Patent ID: 7618716

Claim:
A wavelength plate having the same polarizing characteristics against monochromic lights having a different wavelength, which is obtained by laminating a retardation film (A) that provides a retardation of (1+X)λ to light having a wavelength λ (nm) as defined according to the following expression (1) as an essential component and a retardation film (B) that provides a retardation of (¼+Y/2)λ or a retardation film (C) that provides a retardation of (½+Z)λ, wherein X, Y, and Z each independently represent 0 or an integer between 1 and 10 such that an optical axis of the retardation film (B) or retardation film (C) intersects with an optical axis of the retardation film (A): [(λ S+λL )/2]−200≦λ≦[(λ S+λL )/2]+200 (1) λS: wavelength (nm) of monochromic light in the shortest wavelength side; and λL: wavelength (nm) of monochromic light in the longest wavelength side, wherein each of the retardation films (A), (B), and (C) (i) comprises a cyclic olefin based resin-containing material, and (ii) has a ratio (Re800/Re550) of a retardation (Re800) in light having a wavelength of 800 nm to a retardation (Re550) in light having a wavelength of 550 nm of from 0.90 to 1.05.