Abstract: A method and an apparatus for generating a polarized light beam to be projected onto an object plane are provided. A converging or diverging light beam (18) is generated. The converging or diverging light beam is projected through a member (22, 52) comprising an uniaxial birefringent material, the uniaxial birefringent material having a symmetry axis essentially parallel to the optical axis (12) of the light beam, and the member being placed at a distance from the object plane. Thereby, it is possible to create, for example a radially polarized beam that can be used for various optical purposes, e.g. for optical data reading/writing or for microscopy.

Abstract: A signal processing technique is proposed for compensating for radial to focus crosstalk in an optical storage system including an astigmatic lens (25) and four-quadrant photodetector (26) for generating a focus error signal. A signal processor generates the focus error signal (FESRVO), a tracking error signal (TES) and a central aperture signal (CA) and the proposed radial and focus crosstalk scheme can be described by the following equation (I): Where IFESRVO represents the improved focus error signal and y1j and y2j are vector components for scaling. Instead, scalar adaptive scaling factors ?1 and ?2 may be applied which can be updated by minimising a cost function J(y1, y2), which is able to imply the radial to focus crosstalk components remaining in the focus error signal.

Abstract: The present invention relates to a method of reading out information from a multiple layer optical recording medium (10) by an optical readout device (12), the method comprising the steps of: focusing a central light beam (14) and two satellite light beams (16, 18) onto a first recording layer (20) of the optical recording medium, projecting reflection beams (22, 24) of at least part of the satellite light beams on two split detectors (26, 28), thereby creating satellite spots (116, 118), each split detector being associated with one of the satellite light beams, the reflected light interfering with light reflected by a second recording layer (21), and processing the signals from the split detectors for providing a tracking error signal, wherein the influence of a central part (29) of the reflection beams on the tracking error signal is removed and/or modified, thereby reducing a negative influence of this central part on the quality of the tracking error signal.

Abstract: A method and device for measuring the tilt in an optical disc drive (1) is disclosed. The optical disc drive (1) comprises two lasers (31, 41) generating two laser beams (32, 42) having mutually different optical characteristics. One of these laser beams (32) is continuously ON, and is used for writing or reading data to or form the disc. The other laser beam (42) is repeatedly switched ON and OFF. Tilt is measured by comparing a normalized error signal (RES(ON)) during the ON-phase (TON) with a normalized error signal (RES(OFF)) during the OFF-phase.

Abstract: The invention relates to a device (1) for detection of excitation (110) using a multiple spot arrangement (60), in which a multiple spot generator (50) is matched to the multiple spot arrangement (60) in such a way that light (100) entering the multiple spot generator (50) will be guided to defined areas on the multiple spot arrangement (60).

Abstract: The invention relates to an optical system comprising a fluid chamber 1 and a birefringent part. The fluid chamber comprises first and second fluids 10, 12 having different indices of refraction, the interface between the fluids forming a meniscus 14. The birefringent part is capable of varying characteristics of a first radiation beam 3b and a second radiation beam 3c, the first and second radiation beams having different polarisations. Variation in the configuration of the meniscus causes variation in the characteristics of the first radiation beam and the second radiation beam. Variation in the configuration of the meniscus may be controlled by electrowetting.

Abstract: The invention relates to a holographic data storage medium (4) in which there are sections (20) which are used for data storage and sections (21) which are not. A diffractive structure (30a, 30b) is provided in respect of one or more of the unused sections (21), possibly at each of the boundaries between the used (20) and unused sections (21) or within the volume of a respective unused section (21) of the data storage volume. During read-out, a reference wave (6) is diffracted by the diffractive structure (30b) such that it enters a used section (20) (from the right) in a direction substantially perpendicular to the optical axis (16) of the signal wave (26). During recording, a reference wave (2) is diffracted by the diffractive structure (30a) such that it enters the used section (20) (from the left) in a direction substantially perpendicular to the optical axes (1b) of the signal wave (1).

Abstract: An optical arrangement of at least a coherent light source (1), a strongly scattering object (5) (the PUF), and a pixe-lated photo-detector (6), wherein the pixels are comparable in size with the bright and dark patches of the speckle pattern produced by coherent radiation traversing the scattering object (5). Quantitively, the pixel size should be roughly ?/NA, where ? is the wave-length, and (i) NA=a/z for free-space geometry, with a being the beam radius and z being the distance between the exit surface of the PUF (5) and the pixelated detector (6), or (ii) NA is the numerical aperture of a lens (7) in an imaging geometry. In a preferred embodiment of the invention, there are tentative requirements that the pixels should be at least smaller than ?max?NA and preferably larger than ?max?/NA, where (in an exemplary embodiment) ?max=5 and ?min=0.05, say.

Abstract: A method and system for cross-talk cancellation in a three-spots push-pull tracking error signal in an optical disc system is disclosed. A tracking error signal (TES) is determined from a plurality of error signals (PPa, PPb, PPC). A noise signal (N) is determined from at least two of the plurality of error signals. The noise signal is filtered in a first filter (406).

Abstract: An optical scanning device for scanning an information layer (2) of an optical record carrier (3). The device includes a radiation source (7) for providing at least a first radiation beam of a first polarization along a first optical path, and a second radiation beam of a second, different polarization along a second, different optical path. An objective lens system, having an optical axis (19a), is arranged to converge the radiation beams on the information layer A beam-deflecting element (30) comprising a birefringent material is orientated such that each of said polarized radiation beams experiences a different index of refraction upon passing through the birefringent material, and is arranged to refract at least the first radiation beam towards the optical axis.

Abstract: An optical scanning device (1) for scanning an information layer (2) of an optical record carrier (3). The device includes a radiation source (7) for providing at least a first radiation beam along a first optical path, and a second radiation beam along a second, different optical path. An objective lens system (8) converges the radiation beams on the information layer A beam-deflecting element (30) is arranged to refract said second radiation beam towards the optical axis of the lens system. The beam-deflecting element includes at least one fluid (A). A controller is provided to vary the configuration of the fluid to control the amount of refraction provided by the beam deflector element over a predetermined range.

Abstract: In an optical scanning device (10) capable of scanning an information plane of an optical record carrier (5) of different types such as BD, DVD and CD, the diameter of the radiation spot on the detector (7) is dependent on the numerical aperture of the objective system (4) that is used for scanning the record carrier An optimal design of the optical detection system for scanning a BD, result in a small radiation spot for the other types such as DVD and CD.

Abstract: An optical scanning device (1) for scanning at least one information layer (2) of at least one optical record carrier (3). The device includes a radiation source (7) for providing at least a first radiation beam (4) comprising a first wavelength, an objective lens system (8) for converging the first radiation beam on a respective information layer (2), an information detector (23) for detecting at least a portion of the first radiation beam (22) reflected from the respective information layer, for determining information on said layer, and a spherical aberration detection system.

Abstract: An optical scanning device for scanning different formats of optical record carrier. The device includes a first radiation source (16), a second radiation source (70) and a third radiation source (72) arranged to emit radiation beams having a predetermined first, second and third, different, wavelength. The device further includes a redirector (15) for redirecting the second and third radiation beams. The redirector (15) includes a diffraction structure arranged to redirect the second radiation beam from the second input optical path (48) along the second output optical path (50) and to redirect the third radiation beam from the third input optical path along the third output optical path, so as to improve the colinearity of the second and third output optical paths with respect to a first output optical path of the redirector.

Abstract: An optical scanning device (1) includes a radiation source (7), a detector (23) and a beam splitter (9). The radiation source (7) provides an incident radiation beam (4, 20) along a first optical path (19a) for scanning an information layer (2) of an optical record carrier (3). The detector (23) detects at least a portion of the radiation beam (22) reflected from the optical record carrier (3). The beam splitter (9) transmits the incident radiation beam (4) received from the radiation source along the first optical path (19a) towards the optical record carrier. The beam splitter (9) also transmits the reflected beam (22) received from the optical record carrier (3) along a second, different optical path (19b) towards the detector. The optical scanning device further includes a beam-deflecting element (30; 130; 230; 330; 630; 830; 930) positioned on the second optical path (19b) between the beam splitter (9) and the detector (23).

Abstract: Optical pick-up apparatus for retrieving data stored on an optical storage disc having a plurality of record layers (6, 7), the radiation beam reflected back from the disc when a first layer (7) is irradiated comprising radiation reflected back from the first layer (7) and radiation reflected back from one or more of the other layers(6). A spatial filter (8) is provided which is arranged and configured to spatially filter the radiation beam so as to cause the radiation reflected by the first record layer (7) and the radiation reflected by any of the other record layers (6) of the optical storage disc to be spatially separated, such that at least a substantial portion of the radiation reflected back from the other layers (6) can be selectively eliminated from the radiation beam prior to retrieval therefrom of the data.

Abstract: This invention relates to the use 100 of a challenge-response pair 104, 108 for calibrating a device 101 for authenticating 200 a physical token (102) 102.

Abstract: Tracking system for guiding an optical beam on tracks on an optical disc, said tracking system comprising a photodetector (A1, A2) for detecting optical beams derived from said optical beam, said photodetector generating a first output signal (A) and a second output signal (B), said tracking system comprising first processing means for generating a first differential signal (PP(DC)) corresponding to the low-frequency part of a difference between said first and second output signals. The tracking system comprises second processing means for generating a tracking error signal (PP(AC/DC)) defined by the addition of said first differential signal (PP(DC)) to a second differential signal (PP?(AC)), said second differential signal corresponding to a fraction of the difference in amplitude of the high-frequency components of said first and second output signals. Use: Optical disc player/writer.

Abstract: An optical scanning device for scanning a first optical record carrier, a second, different, optical record carrier and a third, different, optical record carrier, each record carrier having an information layer. The scanning device includes a radiation source system arranged to produce first, second and third radiation beams for scanning the first, second and third record carriers with first, second and third wavelengths, respectively; and a diffraction structure (34) arranged to introduce a first, second and third wavefront modification into the first, second and third radiation beams, respectively.

Abstract: A method and an apparatus for scanning data stored along a track (16) on an optical storage medium (10) are provided. A light beam (12) is projected on the optical storage medium, thereby creating a scanning spot (14) that essentially follows the track (10). The relative position of the scanning spot (14) and the track (16) are varied in a radial direction. The variation of this positions occurs at a frequency v of v =?. S.4- NA/?, wherein NA is the numerical aperture of the light beam (12), X is the C wavelength of the light, S is the scanning speed, and ??0.01. The scanning spot is generated by a wavelength change is translated into a displacement of the beam by a pair of gratings.