Answer: holograms

AnswerCrossword Clue
HOLOGRAMSMost of them are monochromatic
HOLOGRAMSSome credit card security features
HOLOGRAMSThings seen that aren't there
hologramsHOLOGRAM, a three-dimensional photograph
hologramsA three-dimensional image formed by the interference of light beams from a laser or other coherent light source
hologramsA photograph of an interference pattern that, when suitably illuminated, produces a three-dimensional image