Abstract: The invention relates to a method and a system for detecting an individual in a given observation zone by means of N passive infrared sensors (1) each consisting of an optical device (2) provided with a matrix of cells focusing the infrared energy (IR) received onto a single pyro-electric component (3) linked to a calculation unit (4) able to interpret the information received. The device according to the invention is characterized in that it consists, in order to detect an individual in the observation zone, in employing a limited number of N similar infrared sensors (1) centered on the same observation zone, each provided with 2N?1 cells (2C), and hence beams (F), which for each of the latter are masked, according to a different combination in such a way as to provide the calculation unit with the information enabling the individual to be located in terms of position and displacement.

Abstract: A perimeter security system includes a video camera (1), an element (7) for transmitting or retransmitting a radiation lighting a scene observed by the camera (1), and a unit (4) for image analysis and processing and for driving the camera (1). The system is essentially characterized in that it includes, in order to multiply the number of shots while using a single camera (1), at least two mirrors (6, 61) partially inserted into the field of vision of the latter, each mirror having the same vertical orientation but a different horizontal orientation so that the portion of the image seen by the camera on each of the mirrors always represents the same scene relative to the lighting element (7).

Abstract: The invention relates to a method and a system for detecting an individual in a given observation zone by means of N passive infrared sensors (1) each consisting of an optical device (2) provided with a matrix of cells focusing the infrared energy (IR) received onto a single pyro-electric component (3) linked to a calculation unit (4) able to interpret the information received. The device according to the invention is characterized in that it consists, in order to detect an individual in the observation zone, in employing a limited number of N similar infrared sensors (1) centred on the same observation zone, each provided with 2N?cells (2C), and hence beams (F), which for each of the latter are masked, according to a different combination in such a way as to provide the calculation unit with the information enabling the individual to be located in terms of position and displacement.