A multiple wavelength X-ray source includes an electron-generating cathode and an anode with multiple target regions, each of which emits X-rays at a different characteristic wavelength in response to the electrons. The different X-ray radiation outputs are focused by different focusing sections of a focusing optic. The multiple focusing sections are in different respective locations, and each focuses its respective X-ray radiation onto a sample. The focusing sections may be side-by-side mirrors in a Kirkpatrick-Baez configuration, or in a single-bounce, doubly curved elliptical configuration.