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14 May 2010 One-shot measurement of surface profile using an astigmatic microscope system
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We propose a microscopic system which could be applied to three-dimensional surface profile measurement. In the system, a two-dimensional pinhole array is imaged onto the surface under measurement by an objective lens. These spots act as discrete object points which are then imaged to the CCD chip by the microscope which contains two orthogonal cylindrical lenses. Due to the astigmatism of the two cylindrical lenses, the shape of the image of object points on the CCD camera becomes oval unless the object point is located at a position which satisfies the best imaging condition. By calculating the focus error signal using the intensities measured at a group of CCD cells, the information on the distance of the corresponding object point could be found out. The basic concept of the system was checked by computer simulation on the point spread function of various object points. A preliminary measurement system which consists of the same optical components used in the computer simulation has been set up for verification of the idea. Since this system requires only one image to analyze the surface profile, it is a one-shot measurement system, and is insensitive to environmental noises such as mechanical vibration.
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C.-S. Kang, J.-U. Lee, J. W. Kim, J.-A. Kim, J. Jin, and T. B. Eom "One-shot measurement of surface profile using an astigmatic microscope system", Proc. SPIE 7718, Optical Micro- and Nanometrology III, 77180X (14 May 2010);

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