UXI (Ultra-Fast X-Ray Imager) is a solid-state digital camera that captures a sequence of images with user-selectable exposure times as short as two billionths of a second. This is 25 times faster than has been previously achieved with digital imaging technology. The camera also uses a nearly half-megapixel solid-state photosensor array that directly records X-rays, visible light or particles. The combined high sensitivity and multi-frame capability enables a UXI camera to be used with advanced X-ray and optical microscopes for imaging transient phenomena on the microscale. The UXI was developed to enable scientists to study the heating and compression of fusion targets in the quest to harness the energy processes that power the stars.