Research On Three-dimensional Measurement System Based On Spinning Disk Confocal Microscopy

The processing of many key components in the fields of semiconductor,aerospace,medical instruments,automobile manufacturing and so on requires ultra precision three-dimensional surface measurement technology.Currently commonly used techniques include scanning white light interferometry,reflection confocal microscopy,focus variation method,scanning probe microscopy,etc.Among them,confocal microscope has broad research and development prospects due to its advantages of noncontact,high speed,high precision and simple structure.The commonly used laser confocal adopts the point scanning method,which has a slow measurement speed and low light throughput.Spinning disk confocal microscope has faster measurement speed and light utilization,but has high cost and technical difficulty.In this paper,the reflection confocal microscopy measurement technology is deeply studied.Based on the aperture correlation technology,a low-cost fringe disk is designed and completed.Combined with the weighted least square and its iterative Gaussian fitting algorithm,the three-dimensional surface measurement with a speed higher than that of the existing confocal profilometer is realized.The main research contents are as follows:1.Based on the principle of aperture correlation,the confocal technology of differential fringe spinning disk microscopy is studied.According to this kind of disk design,a spinning disk module suitable for conventional optical microscope is designed,and the spinning disk confocal microscope measurement system is simulated with ZEMAX software.The performance of its illumination light path and imaging light path is analyzed and evaluated.At the same time,based on this design scheme,the collaborative control method of the whole measurement system is studied;2.The three-dimensional reconstruction principle of reflection confocal microscopy is studied,especially the principle and characteristics of the axial response curve peak location methods,including centroid method,polynomial fitting,Gaussian fitting and sinc2 fitting algorithm,are deeply studied and compared.Thus,a fitting algorithm that takes into account both fitting accuracy and computational efficiency to the greatest extent is obtained,so as to realize the fast and high-precision threedimensional reconstruction of surface topography;3.A fringe spinning disk confocal three-dimensional measurement system is designed and built.The coefficients of subtracting the wide field image in two confocal modes by experimental calculation.The test experiment of the measurement system is carried out and compared with the commercial confocal profilometer to verify the optical slicing ability,repeatability,accuracy and measurement speed of the system.