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·伦琴偶然发现阴极能使涂有一层氰亚酸盐钡的薄相纸发，当阴极和相纸分别放在不同的房间时也能发。