In order to overcome the short distance (it is critical for seeker) and high cost problems of the dual-mode imager using UFPA and fully meet the task requirement, very innovative ideas and designs are proposed: 1. By using a smaller UFPA format of 240x320/25 u and adding an immersed detector lens on it, the detection distance can be increased 8 times. 2. By designing a 150-mm and F/1 objective lens with non-Ge materials and using its simple production method, the price can be reduced to 1/3 of the Ge lens. 3. By using two heads and a video switch to let the VS and IR share time alternatively on the LCD, we are able to combine the VS and IR images together without blurring the overlapped image. 4. In order to eliminate the parallax between VS and IR for pixel by pixel image fusion and autonomous target recognition, three common optical apertures: common refractive objective lens, common reflective objective lens, and common beam splitter are designed. The common refractive objective lens uses ZnSe as the common front lens then uses normal glass for VS and IR glass for IR to correct their aberrations in VS (0.5-0.9 u) and IR (8-12 u), thus we don't need to correct aberrations in the whole band from 0.5 to 12 u. Without this innovative idea, it is impossible to design a lens for both sensors. 5. All existing UFPA imagers use traditional electronic circuit design with Thermal Electrical Cooler, thus the volume is big, the power consumption is large and the cost is high. Our new design only uses one Altera chip for all digital signal processing and does not use TEC. Therefore, a 3.5 OZ Si-bolometer IR imager (excluding lens) with 240x320/25 u resolution can be produced. Two 1.2 V Lithium
Benefit: The proposed dual-mode imager not only will give great help to Navy for the development of new seeker, but also will greatly assist government agencies to detect and identify suspicious subjects without prompting flight or confrontation in a variety of environments (darkened buildings, jails, alleys, night scenes, smoke, dust, and other adverse weather conditions). Not only fire fighting, anti-terrorist, building security, and hunting, but also most squad cars and police helicopters would require this type of system. In most applications, the visible is used for daytime or artificially lit scenes and the infrared for smoggy or nighttime conditions. Under many daytime conditions, the visible and infrared images can be correlated with each other to maximize the information gathered. Maxtech International, Inc. has predicted that the US market for this type of imaging system will exceed 1.3 billion dollars by 2003.
Keywords: Infrared Sensor, Infrared Sensor, Visible Sensor, Dual-mode imager, Sensor fusion., Security system, Non-Ge objective lens, Common optical aperture, seeker
