HOLOGRAPHY

HOLOGRAPHY:
Holography is a technique which enables three-dimensional images (holograms) to be made. It involves the use of a laser, interference, diffraction, light intensity recording and suitable illumination of the recording. 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.

The holographic recording itself is not an image; it consists of an apparently random structure of either varying intensity, density or profile.

3D DISPLAY

HOW HOLOGRAPHY WORKS:


Close-up photograph of a hologram's surface. The object in the hologram is a toy van. It is no more possible to discern the subject of a hologram from this pattern than it is to identify what music has been recorded by looking at a CD surface. Note that the hologram is described by the speckle pattern, rather than the "wavy" line pattern.
Holography is a technique that enables a light field, which is generally the product of a light source scattered off objects, to be recorded and later reconstructed when the original light field is no longer present, due to the absence of the original objects.[24] Holography can be thought of as somewhat similar to sound recording, whereby a sound field created by vibrating matter like musical instruments or vocal cords, is encoded in such a way that it can be reproduced later, without the presence of the original vibrating matter.

WORK OF HOLOGRAPHY

Holography vs. photography:

Holography may be better understood via an examination of its differences from ordinary photography:

COMPARISON BTW HOLOGRAPHY AND PHOTOGRAPHY

A hologram represents a recording of information regarding the light that came from the original scene as scattered in a range of directions rather than from only one direction, as in a photograph. This allows the scene to be viewed from a range of different angles, as if it were still present.

A photograph can be recorded using normal light sources (sunlight or electric lighting) whereas a laser is required to record a hologram.

A lens is required in photography to record the image, whereas in holography, the light from the object is scattered directly onto the recording medium.

A holographic recording requires a second light beam (the reference beam) to be directed onto the recording medium.

A photograph can be viewed in a wide range of lighting conditions, whereas holograms can only be viewed with very specific forms of illumination.

When a photograph is cut in half, each piece shows half of the scene. When a hologram is cut in half, the whole scene can still be seen in each piece. This is because, whereas each point in a photograph only represents light scattered from a single point in the scene, each point on a holographic recording includes information about light scattered from every point in the scene. It can be thought of as viewing a street outside a house through a 4 ft x 4 ft window, then through a 2 ft x 2 ft window. One can see all of the same things through the smaller window (by moving the head to change the viewing angle), but the viewer can see more at once through the 4 ft window.

A photograph is a two-dimensional representation that can only reproduce a rudimentary three-dimensional effect, whereas the reproduced viewing range of a hologram adds many more depth perception cues that were present in the original scene. These cues are recognized by the human brain and translated into the same perception of a three-dimensional image as when the original scene might have been viewed.

PHOTOGRAPHY

A photograph clearly maps out the light field of the original scene. The developed hologram's surface consists of a very fine, seemingly random pattern, which appears to bear no relationship to the scene it recorded.

HOLOGRAPHY

 In photography, only intensity is recorded  so photography produces two dimensional picture of the  object whereas in holography, both intensity as well as phase of light wave is recorded, thus holography gives three dimensional picture of the object.

 Negative is prepared first in photography whereas in holography no negative is required. The hologram is negative and image  it gives is positive.

If  the  hologram  is  broken  into parts, each part is capable of reconstructing the  entire object. But in photography the destruction of even very small portion of negative or photography results in a irrepareable loss of information.

 Holography has high information capacity as compared to photography.

Applications for Holography

In the past technologies have filtered down to hundreds of areas of life. In the same way 3D holography could spell sweeping changes for the future:

In the living room: bringing full color, holographic 3D images in HDTV comparable quality

With the www and computers now an every day part of so many aspects of home communications, SeeReal technology dovetails perfectly with today’s technological developments: content can be read from computer hard drives, DVD or straight off the Internet.

In the office and development departments: providing realistic images to boost business performance

SeeReal holography is ideal for CAD/CAM applications, allowing designers and engineers to convert ‘true’ 3D content into even ‘truer’ moving 3D simulations. Not only can output now be assessed in real time, but companies can also give clients life-like product demos and show samples in all corners of the globe. Standard stereo content can be converted into true holographic 3D.

PCs and game parlours

Who knows what the future holds, but with interactive applications and real-time gaming already exploding worldwide, the potential avenues for SeeReal holography to open up in this technology field could be boundless. Adventure becomes real life. Action really makes hearts beat.