基于变曝光时间图像采集法提高SPR相位成像检测灵敏度  

Improving SPR phase imaging system detection sensitivity by changing the exposure time periodically

作　　者：张玮[1] 邓焱[1] 王大千[1] 余兴龙[1] 

机构地区：[1]清华大学精密仪器与机械学系,精密测试技术及仪器国家重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2011年第4期433-438,共6页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目(30727001)

摘　　要：提高表面等离子体共振(SPR)阵列检测的灵敏度是蛋白质组学和药物发现与开发的迫切需要。提出了一种基于五步移相时域调制相位干涉成像的变曝光时间图像采集法,通过增大信号幅值来提高光强测量信噪比。在一个相位测量周期的5帧图像中,每帧图像都采用不同的曝光时间,使得每帧图像的灰度值达到最大,从而提高光强测量的信噪比,保证相位成像检测的高灵敏度。实验结果表明,通过优化电路设计和对CCD致冷控温,自行设计的CCD传感系统的检测灵敏度达到了1.2×10-6RIU(refractive index unit)。在此基础上,采用变曝光时间图像采集法可有效抑制光散粒噪声和CCD读出噪声,将检测灵敏度再提高35%。该方法不仅适用于SPR相位成像检测,而且还可用于其他定步长和等步长相移法以及帧间灰度值变化大的图像采集及相关检测。Improving surface plasmon resonance（SPR） array detection sensitivity is crucial for proteomics and drug discovery.An image acquisition method that changes the exposure time periodically was developed based on the five-step phase-shifting technique and the SPR time domain modulation interferometry to enhance the sensitivity.In a single period of phase detection with five images,different exposure time makes each image reach the highest gray value,thus increasing the intensity measuring signal-to-noise ratio（SNR） and the system sensitivity.Experimental results show that a resolution of 1.2×10^-6 RIU（refractive index unit） is achieved by decreasing the camera noise and cooling the CCD chip.The sensitivity can be further increased by 35% using the developed image acquisition method which can effectively suppress the shot noise and the CCD readout noise.The method can be applied to not only SPR phase imaging but also other phase-shifting methods and situations where the gray values of inter-frames are quite different.

关 键 词：表面等离子体共振 时间相位调制 图像采集 变曝光时间 

分 类 号：R197.39[医药卫生—卫生事业管理]