Meissner response of anisotropic superconductors

The response field of a half-space anisotropic superconductor is evaluated for an arbitrary weak external field source. Example sources of a point magnetic moment and a circular current are considered in detail. For the penetration depth $\lambda \ll L$ with $L$ being any other relevant distance (the source size, or the distance between the source and the superconductor), the major contribution to the response is the $\lambda$ independent field of the source image. It is shown that the absolute value of $\lambda$ cannot be extracted from the response field with a better accuracy than that for the source position. Similar problems are considered for thin films.