Abstract: In an optical scanning device suited for scanning two types of record carriers having a different thickness of their transparent layers and wherein an astigmatic element is used in combination with a quadrant detector for generating a focus error signal (Sf), this signal, which is generated when one type of record carrier is scanned, can considerably be improved by arranging an aspheric surface profile in only the central part of the beam coming from said one type of record carrier.

Abstract: In a device for scanning an optical record carrier having two or more information layers, in which a diffraction element with two gratings is used in combination with a composite detection system for generating a focus error signal, a focus offset due to radiation coming from another information layer is prevented during scanning an information layer by providing the diffraction element with a special transition area in which, in principle, equal parts of the first and the second grating are present. Device for scanning an optical record carrier having at least two information layers.

Abstract: A polarization-sensitive beam splitter comprising at least one transparent wedge-shaped element of a birefringent material is made by providing each one of two substrate plates with an orientation layer, whereafter the substrate plates are arranged with their orientation layers facing each other while forming a wedge-shaped interspace. The interspace is filled with a liquid crystalline monomer composition, which is subsequently cured while forming a wedge-shaped element of a uniaxially oriented polymer material. After possible removal of the substrate plates, two or three of such wedge-shaped elements can be joined to a Wollaston prism for use in the pick-up element of a magneto-optical recording system.

Abstract: A head-mounted display includes an image display system which is common for two separate light channels. The head-mounted display further includes an optical system for projecting an image in a left and a right exit pupil of the head-mounted display. Each light channel is provided with imaging optics. The imaging optics of such a light channel have a hollow mirror and a semitransparent mirror or a hollow mirror, a semitransparent mirror and a folding mirror.

Abstract: An optical beam shaper (10) for converting a radiation beam (5, 6, 7, 8) having an elliptical cross-section into a beam (9) having a more circular cross-section is described. This element (10) has a cylindrical entrance surface (12) and a toroidal exit surface (14) and can be arranged close to a diode laser (1) so that the risk of wavefront deviations due to defocusing is reduced. The element has a high coupling efficiency. The beam shaper is also provided with a grating for forming a sub-beam from the radiation beam.

Abstract: The present invention relates to a head-mounted display comprising at least one image display panel and an optical system for projecting an image in a left and right exit pupil of the head-mounted display. The optical system comprises a beam splitter, a hollow mirror and a first and a second light channel each comprising a folding mirror and magnifying optics. The magnifying optics comprise a lens element. An additional lens, one surface of which is provided with a diffractive structure, is arranged between the image display panel and the hollow mirror.

Abstract: The present invention relates to an image display device (1) comprising a two-dimensional display (3; 19, 21; 72) and an optical system (5; 15, 17; 60). The optical system comprises a lens having a first semitransparent reflecting surface (23, 25; 9) and a second semitransparent reflecting surface (27, 29; 11). The first surface is directed towards the display. The second surface is directed towards the viewer. Both the display and the lens are divided into a plurality of segments in order to increase the field of view.

Abstract: A polarizing beam splitter for splitting a non-collimated light beam of a given wave length into two sub-beams, each of a different state of polarization, has a substrate provided with a polarizing stack of thin layers and a compensating means for compensating retardation of the light beam occurred in passing through the polarizing stack.

Abstract: A position detection system (80) is described for detecting movements of an object (20) in at least five degrees of freedom, which system comprises a radiation source (33), a beam splitter (36) for forming a first measuring sub-beam (45) and a second measuring sub-beam (50), a reflector (38) arranged in the path of one of these measuring beams (45, 50) and a composite radiation-sensitive detection system (60). The first measuring sub-beam (45) is used for detecting displacements along three mutually perpendicular axes (X, Y, Z), and the second measuring sub-beam (50) is used for detecting rotations about at least two of these axes.

Abstract: An optical transmissive component (1) is described, which component has an entrance surface (4) and an exit surface (5) for optical radiation (20), in which one of the surfaces (4; 5) is provided with an anti-reflection grating (10; 15). By providing a second surface, (5; 4) with a second anti-reflection grating and by ensuring that the grating strips (11) of the first grating (10) extend essentially perpendicularly to those (16) of the second grating (15) in corresponding areas of the first and the second surface (4; 5), it is prevented that the component is birefringent.

Abstract: A one-piece element for splitting part of the radiation of an incident beam, to form a sub-beam having a different direction. The element includes a mirror for reflecting the sub-beam at an increased angle with respect to the direction of the incident beam. The element is preferably a homogeneous molding, with an internally reflecting mirror.

Abstract: A device for scanning a surface includes a radiation source, a transparent plate provided with a grating having two grating structures, an objective system for focusing the radiation beam on a surface, and a detection system for converting radiation reflected by the surface into electric signals. The first grating structure in the grating is intended, for example, for forming two side beams from the radiation beam. By providing the second grating structure, a monitor beam is obtained in reflection from the radiation beam. The monitor beam is directed onto a monitor detector which generates an electric signal with which the radiation power of the radiation source is controlled.