In 1895 , wilhelm roentgen accidentally discovered that a cathode - ray tube could make a sheet of paper coated with barium platinocyanide glow , even when the tube and the paper were in separate rooms 1895年，威廉?伦琴偶然发现阴极射线管能使涂有一层氰亚铂酸盐钡的薄相纸发光，甚至当阴极射线管和相纸分别放在不同的房间时也能发光。
