| 摘要 |
PURPOSE:To shorten a measuring time, by providing not only an X-direction target and a Y-direction target along an L-shaped line as targets but also an image sensor means so as to detect the secondary displacement of each target image. CONSTITUTION:Slits 300a, 300b are provided without being crossed so as to form a proper gap 8 therebetween. A unidimensional CCD image sensor 9 is arranged to the focus surface of an objective lens 5 so as to be inclined at about 45 deg. to slit images 300a', 300b' for V and H in order to equally cross both slit images 300a', 300b'. Quantity-of-light distribution having two ridges is brought onto the image sensor 9 by the slit images 300b', 300a' for the use of H and V respectively and two ridges are clearly separated into H and V. By this method, the time required in various biaxial measurements is shortened to a large extent.
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