Abstract: According to one aspect of the present invention, a displacement measurement device includes a control circuit controlling an optical path movement mechanism so that a first total sum of a plurality of intensity signals output from a first position detection sensor and a second total sum of a plurality of intensity signals output from a second position detection sensor change at the same time in a case in which a first and second lights and a stage are relatively moved to cross a boundary; and a displacement measurement circuit calculating an average value of first displacement of a object surface based on the plurality of intensity signals output from the first position detection sensor and second displacement of the object surface based on the plurality of intensity signals output from the second position detection sensor to measure the average value as the displacement of the object surface.

Abstract: A laser beam projecting device, comprising a laser light source for emitting a laser beam, a wavelength selecting film for allowing the laser beam from the laser light source to. pass, and a birefringent optical member arranged on an optical axis closer to an exit side than the wavelength selecting film, wherein the wavelength selecting film is tilted so that an incident angle of the laser beam is in a range of 45° to 80°.

Abstract: A laser beam projecting device, comprising a laser light source for emitting a laser beam, a wavelength selecting film for allowing the laser beam from the laser light source to. pass, and a birefringent optical member arranged on an optical axis closer to an exit side than the wavelength selecting film, wherein the wavelength selecting film is tilted so that an incident angle of the laser beam is in a range of 45° to 80°.

Abstract: A laser beam projecting device, comprising a laser light source for emitting a laser beam, a wavelength selecting film for allowing the laser beam from the laser light source to pass, and a birefringent optical member arranged on an optical axis closer to an exit side than the wavelength selecting film, wherein the wavelength selecting film is tilted so that an incident angle of the laser beam is in a range of 45° to 80°.

Abstract: A laser theodolite is provided which comprises a telescope (6), a focusing lens (10) and a reticle (12) provided in the telescope, a polarization beam splitter (13') provided on an optical axis (O) between the focusing lens and the reticle for reflecting a laser beam (S1) in a direction of collimation, and a laser-beam light source portion (16) for emitting the laser light toward the polarization beam splitter (13'). The laser-beam light source portion (16) and the reticle (12) are conjugate with respect to the polarization beam splitter (13').