Optical device for super-resolution

An optical device used for reading an optical disk, comprising:

• a half-wave phase shift mask for shifting the phase of a portion of first linearly polarized light by a half wavelength;
• a polarizing beam splitter for transmitting said first linearly polarized light therethrough, and for reflecting a second linearly polarized light;
• a quarter-wave plate for converting said first linearly polarized light into first circularly polarized light and said first circularly polarized light into said first linearly polarized light, while converting a second circularly polarized light, whose plane is rotating in a direction opposite to said first circularly polarized light, into said second linearly polarized light;
• a first converging lens for forming an optical spot on said optical disk, and for allowing reflected light caused by said optical spot by reflection from said optical disk to pass therethrough in a backward direction;
• and
• a second converging lens for focusing a beam of light reflected by said polarizing beam splitter onto a light detector,
• wherein said optical spot comprises a main lobe of said first circularly polarized light and a side lobe of said second circularly polarized light, and said reflected light comprises reflected light having said second circular polarization caused by said main lobe and reflected light having said first circular polarization caused by said side lobe.

An optical device used for reading an optical disk, comprising:

• an optically active device having a 90-degree twisted nematic liquid crystal element for converting a portion of first linearly polarized light into second linearly polarized light whose plane is oriented at right angles relative to said first linearly polarized light;
• a polarizing beam splitter for transmitting said first linearly polarized light therethrough, and for reflecting said second linearly polarized light;
• a quarter-wave plate for converting said first linearly polarized light into first circularly polarized light and said first circularly polarized light into said first linearly polarized light, while converting a second circularly polarized light, whose plane is rotating in a direction opposite to said first circularly polarized light, into said second linearly polarized light;
• a first converging lens for forming an optical spot on said optical disk, and for allowing reflected light caused by said optical spot by reflection from said optical disk to pass therethrough in a backward direction;
• and
• a second converging lens for focusing a beam of light reflected by said polarizing beam splitter onto a light detector,
• wherein said optical spot comprises a main lobe of said first circularly polarized light and a side lobe of said second circularly polarized light, and said reflected light comprises reflected light having said second circular polarization caused by said main lobe and reflected light having said first circular polarization caused by said side lobe.