Abstract: A lithographic apparatus including an illumination system configured to condition a radiation beam is described. The illumination system includes radiation beam uniformity adjuster for adjusting the uniformity of the radiation beam using segments that are at least partly arranged in the radiation beam and that are mounted on a frame by a torsion bar. The device further includes an actuator configured to rotate the segment in order to change the amount of radiation of the radiation beam that is blocked. The device also includes a first magnetic member mounted on the torsion bar configured to co-operate with a second magnetic member mounted on the frame for generating a position dependent torque about the longitudinal axis that is configured to at least partly compensate a torque exerted on the segment by the torsion bar.

Abstract: An optical attenuator device operates to remove a part of a beam of radiation having a higher than average intensity using at least one optical attenuator element. The device has application in a radiation system, and/or a lithographic apparatus, in particular a scanning lithographic apparatus, wherein the optical attenuator element(s) are provided in a central part of the beam, for example perpendicularly to a scanning direction.

Abstract: A rotatable magnetic-head unit comprises a cylindrical drum with at least one magnetic head for recording and/or reproducing signals on/from a magnetic tape. This magnetic tape is wrapped around a part of the circumference of the drum and is moved past that part of the drum circumference. in order to obtain a stable bearing arrangement for the magnetic-head unit the magnetic head is fixedly connected to the drum, whose wall is supported by means of spiral-groove bearings in the direct proximity of the magnetic heads in a stationary cylindrical housing. The drum can rotate inside the housing. The housing is formed with an opening in which the magnetic tape moves.

Abstract: A free-piston Stirling machine has a piston which can reciprocate and also rotate within a cylinder and which is supported and centered in the cylinder by a grooved dynamic bearing, the piston having two end faces which are acted upon during operation by different fluid pressures. The piston includes at least one sealing part having a circular-cylindrical smooth sealing surfaces and at least one bearing part which is provided in its peripheral surface with a groove pattern. The length of the sealing surface and the size of the gap between the sealing surface and the cylinder wall are selected such that the pressure difference across the bearing surface is reduced so that the piston remains free of radial dynamic instability during operation.

Abstract: A rotary-anode X-ray tube, comprising a rotary anode which is journalled in a vacuum-tight housing by means of at least one sleeve bearing whose mutually co-operating bearing surfaces are made of W or Mo or of an alloy of W and Mo. The bearing is lubricated by Ga or a Ga alloy having a melting point below 25.degree. C. The Ga or Ga alloy lubricant is in molecular wetting contact with the bearing surfaces so that the bearing surfaces are completely separated from each other in the loaded condition. During standstill, as well as during rotation, the lubricant is not forced out of the bearing, so that the bearing surfaces cannot become fused. The wear and the bearing noise are therefore extremely low. The desired, thorough wetting is obtained by making the bearing surfaces, as well as the Ga alloy, oxide-free before they are brought into contact with each other.