利用抗光晕通道倾泻电荷的帧转移EMCCD电子快门方法

Electronic shutter for frame-transfer EMCCD using anti-blooming channel to bleed off charges

  • 摘要: 针对帧转移结构电子倍增电荷耦合器件(EMCCD)对高速运动目标成像模糊、高亮度目标成像饱和且细节缺失的问题,提出了利用抗光晕通道倾泻多余电荷和外部时序控制的电子快门方法,通过帧转移时序将感光区电荷转移到与存储区相邻的抗光晕沟道进行倾泻,实现标准视频连续输出中1/25~1/1 000 s连续可调的电子快门,并推导了抗光晕漏极最大倾泻电流与光照强度之间的数学关系式;使用FPGA硬件图像处理消除了曝光时间缩短引起的漏光-拖尾(smear)效应;采用带有抗光晕结构的帧转移EMCCD开发了原理相机进行实验验证。结果表明,通过该方法控制电子快门可以有效降低旋转运动目标的成像模糊,并实现夜间的高动态范围夜视成像,显著提升图像细节。

     

    Abstract: To resolve the issues of the image blurring of high-speed moving objects and the imaging saturation of high brightness objects and missing detail, an electronic shutter method for frame-transfer EMCCD using anti-blooming channel to bleed off charges and external time frequency control was proposed. Through bleeding off the charges in light sensitive area into the anti-blooming channel which adjacent to the storage area, an adjustable electronic shutter among 1/25 s and 1/1 000 s was realized. And at the same time, the standard video signal was output continuously. The relationship between the illumination intensity and the maximum bleeding-off current of the anti-blooming drain was formulated. The smear effect induced by the short exposure time (shutter time) was corrected online through writing the correction algorithm into the FGPA chip of the EMCCD readout circuit. A prototype system using frame-transfer EMCCD with anti-blooming channel was built up to conduct imaging experiments. The results verify that this electronic shutter can effectively decrease the image blurring of rotating objects and facilitate high dynamic range imaging in the nighttime.

     

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