| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixed point detecting apparatus and a displacement measuring apparatus which can distinguish an individual fixed point detecting pattern from among a plurality of fixed point detecting patterns and easily select a fixed point obtained by each fixed point detecting pattern. SOLUTION: The fixed point detecting apparatus comprises first and second fixed point detecting patterns 2, 3 which comprise a pair of diffraction gratings for diffracting incident light to different directions and are arranged in the direction of the measurement axis; a fixed point detecting light source 4 for making the fixed point detecting patterns 2, 3 irradiated with a light; and optoelectronic conversion devices 5A, 5B, 5C for receiving the diffracted lights diffracted by the diffraction gratings of the fixed point detecting patterns 2, 3 and converting them into electrical signals, respectively. A point, at which the combinations of two optoelectronic conversion devices which receive the two diffracted lights diffracted by the fixed point detecting patterns 2, 3 are different and at which the magnitudes of the electrical signals converted by the two optoelectronic conversion devices are equal, is set as a fixed point. COPYRIGHT: (C)2009,JPO&INPIT
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