Polarizing beam splitter and optical pick-up head comprising the same

A polarizing beam splitter comprising:

• a main body which is formed by a plane parallel plate, is made of a birefringent material and has an incident surface upon which an incident light beam is made incident and by which the incident light beam is refracted and a reflection surface which reflects the incident light beam transmitted through said incident surface, an optic axis of the birefringent material being on a plane which is parallel with said reflection surface;
• a reflecting member provided on said reflection surface of the main body and being made of dielectric materials;
• and
• a polarizing beam splitting member applied on the incident surface of said main body and formed by a stack of a plurality of dielectric material films.

A polarizing beam splitter comprising:

• a main body which is formed by a plane parallel plate, is made of a birefringent material and has an incident surface upon which an incident light beam is made incident and by which the incident light beam is refracted and a reflection surface which reflects the incident light beam transmitted through said incident surface, an optic axis of the birefringent material being on a plane which is parallel with said reflection surface;
• a reflecting member provided on said reflection surface of the main body and being made of dielectric materials;
• and
• a prism made of an optical material having an index of refraction lower than an index of refraction of the main body, said prism being cemented onto the incident surface of said main body.

An optical pick-up head for recording and/or reading information on and/or from a record medium, said head comprising:

• a light source for emitting a linearly polarized light beam;
• an objective lens for projecting said light beam onto the record medium;
• a photodetector for receiving a return light beam reflected by the record medium and converged by said objective lens;
• and
• a polarizing beam splitter arranged between said objective lens and said photodetector and including a main body made of a birefringent material and having an incident surface upon which the return light beam is made incident and by which the return light beam is made incident and by which the return light beam is refracted and a reflection surface which reflects the return light beam transmitted through said incident surface, an optic axis of the birefringent material being on a plane which is parallel with said reflection surface, and a reflecting member provided on said reflection surface of the main body and being made of dielectric materials.