High-numerical-aperture hemispherical detection system based on digital holography

Abstract

The invention discloses a high-numerical-aperture hemispherical detection system based on digital holography. The system employs digital holographic detection technology to carry out high-precision detection of three-dimensional morphology of a hemispherical surface with a large relative aperture and a large curvature. Aimed at the relative aperture and curvature of the hemispherical surface to be measured, the digital holographic hemispherical detection optical path system is designed. A high-numerical-aperture standard converging spherical wave generating device is used to provide highly-converging standard spherical wave for the hemispherical surface to be measured, with the F-number being 0.65 and the image side aperture angle being 43.13 degree. To ensure accurate positioning of the hemispherical tool to be measured relative to a system optical path, a four-dimensional combined mechanical positioning platform is used, and the one-way moving precision of the platform is 0.001 mm. The system adopts a three-dimensional cage structure so that all the optical devices are arranged in a compact and stable structure and are easy to adjust. The system can be used for high-precision detection of three-dimensional morphology of hemispherical surfaces of precise hemispherical bearings, optical lenses and the like with large relative apertures and large curvatures.

Description

technical field [0001] The present invention relates to a hemispherical three-dimensional shape detection system, more particularly, a digital holographic high numerical aperture three-dimensional shape detection system for a hemispherical shape with large relative aperture and large curvature, which belongs to optical precision detection field. Background technique [0002] At present, the three-dimensional shape detection technology of hemispherical surface mainly includes contact three-dimensional coordinate measuring instrument, optical interference detection technology, etc., and interferometer is the most widely used in optical interference detection technology. Digital holography technology uses CCD, CMOS and other photoelectric imaging detectors as recording media to record holograms, store them in digital form, and use computers to digitally simulate and reproduce the optical diffraction process, reconstruct the three-dimensional light field, and obtain the amplitud...

AI Technical Summary

Problems solved by technology

In the patent CN201410152708, a digital holographic spherical surface type detection device based on sub-aperture phase stitching is adopted. Although digital holographic technology is used, a spherical standard mirror is used to generate spherical illumination light for the measured spherical surface. The spherical mirror cannot control the light beam. Beam expansion and high convergence, the aperture angle of the output beam is small, for the measurement of a large relative aperture and large curvature spherical surface, it is necessary to move the position of the measured object relative to the optical path multiple times, the measurement process is more complicated and will introduce a large measurement error ; and the parallelism cannot be adjusted, so the system aberration has a great influence on the measurement results; the 532nm laser is used to provide illumination, and this wavelength has a small measurement range for the surface microtopography of the spherical surface, so the resolution is reduced; five-dimensional The one-way movement range of the adjustment installation platform is small; the system structure is not compact enough, and the assembly is more complicated

[0003] In order to apply digital holography technology to the three-dimensional shape detection of hemispherical surface with large relative aperture and large curvature, and obtain high-precision measurement results, some technical problems need to be solved: (1) For three-dimensional hemispheres with large relative aperture and large curvature On the surface, due to the limitation of beam direction and beam aperture, a single measurement cannot complete the detection of the hemispherical surface shape with large relative aperture and large curvature; (2) During the detection process, in order to ensure the accuracy of the measurement, the outgoing light The converging focus needs to completely coincide with the center of the hemispherical tooling; (3) During the measurement process, the accurate positioning of the measured spherical surface relative to the optical axis; (4) The rational design of the detection system, high stability, easy operation, and high measurement accuracy high

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