The problem is how to produce dynamic colors. We need a tool called grating, through which we can divide our solar light into several kinds of visible light (except purple). Also known as rainbow color.
Because the laser conforms to ① the vibration frequency of two light waves is the same; ② The two light waves have a fixed phase difference at the intersection; ③ The two light waves vibrate in the same direction at the intersection; ④ The amplitudes of the two light waves are the same. Therefore, the laser emitted by the laser can distinguish different colors after passing through the grating and can control the observation angle. Finally, the generated interference fringes are recorded on a special carrier. After development, such a unique holographic anti-counterfeiting label is produced. In industrial applications, such labels are usually copied and mass-produced. In this way, each product will carry an anti-counterfeiting label. (The specific process is complicated, so I won't go into details. )
It can be said that laser anti-counterfeiting technology is a technology to adjust light. As a result, the success rate of scanning, copying and forgery is almost zero. And most of them are exquisite, used in a lot of money and a lot of documents. For example, our ID card, driver's license, passport, Hong Kong and Macao pass and so on.