Abstract: A device for reading from or writing to optical recording media comprising a scanning beam generation means, a focusing means and a photodetector comprising at least two detector zones and serving to receive zeroth- and first-order diffraction beams from the recording medium. The object of the invention is to obtain a reduction in interfering influences in a signal derived from signals of the photodetector, a signal such as, for example, a focus error signal or a track error signal. This object is achieved by virtue of the fact that a beam splitting means is provided, which splits a light spot falling onto the photodetector into two separate partial spots. The device is, for example, a CD or DVD player, but in particular a recording and reproduction device for so-called DVD-RAMs or similar optical recording media.

Abstract: The present invention relates to a device for reading from or writing to optical recording media, which device has a scanning beam generation means, a focusing means and a photodetector comprising at least two detector zones and serving to receive zeroth- and first-order diffraction beams from the recording medium.

Abstract: A dual wavelength optical pickup head in which as many same parts as possible are used as well to direct light beams incident than light beams reflected from a reflective layer of an optical disk. The reuse of as many parts as possible allows to and a second wavelength emitted by a first and a second light source to an optical disk, a dual focus lens objective for focusing said light beams on a layer of said optical disk and a single detector which allows to detect light beams of either said first or said second wavelength.

Abstract: A device for reading from and/or writing to optical recording media, including a beam generator, a focus device, which focuses the beam generated onto the optical recording medium at a focal point, a displacement device, which displaces the position of the focal point on the recording medium in accordance with a first direction of movement in dependence on an actuating signal, and a detector, which detects a beam reflected from the optical recording medium and outputs a regulating signal to a regulator. The regulator generates an actuating signal for the displacement device. The invention allows a higher data transfer rate to be achieved with an acceptable outlay. This is achieved by a beam influencing device arranged in the beam path and, in dependence on a further actuating signal of the regulator, influences the position of the focal point on the recording medium in accordance with the first direction of movement.

Abstract: The present invention to provides for information carriers of different storage densities, a recording and/or playback device which is compatible or can be used for different optical information carriers despite a functional relationship which to be satisfied between the size of the information memory location or pit size and the size of the light spot, without changing the wavelength of the laser used or changing the numerical aperture of the objective lens. In order to operate optical information carriers of different storage densities, use is made of an optical system which has a wavelength and numerical aperture matched to the highest storage density, provides a plurality of secondary beams matched to the respective track width, and has a number of secondary beam detector pairs which corresponds to the number of different information carriers.

Abstract: A device for reading from or writing to an optical recording medium is disclosed which has at least two information carrier layers spaced apart from one another, as well as a light source, an optical unit and a detection unit. The device permits a plurality of information carrier layers to be read from and/or written to simultaneously using light of a single wavelength. A partial beam generating element emits two polarized beams which differ in terms of polarization direction and propagation behaviour.

Abstract: A process and arrangement for tracking and eliminating disturbances which occur in particular while scanning optical information carriers. The invention avoids the inconvenience of disturbance elimination using time-delayed auxiliary beam signals by influencing the auxiliary beams of a scanner working according to a three-beam principle in such a way that they hit the information carrier to be scanned as two auxiliary beams which lie next to each other on the track radius, so that disturbances due to subtraction between the auxiliary light spot signals formed by the auxiliary light spots are eliminated. A birefringent crystal is preferably used in order to direct the auxiliary beams in this manner. The invention is preferably suitable for optical information carrier scanning devices.

Abstract: Alkyl-(3-chlorophenyl)-sulphones are particularly advantageously obtained by chlorination of alkylphenylsulphones if alkylphenylsulphones are chlorinated in molten form with elemental chlorine in the presence of iron(III) chloride and optionally iodine and/or sulphur.

Abstract: Apparatus for cooling at least two bars travelling in parallel linear paths after having been formed from a larger bar in a rolling mill, comprises a common antechamber for receiving the bars, a cooling water inlet and a cooling water outlet communicating with the antechamber, first and second common nozzle chambers, the first nozzle chamber being arranged for receiving the bars from the antechamber and the second nozzle chamber being arranged for receiving the bars from the first nozzle chamber, each of the nozzle chambers being provided with a respective cooling water inlet communicating with the respective nozzle chamber through a respective equalizing chamber, each of the nozzle chambers containing for each of the bars a respective funnel for guiding the bar and a nozzle for receiving the bar from the funnel, the nozzle having passages for conducting water from the chamber into contact with the bar, communicating with each of the nozzles a respective heat exchanger pipe for receiving a respective one of t