One example provides a system for reading birefringent data. The system comprises one or more light sources, a first polarization state generator positioned to generate first polarized light from light of a first wavelength band output by the one or more light sources, a second polarization state generator positioned to generate second polarized light from light of a second wavelength band output by the one or light sources, an image sensor configured to acquire an image of the sample region via the first polarized light and the second polarized light, a polarization state analyzer disposed between the sample region and the image sensor, a first bandpass filter configured to pass light of the first wavelength band onto the image sensor, and a second bandpass filter configured to pass light of the second wavelength band onto the image sensor.

An optical pickup device includes a semiconductor laser that emits a laser beam, and an object lens that concentrates the laser beam emitted from the semiconductor laser on an optical disc. In this optical pickup device, an optical axis of the object lens is inclined with respect to an optical axis of the laser beam that is incident on the object lens so as to generate flares caused by coma aberration on an entrance side in a forward direction of pits of the optical disc.

An apparatus includes a first storage cell with an electrical property. The first storage cell is configured to change the electrical property in response to a first light energy, and to maintain the change to the electrical property. The first storage cell is also configured to alter the change to the electrical property in response to a second light energy, and to maintain the alteration to the change to the electrical property. A second storage cell disposed over the first storage cell in a vertical plane of the first storage cell. A third storage cell disposed adjacent to the first storage cell in a horizontal plane of the first storage cell.

The purpose of the present invention is to provide a hologram reproducing apparatus and a hologram reproducing method, which are suitable for reproducing hologram. The purpose can be achieved by means of a hologram reproducing apparatus, which reproduces information signals by irradiating an optical information recording medium with reference light, and a hologram reproducing method for the hologram reproducing apparatus. The hologram reproducing apparatus is characterized in being provided with: a polarization conversion section, which converts polarization of diffracted light that is generated when the optical information recording medium is irradiated with the reference light; a light receiving section, which receives the diffracted light having the polarization thereof converted by means of the polarization conversion section; and a servo signal generating circuit section, which generates signals for moving the optical information recording medium or the polarization conversion section using the diffracted light received by means of the light receiving section.

An optical information recording/reproduction device is capable of appropriately correcting the angle of a reference beam during data reproduction even when a wavelength deviation or an angle deviation in multiplexing and vertical directions of the reference beam occurs in a holographic memory recording medium. The optical information reproduction device has a laser light source that generates a reference beam; an image-capturing unit that detects a diffraction ray to be reproduced from the optical information recoding medium; and an optical detection unit that has at least two light-receiving surfaces and is used for detecting a diffraction ray reproduced by irradiating the reference beam on the optical information recording medium. The device also has a light-shielding unit that shields part of the diffraction ray detected by the optical detection unit; and an error signal calculation unit that generates an error signal from a detection signal outputted by the optical detection unit.

A method of fabricating an optical element comprises: providing a substrate (1, 50) of a transparent material in which is to be formed a plurality of birefringent nanostructures spaced apart in plane substantially parallel to a surface of the substrate in a first direction (2) by a distance X and in a second direction (3) by a distance Y; generating from the output of a source (20) of femtosecond laser pulses a laser beam group comprising a plurality of focused seeding beams (44) having a circular polarisation and spaced apart along a line by the distance X and a focused writing beam (26) having a non-circular polarisation and spaced apart from one of the seeding beams by the distance Y or the distance X; directing the laser beam group onto the surface of the substrate at a first position and applying one or more femtosecond laser pulses from each beam to corresponding volumes in the substrate; repeatedly translating the laser beam group relative to the substrate parallel to the line of seeding beams and along the first direction by the distance X to a next position and applying one or more femtosecond laser pulses from each beam, in order to deliver a plurality of femtosecond laser pulses from the seeding beams to each corresponding volume to create substantially optically isotropic nanostructures in the corresponding volumes; translating the laser beam group relative to the substrate along the second direction by the distance Y and repeating the repeated translation and application of the femtosecond laser pulses along the first direction; wherein the relative translation of the laser beam group and the substrate aligns the writing beam with successive corresponding volumes in which substantially optically isotropic nanostructures have been created, so that the one or more femtosecond laser pulses applied from the writing beam transform the optically isotropic nanostructure in each corresponding volume into an optically isotropic nanostructure with optical birefringence.

In recording technologies for batch formation of a plurality of recording bits in a recording medium by forming a plurality of optical spots using an ultrashort pulse laser and a spatial optical modulator, the batch recordable bit number has an upper limit, resulting in restricted recording speed. The intensity of the optical spot is corrected to increase the batch recordable bit number for increasing the recording speed.

A light information recording/reproducing apparatus can improve the optical efficiency of an optical system at the time of reproduction to thereby improve the reproduction transfer rate. An optical element (for example, an optical isolator), which removes a return light beam of a light beam, is arranged such that the light beam passes through the optical element at the time of recording information in an optical information recording medium and such that the light beam does not pass through the optical element at the time of reproducing information from the optical information recording medium.

One example provides a computer-implemented method for reading data stored as birefringence values in a storage medium. The method comprises acquiring an image of a voxel of the storage medium, applying a first low-pass filter with a first cutoff frequency to the image of the voxel to obtain a first background image, applying a second low-pass filter with a second cutoff frequency to the image of the voxel to obtain a second background image, the second cutoff frequency being different than the first cutoff frequency, determining an enhanced background image from the first background image and the second background image, determining birefringence values for the enhanced background image, determining birefringence values for the image of the voxel, and correcting the birefringence values for the image of the voxel based upon the birefringence values for the enhanced background image.

3D optical data storage refers to forms of optical data storage in which information can be recorded and/or read with 3D resolution. 3D optical media are generally limited in areal density by the diffraction limit of laser light used to read and/or write data to and/or from the optical media. It is thus advantageous to find ways to store data on 3D optical media with a spot size below the diffraction limit of an associated laser reader to further increase areal density of the optical media. A hybrid approach that utilizes plasmon technology to access a surface layer of the 3D optical media with an extremely small spot size and photon technology to access interior layers of the 3D optical media with a larger spot size may substantially increase overall data density of the 3D optical media.