COLOR SPLITTING/COMBINING PRISM, AND OPTICAL SYSTEM AND PROJECTOR THEREWITH

摘要

A color splitting/combining prism splits apart illumination light from a projector and combines together projection light from the projector. A part of the illumination light that is not used as the projection light passes through the color splitting/combining prism as OFF-light via an image display element in a direction different from the projection light. The color splitting/combining prism includes a dichroic film of which a cutoff wavelength, at which the dichroic film exhibits a transmittance of 50% when splitting two different colors between reflection and transmission, is provided in a wavelength range in which wavelength separation is possible for all of the illumination light, the projection light, and the OFF-light that are incident at different incidence angles respectively.

主权项

1. A color splitting/combining prism that splits apart illumination light from a projector and combines together projection light from the projector, wherein a part of the illumination light that is not used as the projection light passes through the color splitting/combining prism as OFF-light via an image display element in a direction different from the projection light, the color splitting/combining prism comprising:
a dichroic film of which a cutoff wavelength, at which the dichroic film exhibits a transmittance of 50% when splitting two different colors between reflection and transmission, is provided in a wavelength range in which wavelength separation is possible for all of the illumination light, the projection light, and the OFF-light that are incident at different incidence angles respectively, wherein conditional formula (1) below is fulfilled:
0.2≦(λR−λ50)/(λR−λG)≦0.4,  (1)where λR is an oscillation wavelength for red,λG is an oscillation wavelength for green, andλ50 is the cutoff wavelength at which the dichroic film exhibits a transmittance of 50% when splitting two colors of red and green between reflection and transmission in dichroic film characteristics observed with the projection light incident.