| 摘要 |
An object is to suppress reduction in an amount of light received by a light receiver. A displacement sensor 10 includes: a polarizing beam splitter 23 which splits detection light and reflected detection light; and a polarizing beam splitter 25 which splits incident light on a varifocal mirror 27 and reflected light therefrom, and also includes a Faraday rotator 24 and a quarter wavelength plate 26 which change the polarized light of the detection light and the reflected detection light. The polarization angles of the two light beams split by the polarizing beam splitters 23 and 25 are set to p-polarized light and s-polarized light of the polarizing beam splitters by the Faraday rotator 24 and the quarter wavelength plate 26. Consequently, the two light beams can be split by the polarizing beam splitters 23 and 25, and the reduction in the amount of light split by the polarizing beam splitters 23 and 25 and received by the light receiver is suppressed. |
