Abstract: A fire detection system incorporating fiber optics and having a selectively energizable light source for applying light pulses to a fiber optics path and a one way light transmitting element, such as a dichroic mirror, at the remote end of the fiber optics path for reflecting the pulses back to the detection portion of the system, thus providing a Built In Test Equipment (BITE) test capability in the system. Instead of a dichroic mirror, a bandpass filter may be used as the light transmitting member. The bandpass filter is selected to transmit light with wavelengths in the range from about 1.3 to 1.5 microns, in which case the light source is a light emitting diode (LED) emitting light at a wavelength of approximately 0.9 microns. The fiber optics path includes a branch which is coupled to the light source. This branch may comprise one fiber of a multi-fiber bundle or it may be an auxiliary fiber of a commercially available fiber optics combiner.

Abstract: A simple lightweight apparatus for sensing excessive contamination on the faces of an array of light or infrared detectors comprises mounting a light or infrared-emitting diode near one or more of the detectors. When the diode is energized, the associated detectors should detect its radiation, thereby indicating that the detector is operable and that contamination is not excessive.

Abstract: A device having a light emitter coupled to direct light to a portion of a photodetector to provide Built-In Test Equipment (BITE) capability for an optical sensor. A light emitting diode and a photodiode are mounted side by side on the upper surface of a conventional header with suitable electrical connections bonded thereto. A prismatic light bridge member overlies the light emitting diode and extends to cover a portion of one corner of the photodetector. This member serves as a light conduit, directing virtually all of the light from the emitter to the detector by virtue of the near total internal reflection of the surfaces of the light conduit member. An outer enclosure having a transparent glass window serves to seal and protect the respective elements while permitting external radiation to reach the photodetector.Alternative embodiments provide for coupling of light from a single emitter or a plurality of emitters to a single associated photodetector.

Abstract: A fire sensor discriminates between fires and the flash caused by a projectile piercing the wall of a protected area. The sensor system comprises first and second radiant energy detectors, each sensitive to radiation within different spectral bands. Each detector is coupled to a control signal means for generating a control signal when the radiation sensed exceeds a predetermined amplitude. A third control signal means is responsive to the first and second detectors, and is operative to generate a third control signal whenever the ratio of the amplitude of the energy sensed by the first detector to the amplitude of the energy sensed by the second detector is less than a predetermined value; not generate the third control signal whenever the ratio of amplitude exceeds the predetermined value; and delay generation of the third control signal for a predetermined period of time after the ratio of amplitudes falls below the predetermined value.

Abstract: A fire sensor system that can discriminate between a hydrocarbon fire and the effects of a penetration flash has four channels. A first channel of the system detects electromagnetic radiation in a spectral band of relatively long wavelength and a second channel detects electromagnetic radiation in a spectral band of relatively short wavelength. A third channel compares the relative intensity of the radiation detected by the first two channels and will generate a control signal if the ratio of intensities deviates substantially from unity. This third channel control signal, when generated, will be delayed by a first predetermined period of time, and then will trigger an output signal if the first two channels still detect predetermined levels of radiation. The first predetermined delay period is set to be long enough to allow a substantial amount of the radiation of a flash subside.

Abstract: Disclosed is a fire and explosion detection system wherein long wavelength radiant energy responsive signals are processed in one channel and compared to short wavelength radiant energy responsive signals which are processed in a second channel. At least one of the channels is responsive to a wavelength where at least one of the combustion products of the fire or explosion exhibits a strong absorption band in the atmosphere. When the signals from the two channels are coincident in response to a fire or explosion of a predetermined threshold magnitude, an output fire suppression signal is generated.