Differential confocal aspheric surface measurement method and system of normal tracking type

Abstract

The invention discloses a differential confocal aspheric surface measurement method and system of a normal tracking type, and belongs to the technical field of surface topography measurement. The system comprises a scanning mechanism, a differential confocal measurement head, and a rotating workbench. A measured aspheric surface is placed on the rotating workbench. The scanning mechanism employs an X-direction guide rail and a Z-direction guide rail to achieve the scanning in an XZ plane. The differential confocal measurement head is fixed at the tail end of a Z-direction guide rail through a rotating mechanism. The differential confocal measurement head employs a tracking-type differential focal technology for measurement, a sensor is used for measuring the slope change of the measured aspheric surface and the rotating mechanism is adjusted in real time, thereby enabling the differential confocal measurement head to remain perpendicular to the measured aspheric surface, and guaranteeing that the differential confocal measurement head receive more optical signals. Therefore, the method and system can achieve the ultra-precise measurement of the surface shapes of large-aperture and large-curvature aspheric surfaces with large numerical apertures.

Description

technical field [0001] The method and system for measuring a normal-tracking differential confocal aspheric surface belong to the technical field of surface topography, and in particular relate to an ultra-precision interferometric method and method for measuring the surface shape of a large-diameter, high-numerical-aperture and large-curvature aspheric element. system. Background technique [0002] Since the aspheric surface has more degrees of freedom in design, the optical system has greater flexibility, can correct aberrations, improve image quality, expand the field of view, and simplify the structure and weight of the optical system. Therefore, in modern optical systems It has been widely used, especially in high-end technical fields such as astronomical telescopes, deep ultraviolet lithography, laser weapon optical systems, laser nuclear fusion optical systems, and optical imaging guidance systems for guided missiles. At present, there are many measurement methods fo...

AI Technical Summary

Problems solved by technology

This method not only has the characteristics of good vertical resolution and horizontal resolution, but also has good depth response characteristics, high light intensity contrast, and strong anti-scattered light ability; for surfaces with high numerical aperture or large curvature changes, due to the detection system Cannot collect enough return light, so it is difficult to measure its surface

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