HOLOGRAPHY - The Science of Presenting Real

HOLOGRAPHY...….

  Holography is the science of making holograms which are usually intended for displaying 3D- images. It is a physical structure that diffracts light into an image. A holographic image can be seen looking into an illuminated holographic print by shining a laser through a hologram and projecting a image on the screen. 

• three dimensions are height, width, depth.
• also known as lens less photography.
• produces real images
• Dennis Gabor - Father of holography and Holographic techniques

Hologram #Properties

• if you look at these holograms from different angles, you see objects from different perspectives just like you would if you were looking at a real object.
• it shows divisible properties i.e., if you cut one in half, each half contains whole views of the entire holographic image.

Gabor, who invented holography in 1947, introduced the term using two Greek words: “Holos” - whole and “Graphe” -writing. It simply means that the recorded holographic image of the object contains whole optical information about the object – Amplitude and Phase information of the light scattered from the object. Ideally, the hologram is a 3D image reproduced from interference pattern recorded by coherent light beams and holography is a process of reconstructing and writing a hologram.

 White light from the sun or a light bulb is a combination of every color of light in the spectrum, which is not useful for a hologram. However, a laser shines light in a thin, intense beam which is of one color which implies that they are uniform and in-phase. When two laser beams interact, a single new wave pattern is produced: the hologram. Traditionally, holography was usually static and the application limited to displays, but with development in this science, it is used in various field of applications, including art, security, data storage and so on.

Hologram #Working...

• Laser light.....usually helium-neon(HeNe) is used.
• Beam Splitter...device that use mirrors and prisms to split laser beam into two beams.

1. Object beam 
2. Reference beam

• Mirrors.....direct the beams of light to correct locations.
• Holographic films....to record image at very high resolution
• can be seen through naked eyes
• image floats in free space.

BASICS:-

A hologram is a recording in a 2 or 3-d medium of the interference pattern formed when a point source of light (the reference beam) of fixed wavelength meets light of the same fixed wavelength arriving from an object (the object beam). Ordinary light is made up of many different wavelengths, none of which maintains a fixed phase relationship with each other or with themselves over a period of time. It has poor temporal coherence. Such incoherent light is not capable of interfering with itself, which is the most important for the application of holography. So lasers are used to produce light beams which are coherent over 10^10 wavelengths and more.

Creating hologram we requires lasers, beam splitter, photographic or hologram plate, mirror along with two process involved:-

I.RECORDING A HOLOGRAM

II.RECONSTRUCTION OF HOLOGRAM

I.RECORDING A HOLOGRAM

A coherent light from a Laser is directed onto Beam Splitter. A Beam-Splitter divides the laser beam into two identical beams, which are aimed in two different directions. The object beam is reflected by the surface of the object onto the plate. The reference beam directly falls onto the plate. So the laser beams interfere with each other. A laser light hologram is recorded.

To capture the three-dimensionality of an object, the film stores not only the amplitude but also the phase of the light rays. This recorded interference pattern actually contains much more information that a focused image, and enables the viewer to view a true 3-D image which exhibits parallax.

II.RECONSTRUCTION OF HOLOGRAM

The laser light hologram can be reconstructed by using the same laser light as for recording. In the reconstruction of hologram, the object beam and the reference beam strike the hologram plate from opposite directions.

To prevent external light from interfering, holograms are usually taken in darkness, or in low intensity light of a different color from the laser light used in making the hologram. Also, holography requires a specific exposure time, which can be controlled by electronically timing the laser. 

Applications:-

1. Optical computers will use holograms as "circuit elements". Parallel processing is made possible because when a hologram is addressed, all the information comes out simultaneously. 
2. Biomedical applications of holography is actively pursued outside INDIA. Holograms are made made inside the live organs through optical fibers, providing more information than any other previous alternate technique.
3. Compacts disk players use holograms to handle light.
4. Grocery store scanners use spinning holograms.
5. Holographic interferometry is used in numerous laboratories for non-destructive testing. It visually reveals structural faults without damaging the specimen.
6. Holographic scanners are used in store check-out counters for reading the bar codes. A rotating computer-generated hologram is responsible for both the scanning and detecting of the scattered light.
7. Holostore is a holography computer memory system being manufactured to replace your disc drive. It will have thousand time more memory capacity and no mechanical movements.
8. Video Gaming 
9. Teaching & Education

Advantages:-

1. Cost effective

2.higher storage capacity

3.increased feasibility of object

4.enables the achievement of multiple image on a single plate and give 3d images

5.ability to combine with other technologies

DisAdvantages:-

1.provide static images

2.do not produce images of complex movement 

3.requires complicated precise machinery to produce and view an image

4.reference illumination beams are collinear

CONCLUSION

Holography has proved to be a true three-dimensional photographic technique, 

which means that it’s aware of the depth of the space. Capability to record the phase information of the light is the main difference distinguishing it from traditional photography. The only way to store the phase of light is by utilizing the interference phenomenon. A coherent light source is essential to light interference, thus the breakthrough on laser technology lead to the rapid

development of holography. Holography has proved to be a true three-dimensional photographic technique, which means that it’s aware of the

depth of the space. Capability to record the phase information of the light is the main difference distinguishing it from traditional photography. The only way to store the phase of light is by utilizing the interference phenomenon. A coherent light source is essential to light interference, thus the breakthrough on laser technology lead to the rapid development of holography. In the end we saw the various applications of holography and

saw that there is a great potential which lies in it. Especially in the field of data storage, when the current technology reaches its limit, the holographic method might be the next-generation solution. Further, the growing 3D entertainment demand is also an opportunity for holography.

😇😇✌✌

"LIFE IS LIKE A HOLOGRAM. EVEN THE SMALLEST MOMENT CONTANS ETERNITY WITHIN IT"

HAPPY READING........