向高清化和数字化发展的红外成像系统

Infrared Imaging Systems Tending towards High Definition and Digitization

高清(晰度)红外成像系统是一种根据高清电视标准(1280×1024、1920×1080或者1280×720)产生视频信号,具有较高空间分辨率而又不会牺牲热灵敏度的热像仪。空间分辨率越高,可探测到的目标越小,距离就越远。空间分辨率的提高意味着探测器像元数量的增加、像元中心距的减小和像元信噪比的增强。数字化也就是要将模数转换器(Analog-to-Digital Converter,ADC)引入到读出集成电路(Readout Integrated Circuit,ROIC)中。ADC可以用一个高速ADC在芯片级实现,或者用几个中速ADC在列级实现,或者用低速ADC在像元级实现。由于仅需传输数字数据,像元级ADC有助于减小系统噪声,适合用标准的数字CMOS工艺来实现。通过对部分有关英文文献进行归纳与分析,介绍了近年来红外成像系统在高清化和数字化方面的发展动向和趋势。

High definition infrared imaging systems are those thermal imagers that have higher spatial resolution without sacrificing thermal sensitivity and generate video signals according to the high defini- tion television standards （1280×1024, 1920×1080 or 1280× 720）. The higher the spatial resolution is, the smaller the detectable target is and the farther the target is from. The improvement of spatial resolution means that the number of detector pixels is increased, the pixel pitch is decreased and the signal-to-noise ratio in each pixel is enhanced. Digitization involves the incorporation of an analog-to-digital converter （ADC） into a readout integrated circuit （ROIC）. Analog-to-digital conversion can be implemented with a high speed ADC at the chip level or be implemented with multiple medium speed ADCs at the column level or be implemented with multiple low speed ADCs at the pixel level. Because only digital data need to be transferred, the ADC at the pixel level is helpful to the reduction of system noise and is suited for implementation in the standard digital CMOS process. The recent advances and trends of infrared imaging systems in the aspects of high definition and digitization are presented.