of the two detectors may need to be readjusted

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