Invisible Ink Marking Detection Glasses are used in poker gambling to detect invisible marks on playing cards. The invisible markings are printed on the back surface of a card and are invisible to the naked eye. However, they can be made visible by using UV illumination and a CCD camera installed with an infrared (IR) filter. Using these tools, cheating players can gain an advantage over their opponents by knowing their hand strength and the probability of winning.
There are many different methods of making invisible ink visible, depending on the type of ink. Inks that are developed through a chemical reaction may be revealed by heat, reaction with phenolphthalein, or viewing under ultraviolet light. Other invisible inks are made visible by absorbing light of a particular color, such as infrared. In this case, the invisible ink is visible only when illuminated by a narrow band IR source such as our XNite 715nm filter and viewed with an IR sensitive camcorder or camera.
Special security marker pens can be purchased that produce invisible ink for marking metal, plastic, or paper that appears clear under black light. These are often used for property identification and other applications that require invisibly marking a surface for later inspection under blacklight. Invisible ink can also be applied to skin and other surfaces and is useful for identifying individuals, marking admission into nightclubs or other events, and even for tagging or identifying items for ownership, quality control, and assembly control.