U.S. Philips Corporation

Other

Agilent Technologies, Inc.

Technische Universitat Hamburg-harburg

Metek Meteorologische Messtechnik Gmbh

Metek Gmbh

Ernst Brinkmeyer

Wolfgang Brennecke

Manfred H Fuchs

Wolfgang Hoppe

Gerhard Peters

Friedrich-Karl Beckmann

Rainer J Otto

Thomas Waterholter

Jens Cierullies

Christoph Bollig

Wilhelm Dargatz

A LIDAR measuring device and a method for determining the speed of particles in a measuring volume includes a narrowband continuous wave laser light source (), which emits light which is coupled into a measuring branch () and a reference branch (). The light coupled into the measuring branch () is at least partially emitted by a transmitting device in the direction of the measuring volume such that the emitted light is at least partially scattered and/or reflected by the particles in the measuring volume. A part of the scattered and/or reflected light is then received by a receiver device and is coherently superimposed with the light leaving the reference branch (), and the resulting light beam is directed onto a detector () to generate a detector signal characteristic for the resulting light beam. Finally, the speed of the particles in the measuring volume is determined in an evaluation unit () by taking into account the detector signal.

LIDAR measuring device

A stray-light tolerant LIDAR measurement system. The system comprises an interferometer assembly having a continuous-wave laser source, a photodetection arrangement and optical components. The laser source comprises a laser-light-generating component, a downstream optical phase modulator and a control unit connected to the modulator to deliver a control signal corresponding to a pseudo-noise signal defined by a predetermined phase function. The interferometer assembly comprises an evaluation unit which is coupled to the interferometric photodetector assembly to detect the detector signals of same and to determine the presence and/or movement of particles and/or objects from the detector signals wherein, in the case of two wavelengths emitted from the laser light generating components, the detector signals are detected separately in two wavelength regions, and the phase function has a predetermined step-like time course and the evaluation unit scans the detector signals in synchrony with the timing of the steps of the phase function.

Stray-light tolerant lidar measurement system and stray-light tolerant lidar measurement method

The present invention relates to a lidar measurement system for the detection of the presence and/or motion of particles and/or objects in a space region remote from the lidar measurement system and comprising an interferometer arrangement, as well as to a corresponding method using such a measurement system. The interferometer arrangement comprises a continuous wave laser source (), a photodetector arrangement (), and optical components which are adapted to split light () emitted by the continuous wave laser source (), to guide it along a first optical path constituting a measurement branch () and along a second optical path, which is separate from the first optical path and constitutes a reference branch (), and to eventually have it incident in a spatially coherently superimposed manner onto the photodetector arrangement (). The reference branch () has a predetermined optical path length, and the measurement branch () comprises a measurement portion (), in which the light is directed away from the measurement system towards a space region remote from the measurement system and passes through the space region and light backscattered towards the measurement system by particles present in the space region is received again at the measurement system. Further, an evaluation unit () is provided which is coupled to the photodetector arrangement () and is adapted to receive the detector signal thereof and to determine from the detector signal the presence and/or movement of particles in the remote space region. The continuous wave laser source () has a coherence length in the range of 0.1 to 100 m.

Lidar measuring system and lidar measuring method

A method of determination of a property of an optical device under test includes using a first initial coherent light beam, changing a first initial property of the first initial light beam, coupling the first initial light beam to the device under test, detecting a first signal of the first initial light beam received from the device under test, and correcting any a non-linearity in the first signal by interpolating the first signal on a linear scale.

Determination of properties of an optical device

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

An optical multi-port element with an acousto-optical modulator (AOM) has at least two monomode optical waveguide connections, at one side thereof. The end surfaces of the waveguides disposed in the focal plane of a lens situated between the optical waveguides and the acousto-optical modulator. In order to obtain a construction which can be adjusted in a simple manner and which has low attenuation, with a small overall length, it is provided that at least one side of the AOM (1) a single lens (2,3,31) is disposed with its optical axis aligned to the transmission axis of the AOM (1), and that the optical wave-guides (4 to 6, 18 to 20 or 27,28) are disposed with their axes parallel to one another and spaced from the optical axis of the lens (2,3,31) in such a manner that parallel beams (14 to 17), leading from the lens (2,3,31) to the AOM (1), are directed to the active region of the AOM (1) at the Bragg angle to the optical axis.

Optical multi-gate element with an acousto-optical modulator

An optical backscattering meter includes an optical transmitter whose transmission power is modulated (wobbled) with a variable frequency via an oscillator and whose transmission beam is coupled into a light wave cable (LWL) via a beam splitter. It further includes an optical receiver including an avalanche photodiode, to which receiver are applied, via the beam splitter, portions of the transmission beam that are scattered back from the light wave cable (LWL). A mixing signal is formed from a signal proportional to the optical backscattering power and a modulation voltage having the oscillator frequency and is evaluated for determining the location of the backscattering and the intensity thereof. The cost of the optical receiver is reduced by the use of the avalanche photodiode (4), whose bias voltage is a d.c. voltage (U.sub.G) modulated by the modulation voltage (U.sub.M), and because the mixing signal (U.sub.P) can be tapped at a parallel circuit comprising an ohmic resistor R.sub.P) and a capacitor (C.sub.P) inserted in the energizing circuit of the photodiode.

Optical meter with dual functions avalanche photodiode

The invention relates to a polarization scrambler comprising a controllable optical phase retardation element for retarding with respect to one another components of a light beam with a different state of polarization, the light beam propagating through the element, and a control arrangement for controlling the phase retardation element, said control arrangement being adapted to supply a control signal so that as a function of time the phase retardation is controlled in such a way that with a given state of polarization (SOP) of the light entering the polarization scrambler varying states of polarization occur at its output in such a way that, averaged in time, the light intensities emerging in each SOP are at least substantially equal. An arrangement suitable for arbitrary input states of polarization is obtained when at least a further controllable phase retardation element (2, 3) connected to a control arrangement and succeeding the first element in the light propagation direction is provided which, represented on the Poincare sphere, creates states of polarization in accordance with a rotational axis which is different from that associated with the first phase retardation element and in that the phase retardation elements (1, 2, 3 ) are controlled by the control arrangement at different frequencies (f.sub.1, f.sub.2, f.sub.3) or in an uncorrelated aperiodical manner.

Growing community of inventors

Buchholz, Germany

Ernst Brinkmeyer