Optical pick-up device composed of composite prism made of uniaxial crystal and non-axial crystal

摘要

The present invention provides an optical pick-up device comprising a composite prism in which a prism made of non-axial crystal and a prism made of uniaxial crystal are adhered to each other and a grating, and separating into an extraordinary ray and an ordinary ray by means of the prism made of the uniaxial crystal, and further diffracting each of the extraordinary ray and the ordinary ray to o order ray, + primary ray and - primary ray by means of the grating, and then carrying out an optical detection based on the above mentioned diffracted light.