Abstract: An intrusion detector comprising a passive sensor for detecting a person entering a space to be monitored, said intrusion detector comprising a housing provided with a window for said passive sensor, optical means for directing electromagnetic radiation from said person onto the passive sensor, alarm means connected to said passive sensor for generating an alarm in case the electromagnetic radiation from said person being detected by the passive sensor corresponds to a signal value that exceeds a maximum level or falls below a minimum level, a special feature being the fact that the optical means are provided with a mirror curved in two directions for forming at least one protective curtain extending in a vertical plane in the space to be monitored, wherein the passive sensor is disposed on the optical axis at the focus of the mirror, and wherein the mirror directs a beam of electromagnetic radiation from the person, rotated through at least 45°, preferably through at least substantially 90°, onto the passive

Abstract: An intrusion detector comprising a passive sensor for detecting a person entering a space to be monitored, said intrusion detector comprising a housing provided with a window for said passive sensor, optical means for directing electromagnetic radiation from said person onto the passive sensor, alarm means connected to said passive sensor for generating an alarm in case the electromagnetic radiation from said person being detected by the passive sensor corresponds to a signal value that exceeds a maximum level or falls below a minimum level, a special feature being the fact that the optical means are provided with a mirror curved in two directions for forming at least one protective curtain extending in a vertical plane in the space to be monitored, wherein the passive sensor is disposed on the optical axis at the focus of the mirror, and wherein the mirror directs a beam of electromagnetic radiation from the person, rotated through at least 45°, preferably through at least substantially 90°, onto the passive

Abstract: A surveillance detector comprising a light emitter and a light guide which is optically connected to the light emitter, which light guide includes reflectors mounted therein, a special feature being the fact that the light guide is capable of converting the light from the light emitter at least in part into a light beam to be built up in the space to be kept under surveillance, and in that the light guide is capable of guiding light from the light beam that is reflected by an object in the space to be kept under surveillance to a light receiver of the detector, which is optically coupled to the light guide.

Abstract: A surveillance detector comprising a light emitter and a light guide which is optically connected to the light emitter, which light guide includes reflectors mounted therein, a special feature being the fact that the light guide is capable of converting the light from the light emitter at least in part into a light beam to be built up in the space to be kept under surveillance, and in that the light guide is capable of guiding light from the light beam that is reflected by an object in the space to be kept under surveillance to a light receiver of the detector, which is optically coupled to the light guide.

Abstract: The security of fire, intrusion and other security systems is improved by the disclosed monitor and method for providing an indication of the possible degradation in the integrity of a communications link and of the operability of a security sensor, both parts of the security system, and for removing the indication only in the event of a successful simulation.