Measurement Method of Center Thickness of Transverse Subtraction and Differential Confocal Lens

Abstract

The invention discloses a transverse subtraction differential confocal lens center thickness measuring method, and belongs to the technical field of optical precision measurement. In a confocal measurement system, firstly, small and large virtual pinhole detection areas are set on an Airy disk image detected by a CCD through software, and two detected confocal characteristic curves are sharpened through subtraction processing; secondly, differential subtraction processing is carried out on the sharpened confocal characteristic curves to obtain an axial high-sensitivity differential confocal characteristic curve; thirdly, characteristics accurately corresponding to a zero point of the differential confocal characteristic curve and a focal point of the differential confocal measurement system are used to carry out high-precision fixed-focus locating on the position of a center thickness measurement top point of a measured lens; and finally, the center thickness of the lens is accuratelyobtained through ray tracing compensation, so that high-precision measurement of the center thickness of the lens is realized. The method has the advantages of high measurement precision, strong environmental disturbance resistance, simple structure and the like, and has a wide application prospect in the technical field of optical precision measurement.

Description

technical field [0001] The invention relates to a method for measuring the central thickness of a lateral subtraction differential confocal lens, in particular to a non-contact high-precision measuring method for the central thickness of the lens, and belongs to the technical field of optical precision measurement. Background technique [0002] In the field of optics, the measurement of lens center thickness is of great significance. Lens center thickness is an important parameter in the optical system, and its processing quality will have a great impact on the imaging quality of the optical system. Especially for lenses in high-performance optical systems such as lithography objective lenses and aerospace cameras, it is necessary to precisely adjust the axial gap, radial offset and optical axis deflection angle of the lens according to the curvature radius, refractive index and central thickness of the lens in the lens. adjustment. Taking the objective lens of lithography...

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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