In this paper, the development of compact transmission soft x-ray microscopy (XM) with sub-50 nm spatial resolution for biomedical applications is described. The compact transmission soft x-ray microscope operates at lambda = 2.88 nm (430 eV) and is based on a tabletop regenerative x-ray source in combination with a tandem ellipsoidal condenser mirror for sample illumination, an objective micro zone plate and a thinned back-illuminated charge coupled device to record an x-ray image. The new, compact x-ray microscope system requires the fabrication of proper x-ray optical devices in order to obtain high-quality images. For an application-oriented microscope, the alignment procedure is fully automated via computer control through a graphic user interface. In imaging studies using our compact XM system, a gold mesh image was obtained with 45 nm resolution at x580 magnification and 1 min exposure. Images of a biological sample (Coscinodiscus oculoides) were recorded.

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Monochromatic x-rays generated using a multilayer mirror may be a useful diagnostic tool for breast examination by providing high contrast imaging with a low radiation dose.

A Wolter type I aspheric mirror which is a key optical element used in a soft X-ray microscope requires super smooth surface and highly accurate figure. This paper deals with fabrication of the Wolter type I microscope mirror by an epoxy replication method. The required figure accuracy of the mirror optimized with surface roughness of 2 nm rms and photon energy of 539 eV was estimated for a prototype soft X-ray microscope. A master mandrel was prepared by single-point diamond turning and polishing, and a precise aspheric gold mirror with axial symmetry was successfully obtained from the master mandrel through replication processes. The fabricated mirror showed surface roughness of 1.12 nm Ra and figure error of 34 nm rms, and several mirrors could be obtained from only one master mandrel without destroying its surface roughness and shape.

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