Measurements of micro-focus spot size in X-ray tubes and Kumakhov lenses

X-ray lenses and X-ray tubes that are produced at IRO in collaboration with other companies should be certified in accordance with standards. In the report, five different measurement techniques for experimental estimation of focal spot sizes in X-ray tubes are considered. They are: the pinhole, the slit, the edge, the scanning and the grid- wire methods. The same techniques can be used for experimental estimation of focal spot sizes in X-ray lenses. Some experiments and numerical simulation have been performed to estimate accuracy of the above methods. We are developing a simple and reliable wire method. The arrangement consists of an X-ray tube under investigation (or an X-ray tube and an X-ray lens under investigation), a set of W-wires with diameters from 0.03mm to 0.3mm, and X-ray detectors (the CCD- camera, scintillation or semiconductor detector). Agreement between the wire and edge methods of measurements is rather good, while three others give only rough estimations when we used them for measuring focal spots in the range from 0.01mm to 0.05mm.