| 摘要 |
<p>[Problem] To achieve further cost reduction when using a ½ wavelength plate or ¼ wavelength plate made of resin film. [Solution] An optical pickup device is characterised in that it comprises: a first laser light source that emits first laser light of a first wavelength; a second laser light source that emits second laser light of a second wavelength; an object lens; a ½ wavelength plate made of resin film provided on a common optical path between the aforementioned laser light source and the object lens; a beam splitter provided on a common optical path between the ½ wavelength plate and the object lens, that reflects incident laser light in the direction of the object lens with the phase of this laser light inverted; and a ¼ wavelength plate made of resin film provided on a common optical path between the beam splitter and the object lens. The ½ wavelength plate and the ¼ wavelength plate are formed so that, in the relationship of the wavelength of the incident laser light and the phase difference applied to the emitted laser light, both of these have a characteristic with a positive gradient or both of these have a characteristic with a negative gradient.</p> |
