Optical head device and birefringent diffraction grating polariz

Details Optical head device and birefringent diffraction grating polariz Optical head device and birefringent diffraction grating polariz

1997-02-19

1999-03-16

Spyrou, Cassandra

Optical: systems and elements

Polarization without modulation

By relatively adjustable superimposed or in series polarizers

359566, 359 7, 369112, G02B 530

Patent

active

058837418

ABSTRACT:
An optical head device uses a birefringent diffraction grating polarizer configured in a reflection type. The device includes a polarizing hologram element which reflects the light from a light source to a converging lens system and diffracts the polarized light returning from a recording medium. A total reflection film is formed on a surface of a diffraction grating which is provided periodically by an ion exchange region and a dielectric film on a surface of a crystal plate having optically anisotropic characteristics. A polarizing beam splitter film formed on a surface of the polarizing hologram element has reflectivity and transmissivity having dependency on the polarization of the incident light. In another form, a polarizing hologram element includes a polarizing hologram which has diffractive efficiency having dependency on polarization of incident light and a polarizing beam splitter film which has reflectivity and transmissivity having dependency on the polarization of the incident light. The diffracted light is received by multi-split photodetectors. The arrangements enable to make the optical head device compact, light in weight and low cost.

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