Holograms
I still remember the first time I saw a hologram. One could feel the energy change in the crowd. It wasn’t a large cheer or a change in volume, but one could feel everyone holding their breath, wondering, hoping, for that split second that it could be real. This experience took place when I saw Michael Jackson’s ONE in Las Vegas 3 years ago. Still one of the best shows I have ever seen, Michael Jackson’s ONE by Cirque du Soleil immerses the audience into the world of Michael Jackson. Through amazing sound and lighting, ONE takes you on an adventure that nobody can ever forget. One of these amazing lighting techniques is the use of holograms. In the second act, Michael Jackson appears through a mist of gold dust and starts to perform his smash hit “Man in the Mirror”. Throughout his performance Michael Jackson does a variety of moves such a stomping on the stage or dropping to one knee. All of which add to the illusion and leave some people questioning whether or not it is more than just an illusion.
Holograms are not a new technology, however. In 1947, a British scientist names Dennis Gabor developed the theory of holography while working to improve the resolution of an electron microscope. Gabor came up with the word hologram from the Greek words holos, meaning "whole," and gramma, meaning "message." (Khan). After Gabor had published his findings on holograms, many scientists started experimenting on their own with them. In the early years, the mercury arc lamp was the mainly used light source available for making holograms. Because of the low coherence of this light, it was not possible to produce holograms of any depth, thus limiting research. This all changed in 1960 however when the laser was invented. The laser’s light, which was pure, high intense light, was perfect for making and sustaining a hologram. In 1962 Emmit Leith and Juris Upatnieks created the first laser 3-D object. After reading Gabor’s research on holograms, they decided to start their own research. Their final product was the first ever 3-D laser hologram, a toy train, and bird. In 1971, Dr. Dennis Gabor was awarded the Nobel Prize in Physics for his discovery of holography in 1947. (David).
The technology to create a hologram is relatively simple. First, you need a laser and an object you wish to turn into a hologram. Like taking a photograph, creating a hologram is done by bouncing light off an object onto a photographic plate. However when creating a hologram, one needs to be able to capture depth unlike in a photo. This is done by splitting the laser into two. The first part is still bounced off an object onto a plate but the second laser is used to capture depth. It is called the reference beam. The beam captures the depth one seeing in a hologram and encodes it on the photographic plate with the rest of the image. Once this is complete, all you have to do it take the original laser and shine it on the plate. This actually reverses the process and creates the image in a 3D state. In the past year, researchers have been able to create 3D touchable holograms. These researchers from Aerial Burton in Japan, have discovered a solution of speeding up the lasers used for holography so that the holograms are safer to touch. They have employed the use of femtosecond 1Kh infrared lasers that fire up in one second. The user feels an impulse on the finger as if the light has physical substance," (David). This is done in two steps. First, the infrared pulsing laser is fired at a spatial light modulator. This spatial light modulator divides the laser into small focal points. Then the focal points are put through a 3D scanner that shots the hologram into the air. This technology has not yet been integrated into live entertainment, but the applications are limitless.
Holography is a very diverse field and what people know of it as the technology that enables man by recording and displaying 3-D images is just one of the applications it serves. The progress in their invention has lead to the development of Holographic Optical Elements (HOE) which can act has mirrors, lenses, grating and combining all these they can serve other functions as well. Holography can help to develop a myriad of other technical devices which are implemented in various fields of work. Moreover, the latest use of Holographic interferometry is a technological advancement through which microscopic displacements of particles on an object’s surface can be measured, and also, it can be used to find out minute changes in the index of refraction of various kinds of transparent matter like heat waves and plasma. (Jeong 381).
Based on their function there are two main types of holograms. One is called the Refection hologram. It is used to display a true 3-D image which appears near the surface of the hologram and it is also the most common type of hologram that is seen around commonly in galleries and other art features. The source of illumination in this hologram is a spot of radiant, white light which is when held at a specific angle and distance from the viewer, it portrays a holographic image. Therefore, the image that is formed is being reflected from the hologram. The recent most developments in these kinds of holograms are the use of various colors in their reflection and the improvement of the image being reflected so that it is seen as a separate and distinguished image to the viewer. (Jeong 382). Moreover, if the reflection of the hologram falls on a mirror, then the mirror reflects white light. If the object is a diamond, then the holographic image appears to ‘sparkle’ like a diamond. An example of such kinds of holograms and their application in the representation in the present day is the eagle that is present on a VISA card which can be viewed with the help of reflected light. These are however transmission holograms that have a layer of aluminum on the back which makes it ‘mirrored.’ (Jeong 383).
The other kind is the transmission holograms. This kind of a hologram makes use of laser technology. The laser is used to make the recording. In order to produce the holographic image, light is reflected from the back of the hologram and then it is transmitted to the place where the observer is located. The image that is virtual and unreal, on the contrary, appears very sharp and real. These kinds of holograms can be used to produce images that can make a room full of people appear in one place as though they are present in a window. Moreover, if the holographic image is broken down into many pieces, like placing a paper with holes in it on top, then every hole will emit the same kind of image at every place the light from the hologram falls. However it depends on where the hole is present, the image can differ accordingly. Also, if a diverged laser beam moves opposite to the direction of the reflected beam, then the hologram can actually produce a real image on the screen where the object is originally present. (Jeong 384).
Between reflection holograms and transmission holograms, there are hybrid holograms as well. These are actually variations of the above two, and they serve various purposes and perform their functions differently as per their type.
First are the embossed holograms. These are present to serve security purposes and to show the originality of various objects like the symbol of the eagle present on a VISA card. It is made by pressing a 2-D interference pattern on top of plastic foils. High temperature and pressure make the holographic image to get embossed or embedded into a material. (Jeong 384).
Then there are integral holograms. These are used to form stereoscopic images. When the image of the hologram is formed on an LCD, the next view of the hologram is recorded on a strip that is adjacent to the original. Therefore, when the finished image is produced, it shows different images from the left and right eye which mean a stereoscopic image is formed. Computer software in the present day is widely used for manipulation and changing images that are recorded. (Khan).
The other kind is the multichannel holograms. They have an inner application of being used inside computers when the light is changed on the surface that allows observing different scenes. It can help to handle and compute large computer memories.
Holograms have various applications in the present day. Not only are they used for entertainment purposes but they are also employed for safety and security and perform various tabulating purposes. Such as the bar code readers in supermarkets and stores make use of holograms. HOEs are used by pilots for navigation in the air. The field of medicine is making the most of them whereby doctors use holograms to produce holographic CAT images to perform surgeries, and it is also used in medical education for students. They can also make an archival recording of artifacts and old paintings present in museums thus preserving their originality and preventing fraudulent activities.(Khan).
Work Cited
Jeong, H. Tung. “Basic Principles and Applications of Holography.” Fundamentals of
Photonics. 381-385. N,d. Web. 19 Feb 2016.
Khan, Javid. “Biomedical Imaging: 3-D digital holograms visualize biomedical
applications.” Laser Focus World. N,p. 2013. . Web. 19 Feb 2016.
Nield, David. “Researchers create holograms you can touch using high-powered lasers.”
Science Alert. N.p. 2015.Web. 19 Feb, 2016
