Observation of ultrafast phenomena by holography using femtosecond pulsed laser and its application

我们开发了一种超快成像系统，以记录和观察飞秒光脉冲以无帧运动图像的形式在空间和时间中的传播。为了获得运动图像，采用飞秒脉冲激光进行全息术的飞行光记录。我们观察了通过色散棱镜传播的飞秒光脉冲和由集成阵列照明器产生的光脉冲串。该超短光脉冲在棱镜和阵列照明器中的时空特性得到了清晰的观察。在实验中，我们发现当观测位置沿全息图垂直方向移动时，重构像的形状会随着观测位置的变化而发生改变和畸变。从理论上和数值上分析了重建图像特征对观测条件的依赖关系。并对实验得到的重建图像的形状进行了分析。为了验证这一理论，又进行了一个飞秒脉冲激光实验。提出了一种补偿重建图像畸变的方法。我们还成功地观测到了飞秒光脉冲在三维空间中的传播。实验记录和重建了在明胶果冻中传播的飞秒光脉冲，成功地观测到了飞秒光脉冲。我们发现在果冻中传播的飞秒光脉冲的重建图像与真实脉冲前相比发生了翻转。我们讨论了翻转的原因，并建立了一个模型来分析重建图像的形状。对重建图像的形状进行了数值模拟。仿真结果与实验结果基本吻合。该技术实现了放大倍率超过10^<10>的时间显微镜，为观察和分析各种超快现象开辟了可能性。将该技术应用于电子全息或x射线全息，将成为直接观测原子和分子超快动力学的有力工具。少

We developed an ultrafast imaging system to record and observe the propagation of femtosecond light pulses in space and time as form of frameless motion picture. To obtain the motion picture, light-in-flight recording of holography using femtosecond pulsed laser was applied. We observed a propagating femtosecond light pulse through a dispersion prism and light pulse train generated from the integrated array illuminator. The temporal and spatial behavior of such ultrashort light pulse in the prism and from the array illuminator was clearly observed. In the experiment, we have found that the shape of the reconstructed image is changed and distorted depending on the observation position when the observation position is moved along the vertical direction of the hologram. The dependence of the reconstructed image characteristics on the observation condition was analyzed both theoretically and numerically. Also, the shape of the reconstructed image obtained by the experiment is analyzed. An … More experiment to verify the theory was conducted using a femtosecond pulsed laser. We also proposed the method of compensation of the distortion of the reconstructed image.We also succeeded in observing a femtosecond light pulse propagating in three-dimensional space. The experiments were carried out to record and reconstruct the femtosecond light pulse propagating in the jelly made of gelatin and succeeded in observing the femtosecond light pulse. We found that the reconstructed image of the femtosecond light pulse propagating in the jelly was flipped compared to the true pulse front. We discussed the cause of the flip and developed a model to analysis the shape of the reconstructed image. The shape of the reconstructed image was also simulated numerically. The results of the simulation almost agreed with the experimental results.This technology achieves a temporal microscope with more than 10^<10> magnification and will open the possibility for observing and analyzing the various ultrafast phenomena. It will become a powerful tool for directly observing ultrafast dynamics of atoms and molecules when the proposed technique is applied to the electron holography or X-ray holography. Less