Research On Flatness Evaluation Method Based On Phase Stitching In Digital Holography

Digital holography is a non-contact high-precision measurement technology and an important research topic in the field of precision measurement.Compared with traditional holography,digital holography has the ability to record and analyze three-dimensional information of objects.However,due to the limitation of pixel size and photosensitive area of optoelectronic devices during recording,digital holograms have a small recording range and low resolution,which is severely limited.The application of digital holography in the field of large-scale,high-precision measurement.Aiming at the problem of limited measurement area in digital holography,this paper proposes a splicing algorithm based on optimized Harris corner algorithm to realize phase directional stitching.When obtaining the digital holographic image,it is ensured that the adjacent regions have partial overlap,and then the sub-aperture phase images of the obtained objects are spliced;the Harris corner algorithm is used to detect the corner-dense regions as matching templates,and the overlap can be determined efficiently and accurately.region.The algorithm is optimized by combining Gaussian scale space and pyramid matching idea,and the phase splicing of 3D topography is realized by weighted fusion.The three-dimensional shape restoration of the glass sample of "M" was carried out,and the Harris-Laplace pyramid algorithm was used to improve the accuracy and stability of the stitching result.Based on the comparative analysis of the existing flatness evaluation algorithms,based on the basic model of the evaluation algorithm,two performance indicators for measuring the evaluation methods are given.The accuracy of the flatness evaluation of the flatness evaluation algorithm in the three-dimensional information surface is proved by simulation experiments.The flatness algorithm can be used to optimize the stitching algorithm.Finally,the following experiments were carried out on the off-axis Fresnel digital holography experimental system: the three-dimensional shape reconstruction of the smooth surface of the gauge block was performed,and the optimized stitching algorithm was applied to the planar three-dimensional information restoration to achieve a large surface.The three-dimensional appearance of the field of view is reproduced.The flatness error evaluation is carried out on the stitching result.The minimum inclusive area method is the evaluation method of the existing recognized standard,it has higher evaluation accuracy.