Methods and devices for aligning an x-ray optic with a source of x-rays and methods and devices for determining a focusing characteristic of an x-ray optic are provided. The methods and devices simplify the process of aligning an x-ray optic device (for example, a polycapillary x-ray optic) to an x-ray source or for measuring a focusing characteristic, for example, the focal length or beam shape, of an x-ray optic. In one aspect, the device includes a housing having a first aperture adapted for receiving an x-ray optic and a surface having an x-ray flourescent material from which visual fluorescence occurs when impinged by x-rays. The size and shape of fluorescence from the surface may be varied by moving the surface to determine, for example, the focal length of the x-ray optic.