| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wave plate for an optical pickup that can be used also for light beams having wavelengths of 405 nm, 650 nm, and 780 nm, and enables inexpensive manufacture of a large-area piece. <P>SOLUTION: In a quarter-wave plate for an optical pickup, there is formed a photonic crystal, on both surfaces of a transparent substrate, which acts as a 1/2 wave plate and a quarter-wave plate respectively relative to light beams having wavelengths from 740 nm to 840 nm. The directions of an in-plane principal axis in the respective photonic crystals are inclined by 60° to each other. Thus, the photonic crystals give phase differences of about 270°, about 90°, and about 90° to beams of linearly polarized light having wavelengths of 405 nm, 650 nm, and 780 nm, respectively, perpendicularly incident on the substrate, thereby enabling utilization as the quarter-wave plate for the optical pickup which can be used for the three wavelengths. <P>COPYRIGHT: (C)2012,JPO&INPIT |
