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 phthalate crystal. Direct imaging of a plasma pinch line, as well as imaging of a mesh with plasma backlighting in which the same source is used, is shown. For verification, the results are compared with the results by other methods. An absolute intensity calibration of the images is demonstrated with theoretical data for the reflection properties of the crystal. This advance in two-dimensional imaging was possible owing to the recent progress in the precise bending of acid phthalate crystals to defined concave shapes of high quality (sphere, toroid). With these crystals, the two-dimensional imaging method is pushed to the wavelength of 2.66 nm, which is well inside the water window.