基于半导体行业中PCB焊膏印刷检测的实际应用, 采用0.45 WXGA DMD芯片设计了数字条纹投影光学系统.以LED作为光源, 结合透镜阵列照明DMD芯片;同时, 为了减小投影三角关系造成的条纹周期不均匀性对检测结果的影响, 采用双远心光路结构将DMD生成的条纹成像到待测表面, 且适用的最小检测面积为1mm2.光学模拟结果表明, 该数字投影系统在被投影表面上的照明均匀性为91%, 投射条纹的对比度高于0.8, 且条纹周期均匀, 为实际应用与后续条纹分析提供了良好保障.

According to the practical solder paste printing inspection of PCB, digital fringe projector design used 0.45 WXGA DMD chip was performed in this paper. The design adopted LED as light source, and combined with lens array for evenness illumination. In order to reduce the influence of nonuniform fringe on inspection results caused by triangular relationship of projection, double telecentric optical configuration was used for imaging DMD-generating fringe on defected surface. The minimal inspection area of projector can reach 1mm2. Simulation results show that illumination evenness of the digital fringe projector on defected surface is about 91%, contrast of projection fringe is better than 0.8, and keep the fringe pitch uniform. Optical projector designed in this paper provides guarantee for inspection application and following fringe analysis.