Laminated half-wave plate, optical pickup device, polarization converter, and projection display apparatus

摘要

A laminated half-wave plate includes: first and second wave plates having optical axes intersecting each other, wherein when phase differences of the first and second wave plates with respect to a wavelength λ are represented by &Ggr;1 and &Ggr;2, in-plane bearing angles formed by a polarization plane of a linearly-polarized beam incident on the laminated half-wave plate and the optical axes of the first and second wave plates are represented by &thetas;1 and &thetas;2, an angle formed by the polarization directions of the linearly-polarized beams incident on and emitted from the laminated half-wave plate is represented by &phgr;, and an optical axis adjustment amount is represented by a, the following expressions are satisfied: &Ggr;1=180°+n×360°; &Ggr;2=180°+n×360° (where n in &Ggr;1 and &Ggr;2 is a non-negative integer); &thetas;1=&phgr;/4+a; and &thetas;2=3&phgr;/4−a.