Large caliber aspheric surface measuring apparatus and method based on ultra-precise revolving scanning

Abstract

The invention provides a large diameter aspheric measuring device based on ultra-precision rotary scan and a method, belongs to the macroscopic measuring technology. The device comprises an ultra-precision air flotation turntable, a precision angle and angle measuring system, an ultra-precision linear air flotation guide, a length-measuring device and a gradient measurement system. The gradient measurement system comprises a linear polarization He-Ne laser or a semiconductor laser, a diffraction element, a scanning head and an image receiving unit. The linear polarization He-Ne laser or the semiconductor laser and the image receiving unit are separately fixed on the two sides of the base beam. The scanning head is fixed on the ultra-precision linear air flotation guide. The scanning head comprises a radial gradient measurement sub-scanning head and a tangential gradient measurement sub-scanning head, both of which comprise an error compensation light path. The working platforms of the two sub-scanning heads are orthogonal to each other. The invention discloses a large diameter aspheric measuring method based on ultra-precision rotary scan.

Description

technical field [0001] The invention belongs to a profile measurement device and method, and mainly relates to a large-diameter aspheric macro-profile measurement technology. Background technique [0002] Compared with spherical optical parts, aspheric optical parts have more design freedom, which can not only effectively correct advanced aberrations in the optical system, significantly improve the imaging quality of the optical system, but also significantly simplify the structure of the optical system and expand the functions of the optical system. Therefore, aspheric mirrors have been widely used, and the advantages of various large-diameter aspheric surfaces are more prominent and the demand is more urgent. [0003] During the processing of aspheric optical elements, it is very important to accurately measure their surface shape: in a sense, there are no high-precision detection methods and instruments that are compatible with the processing accuracy, and the precision a...

AI Technical Summary

Problems solved by technology

The main disadvantages of this method are: it is difficult to manufacture the compensation lens; for different workpieces to be measured, different compensation devices must be made, which greatly increases the measurement cost, reduces the efficiency, and has poor applicability; the interferometer produced by ZYGO is currently the most recognized by various countries. Representative full-aperture interferometer products

This method is a fast-developing measurement technology for large-aperture aspheric surfaces in recent years. This technology overcomes the inability of traditional interferometers to measure the surface profile information of large-aperture aspheric surfaces, and also overcomes the shortcomings of not being able to measure large numerical aperture optical elements.

The main disadvantages of this technology are: high requirements on the movement accuracy of the movement mechanism, the process of aperture splicing will cause error transmission, thereby reducing the detection accuracy of the entire measured aspheric surface profile, and the measurement speed is low

But its main disadvantage is that the scanning beam is a double thin beam separated from each other, which is not robust to the measurement environment noise, such as temperature drift and air disturbance at the measurement site; the scanning head can only sense the For one-dimensional inclination information, if the three-dimensional measurement of the measured profile is realized, corresponding moving optical devices must be added, such as thick flat glass, Dove prism, etc. Gradient information is collected

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