Polarization rotation and phase compensation in near-field electro-optical system

An optical system, comprising:

• an optical module including an objective lens and a near-field lens disposed relative to said objective lens at a prespecified position;
• an optical medium configured to have substantially arcuate tracks and disposed relative to said near-field lens at a distance smaller than a desired electromagnetic wavelength to form a near-field configuration, said optical medium and said objective lens being on the opposite sides of said near-field lens;
• and
• an optical polarization rotator, located relative to said optical module and configured to rotate a polarization of said optical beam to a direction substantially perpendicular to said tracks, thereby facilitating a separation of a polarization-dependent phase distortion signal from a signal in a reflection of said optical beam from said optical medium.

An optical system, comprising:

• an optical module having an objective lens and a near-field lens disposed relative to said objective lens at a prespecified position, said optical module adding a phase distortion to an optical beam passing therethrough;
• an optical medium disposed on the opposite of said near-field lens from said objective lens at a distance so that optical energy is coupled between said optical medium and said near-field lens by evanescent fields;
• and
• means for imposing a phase profile on said optical beam to substantially reduce said phase distortion.

An optical system in a near-field configuration, comprising:

• a light-producing module operable to produce an optical beam of a selected wavelength;
• an optical head comprising an objective lens located to receive and modify said optical beam and a near-field lens disposed relative to said objective lens at a prespecified position to receive said optical beam from said objective lens;
• an imaging module disposed relative to said light-producing module and said optical head to direct said optical beam to said optical head;
• an optical data storage disk disposed relative to said near-field lens at a distance smaller than said selected wavelength to form a near-field configuration and operable to spin to support said optical head by an air-bearing layer;
• and
• means for imposing a compensating phase profile on said optical beam to substantially reduce a phase distortion.

An optical system, comprising:

• a light-producing module operable to produce an optical beam of a selected wavelength;
• an optical head comprising an objective lens located to receive and modify said optical beam and a near-field lens disposed relative to said objective lens at a prespecified position to receive said optical beam from said objective lens;
• an imaging module disposed relative to said light-producing module and said optical head to direct said optical beam to said optical head;
• an optical data storage disk configured to have tracking grooves and disposed relative to said near-field lens so that optical energy is coupled between said optical disk and said near-field lens by evanescent fields, wherein said optical disk is operable to spin to support said optical head by an air-bearing layer;
• and
• a polarization rotator located between said light-producing module and said optical head and operable to rotate a polarization of said optical beam to be substantially perpendicular to said tracking grooves.

A method for constructing and operating an optical storage system, comprising:

• providing an optical system including an objective lens and a near-field lens to receive and modify an electromagnetic radiation wave at a desired electromagnetic wavelength;
• placing a storage medium responsive to said radiation wave relative to said near-field lens at a distance smaller than said desired wavelength;
• determining a phase distortion that includes at least contributions from lens aberrations from said optical system and from a near-field effect produced by said near-field lens and said optical storage medium;
• and
• compensating for said phase distortion by using an optical phase-compensating element in the optical path of said optical system wherein said optical phase-compensating element is configured to have a compensating phase profile complementary to said total phase distortion.

A method for constructing and operating an optical storage system, comprising:

• providing an objective lens to receive and modify an optical beam of a selected wavelength;
• disposing a near-field lens relative to said objective lens at a prespecified position to receive said optical beam from said objective lens;
• placing an optical storage disk with tracking grooves relative to said near-field lens at a distance smaller than said selected wavelength;
• rotating a polarization of said optical beam to a direction that is substantially perpendicular to said tracking grooves;
• and
• separating a phase distortion signal from a signal produced by reflection of said optical beam from said optical disk.

An optical system, comprising:

• a module including an objective lens and a near-field lens disposed relative to said objective lens with a prespecified spacing and operating to receive and modify an electromagnetic radiation at a desired electromagnetic wavelength;
• a medium configured to have a material responsive to said radiation and substantially arcuate tracks and disposed relative to said near-field lens at a distance smaller than said desired electromagnetic wavelength to form a near-field configuration, wherein said medium and said objective lens are located on the opposite sides of said near-field lens;
• and
• means for reducing an effect of a phase distortion in said radiation to perform at least one of (1) rotating a polarization of said radiation to a direction substantially perpendicular to said tracks, thereby facilitating a separation of a polarization-dependent phase distortion signal from a signal in a reflection of said radiation from said medium;
• and (2) imposing a distortion-compensating phase profile on said radiation to substantially reduce said phase distortion.