Cheque fraud. Image showing how ultra violet (UV) light is used to detect cheque fraud. The upper and lower image show the same cheque (from 1965). The upper image was taken in visible light, while the lower image was taken in UV light. The lower image shows the cheque has been changed to read sixty and ?60 instead of six and ?6. The amendments were made in a different ink, whose different chemical composition means that it also has different fluorescent properties under UV light.