COVERT LASER READABLE (CLR) IMAGE

An image in a hologram that is invisible to the naked eye and cannot be viewed with a microscope. It is visualized in laser light with the help of special devices. It is formed when recording a hologram image using the method of 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 1 micron in depth. A laser beam, directed perpendicularly to the surface of this area, is reflected from microrelief elements and forms an image on the device screen.

     


Scheme of observing a covert laser readable image. Incident laser beams (red arrows) and reflected laser beams (green arrows) visualize CLR images


              a
 

                                   b



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a — Paper substrate;         

b — the same. Area of CLR image location on the hologram (marked with a frame); 

c, d, e — CLR images observed when exposed to a green laser 532 nm. Revealed by the visualizer of CLR images in holograms Regula 2305


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