Abstract: A scanning microscope comprises a system (2, 3, 4) for concentrating a radiation beam from a radiation source (1) to form a scanning spot on an object (5). The radiation from the scanning spot is projected by a second optical system (6, 7) onto a radiation-sensitive detection system comprising two detectors (8, 9). The signals from the detectors (8, 9) are combined into a difference signal 11 and a sum signal 13. These two signals are formed into a complex composite signal which is transferred to the frequency domain in a circuit 22 via a Fourier transform. By performing suitable filtrations on the composite signal in the frequency domain in the circuit 23, quantitative measurements can be performed on the amplitude and phase structure of the object 5. These measurements may be visualized after an inverse Fourier transform in the circuit 24 via an image-processing system 25 on an image display unit 26.

Abstract: Scanning apparatus for a magneto-optical record carrier includes an integrated beam separating and beam splitting element consisting of a supporting body (30) on the surfaces of which are a semi-transparent mirror (22) and a polarization-sensitive beam-splitting layer (26). The semi-transparent mirror separates the scanning beam from the beam reflected from the record carrier. The beam-splitting layer splits the reflected beam into orthogonally polarized sub-beams (27 and 28) which are incident on respective photodiodes or on different regions of a single multiple photodiode. The supporting body may be of a birefringent material which provides orthogonally polarized beam-splitting, in which case the beam splitting layer may be omitted.

Abstract: A zoom lens is described for an electronic camera for still pictures, comprising a front group (G.sub.1), a variator group (G.sub.2) and a main group (G.sub.4). The lens is designed in such a manner that the sum of the spherical aberrations of the front group and the variator group is constant throughout the zoom range and is adapted to that of the main group.

Abstract: A beam splitter (120) arranged in the radiation path of the scanning beam splits off a reference beam synchronously moving with the scanning spot (21) to a reference plane (140). The movement of the scanning spot (21) can be checked by measuring, with the aid of a radiation detector (160), the movement of a reference spot (121) formed by the reference beam in the reference plane. In this way an accurate determination of the position of the scanning spot (21) is possible while using simple beam-deflecting elements (40,42) having a relatively low accuracy. A cylindrical lens (131) gives the scanning spot the shape of a line, so that sensitivity to dust and other contaminations on the reference plane is reduced considerably.

Abstract: A scanning device is described which comprises a rotationally symmetrical rotating reflecting facet disc (3) in which a scanning beam (2, 2') is focussed on a face (5, 6) of the facet elements (4). The sensitivity of the device to surface defects or dust particles on the faces of the facet elements can be reduced by means of a first astigmatic element (20) which widens the beam (2') issuing from the detector (10) at the location of the facet disc in a direction transverse to the scanning direction (18), while a second astigmatic element (21) cancels the astigmatism of the first element.

Abstract: For manufacturing monaspherical lenses, a correction layer of a synthetic resin is provided on a substrate having a spherical surface. In this method, centering is performed by using the curvature of the surface of the matrix. With a correct choice of the radius of curvature of the substrate surface, the substrate approaches the matrix most closely near a collection of inflection points in the matrix surface situated on a circle. A good centering without a guiding mechanism is possible by using the method according to the invention. Moreover, the differences in thickness in the correction layer are small enough to prevent shrinkage defects upon curing of the synthetic resin layer.

Abstract: An opto-electronic focussing-error detection system is described for detecting a deviation between a radiation-reflecting surface and a plane of focussing of an objective system in an optical imaging system. The detection system comprises a beam-splitting element and a radiation-sensitive detection system arranged behind the beam-splitting element and two groups of detectors. The first group is associated with a first sub-beam and the second group with a second sub-beam of two sub-beams formed by the beam-splitting element. The beam-splitting element is a compound wedge comprising two wedge sections having a common base surface and each having an upper surface situated opposite the base surface. The upper surfaces are inclined relative to each other in the plane of the interface between the two wedge sections with that plane extending substantially perpendicularly to the base surface and to the upper surfaces and containing the optical axis of the imaging system.

Abstract: A single lens is described for forming of a scanning spot on an information surface of a transparent record-carrier substrate. The lens has one aspherical surface and one spherical or plane surface. The curvatures of the lens surfaces and the thickness of the lens are selected to compensate for aberrations caused by the substrate.

Abstract: For manufacturing monaspherical lenses, a correction layer of a synthetic resin is provided on a substrate having a spherical surface. In this method, centering is performed by using the curvature of the surface of the matrix. With a correct choice of the radius of curvature of the substrate surface, the substrate approaches the matrix most closely near a collection of inflection points in the matrix surface situated on a circle. A good centering without a guiding mechanism is possible by using the method according to the invention. Moreover, the differences in thickness in the correction layer are small enough to prevent shrinkage defects upon curing of the synthetic resin layer.

Abstract: A collimator lens has a small numerical aperture and a specific focal length. One of the surfaces of the lens is planar and the other surface is aspherical. The aspherical surface is defined by a series expansion with only a few even terms.

Abstract: A method of and a device for high-precision moulding of transparent objects is described. Before the object assumes its final shape, a radiation beam is passed through the moulds of a moulding device and the material contained therein, and the intensity distribution of the radiation spot formed by the beam is compared with a reference, thereby enabling the moulds to be aligned very accurately, so that high-quality products can be manufactured.

Abstract: A collimator lens has a small numerical aperture and a specific focal length. One of the surfaces of the lens is planar and the other surface is aspherical. The aspherical surface is defined by a series expansion with only a few even terms.