The influence of aperture on the imaging quality of microfocus x-ray source

Electron beam (e-beam) with a small spot size is the key to produce microfocus x-ray source. The spot size of the e-beam can be controlled by changing the aperture angle at the target, and the focus size of the microfocus x-ray source is changed accordingly. At the same time, the SNR (Signal-to-Noise Ratio) of the image is reduced because the aperture produces secondary x-ray, which interferes with the x-ray imaging. In this paper, the aperture size and its position are optimized for getting the smallest spot size of the e-beam, and the experimental results show that the resolution is 0.8 mu m with the aperture size of 0.5 mm. In addition, this paper also presents that the image's SNR can be improved by coating carbon film on the back surface of the aperture.