EBAPS的调制传递函数测试系统

Modulation transfer function testing system for EBAPS

电子轰击有源像素传感器(electron bombarded active pixel sensor,EBAPS)是一种新型的真空-固体混合型微光夜视器件,而调制传递函数(modulation transfer function,MTF)作为EBAPS的性能参数之一,能够反映成像系统对不同频率成分的传递能力,但目前国内缺少相应的测试手段。因此,为了表征并评价EBAPS的成像质量,基于像增强器狭缝法测试MTF的原理,设计并搭建了一套EBAPS的MTF测试系统。通过驱动EBAPS器件,利用USB接口将采集到的数据传输至上位机进行图像分析,对狭缝图像进行处理获得线扩散函数(line spread function,LSF),经离散傅里叶变换后得到相应的调制传递函数曲线。在狭缝靶标处照度为2×10^(-2) lx时,一定范围内随着电压升高,EBAPS的MTF先升高后降低,且在外加-1 000 V时取得最大值。在光成像模式下,微调狭缝与传感器成像面的相对位置,连续5次测试得到几个重要频率点的MTF值的标准差均低于0.01,稳定性较好。

Electron bombarded active pixel sensor(EBAPS)is a new type of vacuum solid hybrid low light night vision device,and the modulation transfer function(MTF),as one of the performance parameters of EBAPS,can reflect the transmission ability of imaging systems to different frequency components.However,there is currently a lack of corresponding testing methods in China.Therefore,in order to characterize and evaluate the imaging quality of EBAPS,a MTF testing system for EBAPS was designed and built based on the principle of image intensifier slit method for testing MTF.By driving the EBAPS device and using a USB interface to transmit the collected data to the upper computer for image analysis,the slit image was processed to obtain the line spread function(LSF),and the corresponding modulation transfer function curve was obtained through discrete Fourier transform.When the illumination at the slit target was 2×10^(-2) lx,within a certain range,as the voltage increased,the MTF of EBAPS first increased and then decreased,and reached its maximum value when-1000 V was applied.In the light imaging mode,by fine-tuning the relative position between the slit and the sensor imaging surface,the standard deviation of MTF values for several important frequency points obtained from 5 consecutive tests was less than 0.01,indicating good stability.