Bofors Ab

Aktiebolag Bofors

Bengt Witt

Erland Pettersson

Ola Knutz

Bjorn Thorsson

The invention relates to an active proximity fuse with polarization-related sensitivity. Radiation which is reflected by particles in the atmosphere towards the receiver of the proximity fuse and which does not originate from reflection at the target has a negative effect on the operation of a proximity fuse. To reduce this effect the proximity fuse according to the invention is provided with elements in the transmitter of the proximity fuse for linearly polarizing the emitted radiation and elements in the receiver from suppressing the received radiation with linear polarization essentially coinciding with the direction of the linear polarization of the emitted radiation. This prevents radiation which is reflected by spherical particles, such as water droplets, with unchanged polarization after reflection, from reaching the detector of the receiver, while radiation reflected by the target is depolarized and a certain part of the radiation can be detected.

Active proximity fuse

An active optical proximity fuse comprises a transmitter for transmitting a radiation lobe by means of which a target can be illuminated. A receiver receives radiation reflected from the target and images the target or an area of the latter as a spot on a surf ace belonging to a detector which emits at its outputs electrical signals which mutually vary depending on the position of the spot on the detector surface. The detector outputs are connected to first elements which emit a first signal depending on the position of the spot on the surface, the absolute value of which signal is greater with the position of the spot on first parts, preferably outer parts, of the surface than with the position of the spot on another part, preferably the center part, of the surface. Second elements (13) acting as arming elements compare the first signal with a predetermined reference and emit an arming signal (i.sub.A) when two or more first signals, for example in the form of pulses, occur which exceed the reference. A third element forms a first reference signal (V.sub.reft) which constitutes a part (fraction) of the first signal. A fourth element (14) acting as triggering circuit initiates a triggering signal when the arming signal (i.sub.A) is present and when the said first element, after initiation of the arming signal, emits a first signal which drops below the said first reference signal (V.sub.reft) and exceeds a second reference signal determined by the signal noise.

Active optical proximity fuse

A receiver for receiving optical radiation includes detectors which, on reception, emit an electric signal. The detectors are operative to emit an electric signal of a level which is substantially independent of the angle of incidence of the optical radiation on the receiver.

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Karlskoga, Sweden

Bengt Witt