Polaroid Corporation

Other

Arthur M Gerber

Vivian K Walworth

Warren D Slafer

James J Cowan

Judith Loucks

A thin film is formed on a plastic substrate that is preformed with recording tracks, either continuous or discontinuous, formed of a metal containing film on a thermoplastic substrate. Individually-identifiable recording elements arranged in rows are preferred. Initial reflection of the recording elements are reduced by etching or microscopically roughing the surface to produce discontinuities with dimensions less than one wavelength of the light being used to record on and read from the media. The rough surface may be created on the plastic before the application of the metallic film or the film itself may be roughened after application to the plastic. The resulting micromirrors can have about equal initial reflectivity and absorption of about fifty percent with little or no transmission. The location of the individual recording elements can be determined prior to recording and used as a gauge to permit compensation for changes in the scanning velocity of the reading or writing beam. One bit of digital information is recorded on each recording element either by leaving the reflectivity unchanged or by applying focused energy of sufficient intensity to melt or distort the plastic beneath the metal-containing film and thereby further decrease the reflectivity.

Optical recording medium with high absorption and high reflectivity

A digital recording medium formed of a thermoplastic substrate having rows of equally-spaced microscopic optically-alterable mirrors each supported by a mesa projecting from one surface. The medium can be formed from a single transparent thermoplastic substrate with an array of indentations in a first surface. The bottom of each indentation is coated with a reflective material. When viewed from the opposite surface of the substrate, the indentations become mesas. The mirrors serve as timing and tracking markers during pretesting, recording, and read-out. The area and location of each information bit is determined prior to recording: not as a result of the recording process. The medium is pretested for defects prior to recording by scanning with a laser beam of sufficiently low energy that the reflectivity of the storage areas is not significantly reduced. Storage areas having lower than the predetermined reflectivity are 'fenced off' prior to recording. Recording is by exposure to a laser beam that reduces the reflectivity of selected mirrors. After exposure to the recording laser beam, the mirrors retain enough reflectivity to be distinguishable from the intervening valleys.

Method of making and pretesting a digital recording medium

A digital recording medium formed of a thermoplastic substrate having a regular array of microscopic optically-alterable mirrors each supported by a mesa projecting from one surface of the substrate. The parallel rows of the mirrors are the same distance apart as the mirrors in each row. The medium can be formed from a single transparent thermoplastic substrate with an array of indentations in a first surface. The bottom of each indentation is coated with a reflective material. When viewed from the opposite surface of the substrate, the indentations become mesas. The reflective coating is sputtered onto the first surface thereby coating the first surface and the bottoms of the mesas. The reflective coating is then removed by abrasion from the first surface. Recording is by exposure through a second surface of the substrate to a laser beam that reduces the reflectivity of selected mirrors. After exposure to the recording laser beam, the mirrors retain enough reflectivity to be distinguishable from the intervening valleys. The mirrors serve as timing and tracking markers prior to and during recording, and during read-out. The area and location of each information bit is determined prior to recording: not as a result of the recording process.

Method of making a digital recording medium

A digital recording medium formed of a thermoplastic substrate having an array of parallel rows of equally-spaced microscopic optically-alterable mirrors each supported by a mesa projecting from one surface. A layer of transparent plastic over the mirrors provides dust protection. The medium can be formed also from a single transparent thermoplastic substrate with an array of indentations in a first surface. The bottom of each indentation is coated with a reflective material. When viewed from the opposite surface of the substrate, the indentations become mesas. The micromirrors are formed of a composite of gold and silicon dioxide. Recording is by exposure to a laser beam that reduces the reflectivity of selected mirrors. After exposure to the recording laser beam, the mirrors retain enough reflectivity to be distinguishable from the intervening valleys. The mirrors serve as timing and tracking markers prior to and during recording, and during read-out. The area and location of each information bit is determined prior to recording: not as a result of the recording process. Scanning may be accomplished by reciprocating movement of the medium.

Medium for recording digital information using an array of equally

A method of recording digital information on a thermoplastic substrate having an array of equally-spaced microscopic optically-alterable mirrors each supported by a mesa projecting from one surface of the substrate. The mirrors may be formed of a composite of gold and SiO.sub.2. Recording is by laser beam that reduces the reflectivity of selected mirrors. Each mirror is capable of recording one or more bits of digital information. After exposure, the mirrors retain enough reflectivity to be distinguishable from the intervening valleys. The mirrors serve as timing and tracking markers prior to and during recording, and during read-out. The area and location of each information bit is determined prior to recording: not as a result of the recording process. The mirrors may be scanned along parallel rows or diagonally across the rows.

Method of recording digital information on an array of equally spaced

A digital recording medium formed of a thermoplastic substrate having a regular array of microscopic optically-alterable mirrors each by a mesa projecting from one surface. The parallel rows of the mirrors are the same distance apart as the mirrors in each row. A layer of transparent plastic over the mirrors provides dust protection. The medium can be formed from a single transparent thermoplastic substrate with an array of indentations in a first surface. The bottom of each indentation is coated with a reflective material. When viewed from the opposite surface of the substrate, the indentations become mesas. Recording is by exposure to a laser beam that reduces the reflectivity of selected mirrors. After exposure to the recording laser beam, the mirrors retain enough reflectivity to be distinguishable from the intervening valleys. The mirrors serve as timing and tracking markers prior to and during recording, and during read-out. The area and location of each information bit is determined prior to recording: not as a result of the recording process. The mirrors are scanned diagonally across the rows that make up the array. Scanning is accomplished by reciprocating movement of the medium.

System for recording digital information using a regular array of

An element for optically recording digitally encoded information which comprises a support carrying an array of discrete regular geometric spaced depressions in a surface, each of said depressions carrying material capable of a transformation in response to a level of radiation adapted to effect said transformation, wherein said transformation is optically detectable.

Optical data storage element

A method for forming a photosensitive element which comprises contacting silver halide in a plurality of spaced depressions in a surface with a mixture of a silver halide solvent and preformed sensitivity centers.

Chemical sensitization of silver halide grains

Surface relief patterns of predetermined configuration are fabricated by a process which involves exposing a photosensitive material at a first position to a laser interference pattern, rotating said material about an axis perpendicular to its surface to a second position, exposing said material at said second position to a laser interference pattern, wherein at least one and preferably both of said exposures is individually below the effective threshold for linear response of said material, the points of intersection of the two fringe patterns being exposed above said threshold as a result of the combined exposures, and developing said material. The method provides a facile technique for the manufacture of surface relief patterns and is particularly useful when the pattern is of submicrometer size and difficult to manufacture by mechanical means.

Method for producing a surface relief pattern

A photosensitive silver halide element comprising a support carrying single effective silver halide grains in a predetermined spaced array is prepared by coalescing fine-grain silver halide in a plurality of spaced depressions in a surface by melting said fine-grain silver halide.

Method of preparing a photosensitive silver halide element

A method for forming a photosensitive element comprising a plurality of single effective siler halide grains in a predetermined spaced array which comprises coalescing fine-grain silver halide in a plurality of predetermined spaced depressions in a surface, thereby forming in situ a single effective silver halide grain in each of said depressions and a photosensitive element comprising coalesced single effective silver halide grains in a predetermined spaced array.

Photosensitive silver halide element and method of preparing same

A photosensitive silver halide element comprising a support carrying photosensitive silver halide grains in a predetermined spaced array is prepared by a method which comprises at least partially coalescing fine-grain silver halide in a plurality of spaced depressions in a hydrophobic layer, superposing said layer with a hydrophilic layer during or subsequent to said coalescence, and then separating said hydrophilic layer and said hydrophobic layer whereby said coalesced silver halide grains are retained on said hydrophilic layer in a pattern corresponding substantially to the pattern of said spaced depressions.

Method for forming a photosensitive silver halide element

Narrow grain size distribution silver halide emulsions are prepared by: 1. Forming photosensitive silver halide grains in the presence of a water-soluble thiocyanate compound with a halide/silver molar ratio ranging from not more than about 5% molar excess of halide to not more than about a 25% molar excess of silver; and 2. Growing said grains in the presence of said water-soluble thiocyanate compound for a time sufficient to grow said grains to a predetermined grain size distribution.

Method for preparing photosensitive silver halide emulsions

The present invention is directed to a method for forming the crystals of a photographic silver halide emulsion which comprises crystallizing silver halide grains from a solution of a water-soluble complex of silver halide complexed with excess halide ions. The crystals may be sensitized before the binder is added.

Method of making silver halide emulsions

An electrolytic cell for generating silver ions and halide ions for the formation of photosensitive silver halide grains wherein the cathode comprises elemental halogen and electrically conductive carbon.

Growing community of inventors

Boston, MA, United States of America

Arthur M Gerber