Abstract: To increase the information density of a satisfactorily readable information structure of a record carrier (2), the rearside (4) of the record carrier can be provided with means (82,84;86) for reflecting read beam radiation at an acute angle with respect to the chief ray of the incident read beam (20). In this way sub-beams b(0), b(+1), b(?1) diffracted by the information structure in different orders can be shifted with respect to the pupil of an objective lens (18) without introducing aberrations into the read spot (21). Said means may have a sawtooth or triangular shape (82,84) or be formed by a regular diffraction grating (86).

Abstract: A bar-shaped grating beam-splitter 10 is used for the generation of focus error, tracking error, forward sense and high frequency signal. The beam-splitter is made in bars (40) and is secured to wafer consisting of a plurality of detector chips (14). Securing the bar in position is preferable to securing separate grating beam-splitters individually. Individual light detector grating units are then separated from the wafer.

Abstract: The invention relates to an information carrier containing a non-clonable optical identifier (2) having an optical scattering medium (3) for being challenged by a light beam (5) and for scattering said light beam (5). In order to provide a secure information carrier (1), it is proposed that it further comprises a light absorbing means (3, 4) for reducing the intensity of said light beam (5) so that an integration time for obtaining a response signal by integrating the scattered light beam (8) is extended.

Abstract: A pivoting optical readout device is described in which two folding mirrors (121, 122) are used in an optical path (21) between an optical information carrier and a photodetector unit (112), for rotating a beam of light reflected from the information carrier by 90° such that a push-pull error-tracking signal can be generated.

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: In a zoom lens (30) comprising, from the object side to the image side, a front lens group (12) and a controllable lens group (24), the controllable lens group comprises two lens elements (25, 26) having different dispersions and being movable with respect to each other so as to perform a focusing action. One of the lens elements corrects for the dispersion of the zoom lens. Preferably, the zoom lens comprises at least one folding mirror.

Abstract: A zoom lens comprising, from the object side to the image side, a front lens group (72), a controllable lens group, and a rear lens group (74), the controllable lens group comprising a voltage-controlled electrowetting device, which device contains a first fluid (A) and a second fluid (B) having different refractive indices, with at least two first fluid-second fluid interfaces (40,42). The curvatures, and thus the lens power, of these interfaces can be changed independently by supplying a voltage (V1, V2) to electrodes (22,32) of the device, so that no mechanical movement of lens elements is needed.

Abstract: The invention relates to a scanning apparatus for scanning information in an information carrier (16) comprising a plurality of layers for storing data on a material capable of generating an excited radiation when interacting with an exciting beam (13) produced by an exciting source (11). The scanning apparatus comprises an objective lens (15) for projecting the exciting beam in a layer of the carrier and collecting the excited radiation. The scanning apparatus also comprises a detector unit (19) for detecting the excited radiation collected on the objective lens. According to the invention, the exciting beam has a numerical aperture lower than the lens numerical aperture.

Abstract: Driving apparatus, comprising at least two driving members (1, 2, 3, 4) and at least one driven member (5), wherein each of the at least two driving members are frictionally engaged to the at least one driven member (5) to move said driven member (5), wherein the friction between each driven member (5) and each driving member (1, 2, 3, 4) is such that the driven member moves when over half of the driving members (1, 2, 3, 4) being in frictional engagement with said driven member are moved simultaneously between a first and a second position, wherein the friction between each driven member (5) and each driving member (1, 2, 3, 4) is such that the driven member (5) substantially remains stationary when less than half of the driving members (1, 2, 3, 4) being in frictional engagement with said driven member is moved.

Abstract: An optical scanning device for scanning an information layer of an optical record carrier and including a rotary aim (2; 102; 202; 302; 402; 502) which is arranged to swing about a rotation axis (CR) to alter an angular position of the rotary arm about the rotation axis; a detector arrangement (10) arranged separate from the rotary arm (2; 102; 202; 302; 402; 502) for detecting a radiation beam spot, the radiation beam spot (40; 140; 240; 340; 440; 540) having an angular disposition; a first reflective surface (4; 104; 204; 304; 404; 504) attached to the rotary arm (2; 102; 202; 302; 402; 502); a second reflective surface (6; 106; 206; 306; 406; 506) attached to the rotary arm (2; 102; 302; 402; 502); a first light path (LP 1; LP 1 O 1; LP201; LP301; LP401; LP501) running from a location on the record carrier to said first reflective surface; a second light path (LP2; LP102; LP202; LP302; LP402; LP502) running from said first reflective surface to said second reflective surface; a third light path (LP3; LP103