Thomson Licensing

Deutsche Thomson-brandt Gmbh

Thomson Licensing S.a.

Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Hartmut Richter

Joachim Knittel

Christoph Dietrich

Stephan Knappmann

Dietmar Uhde

Holger Hofmann

Lieu Kim Dang

Christof Ballweg

Heinz-J&ouml;rg Schroeder

Heiko Trautner

Gael Pilard

Werner Brockherde

Christian Büchler

Alan Bruce Hamersley

Hans-Robert Kuhn

Ingo Hehemann

Stefan Kimmelmann

Heinz-Joerg Schroeder

Lieu-Kim Dang

Dietmar Braeuer

Xavier Lebegue

Armin Kemna

Sören Dambach

Alois Kern

Emmanuel Daugeras

Atols Kern

Stefan Kimmmelmann

A device for producing a security mark on an optical data carrier includes directing means for directing a first and a second light beam onto a hologram area of the optical data carrier, wherein the first and second light beams are coherent light beams. The directing means are adapted to direct the first light beam onto the hologram area along a first direction, and the second light beam onto the hologram area along a second direction. Tilting means are provided for tilting the second direction by a predefined tilt angle with respect to the first direction.

Method for producing a security mark on an optical data carrier

The invention relates to a method for storing data in a prerecorded area of an optical recording medium, and to an optical recording medium having at least one prerecorded area in which data is stored according to the method. It is an object to propose a method for storing data in a prerecorded area of an optical recording medium using pits and lands, whereby the signal obtained from the pits and lands is compatible with a high frequency modulated groove signal. According to the invention, the pits and lands adjacent to bit cell signal transitions are arranged in a predefined manner, either in a fixed recurring sequence of pits and lands or symmetrically to the bit cell signal transitions.

Method for storing data on an optical recording medium

The present invention relates to a holographic recording medium adapted to store additional information for the recorded holograms, and to a holographic pickup for a holographic storage system for use with the holographic recording medium. According to the invention, the holographic recording medium has a holographic layer for storing holograms and a servo layer for positioning a light beam for reading and/or recording of a hologram relative to the holographic recording medium, wherein the servo layer is recordable or rewritable. A holographic pickup for use with such a holographic recording medium includes a light source for recording additional data in the servo layer of the holographic recording medium.

Holographic recording medium having a track pitch smaller than a distance between adjacent holograms

The optical recording medium has a recording layer sensitive for recording at a first wavelength and sensitive for reading at a second wavelength, the recording layer having a groove structure, wherein at the first wavelength the groove structure has a diffraction efficiency into a first diffraction order sufficiently large to generate a push-pull signal, and at the second wavelength it has a diffraction efficiency into a first diffraction order close to zero. The optical pickup for recording on an optical recording medium intended to be read with a second wavelength and a second numerical aperture is characterized in that it has a light source for generating a light beam at a first wavelength and a numerical aperture given by the second numerical aperture multiplied with a ration of the first wavelength and the second wavelength.

Compatible optical recording medium

An apparatus for recording angular multiplexed pits on optical recording media using a device for generating a light beam with an asymmetric intensity distribution is described. The device for generating a light beam with an asymmetric intensity distribution has at least one light influencing part for introducing a phase shift of 180&#xb0; in a first half of the light beam relative to the second half of the light beam, wherein the border between the first half of the light beam and the second half of the light beam is rotatable around an optical axis of the light beam.

Apparatus for recording angular multiplexed pits

A method for controlling the quality of storage media, and more specifically a method for determining if the quality of a storage medium decreases. The method includes: determining one or more quality parameters of the storage medium; and comparing one or more of the determined quality parameters with previously determined quality parameters of the storage medium stored in a memory in case the quality of the storage medium has been determined before.

Method for controlling the quality of storage media

A holographic recording medium with an improved servo structure is presented. The holographic recording medium has a hologram layer for storing holograms and a servo layer for positioning a light beam for reading and/or recording of a hologram relative to the holographic recording medium. The servo layer is an essentially flat dye recording layer. A holographic pickup for use with such a holographic recording medium includes a light source for generating a light beam, which interacts with the dye recording layer for recording servo information.

Holographic recording medium and pickup for this medium

The invention relates to a compact optical pickup for a micro optical drive, and to a micro optical drive using this compact optical pickup. According to the invention a pickup for optical recording media includes a light source for generating a light beam for reading from and/or writing to an optical recording medium, a flexible arm serving as a focus actuator, an objective lens situated on the flexible arm for focusing the light beam onto the optical recording medium, an optical bench for directing the light beam towards the optical recording medium one or more detectors for detecting the light beam reflected by the optical recording medium, and a mirror, which is arranged inclined with respect to a transparent block of the optical bench, for directing the light beam reflected by the optical recording medium towards a first detector.

Compact pickup for micro optical drive

The present invention relates to an appliance for reading from and/or writing to optical recording mediahaving a first laser diode LDfor producing a first scanning beam ASat a first wavelength &#x3bb;and having a second laser diode LDfor producing a second scanning beam ASat a second wavelength &#x3bb;, with the scanning beams AS, ASrunning along a common optical axis, scanning an information layeron the recording mediumand falling on a single photodetectorin order to produce an information signal IS, with a beam combination element being arranged at one point on the optical axis. According to the invention, the beam combination element is a diffraction grating

Device for reading and/or writing optical recording media

The invention relates to an optical pickup for an optical recording medium, an electrically controlled diffraction grating suitable for use in such a pickup, and to an apparatus for reading from and/or writing to optical recording media using such an optical pickup or diffraction grating. According to the invention, an optical pickup for optical recording media having two or more data tracks, with a light source for emitting a light beam for reading from and/or writing to an optical recording medium, includes an electrically controlled diffraction grating, which is switchable between at least two states for generating one or more light beams from the light beam emitted by the light source for reading from and/or writing to one or more of the data tracks.

Optical pickup

The present invention relates to an optical recording medium having at least two information carrier layers, on which information can be written by means of a focused light beam. In this case, a separating layer is arranged between the information carrier layers and a respective transparent covering layer is arranged between the information carrier layer and the surface of the recording medium, the thickness of which covering layer substantially exceeds that of the information carrier layer. One object of the present invention is to propose an optical recording medium in the case of which it is possible to write to both information carrier layers using a low optical power. Further objects of the invention are to specify an apparatus and also a suitable method for writing to a recording medium of this type. A recording medium according to the invention has information carrier layers which are both semi-transparent.

Optical recording medium having at least two recordable layers

The present invention relates to a holographic disk medium () with servo marks (), and more specifically to a holographic disk medium () having a common reflective layer () for reflecting a servo beam () and object and reference beams (). According to the invention, a holographic disk medium () with a recording layer () for recording holograms () and a reflective layer () for reflecting a servo beam () and object and reference beams (), includes servo marks () which are located in the reflective layer () at least partly below the holograms (), wherein the servo marks () are designed such that their influence on the object and reference beams () is minimized.

Holographic disk medium with servo marks

When an optical recording medium having a plurality of data layers is being read from and/or written to, the input beam experiences an aberration, inter alia in the top layers of the data layers. In order, nevertheless, to achieve a high data density, a device for correcting the spherical aberration is located in the beam path of the input beam. In the case of the use of an optical diode in which the input beam and the reflected beam have directions of polarization perpendicular to one another, such a device is expensive to implement and associated with a reduced optical efficiency. It is an object of the invention to propose an apparatus for reading from and/or writing to optical recording media, in the case of which a high optical efficiency and balancing of the spherical aberration are achieved with low outlay. For this purpose, the device for correcting the spherical aberration is set up such that the reflected beam traverses it uninfluenced, whereby means for correcting the imaging of the reflected beam onto at least one detector unit are provided in the further beam path.

Apparatus for reading from and/or writing to optical recording media

The invention refers to a device and a method for scanning an optical data carrier by means of a main scanning beam being reflected by the data carrier and being detected by means of a photodetector, the data carrier having first and second layers to be scanned, the second layer being scanned through the first layer, light passing the first layer being shaded dependent on local properties of the first layer. An object of the invention is to propose a device having increased performance even for use with multi layer disks having a layer causing light fluctuations on a layer to be scanned, as well as a respective method. According to the invention such device is provided with means for keeping an output signal of the photodetector independent of variations of shading.

Device and method for reading multilayer optical disk with compensation of shading effects

An optical recording medium having at least two information carrier layers, on which information can be written by means of a focused light beam. In the present invention, a separating layer is arranged between the information carrier layers and a respective transparent covering layer is arranged between the information carrier layer and the surface of the recording medium, the thickness of each transparent covering layer substantially exceeds that of the respective information carrier layer. One object of the present invention is to propose an optical recording medium in the which it is possible to write to both information carrier layers using a low optical power. Further objects of the invention are to specify an apparatus and also a suitable method for writing to recording medium according to the present invention. A recording medium according to the invention has information carrier layers which are both semi-transparent.

Growing community of inventors

Villingen-Schwenningen, Germany

Hartmut Richter