As a child we all have played with those 3D stickers and even with holograms that used to come in the books. And always wondered about how these are made? How is it possible that we are able to see the image only when we tilt it at angle of light? Who invented them?
But did anyone of you ever thought that, that simple technology being used for fun could become an integral part of our day to day work? Or that could lead to a latest invention in it like Headtops by Windows. This blog is about the basics of Holography Technique and the present use of it.
What is Holography and Hologram?
Holography is a technique of producing a Three Dimensional image of the object. The three dimensions included in it are Height, Width and Depth. In a lay man language, we can say, it is a 3D image produced on a 2D surface which gives us the information of the surroundings of the subject.
The image produced through holography technique is called as hologram. Holograms are such photographs that never die. If the hologram is cut into pieces, then every piece would be able to produce the whole picture. We can see many examples of holograms around us, on the currency notes, on the ID cards, on the CDs and DVDs, on software packaging, on the packets of electronic instruments and much more. Holograms were invented to stop forgery, but didn’t become a very effective practice.
Looking to Start
Holography dates back to the year 1947. Hungarian Physicist, Dennis Gabor, was the first one to present the foundational concepts on Holography in a patent. He gave these concepts while working on improving the image producing capability of electron microscope. His idea was to a take the image using the streams of electrons or the light of single color rather than normal light. But at that time there was no such instrument, so he could not proceed further in his research. This became possible after the invention of Laser Lights in the early 1960 and the first 3D image was produced. After that it took some pace in its development of different types and use. Till 1970’s and 1980’s the static holography had been quite much in boom but it didn’t stand up to the expectation as were seen the science fiction fantasy movies like Star Wars and Iron Man. But from 1990’s onward the research on it almost became dormant and limited to the US and Japan military research works. But the recent invention of Headtops by Windows has opened up new horizons for Holography.
Working Technique to make Hologram
Holography is based on the principle of Interference. Interference is the phenomenon that occurs when the two waves meet while travelling through the same medium. For holography we need light of single color such as laser light, an object to be captured and a recording medium with the proper materials.
To make the hologram a laser beam has to be reflected off the object we want to capture. The process is to split the laser beam into two separate halves using the Half Mirror. One beam is targeted to the object after it bounces off a mirror and reflects onto the plate on which the image has to be captured. This is called as the Object Beam. The other half of the laser beam is bounced off the other mirror and targeted on the same photographic plate. This is called as the Reference Beam. A hologram is formed where the two beams meet up in the plate. The information or the image of the object is burned permanently into the photographic plate by the laser beams.
Types of Hologram used in Holographic Art:
There are many types of holograms. But the basic types of hologram classification depending on the method of development are as follows:
- Transmission Holograms: The transmission hologram is viewed with laser light, usually of the same type used to make the recording. This light is directed from the behind the hologram and image is transmitted to the observer’s side. The virtual image can be very sharp and deep. If an undiverged laser beam is directed backward through the hologram, a real image can be projected onto a screen located at the original position of the object.
- Reflection Holograms: It is the most common type of Hologram, in which the 3D image is seen near the surface of hologram. These could be in single color or multicolor. The hologram is illuminated by a spot of white incandescent light, held at a specific angle and distance and located on the viewer’s side of the hologram. Thus the image consists of light reflected by the hologram.
- Computer Generated Holograms: By developing an application which works on the algorithms of Holography we can generate the holograms varying as per our imagination. Three important parameters of holography are the light source, the hologram and the image. By feeding two parameters, third would be calculated on its own. This has become a sub branch of holography which is growing rapidly.
Till now the use of this technology has been confined to the static images only. Applications of holography in the dynamic domain has begun in this decade. And we would see many gadgets with this technique. This was the article about the basics of holography. In the subsequent articles on holography we would tell you how we are predicting the future of Holography. More about the Headtops and HoloLens and there face in future.