X-ray Optics

X-ray optics is the branch of optics which manipulates X-rays instead of visible light. While lenses for visible light are made of transparent materials that can have a refractive index substantially larger than 1, for X-rays the index of refraction is slightly smaller than unity. The principal methods to manipulate X-rays are therefore by reflection, diffraction and interference. Examples of applications include X-ray microscopes and X-ray telescopes. Refraction is the basis for the compound refractive lens, many small X-ray lenses in series that compensate by their number for the X-rays' minute index of refraction. The imaginary part of the refractive index, corresponding to absorption, can also be used to manipulate X-rays: one example is the pin-hole camera, which also works for visible light.