Measuring method of 3D profilometry of free-form surface based on computer-generated hologram

Abstract

The invention relates to a measuring method of 3D profilometry of free-form surface based on computer-generated hologram, comprising the following steps: generating a computer-generated hologram with an ideal free-form surface wavefront according to a mathematical model of the free-form surface; carrying out holographic record on an actual to-be-measured free-form surface; sampling a hologram recorded by a medium through a charge coupled device so as to obtain a digital hologram; respectively carrying out digital reconstruction on the digital hologram and the computer-generated hologram so as to obtain a to-be-measured free-form surface and CGH wavefront information, and carrying out coherent addition on the two wavefronts so as to obtain an interference pattern; carrying out phase computation on the interference pattern so as to obtain the phase position of an ideal free-form surface and the phase position of the to-be-measured free-form surface; calculating according to the phase positions obtained by calculation so as to obtain the height information of each pixel dot; and then obtaining the 3D profilometry of the free-form surface. Due to the fact that the measuring method is a contactless optical measuring method, the surface of the free-form surface is prevented from damage, and the measuring range and the measuring object are not limited; the precision is high, thus the accurate real-time detection can be realized. The measuring method can provide accurate data for precise processing of the free-form surface.

Description

technical field [0001] The invention relates to a method for measuring three-dimensional shape of a free-form surface, which belongs to the technical field of advanced optical manufacturing and detection. Background technique [0002] With the development of advanced manufacturing technology and precision processing instruments, the design and processing of free-form surface components are becoming more and more precise and complex, and the requirements for surface quality and surface accuracy are also increasing. Moreover, free-form surfaces generally have no symmetry and high surface accuracy. The roughness is small, so precise inspection of free-form surfaces is very difficult. [0003] Freeform surface measurement methods can be divided into two categories: contact and non-contact. Contact measurement is easy to damage the surface to be measured, so it is not suitable for precision measurement; for the surface topography of precise objects, non-contact measurement metho...

AI Technical Summary

Problems solved by technology

However, the early CGHs were all made with the technology of photoreduction, the manufacturing process was complex, the production cycle was long, and the production accuracy was not high, which limited its application in detection.

Images