Application of optical diffraction method in designing phase plates

Continuous phase plate(CPP),which has a function of beam shaping in laser systems,is one kind of important diffractive optics.Based on the Fourier transform of the Gerchberg-Saxton(G-S) algorithm for designing CPP,we proposed an optical diffraction method according to the real system conditions.A thin lens can complete the Fourier transform of the input signal and the inverse propagation of light can be implemented in a program.Using both of the two functions can realize the iteration process to calculate the near-field distribution of light and the far-field repeatedly,which is similar to the G-S algorithm.The results show that using the optical diffraction method can design a CPP for a complicated laser system,and make the CPP have abilities of beam shaping and phase compensation for the phase aberration of the system.The method can improve the adaptation of the phase plate in systems with phase aberrations.     

高功率激光光束经颗粒污染后的近场衍射效应

采用高功率激光驱动器设计软件Laser designer数值研究了激光光束经颗粒污染后的近场衍射特性. 对颗粒污染所产生的调制进行了分类, 并详细分析了真空和石英玻璃中, 振幅调制型和位相调制型颗粒污染对光束近场的影响. 研究结果表明, 无论在真空或石英玻璃中, 位相型颗粒污染对高功率激光光束的近场调制影响较大. 且在石英玻璃中, 位相型硬边颗粒污染所引起的高功率激光光束小尺度自聚焦热像调制现象相当严重. 而由颗粒污染引起光束强区的横向偏移, 却在一定程度对小尺度自聚焦有抑制作用.     

神光Ⅱ第九路光路自动准直系统研究

光路自动准直系统应用于惯性约束聚变的高功率激光装置中。针对神光Ⅱ第九路装置,设计了一套可行的准直方案,并在装置上进行了实验。实验结果表明,自动准直系统能够在15minSq顺利完成光路的自动调整,小口径近场调整准直精度小于±0．5mm,大口径近场调整准直精度小于±1．0mm,远场准直精度小于±1”,满足了装置的设计要求。     

图像处理在光路自动准直系统中的应用

光路自动准直系统应用于惯性约束聚变的高功率激光装置中的光束自动调整。图像处理是光路自动准直的关键技术之一。针对神光Ⅲ原型装置,结合阈值化、重心法、中值滤波和圆拟合等多种不同的图像处理方法设计了一套合理的准直方案,并且在模拟实验平台上进行了实验验证。实验结果表明,光路自动准直系统能够在15min之内顺利完成光路的自动调整,光束近场调整精度优于近场光斑的±0.5%,光束远场调整精度≤±0.3″,满足了原型装置的总体要求。     

Design and application of a laser beam alignment system based on the imaging properties of a multi-pass amplifier

Image relaying is presented as a technique for aligning beams onto mm-sized target of high power laser. On the basis of summarizing the preceeding work on the near-field image relaying of multiple spatial filters, the far-filed image relaying is suggested firstly. The near-field and far-field image relaying properties of multiple spatial filters in laser beams automatic alignment system are analyzed. A geometrical optics approach and an ABCD ray matrix theory are used throughout. The reasonable and optimum scheme for automatically aligning multi-pass beam paths is presented and demonstrated on the multi-pass amplifier system of the SG-Ⅲprototype.