Puzzling color code method of rainbow holograms

Abstract

A special code rainbow holography is presented. By dividing the code image and recording with special method the rainbow holograms which can hardly be counterfeited have been obtained. iINTRODUCTION The optical holography is an important means in security and anticounterfeiting . Up to now some secu. rity methods ofhologrophy have already been proposed. In these methods embossed rainbow hologram tech. nique is the main means. However with the popularity and improvement of rainbow holography emulating and counterfeiting of the holograms which contain information about simple images is quite possible. In this paper a new puzzling colour code method ofrainbow holograms is presented. . THEORY The puzzling colour image makes up of a obct image which is constructed with a certain colour spots and a large number of other colour noise spots used for feigning. When we make the hologram we divide the background noise spots used for feigning as well as the object image which is going to be coded into several parts and record each part on the same recording film with different angle of reference beam and corresponding different slit position respectively so reconstruction conditons are restricted seriously by recording conditions. Under common reconstruction conditions except for getting some colour spots in disorder in dif. ferent viewing direction one is unable to obtain the complete coded object image in distinguishable. This is called puzzling colour code method. . EXPERIMENT