Embedded Automatic Focus Method for Precise Image Sampling

In the high precisely analyzing and inspecting for IC wafer image, the real-time sampling and automatic focusing of image is the key technology to guarantee acquiring sharply focused image. In this paper, a vision detecting based on embedded high-speed image sampling and automatic image focusing judgment is put forward, which includes the multitasking real-time image sampling, the precise stages control, and the management and task scheduling of automatic focus process. During the process of image sampling, FPGA and chromatic image transducer is the core of the image sampling, and to appraise the definition of the image with gray gradient judging function, compare the focusing data of mean-variance appreciation with gray level appreciation. After analyzed, the gray level focus method, which meets the need of the IC wafer micro imaging system, is obvious unimodality, with a little local peak and a low error.