Impulsphysik Gmbh

Deutsche Forschungsanstalt Fur Luft-Und Raumfahrt E.v.

Eberhard Gelbke

Christian Werner

Jurgen Streicher

Frank Frungel

Ulrich Oppel

Hartmut Herrmann

Wilhelm Krichbaumer

Christoph Munkel

Uwe F Berghaus

The lidar arrangement (1) has a transmitter (3) for linearly polarized radiation (12), a receiver (5) with a first receiving device which measures intensity of the backscattered radiation (15) coinciding approximately with the transmitted radiation cone (12) in a polarization plane of the cone and in a perpendicular polarization plane, wherein the receiver further includes a second receiving device which measures the intensity of backscattered radiation (17) outside the transmitted cone (12), the outer backscattered radiation has the shape of a conical shell which surrounds the backscattered conical shell of the first mentioned backscattered radiation (15) and of the transmitted cone (12); the received separate radiation cones (15 and 17) are split in a polarization analyzing optical element into two mutually perpendicular partial light beams, each consisting of an inner partial beam portion (15a, 15b) and an outer partial beam portion (17a and 17b), the inner and outer partial beam portions are separately detected and the resulting output signals are amplified by an amplification factor which depends on the distance of the lidar from a visibility obstacle, the distance-corrected amplified signals are evaluated in a signal processing unit to distinguish between different kinds of the visibility obstacle, and the evaluated obstacle such as fog, rain, snow or solid obstacle and a distance thereof are indicated on corresponding indicators.

Lidar arrangement for measuring atmospheric turbidities

An onboard power supply and metering unit is connected, via an overboard cable e.g., 1000 meters long, to an underwater light-pulse projecting unit and a fluoroescence-sensing receiver unit. The operating power is transmitted to the underwater units by an onboard constant-current source, instead of a voltage source. Likewise, the output signal of the receiver unit is transmitted through the cable in the form of a current, not a voltage. The current of the receiver's photodiode is integrated, the peak value of the integral determined and held, this held value logarithmized, the logarithmized value sampled and held, and the held voltage converted to a current constituting the output signal. The offset of the peak detector and the input stage of the log amplifier are balanced automatically, by a balancing signal applied during pulse measurements, but derived between pulse measurements. The balancing signal is derived by integrating a signal derived from the log amplifier's output signal, and is applied to the input of the peak detector, with the peak detector converted to simple voltage-follower operation during the deriving of the balancing signal.

Deepwater in-situ fluorometer

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Uetersen, Germany

Eberhard Gelbke