Seeing elements by visible-light digital camera

A visible-light digital camera is used for taking ordinary photos, but with new operational procedures it can measure the photon energy in the X-ray wavelength region and therefore see chemical elements. This report describes how one can observe X-rays by means of such an ordinary camera - The front cover of the camera is replaced by an opaque X-ray window to block visible light and to allow X-rays to pass; the camera takes many snap shots (called single-photon-counting mode) to record every photon event individually; an integrated-filtering method is newly proposed to correctly retrieve the energy of photons from raw camera images. Finally, the retrieved X-ray energy-dispersive spectra show fine energy resolution and great accuracy in energy calibration, and therefore the visible-light digital camera can be applied to routine X-ray fluorescence measurement to analyze the element composition in unknown samples. In addition, the visible-light digital camera is promising in that it could serve as a position sensitive X-ray energy detector. It may become able to measure the element map or chemical diffusion in a multi-element system if it is fabricated with external X-ray optic devices. Owing to the camera's low expense and fine pixel size, the present method will be widely applied to the analysis of chemical elements as well as imaging.