A Brief Overview of the Holographic Technology

Introduction :

Holography can be defined as a unique photographic technique which records light scattered from a particular object and presents it in such a way that the resultant image appears to be three-dimensional. three-dimensional. Over the years, many different kinds of holograms have been created for use in different fields, such as the reflection ones which are used primarily for security reasons on driver’ driver ’s license, credit cards, etc. On the other hand, transmission holograms enable laser light to pass through them, so that the image can be viewed easily from the side. hey are two-dimensional surfaces which show !" images of real life objects. One does not even require to wear specially designed glasses for viewing them properly. Holograms have many different traits which are quite surprising as well as utilitarian. #or e$ample, they can be viewed from different perspectives just like real objects. %ome can even appear to be moving when an individual walks past them and views them from distinct angles. %till others are capable of changing colours and incorporating views from entire different objects, but that depends on how a person is looking at them. &f a hologram is cut into two halves, each of them contains entire views of the whole holographic image. %ame is true even for a tiny fragment cut from a whole image. &n addition to that, the hologram of any magnifying glass is capable of magnifying other objects just like the real thing.

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How Is A Hologram Made? 'aking a simple hologram does not involve the usage of too many tools. he main main item itemss requ requir ired ed are are a lase laserr, lens lenses es , a beam beam spli splitt tter er,, mirr mirror orss and holographic rear projection film. &n general, the laser points at the beam splitter which results in division of the light into two equal parts. 'irrors are used for directing the path of the two equally light rays so that they pass through the lenses. One of the rays is made to fall on the object and get reflected from it onto the proj projec ecti tion on film film.. he he othe otherr beam beam (als (also o know known n as refe refere renc ncee beam beam)) hits the film without suffering any



Diference Between Reection and Transmission Transmission Holograms :

*eflection holograms are generally mass-produced by a stamping method, and they they can can be made made almo almost st as elab elabor orat atee as thei theirr tran transm smis issi sion on coun counte terp rpar arts ts.. However, the former types are often denser than the latter. hey have e$cess physical space in order to record interference fringes, which means that they consist of more reflective surface layers where the light can hit. +s light enters the very first layer, a part of it gets reflected towards the source of the light while the remaining part penetrates into the second layer. hus, the light from ever every y laye layerr inte inters rsec ects ts with with that that in the the laye layers rs on top top of it. it. his his uniq unique ue phenomenon is called the ragg effect, a very important aspect involved in reconstruction of object beam in the reflection holograms.



Some Key Traits o Te Bragg !fect

&n addition to reconstructing the object beam, the ragg effect can also do several other things. &t is capable of altering the way holograms generally reflect light, especially those which can be viewed in white light. &t is one of the primary reasons why a novelty hologram appears greener even when created using a red laser. esides that, the ragg effect works distinctly for distinct wavelengths of visible light when viewed from different angles.

Holograms and Te "igt &n order to comprehend the formation of interference fringes on rear projection

film, it is important to know a few things about the visible light. #irst of all, light consists of high frequency magnetic and electrical waves travelling in a straight line and blocked only by obstacles. he obstacles are generally objects which which

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ormally, white light consists of all the different light frequencies travelling in all directions. On the other hand, laser light is monochromatic in nature - it is of one colour and one wavelength. hen a laser is turned on and e$posed onto a holographic plate after being directed through the diverging lenses, the two intersect intersecting ing beams form a pattern pattern of hyperbolo hyperboloids. ids. he plate plate captures captures a crosscrosssection of the hyperboloids, but the microscopic interference fringes formed cannot be understood by the human eye. &t is when monochrome light is made to pass through the image that a viewer can see a clear !" image. &rrespective of whether the interference fringes are clear or dark, they reflect some portion of the light. %ince each one of them behaves like a microscopic curved mirror, they follow the universal laws of reflection. herefore, it can be said that light creates a hologram in a way similar to that of the formation of a virtual image behind a plane mirror. mirror.

A Brief Overview of the Holographic Technology

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