条纹相机测量中的光束取样

LIGHT-BEAM SAMPLING IN STREAK CAMERA MEASUREMENTS

从实验上探讨了用条纹相机测量大口径高功率固体激光束的脉冲波形时,取样光斑的大小对波形的精细结构与脉宽的影响。

Time waveform of high power pulsed laser is very important for studies of lasers and laser-plasma interaction. At present, the best measurement method is using streak camera. The diameter of final output beam increases up to 200mm with the development of giant Nd-glass laser facilities.But the cathod area of streak tube is limited. Therefore, how to measure the laser pulse waveform correctly becomes a problem that needs to be solvedIn the experiments we utilized a optical streak camera system whose time resolution is up to l.8ps. We have proved that light-beams of various different spot-sizes, i.e. a whole output aperture D, 2/3 D, 1 / 2 D or 1/3 D, even 1/10 D, 1/40 D, etc-, were sampled from a high power Nd-g!ass laser of output aperture D=200mm, and projected on the streak camera, both fine-structure of laser pulse waveform and me pulse duration would be rather changeable. The experiments were conducted at the giant Nd-glass laser facility of our institute. When pulse duration (FWHM) is 100ps, the maximum output power of 1 TW can be reached for a single beam. For the sake of contrast, the laser facility can also output pulses of 1ns, 0.6ns or 0.1ns duration respectively-measured by using streak camera, the sampling light spot-size of whole diameter D, or over 1/3 D should be taken in order to keep the high accuracy of streak camera measurement. If the sampling. light spot-sizes are too small, it would cause the distortion of pulse waveform, especially the distortion of pulse front.