Scanning Path Planning Of Two-photon Polymerization Fabrication By Femtosecond Laser

The femtosecond laser two-photon polymerization(two-photon polymerization,hereinafter referred to as TPP) is considered to be one of the most promising technique,which could achieve the process of three-dimensional micro-nano structure fuctional device. It has the characteristics of high precision, good spatial selectivity and true three-dimensional processing ability. It has broad application prospects in the fields of microelectronics, optoelectronics, communications, biomedicine, MEMS and metamat-erials.The femtosecond laser two-photon polymerization technology based on the nonlinear two-photon absorption of photopolymerization materials with femtosecond laser pulse. Scanning the layered cross section by scanning system, then the cross-sectional area could be solidified. Through layer by layer processing,three-dimensional micro-nano structure could be formatted. Therefore during the processing, as an important influence factor to affect the accuracy and efficiency of the forming parts, the scanning path scheme is needed to be further studied.This paper studies from two aspects, respectively as section contour data fitting and the generation algorithm of scanning path. Because the scanning path scheme on basis of section contour data, it is necessary to fit the section contour data. And the fitting method of linear and non-uniform rational B-spline curves is adopted in this paper. The algorithm is based on the least square method, according to the judgment of slope and length, the data was processed by subsection fitting. Moreover through the dichotomy to optimize the number of control points. Through the analysis of example simulation, the original section contour can be approached by less NURBS curve within the scope of allowable error.Then the compound scanning pattern which combined by contour offset scanning and grouping raster scanning is adopted, then fill the two-dimensional section contour.Through the relationship of the cycles in a contour, the judgment of stop scanning in the algorithm of contour offset scanning and the optimal selection of intersection points in the algorithm of grouping raster scanning for the data processing. The algorithm effectively avoids the empty stoke of the traditional reciprocating scanning and instability and complexity of the contour offset scanning algorithm. What’s more, it can prolong the useful life of laser.At last, LabVIEW software as a development tool for the modular structure design of the scanning path generating system. Through the analysis of the structure of CLIlayered file format which is from the sliced three-dimensional model. The CLI layered file could be read, displayed and generate the scanning path. Through the analysis of example simulation, the feasibility of the scanning path generating system could be verified.