Long Depth of a Focus Optical Microscopy Based on Computer Image Processing

点击翻译按钮获取中文摘要

There is a growing interest in micro electro mechanical systems. For the assembly operation of micro machining partsoptical microscope is used. It is often experienced that these operation under optical microscope is not easy, because depth of a focus of optical microscope is too short. From this point of view, a original method to get long depth of focus of optical microscope image using computer image processing has been proposed. The microscope objective is determined positioning by actuator such as PZT.At each located position, digital picture image through CCD camera is taken into a computer. The computer extractes has area where the image is in focus from these pictures, then it composes whole frame image. The depth of focus of the composite picture image is nearly equal to the sistance of motion of objective lens. As for the methods that distinguish between in-focus-area and out-focus-area, three different methods have been proposed. They are named here as differnce of luminance method, distributiuon of luminance method, and distribution of sequence of hadamard transfer method respectively. Processing time and accuracy point of view, distribution of sequence of hadamard transfer method is the best within these three methods.This method has been applied to the observation of several specimens such as standard surface roughness test-piece, grooved metal surface and so on, with excellent results. By adding displacement information to the recorded CCD camera image, this method is also applicable to the three dimensional surface topography measurement.