Patent Number: 052221130
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring to the drawing, reference numeral 1 identifies the X-ray source in the microscope. This X-ray source is a plasma focus source of the kind described in U.S. Pat. No. 4,596,030 incorporated herein by reference. This plasma focus source supplies a point-shaped plasma for short times. The plasma emits X-radiation at a dominant emission wavelength on the Lyman-.alpha. line of six-times ionized nitrogen. The plasma focus source 1 is driven by a capacitor bank 2 which is electrically charged in the time between discharges. The X-radiation emanating from the plasma focus 1a is focussed with the aid of a reflecting condenser 3 on the specimen mounted on a specimen holder 4. The reflecting condenser 3 has the form of a rotational ellipsoid and reflects the X-radiation incident on its mirror surfaces at a grazing incidence. The reflecting condenser 3 is closed off at one or both ends thereof by respective foils 15 and 16 which protect the sensitive mirror surfaces against contamination. The foils are produced from a material such as polyimide which is absorbent as little as possible in the spectral range of the X-radiation. A so-called microzone plate 5 is mounted above the specimen plane. This microzone plate defines the actual imaging optics of the X-ray microscope. The spacing of the microzone plate 5 from the specimen plane is greatly exaggerated in the schematic. Actually, the microzone plate has a diameter of 20 to 50 .mu.m and is disposed only a few tenths of a millimeter above the specimen to be investigated. The microzone plate 5 images the specimen greatly enlarged on a detector 6. The detector 6 is a solid-state camera in the form of a CCD-camera such as a camera having the product number NXA 1011 of the Valvo company which is a corporation doing business in Germany. The detector 6 is sensitized for the X-radiation in that the cover glass is removed and the photosensitive surface is covered with a fluorescence colorant such as Gd.sub.2 O.sub.2 S:Tb. The CCD-camera 6 is mounted on a carrier 7 which can be displaced along the optical axis as indicated by the arrow with the aid of an adjusting device 8 for the purpose of focussing or magnification changing. The focussing itself is preferably done by changing the distance between the microzone plate and the specimen. The components of the X-ray microscope described above are arranged in a cylindrical column 9 mounted on the capacitor bank 2. The column 9 is at a vacuum and the space around the specimen stage 4 can be filled with a gas such as helium or hydrogen which is only slightly absorbent in the range of the X-radiation used and the space is separated from the vacuum system by means of two X-ray transparent foils (not shown). The signal lines of the CCD-camera 6 are passed through the adjusting device 8 and are connected to an electronic unit 10 which reads out the image of the CCD-camera 6. This camera electronic unit 10 is synchronized via a control unit 11 with the electronics (not shown) for the operation of the plasma focus source in such a manner that after each X-ray pulse supplied by the plasma focus source 1, an image is taken in and stored in an image memory 13. The images stored there can be viewed by means of a monitor 12 likewise connected to the electronic unit 10. Variations from the configuration described herein are within the scope of the invention. Accordingly, an X-ray film cassette can be used in lieu of the CCD-camera 6. In addition, other mirror optics can be used in lieu of the reflecting condenser in the form of a rotation ellipsoid operating at grazing incidence. An example of such other mirror optic is a mirror arrangement of the so-called Schwarzschild type which is described, for example, on page 566 of the reference text of K. Mutze et al entitled "ABC der Optik", published by Werner Dausien (1972). It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.