| 摘要 |
PROBLEM TO BE SOLVED: To make focal point size smaller than the electron beam irradiation region, by having an X-ray generating part of an object wavelength and a base, that hardly generates X-rays of the object wavelength in the electron beam irradiation region on the surface of a target. SOLUTION: A rotating target 10 is comprises of a base 12 of a hollow cylinder shape, made of carbon and a ring shape X-ray generating material 14. The ring shape X-ray generating material 14 is clipped between two base parts, and its thickness is very small being 1-10μm. When the electron beams 68 are irradiated on the outer circumference of the rotating target 10, X-rays of an objective wavelength are generated only from the X-ray generating material 14 (for example, tungsten) that exists in the electron beam irradiation region and these X-ray beams 70 are extracted from the X-ray take-out window 72. Accordingly, the width of the focal point size on the target becomes 1-10μm. Although X-rays are generated also from the base 12 made of carbon, they are absorbed by the X-ray extracting window 72 made of beryllium 72 and do not go outside of the X-ray tube.
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