U.S. Philips Corporation

Wolfgang Hoppe

Friedrich-Karl Beckmann

Reinhard Knochel

Friedrich K Beckmann

Johann E Kruger

Jurgen Kordts

Olaf H Dossel

Gert Rabe

Ernst Brinkmeyer

Manfred H Fuchs

Rolf U Kobs

Kai-Michael Ludeke

Wolfgang Brennecke

Horst Dotsch

Wolfgang Meyer

Wilfried Edeler

Bernd R David

A miniaturized SQUID module (10), notably for multi-channel magnetometers, for measurement of varying magnetic fields in a field strength range below 10.sup.-10 T, includes superconducting and shielded connections between a SQUID chip (19) and a gradiometer (12). The module can be mounted in the lower part of a cryostat and enables a large number of measurement points per unit of surface area. The SQUID chip (19) is arranged on a fully shielded supporting plate (18) which has a width of only a few millimeters and which is provided with electronic circuitry (23), the SQUID chip (19) being connected in a superconducting manner, at least by soldering, to the wires (11) of the gradiometer (12) via a superconducting, solderable and bondable intermediate support (27).

Miniaturized squid module having an intermediate super conducting

Heterodyne optical time domain reflectometer (OTDR) for determining the attenuation behavior of a monomode waveguide (test waveguide) by measurement of the backscattered parts of light pulses transmitted in said waveguide. An acousto-optic modulator (AOM) which deflects the transmission beam from a laser into the waveguide to be tested at a light frequency which is modulated with the acoustic frequency when the AOM is acoustically energized in a pulse mode. The light pulses backscattered from the test waveguide are superimposed on a local oscillator beam (LO) constituted by the laser beam which traverses the AOM when the AOM is not energized. The optical system losses are reduced in that the superposition is realized in a passive coupler, particularly a fibre coupler (10, 26).

Heterodyne optical time domain reflectometer

The invention relates to an optical time domain reflectometer (OTDR) with heterodyne reception for determining the attentuation of an optical waveguide (measuring waveguide) by measuring the back-scattered portion of light pulses sent into the measuring waveguide. This structure is comprised of a modulated laser light source sending a send beam into the measuring waveguide and a laser light source which constitutes a local oscillator and transmits continuous light, on whose light of a wavelength differing by an intermediate-frequency from the back-scattered light from the transmission light source is superposed and is applied to a photodetector having an intermediate-frequency electric output signal which is filtered and evaluated. To improve the signal-to-noise ratio it is provided that the transmission light source is a transmission laser 1 whose light is influenced in consecutive time intervals (t.sub.1 to t.sub.2) such that the light frequency varies between two cut-off frequencies f.sub.L1 and f.sub.L2 and that the light source forming the local oscillator is a laser transmitting light at a frequency f.sub.LO, which is located outside the range between the cut-off frequencies f.sub.L1 and f.sub.L2 and differs from a frequency value (f.sub.LM), located between the frequencies f.sub.L1 and f.sub.L2, by the intermediate frequency (F.sub.ZF).

Optical time domain reflectometer with heterodyne reception

The invention relates to an optical time-domain reflectometer (OTDR) using heterodyne reception for determining the attenuation of an optical fiber guide by measuring the backscattered portion of light pulses launched into the fiber. The reflectometer comprises a light source whose light is split into a local-oscillator beam and a measuring beam. The measuring beam is pulsed by an acousto-optical modulator (AOM) and is then launched into the optical fiber to be tested. The measuring beam thus has a frequency which is offset from the optical frequency by an acoustic frequency. The local-oscillator beam and the back-scattered portion of the measuring beam are both directed to an optical receiver producing an electric output signal. A component of the output signal has a frequency corresponding to the acoustic frequency. The time-dependent amplitude of this component is a measure of the length-dependent attenuation of the optical fiber. In order to reduce the losses in the path between the light source and the optical receiver via the fiber to be tested, the acousto-optical modulator (AOM) also functions as an optical deflection element.

Optical time-domain reflectometer using heterodyne reception

The invention relates to an optical branching device which may be used as an optical isolator, circulator or switch. The device comprises two polarization-sensitive beam splitters. Each beam splitter comprises a prism and a rhombohedral plate between which a liquid crystal film is interposed. An optical device for rotating the plane of polarization of linearly polarized light is arranged between the two beam splitters. The polarization rotation device may comprise a Faraday rotator with a constant or a switchable direction of magnetization and a half-wave plate. Alternatively, the polarization rotation device may comprise a liquid crystal film interposed between two electrodes.

Optical branching device using a liquid crystal

The invention relates to a device for transmitting microwaves between two bodies which are rotatable relative to each other. Two annular waveguides are arranged on a common axis. Each waveguide has a coupling slot along its circumference. A transmitting aerial projects into each coupling slot and is moveable relative to the associated waveguide. The electromagnetic waves generated by the transmitting aerials are received by receiving aerials at the ends of the waveguides, respectively. The outputs of the receiving aerials are prepared for further processing.

Device for microwave transmission between two bodies which are rotatable

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Norderstedt, Germany

Wolfgang Hoppe