US Patent 7983394 Multiple wavelength X-ray source

A multiple wavelength x-ray source includes a multi-thickness target, having at least a first and a second thickness. The first thickness can substantially circumscribe the second thickness. An electron beam can be narrowed to impinge primarily upon second thickness or expanded to impinge primarily upon the first thickness while maintaining a constant direction of the beam. This invention allows the target thickness to be optimized for the desired output wavelength without the need to redirect or realign the x-rays towards the target.