Research On Aspheric Presentation And Application Oriented By Null Compensation Measurement Principle

Aspheric optical elements are key components to support the good performance of high-end optical systems,which are widely used in military defense,space remote sensing,industrial livelihood and other technical fields.Due to the specificity of surface shape,aspheric processing and detection technology has been a hot and difficult topic in the field of optical manufacturing.Giving information about aspheric detectability in the design phase of optical systems,balancing the technical difficulties between aspheric design and measurement and enhancing the technical relevance will help the further development of aspheric optics.Based on the principle of null compensation measurement,the paper proposes a new characterization method of aspheric shape:Null asphere.This method enables the optical system design and aspheric null compensation measurement system design at the same time and mutual feedback.Using the tolerance of the system to optimize the compensation measurement optical path structure so as to achieve aspheric can be measured,and will be applied to the re-optimization of the optical system design.Firstly,a model of spherical wave single-lens null compensation measurement system is constructed based on the principle of null compensation measurement.The derivation of null aspheric surface expression is carried out by ray-tracing algorithm.Analyzed and verified the generality of null aspheric expression.The relationship between the characterization parameters in the measurement system and the surface properties of the null aspheric surface is quantitatively described from the perspective of aberration compensation.Next,a ray-tracing algorithm is proposed for the design of null aspheric optical systems.The Newton iterative method is used to approximate the surface coordinates for the indirectness of the null aspheric expression,and the accuracy of numerical calculation is better than 10-4 nm.Based on this method,the calculation of the intersection point coordinates of the spatial ray with the null asphere and the direction vector of the ray propagation after passing through the null asphere are given.Afterwards,the user-defined surface shape function of the ZEMAX is used to customize the null asphere.The deviation between the surface shape presented in the software and the mathematically described surface shape due to the accuracy of the numerical calculation is less than 10-3 nm.The residual wavefront difference of the null compensation measurement system is PV 0.0005 λ and RMS 0.0001λ.The surface characterization accuracy meets the system design and null compensation measurement requirements.Finally,a three-band fusion imaging system is designed using the null asphere,and the imaging quality of the system can meet the resolution requirements of the detector in all three bands.The performance comparison with the three-band fusion imaging optical system using partial null asphere design shows that the spherical wave single-lens null compensation measurement system can directly meet the system design requirements without partial null compensation algorithm for residual wavefront solving,and the aspheric detection process is straightforward and convenient.