Hunt J T, Glaze J A, Simmons W W, Renard P A
Appl Opt. 1978 Jul 1;17(13):2053-7. doi: 10.1364/AO.17.002053.
Self-focusing effects in large, high power laser amplifiers become manifest as small-scale beam instabilities and as large-scale phase aberrations. Spatial filtering has been shown to control instabilities; spatial filters constitute appropriate lens pair elements for image relaying as well. In this paper, image relaying is presented as a technique for preserving the transverse intensity profile of a high power beam as it propagates long distances through nonlinear elements. As a consequence, amplifier apertures can be filled more effectively, leading to a doubling of fixed-aperture system performance. A rationale for optimal selection of spatial filter bandpass is also presented. This selection, as might be expected, depends upon details of the beam's spatial structure as it enters any filter. A geometrical optics approach is used throughout; nevertheless, derived results remain valid when diffraction is included.
在大型高功率激光放大器中，自聚焦效应表现为小尺度光束不稳定性和大尺度相位畸变。空间滤波已被证明可控制不稳定性；空间滤波器也构成用于图像中继的合适透镜对元件。在本文中，图像中继被提出作为一种在高功率光束通过非线性元件长距离传播时保持其横向强度分布的技术。因此，放大器孔径可以更有效地被填充，从而使固定孔径系统的性能提高一倍。还提出了空间滤波器带通最佳选择的基本原理。正如预期的那样，这种选择取决于光束进入任何滤波器时的空间结构细节。全文采用几何光学方法；不过，当考虑衍射时，所得结果仍然有效。
