| 摘要 |
PROBLEM TO BE SOLVED: To reduce in size and weight the optical components of a length length measuring machine. SOLUTION: The laser length measuring machine comprises a laser head 20, an interferometer 22, a reference target 24, a measuring target 26, and a pair of 1/4-λplates 28, 30. The head 20 has a laser emitting port 20a for emitting a laser beam L0 , and an incident port 20b for receiving interference light L9 . The interferometer 22 has a polarized beam splitter 22 for splitting the beam L0 into two components to interfere the reflected reference light L4 from the target 24 with the reflected measured light L8 from the target 28, and a reflecting prism 22b for introducing the light L9 to the port 20b. The targets 24, 26 are formed of corner prisms for emitting the incident beams in parallel, and so regulated at the optical axes as to introduce the beams to the centers of the prisms. The plates 28, 30 are installed between the splitter 22a and the targets 24, 26 so that the crystal optical axes become 45 deg. with respect to the vibrating directions of the linearly polarized beams split by the splitter 22a.
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