Patent ID: 7701633
Filing Date: 2010-04-20
Classification: G02B

Abstract:
1. A prism optical system including an optical low-pass filter disposed on an incident side of a luminous flux, and a prism arranged to perform a color separation to a plurality of color bands by an optical thin film, the prism optical system comprising: the optical low-pass filter disposed on an incident side of the prism; and at least two quarter-wave plates having a phase elimination function, and each disposed on one of an incident surface and an outgoing surface of the optical low-pass filter; wherein the prism optical system is configured to satisfy the following equation, where X 1 is a phase elimination efficiency at 550 nm wavelength when the incident side quarter-wave plate is inserted between crossed Nicols, and X 2 is a phase elimination efficiency at 550 nm wavelength when the outgoing side quarter-wave plate is inserted between the crossed Nicols, and wherein the optical low-pass filter includes at least one intermediate side quarter-wave plate with the phase elimination function which is disposed between the incident-side quarter-wave plate and the outgoing side quarter-wave plate; and the prism optical system is configured to satisfy the following equation, where X 3 is the phase elimination efficiency of the intermediate side quarter-wave plate at 550 nm wavelength.