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    SUBMITTED TO:- SUBMITTED

    BY:- MR:-BHARPUR SINGHHIMANSHU YADAV

    ROLL NO. B53

    B.TECH (ECE)

    REG NO.10906992

    SEC: C6904

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    ACKNOWLEDGMENT

    I would like to express my gratitude to all those who gave me the possibility to complete this

    term paper. I want to thank the Department of ECE of LOVELY PROFESSIONAL

    UNIVERSITY for giving me permission to commence this Term paper, to do the necessary

    research work and to use departmental data. I have furthermore to thankMr. BHARPUR SINGH

    who gave and confirmed this permission and encouraged me to go ahead with my term paper.

    I am again deeply indebted to all my friends whose help, stimulating suggestions and

    encouragement helped me in all the time of research for and writing of this term paper.

    THANK YOU.

    HIMANSHU YADAV

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    HOLOGRAPHYContents

    1. Introduction

    2. History

    3. Theory

    3.1 Interference and diffraction

    4.Working of a Hologram

    5. Making a Hologram

    6.Conventional vs. Holographic photography

    7.Applications

    7.1 Data storage

    7.2 Security

    7.3 Art

    7.4 Games

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    7.5 Other applications

    8. Reference

    1.INTRODUCTION

    Holography

    Holography (from the Greek, -hlos whole + -

    graf writing, drawing) is a technique that allows the

    light scattered from an object to be recorded and later

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    reconstructed so that it appears as if the object is in the

    same position relative to the recording medium as it was

    when recorded. The image changes as the position and

    orientation of the viewing system changes in exactly thesame way as if the object were still present, thus making

    the recorded image (hologram) appears three

    dimensional.

    1. History of Holography

    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 and introduced an important off-axis

    technique.

    2.Theory

    Though holography is often referred to as 3D

    photography, this is a misconception. A better

    analogy is sound recording where the sound field is

    encoded in such a way that it can later be

    reproduced. In holography, some of the light

    scattered from an object or a set of objects falls on

    the recording medium. A second light beam, known

    as the reference beam, also illuminates the recording

    medium, so that interference occurs between the

    two beams. The resulting light field is an apparently

    random pattern of varying intensity which is the

    hologram. It can be shown that if the hologram is

    illuminated by the original reference beam, a light

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    field is diffracted by the reference beam which is

    identical to the light field which was scattered by the

    object or objects.

    3.1 Interference and diffraction

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    The interference fringes in a hologram cause light

    to scatter

    in all directions, creating an image in the process.

    The fringes diffract and reflect some of the light

    (inset),

    and some of the light passes through unchanged.

    Interference occurs when one or more wave fronts aresuperimposed. Diffraction occurs whenever a wavefront

    encounters an object. The process of producing a

    holographic reconstruction is explained below purely in

    terms of interference and diffraction.

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    The light that reaches the holographic emulsion is just like the waves in

    the aquarium. It has peaks and troughs, and some of the waves are taller

    while others are shorter. The silver halide in the emulsion responds tothese light waves just like it responds to light waves in an ordinary

    photograph. When you develop the emulsion, parts of the emulsion that

    receive more intense light get darker, while those that receive less

    intense light stay a little lighter.

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    3.Working of a Hologram

    There are lots of different ways to arrange these tools -- we'll stick to

    a basic transmission hologram setup for now.

    1. The laser points at the beam splitter, which divides the beam of

    light into two parts.

    2. Mirrors direct the paths of these two beams so that they hit

    their intended targets.

    3. Each of the two beams passes through a diverging lens and

    becomes a wide swath of light rather than a narrow beam.

    4. One beam, the object beam, reflects off of the object and onto

    the photographic emulsion.

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    5. The other beam, the reference beam, hits the emulsion without

    reflecting off of anything other than a mirror.

    Working of a hologram can easily be understand by the

    following diagrams

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    In holography, light passes through a shutter and

    lenses before striking a light-sensitive piece of

    holographic film.

    4. Making a Hologram

    It doesn't take very many tools to make a hologram. We

    can make one with:

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    A laser: Red lasers, usually He-Ne) (helium-neon

    lasers), are common in holography. Some home

    holography experiments rely on the diodes from red laser

    pointers, but the light from a laser pointer tends to beless coherent and less stable, which can make it hard to

    get a good image. Some types of holograms use lasers

    that produce different colors of light as well. Depending

    on the type of laser you're using, you may also need a

    shutter to control the exposure.

    Lenses: Holography is often referred to as "lensless

    photography," but holography does require lenses.However, a camera's lens focuses light, while the lenses

    used in holography cause the beam to spread out.

    A beam splitter: This is a device that uses mirrors

    and prisms to split one beam of light into two beams.

    Mirrors: These direct the beams of light to the correct

    locations. Along with the lenses and beam splitter, themirrors have to be absolutely clean. Dirt and smudges

    can degrade the final image.

    Holographic film: Holographic film can record light at

    a very high resolution, which is necessary for creating a

    hologram. It's a layer of light-sensitive compounds on a

    transparent surface, like photographic film. The

    difference between holographic and photographic film isthat holographic film has to be able to record very small

    changes in light that take place over microscopic

    distances. In other words, it needs to have a very fine

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    grain. In some cases, holograms that use a red laser rely

    on emulsions that respond most strongly to red light.

    5. Conventional vs. Holographic photography

    Conventional:

    2-d version of a 3-d scene

    Photograph lacks depth perception or parallax

    Film sensitive only to radiant energy

    Phase relation (i.e. interference) are lost

    Hologram:

    Freezes the intricate wave front of light that

    carries all the visual information of the scene

    To view a hologram, the wavefront is

    reconstructed

    View what we would have seen if present at the

    original scene through the window defined by

    the hologram

    Provides depth perception and parallax

    Converts phase information into amplitude

    information (in-phase - maximum amplitude,out-of-phase minimum amplitude(s

    Interfere wavefront of light from a scene with a

    reference wave

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    The hologram is a complex interference pattern

    of microscopically spaced fringes

    holos Greek for whole message

    If we tear a hologram in half, we can still see the

    whole image in each piece. The same is true with

    smaller and smaller pieces.Though its not so in

    conventional photography.

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    6.Applications

    1. Data storage:-Holographic data storage is a techniquethat can store information at high density inside crystals or

    photopolymers. The ability to store large amounts of information in

    some kind of media is of great importance, as many electronic

    products incorporate storage devices. The advantage of this type of

    data storage is that the volume of the recording media is used instead

    of just the surface.

    2. Security:- Security holograms are very difficult to forgebecause they are replicated from a master hologram which requires

    expensive, specialized and technologically advanced equipment. They

    are used widely in many currencies such as the Brazilian real 20

    note,etc.

    3. Art:- . Holographic art is often the result ofcollaborations between scientists and artists,

    although some holographers would regard

    themselves as both an artist and scientist.

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    4. In the future, we may be able to use hologramsto do everything from watching TV to deciding

    which hair style will look best on us.

    5. Games :- various video games are based on theholography principle.Such as HALO,DEAD SPACE etc

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    6. Other applications

    Holographic scanners are in use in post offices,

    larger shipping firms, and automated conveyor

    systems to determine the three-dimensionalsize of a package. They are often used in

    tandem with checkweighers to allow

    automated pre-packing of given volumes, such

    as a truck or pallet for bulk shipment of goods.

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    7. REFERENCES:-1. WWW .GOOGLE .CO .IN /HOLOGRAPHY /PHY .COM

    2. WWW .PHYEDU .COM

    http://www.google.co.in/HOLOGRAPHY/PHY.COMhttp://www.phyedu.com/http://www.google.co.in/HOLOGRAPHY/PHY.COMhttp://www.phyedu.com/