System of Measuring the Sub-Pixel Edge of CCD Image´s

In order to improve the precision, speed, integration and reliability of the linear CCD system, which was used to detect the sub-pixel edge of picture, a new digital system based on auto focusing was designed. The system captures the image of the tested work piece through a CCD, puts the image data into computer, gathers coordinate of tested edge of work by the method of digital image processing and auto focusing. The data of signals memorized in computer were processed by using software system of data collecting. Thereby, the inspection of precise size and location of defects were achieved. The result shows that The resolving power of this method can reach 20 μm and the error is less than 10%.The possibility that the impurity particles can be checked out is up to 100%.