Abstract: There is provided an apparatus for storing/restoring holographic data and a method for coding/decoding holographic data. In a recording mode, the apparatus divides input data into a plurality of groups, each of which includes two binary digits; and encodes each of the groups into a 2×2 data block wherein a first row of the 2×2 data block has the two binary digits and a second row thereof has another binary digits generated by applying a binary differential calculation on the first row. In a restoring mode, the apparatus divides a signal restored from a storage media into a plurality of 2×2 data blocks; and decodes each of the 2×2 data blocks into two binary digits by comparing values of a first row of the 2×2 data block with those of a second row thereof. In this way, phenomena of isolated “on” or “off” can be avoided.

Abstract: A holographic digital data storage apparatus detects a wobbling in a disc shaped storage medium, wherein the apparatus includes a beam generator and finding means, the disc including therein one or more holographically generated patterns. The beam generator projects at least two wobble detection beams to the holographically generated patterns, the wobble detection beams having different diffraction efficiencies provided at respective characteristic angles, wherein the characteristic angle is an angle between an optical path of one wobble detection beam and that of its corresponding pattern forming beam used in forming one of the holographically generated patterns and a diffraction efficiency is given by a ratio of a power of a diffracted beam of one of the wobble detection beams to a power of said one of the wobble detection beams. The finding means finds at least a difference between the diffraction efficiencies to thereby determine the wobbling in the disc.

Abstract: A data input method is applied to a holographic digital data storage system in which sequential binary input data bits are arranged in an interleaved manner among pages. A first data bit is arranged in a specific position of a predetermined page, a second data bit is arranged in a specific position having similar beam intensity with that of the first data bit. Using this method, the holographic digital data storage system can be less affected by the adverse effect of spatial beam intensity variations and makes the entire data interleaved automatically to obtain more stable output data.

Abstract: There is provided an apparatus for storing/restoring holographic data and a method for coding/decoding holographic data. In a recording mode, the apparatus divides input data into a plurality of groups, each of which includes two binary digits; and encodes each of the groups into a 2×2 data block wherein a first row of the 2×2 data block has the two binary digits and a second row thereof has another binary digits generated by applying a binary differential calculation on the first row. In a restoring mode, the apparatus divides a signal restored from a storage media into a plurality of 2×2 data blocks; and decodes each of the 2×2 data blocks into two binary digits by comparing values of a first row of the 2×2 data block with those of a second row thereof. In this way, phenomena of isolated “on” or “off” can be avoided.

Abstract: A block coding algorithm uses an original block group having n+1 original blocks of m-bit message, which a first original block of m-bit message is encoded as a reference block of n-bit codeword and n original blocks of m-bit message placed after the first original block of m-bit message are encoded as n weighted blocks of n-bit codeword, based on a bit sequence of the reference block. A block decoding algorithm decodes n weighted blocks to generate corresponding original blocks of m-bit message and reconstructs the first original block of m-bit message from a sequence of reference bits, wherein each reference bit implies whether each of n weighted blocks is an A type weighted block or a B type weighted block.

Abstract: In a coding method, a (2N-1)st original block of m bits is encoded as an A type weighted block of n bits and a 2Nth original block of m bits is encoded as a B type weighted block of n bits. In a decoding method, if a weighted block of n bits is the A type block, the weighted block of n bits is decoded as the (2N-1)st original block of m bits, and if otherwise, the weighted block of n bits is decoded as the 2Nth original block of m bits.

Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.

Abstract: The holographic digital data storage system is compatible with a CD/DVD player. A polarization direction of the beam is altered by a first wave plate and the size of the polarized beam is expanded by a beam expander. The expanded beam is split into a vertical polarized beam and a horizontal polarized beam by a polarization splitter; a polarization direction of the horizontal polarized beam is altered by a second wave plate. An optical path of the vertical polarized beam is adjusted by a first mirror to generate a first path-controlled beam; an optical path of a third directional polarized beam is controlled by a second mirror to generate a second path-controlled beam; the first and the second path-controlled beams are concentrated by using a first and a second lenses, respectively; and the interference of two beams is recorded on a medium.

Abstract: A method for mapping 2N message N-tuples into 2N+1 codeword (N+1)-tuples is developed. The 2N+1 codeword (N+1)-tuples are categorized into M subsets of codeword (N+1)-tuples, wherein M is an integer larger than 1, each subset G has NG codeword (N+1)-tuples and the total number of codeword (N+1)-tuples in the M subsets is 2N. Each subset G has a predetermined number KG of lower bits and a predetermined number (N+1−KG) of higher bits, and the number of lower bits in every codeword (N+1)-tuple in any subset is not equivalent to that of lower bits in every codeword (N+1)-tuple in any other subset. The 2N message N-tuples are matched with the 2N codeword (N+1)-tuples in the M subsets, respectively, in one-to-one correspondence to generate a lookup table.

Abstract: A volume holographic data storage (VHDS) system incorporates therein a storage device having a plurality of storage media for storing multiple holograms. The VHDS system comprises a light source for generating a coherent light beam, a beam splitter for splitting the coherent light beam into a reference and a signal beams, a storage device having a base and a plurality of storage media mounted on the base for three-dimensionally storing the multiple holograms thereinto, a pair of mirrors for directing the signal and the reference beams to the storage device, respectively, and a motor for rotating the storage device about an axis perpendicular to a plane which includes the signal and reference beams, wherein the axis passes through a center point of the storage device. In the storage device, each of the storage media is mounted on top of the base angularly separated by an angle of &bgr;degrees.

Abstract: A method for patterning a thin film layer into a predetermined configuration improves resolution thereof by exposing a partial depth “d” of a photoresist layer to a light beam. The patterning method includes the steps of: (a) preparing a semiconductor substrate with the thin film layer, an intermediate layer and a photoresist layer formed thereon, successively; (b) exposing a partial depth of the photoresist layer to a light beam; (c) removing the portion of the photoresist layer exposed to the light beam by using a solution to thereby obtain a patterned photoresist layer; (d) etching the intermediate layer by using the patterned photoresist layer as a mask; and (e) patterning the thin film layer into the predetermined configuration by using the etched intermediate layer as a mask.

Abstract: A holographic storage system implements both a rotational and an angular multiplexings in combination. The system comprises a light source, a pair of wedge prisms, a beam splitter, a first, a second, a third and a parabolic mirrors, a SLM(spatial light modulator) and a storage medium. In the system, a light beam emitted from the light source is split into a reference and a signal beams by the beam splitter. The signal beam reflected by the first mirror to the SLM which modulates data in the firm of pages. The modulated signal beam falls into the storage medium, while the reference beam is reflected by the second mirror to the wedge prisms which deflect the reference beam to an arbitrary position on the third mirror. The deflected reference beam is reflected onto the parabolic mirror by the third mirror. The deflected reference beam is converged onto the storage medium by the parabolic mirror.

Abstract: A method for planarizing a patterned structure on a top surface of a substrate comprises the steps of depositing an insulating layer on the patterned structure, implanting ionized atoms of a predetermined depth onto the surface of the insulating layer, coating a photo resist on the insulating layer and partially removing the photo resist so that a portion of the insulating layer on the patterned structure is unmasked at a substantially same magnitude of lateral length as a width of the patterned structure, exposing the unmasked portion of the insulating layer to an etchant until the unmasked portion of the insulating layer is removed to be generally flushed with the remainder of the insulating layer and removing the photo resist from the insulating layer. The method further comprises the steps of repeatedly performing etch back processes, after the removing step.

Abstract: A method for planarizing a non-planar layer includes the steps of (a) forming a dielectric layer on top of the non-planar layer, the dielectric layer having protuberances due to the non-planar layer; (b) applying a seed layer on top of the dielectric layer, the seed layer having humps due to the protuberances of the dielectric layer; (c) forming a photoresist layer on top of the seed layer; (d) patterning and partially removing portions of the photoresist layer to thereby expose parts of a top surface of the seed layer; (e) forming a conductive layer on top of each of the exposed parts of the seed layer; (f) removing remaining portions of the photoresist layer until the seed layer thereunder is exposed; (g) removing parts of the photoresist layer still remaining, the seed layers protruding between the conductive layers and parts of the dielectric layer in such a way that the protuberances in the dielectric layer are completely removed; and (h) removing each conductive layer and the seed layer thereunder.

Abstract: A method for forming a lower magnetic pole in a thin film magnetic head reduces the steepness of steps thereof. The method begins with the preparation of the mask layer, including a bottom surface and a sloping wall having an angle of inclination .theta. with respect to the bottom surface on top of the magnetic layer. Thereafter, the magnetic layer is patterned into the lower magnetic pole, including a flat bottom surface and an inclined wall which has a reduced steepness in comparison to the sloping wall of the mask layer. The inclined wall is made less steep by controlling the ratio of the etching rate of the magnetic layer to that of the mask layer.

Abstract: A method for forming a patterned metallic layer on a substrate is employed to form a first layer on top surface of the substrate. A patterned mask layer is then deposited on top of the first layer, thereby exposing selected portions of the first layer. Thereafter, a second and a third layers are successively formed on top of the selected portions of the first layer, and the patterned mask layer is removed. Subsequently, the first layer is removed except the portions thereof intervening between the top surface of the substrate and the second layer by using a dry etching method to thereby form the patterned metallic layer including the second layer and the exposed portions of the first layer.

Abstract: A method for forming a conductive layer on a substrate having a patterned seed layer thereon includes the steps of: (a) depositing a polyimide layer on the patterned seed layer and a part of the substrate which is not covered with the patterned seed layer; (b) directing a light beam onto a portion of the polyimide layer formed on top of the patterned seed layer; (c) developing the portion of the polyimide layer, thereby exposing the patterned seed layer; (d) curing the remaining portion of the polyimide layer at an appropriate condition, thereby turning it into an insulator; and (e) electroplating the conductive layer on the exposed patterned seed layer.

Abstract: An apparatus for polishing a dielectric layer deposited on a top surface of a semiconductor substrate includes a table, a semiconductor substrate, a carrier, a pipe, a nozzle and an actuator assembly provided with a base, a power source, a cavity and a thermally expanding material. The actuator assembly controls the vertical position of the table by supplying a current to the thermally expanding material.