Phase-contrast method for determining the size of the effective focal spot of a nanofocus X-ray tube

The work is devoted to the development of a method for testing the focal spot size of nanofocus and microfocus X-ray tubes based on phase contrast radiography of test objects. The method is based on the comparison of the interference X-ray image with the calculated values obtained by the exact numerical solution of the wave equation. The high sensitivity of the method to the size of the source is ensured by the fusion of interference fringes with contrast of different signs. The formation of X-ray phase contrast images of test objects is analyzed on the basis of the wave equation using numerical modeling of the intensity profile. An analytical expression has been obtained to estimate the size of the X-ray tube focus. The results of calculations of phase contrast profiles for a nylon fishing line and a reference nanofocus test are presented.