SOFT-X-RAY IMAGING WITH TOROIDALLY CURVED THALLIUM ACID PHTHALATE CRYSTALS IN THE WATER WINDOW

Two-dimensional imaging in the wavelength region of the water window ( N Ly alpha) is demonstrated with a toroidally curved thallium acid pht halate crystal. Direct imaging of a plasma pinch Line, as well as imag ing of a mesh with plasma backlighting in which the same source is use d, is shown. For verification, the results are compared with the resul ts by other methods. An absolute intensity calibration of the images i s demonstrated with theoretical data for the reflection properties of the crystal. This advance in two-dimensional imaging was possible owin g to the recent progress in the precise bending of acid phthalate crys tals to defined concave shapes of high quality (sphere, toroid). With these crystals, the two-dimensional imaging method is pushed to the wa velength of 2.66 nm, which is well inside the water window. (C) 1998 O ptical Society of America.