WAVELENGTH SELECTING WAVELENGTH PLATE AND OPTICAL HEAD DEVICE USING IT

摘要

An optical rotation plate has an optical rotation material layer. A phase plate has at least one double-refraction material layer formed on the first surface side of the optical rotation plate. The first surface is disposed so as to face the emission side of the optical path. This results that a first linearly polarized light group and a second linearly polarized light group have phase differences different from each other. The first linearly polarized light group contains at least linearly polarized light of a first wavelength, and the second linearly polarized light group contains at least linearly polarized light of a second wavelength different from the first wavelength.