The focusing equation, caustics and the condition for multiple imaging by thick gravitational lenses
The focusing equation, caustics and the condition for multiple imaging by thick gravitational lenses
复制标题
厚引力透镜多重成像的聚焦方程、焦散及条件
DOI：
10.1093/mnras/233.2.265
复制
发表时间：
1988
影响因子：
4.8
通讯作者：
K. Subramanian
中科院分区：
文献类型：
--
作者：
T. Padmanabhan;K. Subramanian
本文研究了任意厚或薄的引力透镜产生多重象的条件。作者证明了用透镜产生多重象的充要条件是：透镜应产生一个与观察者共轭的点，该点沿着某个零测地线，在一个小于光源的仿射距离处。它表明，以前的结果多次成像薄透镜可以作为一个特殊的情况下获得。作者还表明，对于产生多个图像来说，厚透镜并不比适当设计的薄透镜更有效。
The conditions for the production of multiple images by an arbitrary (thick or thin) gravitational lens are studied. The authors show that the necessary and sufficient conditions for the production of multiple images by a lens is the following: The lens should produce a point conjugate to the observer, along some null geodesic, at an affine distance smaller than that of the source. It is shown that previous results on multiple imaging by thin lenses can be obtained as a special case. The authors also show that a thick lens cannot be more efficient than a suitably designed thin lens for the production of multiple images.