What is a HOLOGRAM?
Well, a hologram is like a picture. Sort of. You see, when you look at a picture -- like a photograph -- it is flat. If you took a regular picture of a big marble, and it had a smaller marble behind it, you would not be able to look around the big marble to see the little one.
With a HOLOGRAM, you would be able to look around the big marble and see the little one behind it. It's true. That's because a hologram is in 3-D. The letter "D" in "3-D" stands for the word "dimension". The "3" in "3-D" stands for how many "dimensions" something has.
A photo, a piece of paper -- or even this computer screen -- is 2-D, or two dimensions: up and down (1) and left and right (2). When something has 3-D, like the world in which we live -- or a hologram -- it has an added dimension: up and down (1), left and right (2) and forwards and backwards (3). When talking about dimensions, we call forwards and backwards "depth". So . . . when we say that a hologram has 3 dimensions, it means we can see up and down, and left and right, just like a picture or photo . . . but we can also look "into" the hologram because the hologram, and the objects that it contains, has depth.
Looking at a certain types of holograms is just like looking at something that is really in front of your eyes. In fact, some holograms are so real that you want to take your hand and touch the object in it -- but your hand goes right through thin air. Imagine getting up to get a soda while you're watching a holographic Super Bowl. When you walk across your living room, you'd walk right through the players. You could try to kick the ball, but your foot would pass right through it.
Why should I learn about holograms?
Have you ever watched an old movie on TV? Perhaps it was in black and white. Perhaps looking at it was slow and booorrrring. When you see something new on TV, it is usually made with the help of computers and is very fast and exciting. But everything gets old. Even those big-screen TV's that seem so hi-tech will one day be very boring. Why?
Well, someday everything that we look at will be holographic images. In fact, all of those "really cool" special effects that you love in the movies today . . . would you believe that someday you will actually LAUGH at them? One day in the future, 3-D holographic images will be sent into our homes and we will see all the action as if it is taking place right in our own living rooms.
Why don't we have that now?
We do not have it now because we are not as advanced in science and technology as we sometimes like to think we are. If you have an antenna, cable TV, or a sattelite dish, you know that what you watch on TV has to get there somehow. It's OK for us to send regular pictures to a TV, but we cannot send a hologram. In fact, we are not even close to being at the point where we can send a hologram and have it show up in someone's house. It's going to take a lot of clever minds (like your own) to make this happen. But it will happen. And maybe, yes maybe, you'll be part of it.
So . . . what are holograms used for? Both now and in the future?
1. With holography, we can test all kinds of things . . . from automobile engines, to aircraft tires, to artificial bones and joints. This type of holography is called "interferometry", and the resulting hologram is called an "interferogram".
2. Holography is also used in medical imaging where doctors can look at a 3-dimensional cat scan and actually go in and take measurements within the holographic image.
3. Very simple (and colorful) holograms are used on consumer packaging materials such as cereal and toothpaste boxes, and a host of other items.
4. Holograms are used for security for credit cards and for identifying manufactured objects such as clothing to help cut down on conterfeiting.
5. Holographic Optica Elements (HOE's) are used by airplane pilots for navigation. It allows them to keep their eyes on the sky or runway, while still being able to read their instrumentation . . . which appears to float in front of their cockpit window. This feature is already available as an option on several automobiles.
6. Holographic lenses and contacts can make one lens provide several different functions, such as correcting regular vision and also act as magnifiers for reading -- all in the same lens, and throughout the entire lens at the same time.
7. Holograms can be made into portraits of people, pets, etc.
8. Artists use holography to express their creativity and are shown in galleries around the world.
9. They are used in printing for magazine and book covers. National Geographic as well as Sports Illustrated (Michael Jordon) have been famous examples.
10. They can be used for point-of-purchase advertising, taking the place of a photograph of a product or service in a store or supermarket.
11. Holograms can be used for data storage such as holographic hard drives. The entire contents of the library of congress can be stored in the area the size of a sugar cube.
12. As the technology grows and develops we will see holographic television and motion pictures as mentioned earlier.
What is a LASER? And why do you need one to make a hologram?
Lasers are very simple tools. Especially the lasers that are used to make most holograms.
Do you want to know how simple lasers are? OK! I'll tell you! A laser is a very thin glass tube, about the size of a straw that you use to drink a soda. In this glass tube is a gas. Not like the gas you put in your car . . . but the kind of "gas" that the air we breathe is made of. There are two gases in most of the lasers used to make holograms. They are: Helium, pronounced: Heel Lee Um. And, Neon, pronounced: Knee Ahn. The laser is called a Helium-Neon Laser.
Now, when you plug the laser into the wall and turn it on, electricity passes through this gas and it begins to glow -- in fact, it glows just like a neon pizza sign. But remember, we have a laser. And if we have a laser, then we better have a laser beam!
The way we get a laser beam out of this tube is we take two mirrors and put them at the ends of the tube: one at one end, and another at the other end. This makes it so that light begins to bounce back and forth between the two mirrors. But WAIT!!! We still don't have a laser beam coming out of the laser!!!! Don't worry, here's how they do it:
One of the mirrors makes ALL of the light bounce off of it. But the other mirror, lets SOME of the light pass through. And the light that passes through, comes out as the laser beam. Very simple, huh?
What do LASERS have to do with HOLOGRAMS?
Right now, we still need lasers to MAKE holograms -- because only a laser can provide the special light that's needed. But we do not need a laser to VIEW a hologram. When I saw my first hologram, I was in the 8th grade and the year was 1968. Back then, you needed a laser to make and see most holograms.
Recently, we've worked out a way to get rid of the expensive gas lasers. You can now make holograms with a little laser pointer -- the same laser pointers that you see selling in stores for as little as $10! This has opened holography up to many more people than before -- even students in elementary school (just like you) are making their own 3-dimensional holograms in their classrooms and in their own holography set-up at home.
1 comment:
reference is
http://www.holoworld.com/holo/kids.html
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