Analysis Of Manufacturing Error Based Research On Optimization Of Laser- Direct Writing Strategy

Diffractive optics is a new branch of optics. The Binary Optics Element (BOE) is designed by computer and manufactured by micro and nano fabricating technology. This kind of BOE with typical relief structures has many advantages, including small volume, low price and high diffraction frequency. Especially, BOE can realize the arbitrary transform of wavefront which expands its application to lots of science field such as laser fabricating and biomedical instruments. BOE has wide application prospects.However, with the increasing requirement on BOE, fabricating technology becomes the critical factor which obstracting its development. Aiming at typical manufacturing errors existed in the Laser-direct Writing Method (LWM), this study"Analysis of Manufacturing Error based Research on Optimization of Laser-direct Writing Strategy"does the comprehensive analysis of two representative BOEs - binary phase gratings and Fresnel lenses. The analysis results can guide the optimization of writing strategy. The following are the major issues in this paper.Firstly, the mathematics-description and physical models of typical manufacturing errors and the elements with errors are proposed. For two dimensional elements, the analyzed errors include phase error, width error and slope error; and for circular symmetrical diffractive optical elements, the spherical aberration caused by approximation of slope is presented and analyzed. These physical and mathematical models are the groundwork of followings;Secondly, the study on both scalar and vector analysis of gratings and Fresnel lens are processed aiming at the specificity of size of element manufactured by LWM. Numerical results show that there are many differences between these two methods. And vector method has irreplaceable function for the sub-micron diffractive optical elements; Thirdly, the comprehensive study on 4-step binary phase grating with error discloses the influence on the performance of elements and can be further used for the guidance of optimization of writing strategy. Results show that the equivalent phase error of 10% causes efficiency decline of 2.5%; and the worst equivalent width error of 10% causes efficiency decline of 2%. For slope error, it causes a small increase of diffractive efficiency. Furthermore, for the purpose of closing to actual manufacture, the study on the efficiency influence of single step with error is processed. The study of this part can benefit for both design and manufacture of BOE;Finally, the analysis result of spherical aberration of Fresnel lens shows different impacts of different parameters. Under the same relevant parameters, the bigger phase factor causes bigger diffuse focal length; much more zones of Fresnel lens produces smaller diffuse focal length; with the same phase factor, a certain focal length brings a relevant smallest diffuse focal length. According to the physical model of this part, a valuable conclusion can be easily acquired, which is that multi-slope approximation of Fresnel lens can decrease diffuse focal length substantially.The whole study of this dissertation gives comprehensive analysis of manufacturing error existed in LWM. These analysis results can benefit for design or manufacture technology of BOEs.