| 摘要 |
<p>A device for the selective detection of objects, such as aircraft, missiles, helicopters and alike, by means of outgoing rays from the objects, preferably IR-rays, comprises at least one sensor unit (1). The device comprises at least two optical entrances at a distance relative to each other across a sight line from the device to the object. The sensor unit (1) comprises at least one focusing means (15) for focussing the rays to a focal plane. The sensor unit is equipped with at least one radiation-sensitive detector element (16) arranged to emit signals corresponding to the radiation. The device is arranged to variably scan an angular field in azimuth and/or elevation. The device further comprises an evaluation unit (2) arranged to receive said signals. The invention is characterized particularly in that the evaluation unit (2) is arranged to select objects which seem to be of similar size with regard to the angle measured from the position of the device, in on one hand large objects being at a long distance, such as aircraft etc., and on the other hand small objects being at a short distance, such as birds, by suppressing signals whose amplitude as a function of the scanned azimuth or elevation angle shows a relatively great extension compared with signals which show a relatively small extension.</p> |
