- 期刊
Shape-From-Focus 3D Measurement with Image Alignment
以對焦尋形法為基礎之方法最佳化與量測
摘要
本研究中，建構出一套以紅光LED環型燈為光源，針對微小工件量測之顯微量測系統。系統以CCD攝影機為取像裝置，搭配立體顯微鏡，並以步進馬達搭配分釐卡，使移動平台作上下的垂直移動。利用對焦尋形法來求得待測物之三維輪廓資訊。由於光軸與移動平台並不垂直，必須經由位置補償修正其偏移的影像。SML及SEML運算子可計算出待測物影像在對焦與失焦間的差異，進而得到待測物輪廓之深度變化資訊。在ML及EML運算後，加入高斯平滑濾波可消除影像中的雜訊。中值濾波可消除孤立點並保留影像邊緣輪廓。高斯擬合與內插則可消除雜訊並突顯待測物的高度。藉由自定指標與重建待測物輪廓去判定方法之優劣，以其最佳方法套用至錫球輪廓重建與高度量測上。
關鍵字
無資料並列摘要
When using the Shape-From-Focus (SFF) approach to reconstruct 3-D profile for minute object such as BGA, it was found that the alignment of the image series become quite difficult. In addition, the image shift in terms of image position is nonlinear. In order to overcome this problem, the position shift for each frame was calculated, and images were reconstructed using the interpolation technology. It was found that the quality of 3-D profile reconstructed is greatly improved. In this paper, we also test a couple focus measures. It was found that using a Gaussian smoothing operator between the sum operator and the enhanced modified Laplacian had a better performance than others. After the calculation of the focus measure, there are several approaches to determine the surface profile for each individual image pixel. Medium filter without Gaussian fitting was suggested for shape determination after this test. Although the cloud data are still a little bit noisy, but with shape fitting, the ball height and the ball radius can be properly calculated.