Study On Specification And Analysis Of Frequency Band Errors In Deterministic Optical Machining

Deterministic optical machining method improves the accuracy and the efficiency of optical machining compared with conventional optical manual fabrication. But there are many Mid- and High-spatial frequencies in deterministic machining. These spatial frequency band errors degrade optical performances significantly and are difficult to be controlled. The key reasons are:①There is lack of a quantitative specification method of frequency band errors relation to optical performances at present.②There are limitations in present Power Spectral Density (PSD) method to analyze the influence of different deterministic machining method or different technical parameters on frequency band errors and optical performances. The major research efforts in the dissertation are to offer the references for the control of frequency band errors in deterministic machining, and include the following points revolving about specification and analysis of frequency band errors in deterministic machining:①A wavelet specification method based on PSD Character Curve is proposed. The character of frequency errors spectrum is reflected and the optical surface is evaluated, moreover, the corresponding region of unqualified frequency is found to provide effective guidance for deterministic machining.②A wavelet specification method based on Harvey-Shack scattering theory is proposed. The quantitative relation between frequency band errors in deterministic machining and optical performances is established.③A specification method of frequency band errors in deterministic machining based on optical performances is proposed. According to the experiment result of the wavelet specification method based on Harvey-Shack scattering theory and statistical optics theory, the influences of frequency band errors on optical performances are obtained.④An analysis method of frequency band errors in deterministic machining based on wavelet theory is proposed. The relation between technical parameters and distribution of frequency spectrum of workpiece surface is established and the occurred reason of notable frequency error is found, and moreover, some elementary conclusions are obtained through some experiments in deterministic machining (emphasis on Ion Beam Figuring and Magnetorheological Finishing) and subaperture stitching test according to the analysis method.⑤An analysis method of frequency band errors in deterministic machining based on optical performances is proposed. The analysis method of frequency band errors based on wavelet theory and the specification method of frequency band errors based on optical performances are combined by inserting the specification method of frequency band errors in the analysis of errors, thereby the references for selecting appropriate deterministic machining method and appropriate technical parameters to control frequency band errors of optical surface are offered. Finally three maching experiments are introduced in deterministic machining by using this analysis method.