The X-ray source in the X-ray imaging equipment used in the laboratory usually adopts the X-ray generated with accelerated electron bombardment on the metal target (as shown in Figure 1 below). This kind of X-ray is polychromatic light, which is composed of X-ray photons with different energies. Figure 2 is a typical X-ray energy spectral curve.
Figure 1. Diagram of X-ray tube reflective target
Figure 2. Diagram of X-ray tube transmission target