| 摘要 |
An astigmatism and phase shift auto focusing apparatus and method by using a DMD(Digital Micro mirror Device) moire pattern generator are provided to obtain a spatial distance precisely while reducing a measurement error, shorten a processing time, and obtain high precision and a wide measurement range at a low cost. A collimated optics unit(150) receives a light source(102) emitted from an LED or an optical fiber to generate a collimated beam in an optical system(100). A concentric circle pattern projecting unit(160) generates a pattern to be projected from the optical system. A beam splitting unit(170) generates a polarized beam in the optical system and splits an astigmatism beam and a phase shift beam. An imaging lens unit(180) includes a conic lens(119) for projecting beams generated by the concentric circle projecting unit. An image acquiring unit(190) receives the astigmatism beam and the phase shift beam from the optical system. A measurement target transfer unit(220) includes a transfer table(121) on which a measurement target(118) is mounted, and a driving unit(120) for driving the transfer table. A control module unit(202) controls the operation of the image acquiring unit for measuring the measurement target. A central controller(204) controls the control module unit, and calculates the height of an object unwrapped with respect to an acquired image.
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