20- $\mu{\hbox {m}}$ Resolution Imaging of Soft X-Ray Emitters

The performance of a soft X-ray (3 to 10 keV) coded aperture microscope designed for 18 mum resolution over a field of view (FoV) of 7.9 mm times 7.9 mm with a sensitivity of 8times10^-4 at 1 cm is presented. The microscope is based on a commercially available deep-depletion CCD detector with 20 mum pixels and peak intrinsic efficiency 75%. The aperture is an arrangement of 45600 10-mum holes in a 604 times 604 NTHT MURA pattern and is fabricated by electroforming as a 5 mum deposition of Au on a 5-mum NiCo substrate providing mechanical stability. Experimental results show 23-mum resolution, 1.1times10^-3 sensitivity (inclusive of penetration), and a FoV of 8.08 mm times 8.08 mm at 1.088 cm. Images of activity distributions with less than 1 MBq can be obtained in 1 min. Due to multiplexing, the sensitivity increase does not always translate to a signal-to-noise ratio increase, but the advantage is clear for sparse activity distributions as may be encountered in studies of the biochemistry and diffusion mechanisms of biological electrolytes and metabolites, as well as of cell migration, signaling, and trafficking.