Research On The Key Technologies In The Application Of Space Optical Freeform Surfaces

The application of free-form surface in optical system,increase the degree of freedom of the system without increasing the number of optical elements,can effectively reduce the number of optical system design and residual optical elements,and improve the image quality and simplify the structure of the optical system.As a kind of special surface complex,non rotational symmetry of the free surface have a greater degree of freedom in design,so that the optical system designers can according to the special needs of the design parameters of space camera,break through the traditional concept of the optical system used in the system,a new design.Therefore,it has the advantages of reducing the number of optical components,improving the imaging quality,and adapting to the requirements of lightweight.At present,the space remote sensing optical system is developing towards large diameter,long focal length,small volume and light weight.With the continuous development of science and technology,put forward higher requirements on the imaging performance and quality,which presents a huge challenge to use only the traditional spherical and aspherical optical system,and the use of freeform optics,based on asymmetric structure with,provide space layout,flexible expansion optimization of freedom,improve off-axis aberration balance ability,ability to adapt to the field,has become an inevitable trend.Since the last century,in 90 s,the first free surface in the lighting optics,helmet display system has been successfully applied,in recent years,foreign developed countries invest a lot of money and research strength,made a breakthrough in the field of related research and technology of freeform optical system for freeform off-axis optical system development has laid a solid technical foundation based on.The application of optical system based on free form surface has become an important direction of the development of modern high performance space optical system.The demand for the manufacture of high precision freeform optical elements.As from spherical to non spherical and non spherical shaft from the change in surface description increased from two times to the radius of curvature of surface coefficient,aspheric coefficient,off-axis parameters,free surface description to the existing detection and processing methods as the basis,put forward a set of reliable parameter index system.To guide the manufacturing of freeform surface;at the same time,will also require the processing of existing detection technology has improved.Therefore,research on the key technology in the application of the space optical system of freeform surface,guarantee the manufacturing accuracy of freeform optics,the optical system meets the design specifications,has become an important issue in the application of free surface in space optical system.Based on the above problems,this paper makes a research on the following aspects: the characterization of the space optical free-form surface,the analysis of the characteristics of the differential and the frequency band,and the application of the detection and processing technology:(1)Based on the study of the commonly used surface shape and the type of optimization,the differential information and frequency information are analyzed.The form of tolerance representation and its physical meaning are analyzed.(2)Through the analysis of the free surface differential characteristics,using the surface slope in the grinding stage in contour detection accurate compensation contact measurement error;the use of surface curvature in non zero subaperture stitching detection is realized by decoupling the lens surface error,standard surface error and adjustment quantity,reduce the the sensitivity to noise stitching algorithm,improve the detection accuracy of scanning;curvature detection and surface reconstruction algorithm,theoretical analysis and experimental verification of the method parameters calculation precision.(3)By means of the free surface curvature distribution characteristic description,establish the model to analyze the effects of grinding parameters do not coincide degree and the convergence rate of the workpiece;the small grinding head,through process test and parameter selection,improve the removal rate and stability of polishing of materials;use of regional processing strategy,improve the convergence efficiency of the time.(4)Presented a model to describe the free surface due to the edge effect caused by the removal amount of deviation,analyzes the application of knife type inhibition function to the edge effect theory of removal,the optimization results obtained knife motion parameters.Design and implementation of a single spindle composite motion structure,combined with frequency band error weighted optimization algorithm,to achieve the effective suppression of the edge effect of the machining process.