| 摘要 |
PROBLEM TO BE SOLVED: To provide an interference type position measuring instrument having a large mounting tolerance, extremely resistant against contamination, and allowing compact structure. SOLUTION: This instrument comprises a light source 1 for emitting a light beam along an optical axis direction, a scale grating 3, scanning lattices 4.1, 4.2 arranged in a scanning plate 4, a detecting grating 5, and detection elements 6.1, 6.2, 6.3. When the scale grating 3 joined to the first body is moved relatively with respect to the light source 1 joined to the second body and the scanning lattices 4.1, 4.2, a specified spatial interference fringe pattern is formed within a detection face. The scale grating 3 divides the incident beam into two beams of a beam (+) and a beam (-). The beam (+) is made to be incident on the scanning lattice 4.1, and the beam (-) is made to be incident on the scanning lattice 4.2. The beams emitted from the scanning lattices 4.1, 4.2 are divided to three directions in the detecting grating 5 to be detected by the detection elements 6.1, 6.2, 6.3. COPYRIGHT: (C)2004,JPO
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