CONTENTSINTRODUCTIONHISTORYWHY LASER?CONSTRUCTIONWORKINGRECONSTRUCTIONAPPLICATIONSADVANTAGES AND DISADVANTAGESCONCLUSION
INTRODUCTION Holography (from the Greek) is the science of producing holograms. It is an advanced form of photography that allows an image to be recorded in three dimensions.The image changes as the position and orientation of the viewing system changes in exactly the same way as if the object were still present, thus making the image appear three-dimensional.
HISTORY Invented in 1948 by Dennis Gabor for use in electron microscopy, before the invention of the laser. Leith and Upatnieks (1962) applied laser light to holography.
WHY LASER? Lasers produce monochromatic light -- it has one wavelength and one color. Because of the need for coherent interference between the reference and object beams.
CONSTRUCTIONLaser : Red lasers, usuallyhelium-neon (HeNe) lasers,are common in holographyBeam splitter: This is a devicethat uses mirrors and prisms tosplit one beam of light intotwo beams.Mirrors: These direct thebeams of light to the correctlocations.
Holographic film:Holographic film canrecord light at a very highresolution, which isnecessary for creating ahologram. Its a layer oflight-sensitive compoundson a transparent surface,like photographic film.
APPLICATIONSIt is used for producing a three dimensionalimage.Authentication.1. Identity card.2. Passport.3. Sticker or Tag.
ADVANTAGESHolography is a high resolution three dimensional recording of an object from a limited perspective.Security: Holograms are widely used for security purpose.It is not possible to duplicate Holograms Holograms are quick and easy optical validation.
DISADVANTAGES Hard to see without good direct point source of light. Not that bright. It is expensive. Require complicated precise machinery to produce and view an image
CONCLUSION Holographic images provides viewer a 3- dimensional view of an object and they are effective in authentication purpose.