Abstract: The present invention relates to a thermally sensitive array device for detecting a presence of a target object in a surveillance area. The device comprises a plurality of at least two thermally sensitive sensors provided in an array arrangement, each thermally sensitive sensor being associated with one of a corresponding plurality of at least two surveillance spots comprised in the surveillance area. Each thermally sensitive sensor comprises a sensitive element adapted to absorb a portion of thermal infrared radiation emitted from one of said plurality of targets located inside the surveillance cone corresponding to the thermally sensitve sensor. Thermally sensitive sensor can be thermopiles, Bolometers or any other type. Electronic circuits in each thermally sensitive sensor are adapted to measure a signal generated in the thermally sensitive sensor as a consequence of the temperatures of the target.