Abstract: The invention presents the concept of self-referenced holographic data recording. In exemplary embodiments, the invention comprises methods of recording holograms on holographic data storage media; media produced by such methods; and self-referencing holographic data storage systems. A method of recording data in a holographic recording medium may comprise illuminating a medium with a data encoded first optical beam, optically directing a zero frequency Fourier component of the first optical beam to create a second optical beam, and illuminating the medium with the second optical. In some embodiments, for example, a self-referencing holographic data storage system has a single optical path directed towards a medium.

Abstract: The diffraction-based monitoring techniques described herein can be used, for example, as quality assurance measure in manufacture of magnetic recording media with servo tracking. In one embodiment, the invention presents a system comprising a light source such as a laser that directs light upon a surface of a magnetic recording medium. The magnetic recording medium has two or more physical marks, and the light striking the magnetic recording medium produces a diffraction pattern. A light detector such as a photodiode detects some or all of the diffraction pattern. The physical marks may be servo tracks on the magnetic recording medium, and the detected diffraction pattern is a function of the characteristics of the servo tracks.

Abstract: In one embodiment, a holographic data storage medium includes a substrate, a holographic recording material, and an optically detectable tracking pattern on the medium. The substrate may have first and second substrate portions. The holographic recording material may be a photopolymer, and the medium may have a sandwiched construction, where the holographic recording material is sandwiched between the first and second substrate portions. The optically detectable tracking pattern may be replicated on at least one of the substrate portions. Alternatively, the optically detectable tracking pattern may be recorded as a holographic grating in the holographic recording material. The tracking pattern may facilitate the ability to pinpoint the location of the holographic bit maps on the holographic medium to within a fraction of a micron.

Abstract: The invention includes a method of generating a position error signal in a holographically imaged data recording system. This method comprises using an optical imaging system to image a plurality of holographically recorded pixels onto a plurality of camera pixels forming a data page. Each holographically recorded pixel is imaged onto an array of at least two adjacent camera pixels in any direction. The output signals from the arrays of camera pixels are used to calculate a position error signal. In a preferred embodiment, the holographically recorded pixel is imaged onto an array of four adjacent camera pixels that form a square having two pixels in each direction.

Abstract: A system for reading data from recording media having topographical features readable with a slider-mounted non-magnetic transducer sensitive primarily to changes in local aerodynamic boundary conditions.

Abstract: A data storage master disk and method of making a data storage master disk. The data storage disk master is for use in a data storage disk replication process. The data storage disk molding processes produces replica disks having a surface relief pattern with replica lands and replica grooves. The method includes providing a master substrate. The master substrate is at least partially covered with a layer of photosensitive material. A surface relief pattern having master lands and master grooves is recorded in the data storage disk master, including the steps of exposing and developing the photosensitive material. The exposing and developing of a specified thickness of photosensitive material is controlled to form master grooves extending down to a substrate interface between the master substrate and the layer of photosensitive material, such that the width of the master grooves at the substrate interface corresponds to a desired width of the replica lands.

Abstract: A data storage master disk and method of making a data storage master disk. The data storage disk master is for use in a data storage disk replication process. The data storage disk molding processes produces replica disks having a surface relief pattern with replica lands and replica grooves. The method includes providing a master substrate. The master substrate is at least partially covered with a layer of photosensitive material. A surface relief pattern having master lands and master grooves is recorded in the data storage disk master, including the steps of exposing and developing the photosensitive material. The exposing and developing of a specified thickness of photosensitive material is controlled to form master grooves extending down to a substrate interface between the master substrate and the layer of photosensitive material, such that the width of the master grooves at the substrate interface corresponds to a desired width of the replica lands.

Abstract: A system and method for conditioning a photoconductive radiation detector achieve charge redistribution within a photoconductive layer without the need for charge removal or charge injection techniques. A first conditioning voltage is applied across the detector to establish a first electric field. The first electric field is reversed relative to fields applied to the detector during image exposure and image read-out operations. While the first conditioning voltage is maintained, the photoconductive layer is exposed for a period of time to first conditioning radiation having one or more wavelengths selected to penetrate at least a portion of the photoconductive layer. A second conditioning voltage, less than the first conditioning voltage, then can be optionally applied across the detector to establish a forward bias electric field. While the second conditioning voltage is maintained, the photoconductive layer is exposed for a period of time to second, broad spectrum conditioning radiation.

Abstract: A radiographic image reader acquires electronic signals corresponding to a latent image of an object produced by radiation exposure of a photoreceptive medium within a cassette. The radiographic image reader comprises a light-tight enclosure with at least one access port for inserting and removing the cassette. A scanner subsystem is mounted within the light-tight enclosure for scanning the photoreceptive medium within the cassette to initiate the acquisition of the electronic signals representative of the latent image. A cassette registration and interface subsystem within the light-tight enclosure comprises an electronic interface structure for electronically connecting the photoreceptive medium within the cassette to an electronic component external of the cassette to obtain the electronic signals corresponding to the latent image.

Abstract: An imaging tracking system and method for tracking optical media using a two wavelength optical head.

Abstract: A wallet-sized data card includes a magneto-optic active region configured for rotational recording of data. A fender projecting outwardly from the card is disposed adjacent an outer circumference of the recording region for protecting the magneto-optic recording region.