Broad Spectrum X-ray Optics

Capillary X-ray optics use hollow capillaries for controlling incident X-rays in many, varied X-ray applications. These optics are formed from a single capillary (monocapillary), or up to several million hollow glass capillaries (polycapillary) that have been fused together and tapered to desired profiles. The principle behind their operation is multiple total external reflection of X-rays along the smooth inner walls of the capillary channels. Reflection of X-ray photons occurs at the boundary between media with different refractive indices. When an X-ray strikes the reflecting surface of a capillary at a grazing angle smaller than the critical angle of the material, it undergoes total external reflection. X-rays satisfying the total reflection condition can be effectively transported through the capillary channels, and therefore formed into a desired wavefront pattern defined by the shaped profile of the optic.

One of the distinguishing features of capillary optics is their broad energy (wavelength) bandwidth. They are therefore sometimes referred to as polychromatic optics. A capillary optic collects a large solid angle of X-rays from a divergent X-ray source and redirects them into either a quasi-parallel beam, in which case the optic is known as a collimating polycapillary optic, or a focused beam, where the optic is a focusing polycapillary optic.

Characteristics of Capillary Optics: