Study On Ray Tracing Measurement Methods For Quadric Surface Parameters

The aspheric mirror is highly favored in the imaging optical system as the aspheric mirror can effectively correct the aberration of the imaging optical system,which can improve the imaging quality,and make the system smaller and lighter.Aspheric mirror detection technology consists of surface detection and parameter detection.At present,the commonly used methods for detecting aspheric parameters include coordinate scanning method,filament shadow method,pentaprism scanning method and laser tracker method.The existing parameter detection methods can be divided into the following two categories.One is the optical imaging method,such as filament shadow method.The other method is about the coordinate scanning detection which can get the surface error and aspherical parameters simultaneously.While this method ignores the relationship between aspherical mirror parameters and imaging quality.Because the aspherical mirror parameters of the solution depends on the establishment of mathematical models and solving the equation.In view of the above situations,this thesis presents a method for measuring aspheric mirror parameters of quadric surface based on ray tracing,which can obtain the quadric surface parameters through imaging and obtain the surface error as well.The main contents of this thesis include:Firstly,the equation of quadric surface and the formula of Gauss in optics are established,and the relation between image distance and aspheric parameter is established theoretically,which lays a theoretical foundation for the proposed method.Secondly,according to the light of the geometric propagation law,the light direction is simulated by using Matlab software to further verify the feasibility of the method.The quadric surface aberration-free points are found through ray tracing method,which achieves the measurement of quadric surface parameters.And several factors influencing the accuracy of the method are analyzed.Thirdly,the reverse Hartmann measurement system is constructed to measure the mirror,and obtain the slope information of each point on the mirror.Then using the method proposed in this thesis to deal with the data,the aspheric parameters are obtained and the results of the measurement are analyzed.In addition,Matlab software is also used to realize the evaluation method of image quality based on the spot diagram RMS radius.At the same time,the method of slope calculation and aspheric mirror reconstruction of the reverse Hartmann measurement system is also analyzed.