LAMINATED HALF-WAVE PLATE, POLARIZING CONVERTER, POLARIZED LIGHT ILLUMINATION DEVICE AND LIGHT PICKUP DEVICE

摘要

[Problem] To obtain a means for forming a laminated half-wave plate for a triple-wavelength compatible optical pickup device. [Solving Means] A first and a second wave plates using quartz crystal having birefringence are laminated together in such a manner that their optical axes intersect to form a laminated wave plate functioning as a half-wave plate as a whole. Phase differences of the first and the second wave plates relative to an ordinary ray and an extraordinary ray with respect to a predetermined wavelength λ are set to be &Ggr;1 and &Ggr;2, an order of a high-mode order is set to be a natural number n, whereby the high-order mode laminated half-wave plate is formed so as to satisfy: &Ggr;1=180°+360°×n; and &Ggr;2=180°+360°×n.