Wednesday, November 15, 2017

A security mark (an image, symbols or text) which is invisible to the unaided eye and under a microscope. The image is visualized in laser beams with the help of special devices. It is formed when recording a hologram image using the method of the electron-beam lithography. A covert laser readable image is an area on the hologram surface which has specific microrelief of 1 micron in size and less than a micron in depth. A laser beam which is perpendicular to the surface of this area reflects from microrelief elements and forms an image on the device screen. This is visualize at a laser beam of 532 nm (ID cards)





No comments: