Abstract: A magneto-optical recording apparatus provided with a magnetic field modulator (8). The magnetic-field modulator (8) has a field coil (18) for generating a magnetic field and switches (11,12,15,16,22) for coupling at least one terminal (17) of the magnet coil (18) to a first potential point (10) at a first potential (Vp) or a second potential point (14) at a second potential (Vn) depending on the logic value of a control signal (vs), in order to produce in the field coil an alternating current whose polarity depends on the logic value. The field coil (18) is arranged in a parallel resonant circuit (18,21). The switches have means (12,16) for inhibiting, after the terminal (17) has been uncoupled from one of the potential points (10,14), current supply from the other potential point for a time interval corresponding to half the resonant period of the resonant circuit (18,21). This magnetic-field modulator provides a very rapid reversal of the current through the field coil.

Abstract: In an electron microscope correction of spherical and chromatic aberration can be achieved in a number of freely adjustable directions by using a multipole correction element whereby a magnetic or electrostatic octupole field, rotatable about the optical axis, or a combined rotatable magnetic and electrostatic quadrupole field is generated. A corrected overall image can be obtained by combination of images successively corrected in different directions. In the case of holographic images, correction in the direction perpendicular to the line direction in the hologram enhances the accuracy of phase determination. A correction element of this kind, having comparatively small dimensions of from 1 to 2 cm, can be simply mounted, notably in a transmission electron microscope, in a space provided for the stigmator.

Abstract: A device for doubling the frequency of a light wave and having a satisfactory waveguide action is obtained in a simple manner by providing, in a nonlinear optical material 11, periodic domains 12 having a reduced second-order susceptibility and an increased refractive index relative to the nonlinear optical material by means of proton exchange or proton implantation. By means of a heat treatment, the refractive index of the material in the periodic domains is reduced to a value which is less than 0.10 higher than that of the nonlinear optical material, thus obtaining a low degree of light scattering.

Abstract: A transparent substrate has an information layer on an entirely flat side, and a centering member on the other side adapted to cooperate with centering means of an apparatus for inscribing and/or reading the disc. The centering member may be glued in place and have an aperture for engagement by an apparatus spindle.

Abstract: In the manufacture of tube glass, in which following the drawing of a tube from molten glass the inside surface of the tube is treated with a chemically reactive gas or gas mixture, a gas or gas mixture which is not reactive at the drawing temperature of the glass is dispensed into the tube in the direction of drawing. At a location in the tube where the tube has cooled down so far that the diameter is constant, the gas or gas mixture is made to react by means of a plasma which is generated in the tube.

Abstract: A strain gauge element in which the compression forces applied by at least one of the pressure members are transmitted to a first surface of the strain gauge by a cross formed by two cylindrical rods, the contact between the strain gauge (or the said pressure member) and the cross being exerted on a generating line of one of the rods (or the other rod) of the cross, permitting the said pressure member to carry out a tilting movement about the said rod (or the other rod).The reactionary compression forces applied to a second surface of the strain gauge are applied either by at least one cross or by rods.

Abstract: The invention relates to an X-ray diffractometer device, comprising an X-ray source, a collimator device for the source, a sample support, a collimator device for the beam reflected by the sample and a counter producing an output signal in the form of a voltage which is proportional to the number of photons reflected by the sample. This device furthermore includes a motor drive for the sample support, recording means for the signal Y originating from the proportional counter as a function of the angle .theta. between the plane of incidence of the sample and the incident beam, denoted X, mechanical means having a support for a plurality of filters having different coefficients of absorption and including a motor drive for this filter support, data processing means for selecting one of the filters of the filter support and for controlling the motor drive of the sample support, the motor drive of the filter support and the recording means, respectively.

Abstract: The invention relates to an optical plug connector comprising two plugs (1,2) each of which holds an end portion of an optical waveguide (OWG 10) and which can be inserted from opposite sides into a coupling sleeve (7) until the end faces of the OWGs (10) are located against each other, and comprising a guide element (5,9) for guiding and aligning the OWGs (10), which guide element can be axially inserted in both plugs (1,2) and which extends beyond their joint area. Damage to the OWGs caused by an inappropriate attempt to form a plug connection without using a guide element is precluded in that stop elements (17,18) are provided at the plugs, which stop elements cooperate with the stop elements of the mating plug in such a manner that when the guide element (9) is not inserted, the OWG-holding elements (12) of the plugs are prevented from moving completely towards each other in an axial direction.

Abstract: An infrared detector device for at least two wavelengths, i.e. 3 to 5 microns and 8 to 14 microns, comprises detector elements (10 and 20) formed in two or more infrared-sensitive materials with different badgaps, e.g. in cadmium mercury telluride. These materials may be provided side-by-side in a single level on a substrate (3) or preferably as different levels (1 and 2) on the substrate (3). Each detector element (10 and 20) comprises a p-n junction (11 and 21) between opposite conductivity type regions (12,13 and 22,23). Electrical connections (15,25,24) extend from these regions to the substrate (3). Freedom in design and fabrication is obtained by a connection structure in which one connection (25) of the longer-wavelength response element (20) contacts both the semiconductor material (2) of that element (20) and the larger-bandgap material (1) of the shorter-wavelength response element (10), at a side-wall (42) of both materials.

Abstract: In a plasma generator for high-frequency supply of an induction coil containing a plasma of an aerosol with a substance to be analyzed, quarter-wave conductors of a quarter-wave resonant system are incorporated in the apparatus after having been divided and folded, which provides a significant saving in space. Added to the conductors are electric auxiliary circuitry for balancing the resonant system and for matching the frequency to a filled induction coil. The conduction coil is capable of up and down movement in a disturbance-free manner, the coil always being maintained at zero potential.

Abstract: An infrared detector comprises an envelope in which a detector element (3) is mounted on an end of a cold finger (1). A chemically-active getter (30) is present in the space between the cold finger (1) and the envelope window (7) and outer wall (2). In accordance with the present invention the getter comprises a porous layer (30) of chemically-active getter material deposited on an inside surface area of the outer wall (2) at a location separated from both the cold finger (1) and the window (7). The getter (30) can be activated (or re-activated) by heating through the portion of the outer wall (2) on which the getter material (30) is deposited, e.g. using a heater coil (50). Preferably the getter material (30) on the outer wall (2) extends around heat reflector, e.g. a reflective surface area of the cold finger (1). The cold finger (1) may be operated to cool the detector element (3) while heating the layer ( 30) to activate the getter.

Abstract: In a device for performing measurements on at least partly transparent objects such as optical fibres a radiation beam is directed on the object. The radiation deflected by the object is imaged by means of a lens system (321, 322) on a radiation-sensitive detection system (330). As a result of refraction on interfaces between areas having a different refractive index (311, 312) in the object and between the object and the surroundings (315), dark or light bands corresponding to the projection of the interfaces are produced on the radiation-sensitive detection system (330). Thus measurements can be performed on the internal structure of the object.

Abstract: An optical scanning device comprises an optical system for imaging a part of the surface (10) to be scanned on the detection system (22-25; 122-125). The optical system comprises an objective system (43) and two cylindrical lenses (41, 42) and/or two systems of cylindrical mirrors (141a, 141b, 142a, 142b). In the direction in which the cylindrical lenses (41, 42) have their optical power, the objective system (43) functions as an imaging lens so that a light-intensive and spatial image of the surface is formed at the detection system (22-25). Due to the achieved large numerical aperture, the image formed can also be observed three-dimensionally so that information about the profile of the surface can be obtained by means of the scanning device.

Abstract: The invention relates to a magneto-optical recorder with magnetic-field modulation. It comprises a laser (8) for producing a light beam (6), an optical focussing system (9) for forming a focal spot (12), and a servo device (10) for maintaining the focal spot (12) in focus on the surface of a thermo-magnetic record carrier (4), and for supplying a correction signal (V.sub.c) which is representative of the position of the surface of said carrier. A current modulator modulates the current through a coil (15) of a magnetic head. A compensation device (7) is responsive to said correction signal (V.sub.c) to change a parameter influencing the field of the coil, in such a way that the field strength at the surface of said carrier (4) is substantially independant of the position of said surface.

Abstract: For exact positioning of optical elements, a spectrometer is provided with a holder which is constructed using plates having a sector of circle shape and a side wall portion comprising a cylindrical surface portion. The cylindrical surface portion is provided with an exactly circular abutment face in which an entrance slot and an exit slot are provided. Relative to this abutment face, an entrance slit and an exit slit can be extremely exactly positioned with respect to one another along an exact circle. The holder is preferably constructed using two axially stacked compartments, in a cylindrical surface portion of which the slot or slots is/are provided between the compartments.

Abstract: The described optical transmitter comprises a laser diode (2) and optically coupled thereto a photodiode (3) operating as a monitor diode. The photoelectric current of the monitor diode (3) is used for adjusting the light power of the laser diode (2). In addition, the optical transmitter includes modulators used for modulating the current of the laser diode (IL) by a useful signal (b.sub.n) and a pilot signal (B.sub.k). The device includes circuitry to control the laser diode, in response to the photodiode, so that jitter in the signal is avoided. The device is capable of operation with bit frequencies in the GHz range.

Abstract: Magnetic head including a core (1, 3) of soft magnetic material having a contact face (7) and a winding aperture (5) and a coil (14) wound around the core. A layer (13) of a superconducting material is present in the non-magnetic transducing gap (11) in the core and a layer (15) of a superconducting material is provided on at least a plurality of the outer faces, for example the side faces (17).

Abstract: Device for doubling the frequency of a light wave, comprising a non-linear optical medium of an oriented synthetic resin composition for guiding a fundamental light wave, while forming a second harmonic wave, which medium is composed of a waveguide having a spatially periodic structure for phase matching. The oriented synthetic resin composition exhibits alternate regions having a mutually different second order (non-linear optical) susceptibility. Said structure can be manufactured in an efficient manner by exposing the synthetic resin composition to patterned radiation.

Abstract: The invention relates to a photocoupler for surface mounting. The device includes a first support (20), a phototransmitter element, a second support (20') having a photoreceiver element, and an electrically insulating assembly housing (1) in which the first and the second supports (20, 20') are assembled together by snap connections (11, 12) in a longitudinal direction of the assembly housing in such a way that the phototransmitter element and the photoreceiver element face on another. The first and the second support (20, 20') have a lateral surface (26) provided with conductor tracks (22, 24) in electrical contact with the said respective elements to enable surface mounting.

Abstract: A mirror unit (11) comprising a mirror holder (12) having a cylindrical support surface (13), and comprising a flexible mirror (14) having a mirror side (15) and a rear side (16); the mirror (14) which has been elastically deformed into a cylindrical mirror rests with its mirror side (15) directly on the support surface (13) of the mirror holder (14) without an intermediate layer, the mirror holder being provided with a shaft (17) which leaves open an optically directly and freely accessible region (19) at the mirror side (15) of the mirror (14) (front surface mirror), this region (19) acting as the functional mirror surface.