Research On Compensation Testing Method For Large-aperture And High-order Aspheric Surface

Large aperture optical system has higher imaging resolution and stronger light gathering ability,so it has many applications in astronomical telescope,space imaging system and so on.With the continuous progress of optical processing technology,the design of optical system has higher requirements,and the application of large aperture aspheric optical elements in optical system is more and more.Large aperture aspheric optical elements play an irreplaceable role in the expansion of the optical system field of view,the lightening of the system weight,the correction of aberration,the improvement of imaging quality,and the compression of space.They have great advantages in improving the overall performance of the optical system.In the actual production,it is difficult to process large caliber and high-order aspheric surface,one of the reasons is restricted by the detection method.In this paper,the high-order aspheric surface compensation detection method is studied,and the zero compensation detection method of high-order aspheric surface is proposed.Combined with the detection of two high-order aspheric mirrors in an optical system,the main mirror aperture is 900 mm,and the three mirror aperture is 370 mm.According to the relation between geometrical aberration and wave aberration,the third-order aberration theory formula of high-order aspheric surface is derived.In this paper,the normal aberration of higher aspheric surface is derived and the properties are discussed.Based on the third-order aberration theory of the high-order aspheric surface,the initial structure formula of the high-order aspheric surface compensation detection system is derived.Combined with the initial structure formula,the compensation detection system based on the parallel light and the compensation detection system based on the spherical wave are designed for the main mirror and the three mirrors respectively,and the two systems are compared.Finally,the compensation detection system based on the spherical wave is selected.Through the analysis of the spherical wave compensation detection system,the compensator with reasonable design and scientific tolerance distribution is obtained.By measuring the relevant parameters of the compensator after actual assembly,the front and back intercept of the optical path is calculated.Based on the fabricated compensator,the optical path is built and debugged.Before testing,the sensitivity matrix of the system offset is established for the offset of the compensator,such as eccentricity,tilt,displacement,etc.After grinding the main mirror and the three mirrors,the RMS value of the actual shape accuracy of the main mirror is 0.0220 ?(? = 632.8nm),and the RMS value of the three mirror is 0.0295 ?(? = 632.8nm).After the main mirror is adjusted vertically,the final RMS of the optical system is 0.12883 ?(? = 632.8nm)after the adjustment of the main mirror and three mirrors..