A non-contacting optical imaging system for evaluating a film is very helpful for research in micromechanics. As shown in Fig.1, this system consists of one CCD camera and microscope to scan the pattern, and is connected to the frame grabber. The frame grabber VIGAS card is a video digitizer which can digitize video signals from the CCD camera in real time and store the digitized image into the on-board frame memory. The image also can be displayed simultaneously on the analog video monitor. In the monitor screen we can see the microstructure of the surface of a film appeared, and every part of a specimen must be put under consideration. The xy-table is driven by the computer to carry the holographic plate moving step by step automatically.

In particular, many papers show that quantitative evaluation in the microstructure of a surface can provide a straightforward explanation of the outlines of a film. R. G. Brandes and R. K. Curran[1] paid attention to the modulation transfer function in the photoresist fabricating process by utilization of the photograph of a SEM (scanning electron microscope) of a film and simple image processing technology. They analyzed the SEM photograph to realize the influences of the process parameters in the photoresist film with sub-micrometer fringes[2]. We also used an image processing technique to analyze the SEM photograph as the measurement of the behaviors of the film and the process parameters on the plates or an embossing hologram product. We can also compare the computer simulation of the intensity distribution of the holographic interference light field and the fringe shape of the image processing results to determine the fabrication characters of a film.

Conventional method to investigate a film is to hold the plate facing to the safelight or in front of a white paper on the wall to check if the film came out fairly transparent by eye observation[3-5]. The degree of the transmission of the emulsion of the film can present the film thickness. But it's not a precise method for we can only distinguish 10 to 20 gray levels in the range of the brightness of a film.

The apparatus also has particular use in the detection of micro-particles of a film. These micro-particles are analyzed by calibration scale dimensionally for the identification of dust spots, with the criteria for analysis being the gray level variations

at each ten micrometers of the film. We found it was onerous to do these works without a computer image processing aid. These works present various approaches to investigate the surface of the microstructure having various profiles. The measured size factors in the particles of a film with a suitable image processing algorithm are used to determine, precisely enough and quickly, the particle's dimension and location. Also there have been improvements in the algorithms which can be applied to many other image processing activities.

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