With the development of modern science and techology, MEMS becomes an important branch. The micro operating system becomes an interested spot. During the micromanipulation process, observing the micro components by optical microscope is a crucial technology.
Limited by the optical parameters, focus of the optical microscope is small. For example, focus of 10x object lens is about 10 micron. The observation of some bigger micro objects, which size is tens or hundreds of times of 10 micron, are certainly impossibe by one time imaging. Some researchers had tried to extend the focus by improving the structure of microscopy, but the results are not satisfying.
The optical microscope has CCD sensor as detector. Moving the object carrier, series adjusted focus images can be given. As the distance between CCD sensor and object lens is fixed, these images are with the same amplification ration. We can use computer to analysis these images for extending the focus.
Through series images to extend focus, core of this method is analyzing and processing these series images, and at last composing one image, which is clear at each vertical depth.
On this image, the position of each micro object can be measured easily. Sub-pixel processing technique makes the measure precision achieve micron degree. The distance, which is recorded while adjusting the object carrier, can help to locate the vertical position of micro object, experiments show that the locating precision could up to micron degree also.
Using this method avoids changing optical system hardware, and is easy achieved. Clear image can be got in the adjustable range of object carrier. The range of focus is extended. The precision can be up to micron degree on 3D direction. So the method is useful on observing and measuring of micro object, has theoretical and practical value.