Design of cooled infrared dual-band zoom optical system with large-magnification-ratio
The development of third-generation infrared focal plane detectors allows them to respond simul-taneously to two different bands of infrared radiation,and the dual-band image brings significant benefits to target detection and identification.In this paper,a cooled infrared dual-band zoom optical system with large-magnification-ratio is designed for aerial detection applications.The system includes a 320×256 dual-color infrared-cooled detector.It operates in the bands of 3.7-4.8 μm in mid-wave and 7.7-9.5 μm in long-wave.The optical system adopts the combination of refractive and catadioptric structures to realize an optical four-field-of-view switching wide-range zoom.In order to realize the 100％cold diaphragm efficiency,a second-ary imaging mode is adopted.The four-field-of-view focal lengths of the optical system are 32 mm,200 mm,800 mm,and 1 600 mm,and the zoom ratio is 50×.The experimental results show that the optical system is close to the diffraction limit at a modulation transfer function eigenfrequency of 17 lp/mm in each dual-band zoom state.The optical system has dual-band characteristics,extensive zoom ratio and large range,fast switching of multiple fields of view,simple and compact structure,and high-quality imaging,which will be useful in a wide range of security fields such as searching,reconnaissance,and so on.
dual-bandcooledlarge-magnification-ratiooptical system
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