| 摘要 |
PROBLEM TO BE SOLVED: To provide, in an optical system including a light source for illumination emitting laser beams and a prism for a projection optical system, a prism for a projection optical system and an optical system using the same that can reduce the reflection of light transmitting through the prism to suppress the problem caused by unnecessary reflection light, and improve the utilization efficiency of the light emitted from the light source.SOLUTION: There is provided a prism PR for a projection optical system that has a first surface PR1a that totally reflects illumination light I and transmits projection light P, and a second surface PR2a that is arranged opposite to the first surface with an air gap therebetween and receives the projection light emitted from the first surface, where the first surface includes a reflection prevention film 7 in which an average reflectance of the s-polarization reflectance and p-polarization reflectance of the center angle of the projection light is 2% or less in three wavelength ranges: a first wavelength range of a blue region, a second wavelength range of a green region, and a third wavelength range of a red region. |
