| 摘要 |
PROBLEM TO BE SOLVED: To provide a half mirror, with which polarization plane control is facilitated, suitable for use as a beam splitter for splitting an emitted beam and a returned beam from light sources by making equal light transmission/ reflection characteristics due to laser beams having the wavelength of 650 nm and the wavelength of 780 nm. SOLUTION: A multilayer membrane 3 laminated on a glass substrate surface 21 of a half mirror 1 is a nine-layer structure where the material quality, refractive index and optical thickness of each of multilayer membranes are suitably set and the light transmission/reflection characteristics due to (s) and (p) polarized components thereof are equal for both the wavelengths of 650 and 780 nm. Thus, the polarization plane control for the laser light sources of two wavelengths is facilitated. |
