Abstract

Soft x rays are an excellent probe for high spatial resolution detection of low atomic number specimens. We have developed a scanning microscope at the National Synchrotron Light Source (NSLS) which uses a small (~0.2-μm) spot of x rays in the 24-44-Å wavelength range. The microscope can form transmission images in real time at a fixed wavelength, or, by making an image of the difference in transmission on either side of an element's absorption edge, it can make a high resolution map of that element’s concentration. We have used the microscope primarily for imaging and microanalysis of biological specimens. However, with minor modifications the instrument can be used for high resolution material science studies of surfaces or bulk specimens without the requirements of excessive specimen thinning or vacuum compatibility presently required by electron probe instruments. The x-ray probe is presently formed by a Fresnel zone plate fabricated at IBM using electron-beam lithography. We will improve the resolution considerably with higher resolution zone plates fabricated by a variety of techniques. We will also increase the throughput of the instrument several orders of magnitude by moving from a bending magnet source of synchrotron radiation to the soft x-ray undulator soon to be installed on the x-ray storage ring at the NSLS. With these improvements we plan to make high resolution (< 1000-Å) scanned images in <1 min.

© 1985 Optical Society of America