Passive Infrared Imager for Fire Fighting Applications

Fire creates smoke and dust. Their particles bloke firefighter's view because the particles scatter visible light (wavelength less than 1u). However, fire also creates infrared radiation with wavelength longer than 1u which will not be scattered by smoke and dust. Therefore it can be detected by an IR detector. In this proposal, a passive IR imager is designed to let the firefighter see fire and human being through smoke and dust. The innovation points of the system design are: use commercial available staring BST or microbolometer FPA with medium resolution of 120x160 pixels operating at room temperature to dramatically reduces the system complexity, weight, power consumption and cost. A wide bandpass filter from 2u to 12u is designed. An optical window and a fast speed (F=1) diffraction limited IR zoomlens with anti-reflection coatings are also designed. These bring the system NETD to 0.1 K, and the imager can be operated by battery.A handheld IR camera is not convenient for firefighter. In this proposal the most innovation issue is to mount the IR imager in the modified helmet and share the CRT and relay optics with the document display. By using a neural network chip, the image for fire or person can be recognized and enlarged automatically. The firefighter not only can look the IR image on the combiner at any time, but also can see the surrounding visible objects to allow him walk and work freely. As an alternative of helmet, the only 1 pound weight IR imager mounted on the firefighter's head or shoulder will use a removable flat LCD. By pulling the LCD to his eye, he can conveniently see the IR image of fire or person.