用于双光子激发荧光寿命显微成像的高重复频率皮秒扫描相机

建立了一台基于新研制的高重复频率皮秒扫描相机的双光子激发荧光寿命显微成像系统,重点介绍所研制的高重复频率皮秒扫描相机。为了在高时间分辨力的同时扩大时间测量范围,实现大面积两维空间高时间分辨取样测量,从而提高采样速率和更有效地发挥扫描相机的作用,设计和研制了一种大面积、高时间分辨力扫描变像管和一种重复频率高达1MHz的斜坡电压扫描电路。基于上述关键部件所研制的扫描相机具有重复频率高、扫描速度可调、时间分辨力高、工作面积大、非线性低、触发晃动小等优点。用钛宝石飞秒激光器作为激光脉冲源,通过脉冲提取器将76MHz的高重复频率降低为1MHz,采用可调延时器和标准具对扫描相机的时间分辨力、扫描速度和非线性进行标定。该系统的时间分辨力达到6.5ps,非线性为2.60%,可测量的时间范围从十几皮秒到几十纳秒。测量了若丹明6G和香豆素314两种标准荧光染料的荧光寿命,取得了与参考文献一致的实验结果。

A High Repetition Rate Picosecond Streak Camera for Two-Photon Excited Fluorescence Lifetime Microscopic Imaging

A two-photon excited fluorescence lifetime microscopic imaging system based on a newly-developed high repetition rate picosecond streak camera is presented. The high repetition rate picosecond streak camera is the emphasis for introduction. In order to increase the measurable sweeping range and maintain high temporal resolution as well, and in order to realize high temporally resolved sampling measurement in two dimensions to improve sampling speed and exploit effectively the advantages of the streak camera, authors specially designed and developed a streak image tube with large area and high temporal resolution and a ramp voltage streak circuit with repetition rate up to 1 MHz. The streak camera based on the key components above mentioned is characterized with high repetition rate, tunable sweep rate, high temporal resolution, large effective area of work, low nonlinearity and small triggering jitter. A Ti:sapphire laser provides mode-locked, ultrafast femtosecond pulses with a fundamental frequency of 76 MHz which is reduced to 1 MHz with a pulse picker. The temporal resolution, sweep rate and nonlinearity are calibrated with a tunable delay generator and etalons. Temporal resolution of the system is 6.5 ps, nonlinearity is 2.60%, and the measurable time range is from ten picoseconds to tens of nanoseconds. Streak images of Rhodamine 6G and Coumarin 314 are obtained and the results agree well with those reported in the literatures.