The Compensation Processing Technology Of Free-form Optical Element With Small Aperture

With the various requirements for the image quality,volume and weight of modern optical systems,the application of free-form optical elements has become more and more extensive,and the requirements for the surface quality of the optical elements have become higher and higher.The application of free-form optical elements can reduce various optical aberrations in the optical system and improve the image quality of optical equipment;on the other hand,it can reduce the size of optical elements and the number of optical elements,and reduce the weight of the optical system.Therefore,the demand for high-precision manufacture and test technology of free-form optical components is becoming more and more urgent.It is of great significance to study the high-precision processing technology of small aperture free-form optical elements with the large demand for optical systems such as mobile phone lenses and AR lenses.In this paper,starting from the surface characteristics of free-form optical elements,ultra-precision turning processing technology is used to process free-form optical elements.And then the article uses white light interference detection technology to obtain surface topography,and obtains the surface shape error through data processing.And then the article adopts the compensation processing method to improve the surface quality of free-form surface optical components.The article realizes the high-precision manufacturing of such components and obtains a complete set of high-precision manufacturing technology for small-aperture free-form optical components.Starting from the mathematical description of free-form surfaces and using single-point diamond turning processing technology,this article studies the selection of tool parameters,machining parameters,and machining trajectories in the ultra-precision machining process.and obtains the mathematical relationship that the tool parameter selection needs to satisfy when processing different free-form surfaces;at the same time,based on the equipment performance and the quality of the processed surface,the selection of processing parameters and the processing path are analyzed,which provides a theoretical basis for obtaining a suitable turning processing program.And then the splicing detection technology based on white light interference is studied,which solves the problem of surface topography measurement of small aperture free-form surface optical components.Due to the six-degree-of-freedom translation and rotation deviation between the measured surface topography and the theoretical topography,the focus is on the best matching problem between the two sets of data.By constructing an evaluation function,using multi-parameter optimization method,the method obtains the optimal matrix transformation parameters when the measured surface topography matches the theoretical topography,and then the surface shape error is obtained.The corresponding data processing program is written based on MATLAB and the correctness of the data processing method is verifies.Starting from the analysis of the error sources in the ultra-precision machining process,the reasons for the surface shape errors of the machining components are revealed.Then a non-real-time compensation processing technology is proposed.Under the premise of ensuring the processing environment remains unchanged,with the surface shape detection results,the machine program is corrected,and then the components are compensated machining,thereby improving the surface shape accuracy.With the processing,testing and compensation technology of small-aperture free-form optical components,two free-form surface components with different parameters are subjected to compensation processing experiments.Through one to two compensation processing,the root mean square(RMS)of the surface error is reduced from the order of hundreds of nanometers in the first processing to the order of ten nanometers,which effectively improved the surface quality and obtained good experimental results,which verified the effectiveness and practicability of the technology.