Optical design of long-distant and directional flame detection based on pyroelectric sensor

As the viewing range of the existing fire detection devices is normally short, and directional detection of the flame can not be achieved, it can not be used in many cases. An optical design and implementation based on flame pyroelectric sensor are present in this paper. Two types of directional flame detection are provided. One is to achieve plane-type directional detection, and the other is to achieve line-type directional detection. For plane-type directional detection, the optical viewing angle design of detection device in the horizontal and vertical direction is asymmetric. The viewing angle of vertical direction is much bigger than that of horizontal direction in order to detect the flame anywhere in vertical plane as far as possible. On the other hand, the viewing angle of horizontal direction is expected to be smaller so as to ensure directional flame detection. The size of viewing angle is controlled within a certain range through a special optical design including lens and slit. The design of line-type directional detection is achieved based on ultra-small viewing angle of the lens. Based on such design of flame detectors, the detection range can be adjusted by changing the optical parameters, so long-distance flame detection can be achieved. This scheme has a broad application prospects in many fields, such as forest fire prevention, automatic fire cannons, etc., because of directional flame detection. Experiments show that this method has achieved the expected results.