Lens refractive index and thickness measuring method and device based on differential confocal technology

Abstract

The invention relates to a lens refractive index and thickness measuring method and a device based on the differential confocal technology, which belong to the technical field of optical precise measurement. The invention is used for the high-precision measurement of the refractive index and the thickness of a spherical lens. The invention is based on a ray tracing principle, utilizes an absolute zero point of a laser differential confocal responding curve for accurately determining the intersection point of the front surface of the lens to be measured and an optical axis, the intersection point of the back surface of the lens to be measured and the optical axis, and the position of a measuring lens with or without the lens to be measured, then, the position of the measuring lens and the curvature radius, the focal length and the pupil of the measuring lens which are measured in advance are utilized for carrying out facet ray tracing calculation on two spherical surfaces of the lens to be measured and the reference reflecting surface, and finally, the high-precision nondestructive measurement on the refractive index and the thickness of the lens to be measured is realized. The invention has the obvious advantages of simple operation, high measuring precision, strong environmental disturbance resistance capability and the like, and can be widely applied to the refractive index and thickness measurement of various spherical lenses, particularly the refractive index and thickness measurement field of thin lenses.

Description

technical field [0001] The invention relates to a method and device for measuring the refractive index and thickness of a lens based on differential confocal technology, which belongs to the technical field of optical precision measurement and is used for high-precision measurement of the refractive index and thickness of spherical lenses. Background technique [0002] The spherical lens is the most commonly used element in the optical system. The refractive index, radius of curvature and thickness of the spherical lens are its basic parameters, which directly determine the performance parameters such as the focal length of the lens, the position of the main plane, and the theoretical phase difference. Therefore, the parameters of the spherical lens include the radius of curvature, The measurement of lens thickness and refractive index has always been the most basic measurement problem in optical measurement. At present, there are many methods for measuring the radius of cur...

AI Technical Summary

Problems solved by technology

The measurement process of this method is simple and can be measured independently, but its disadvantages are: the data processing process is cumbersome, and it uses interference imaging, which is susceptible to environmental interference and the measurement accuracy is not high

This method achieves very high precision in the measurement of small fluctuations in the refractive index of the lens, but its disadvantages are: it needs to use a complex temperature control system, the calculation is cumbersome, and the absolute refractive index of the measurement sample needs to be measured by other methods; and the method method cannot be used to measure the thickness of lens samples

For example: the document "Differential Confocal Scanning Detection Method with High Spatial Resolution" (National Patent: 200410006359.6) proposed a super-resolution differential confocal scanning detection method, which made the axial resolution of the system reach the nanometer level and significantly improved Anti-environmental disturbance ability, but the differential confocal technology is mainly applicable to the field of microscopic microscopic measurement, and this technology is directly applied to the fixed focus, and then the measurement of spherical refractive index and thickness has not been seen so far.

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