Frank DeFreitas Holography | Allentown, PA | Phone: 610-770-0341
The Science of Holograms for Kids
Updated 29 March 2013
ABOVE: This short video will show you how you can see a hologram from many different sides, as if you were looking at the real object sitting in front of you.
By arriving here, you have found the original "kids page" for the science of holograms on the Net. The following information is taken from my classroom booklet "Introduction to Holography", which was used by my students at The Franklin Institute in Philadelphia, Pennsylvania. You have my permission to print and use this page for reports. Please give credit to holoworld.com. And don't forget to take the HoloKids quiz at the end. You can then print out your very own HoloKids certificate!
To start off, I'd like to give you an idea of what lasers and holograms are. Ready? Okay! Let's GO . . .
Do you think that holograms are only for big kids and adults? I say "no they're not"! I have visited many elementary and middle schools bringing lasers and holograms to students just like you. Holograms are going to be a big part of your future someday. And I hope that with this page, I can help you learn a little bit about them.
What is Holography?HOLOGRAPHY is the science of making a three-dimensional image of an object using the special light from a LASER. Unlike photography, which only records the brightness and contrast of an object, a HOLOGRAM records brightness, contrast and DIMENSION. This allows holography to display the final image in true 3D. It is the most accurate 3D image in the world today. You do not need any special glasses to view a hologram. Although the hologram is most famous for 3D images, holograms can also be of a 2D image as well. What both share in common is that they were created through the use of a LASER.
BUT DID YOU KNOW THIS??? . . .
Get ready for news that might surprise you: holograms do not have to be 3D. That's right! In fact, in 2012, many of the holograms produced do not have anything to do with 3D at all. You see, there are many technical and scientific uses of holograms that are not related to 3D images. One type of use is for what are called "holographic optical elements" or "HOE's". These types of holograms usually do not contain any type of object image at all. They are used to alter and direct light in some special way. Other types of non-3D holograms would be holographic diffraction gratings, and even holographic data storage. Some day soon, and in some cases already today, when you store your photos and documents in "the cloud", your information is actually being written to hologram storage drives. In other words, your data (or bits and bytes of information) is written to a hologram that stores the information just like the old hard drives or CD or DVD drives, but at much greater capacity. So please remember this: holograms do not have contain 3D images. You won't find many web sites mentioning this fact, but it is a very important fact for any young scientist and technician!
Early History of Holograms
The first hologram was conceived of, and produced in 1948 by Dr. Dennis Gabor, a researcher at the Imperial College of London. For his theories and work, he received the Nobel Prize in physics in 1971. Gabors early holograms were created without the use of a laser, since the laser wasn't invented until 1960. Therefore his holograms were only capable of showing the slightest amount of depth (about the thickness of a postage stamp). His light-producing instrument was a very highly-filtered, mercury-vapor lamp.
The Invention of the LASER
With the invention of the laser in 1960, researchers finally had the proper type of light to begin recording an object dimensionally. Emmett Leith and Juris Upatnieks in the United States (University of Michigan), along with Yuri Denisyuk in the former Soviet Union, all familiar with the work of Gabor, applied this special new light of the laser to produce the first practical holograms in 1962.
These early holograms required a laser to both record and view the image. It wasn't long however, before new techniques allowed the hologram, although still requiring a laser to record, to be viewed with ordinary light (such as a light bulb). Also, many different types of holograms were developed, each with their own technique used to produce them.
The excitement of viewing a hologram is only exceeded by the thrill of actually making one. Today, in 2011, it is fairly easy to make small holograms using inexpensive and easy-to-find equipment. Students from elementary school to high school are making holograms. The expensive lasers of the past have been replaced by the inexpensive laser pointers of today. You'll find a lot of information here at holoworld.com about making your own holograms. And, if I may take the liberty of saying so, I wrote the world's #1 selling book: Shoebox Holography. So you're in the right place.
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 are able to look around the big marble and see the little one behind it. Its true. That's because a hologram is in 3D. The letter "D" in "3D" stands for the word "dimension". The "3" in "3D" stands for how many "dimensions" something has.
A photo, a piece of paper, or even this computer screen, is 2D, or two dimensions: (1) up and down, and (2) left and right. When something has 3D, like the world in which we live, or a hologram, it has an added dimension: (1) up and down, (2) left and right, and (3) forwards and backwards, or 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 television show. When you walk across your living room, you'd walk right through the actors!
How are HOLOGRAMS made?
Holograms are made in laser laboratories, but they are also made in homes and schools every day. There are a few important things that need to be done before you can make a hologram, but none of those things are very hard to do. To give one example, a hologram must be made in a very quiet and darkened room. That's not too difficult, right? It is beyond the scope of this simple web page to go through the entire process step-by-step, but if you look at my main web page, you'll find other areas of HoloWorld that will help you better understand how a hologram is made. Step-by-step. For now, we'll just say that simple holograms are made using a laser, a lens, and a recording medium, such as a light-sensitive film or glass plate.
Why should you learn about HOLOGRAMS?
Have you ever watched a really 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?
How will HOLOGRAMS be used in the future?
Well, someday everything that we look at will be holographic. 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, 3D 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. There will also be holographic medical imaging, and a host of other uses. One could say that just about any type of image today, will be a holographic image tomorrow. I have a list (below) of ways that holograms will be used in the future.
Why don't we have holographic TV?
We do not have holographic TV 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 satellite dish, you know that what you watch on TV has to get there somehow. Its OK for us to send regular pictures to a TV, but we cannot send a hologram. In fact, even in 2011, 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 is 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!
A LASER illuminates a 3D Hologram of chess pieces in the author's laboratory.
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 (because the 3D image is made entirely out of light).
3. Very simple (and colorful) holograms are used on consumer packaging materials such as cereal and toothpaste boxes, and a host of other items. This increases their attraction on the supermarket and store shelves.
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 Optical 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 art galleries around the world.
9. Holograms are used in printing for magazine and book covers. National Geographic (American Eagle) 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. It appears as if the product is right in front of you.
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 LIGHT? And why is it important with HOLOGRAMS?
In order to understand a hologram (and how to make one), it is also important to understand light. Why? Because the holographic image is made up entirely of light.
What is light? The truth is, no one really knows for certain. Much of light still remains a mystery. One of the problems in trying to find out is that we cannot actually see it. What we see is the *effect* that light produces by hitting an object and bouncing back to our eyes. This is called "reflection". But where is the light? Part of the difficulty in detecting and measuring light lies in its speed. At 186,000 miles per second, and never ever at rest, it is hard to get a hold on it! But what we do know about light gives us enough information to make holography possible.
One of the more common instruments we use to produce light is the lightbulb. An ordinary household lightbulb produces light that we perceive as primarily white light. This is because, in actuality, the bulb is producing many different colors (or wavelengths) at the same time which, when combined, produce white. The light is also traveling away from the lightbulb in many different, random directions. There is very little structure or uniformity in each of the colors or waves. We call this type of light "incoherent" light. Incoherent light is incapable of producing any holographic image (a hologram).
To produce a hologram, we need a light source that produces what is known as a "coherent" type of light. The requirements needed for a source of light to be considered coherent is that the light is of a single frequency and wavelength. Prior to 1960, there were no known sources of true coherent light that could provide great depth in a hologram. The introduction of the LASER changed all this.
What is a LASER? And why is it important to HOLOGRAMS?
This computer drawing of a working laser is from 1994.
Back then, the Internet was just starting to show images!
(we didn't have images on the early Internet -- just text!).
Laser light is a special type of light. First, it is what is known as monochromatic, or one single color or wavelength. Second, and as mentioned already above, it is coherent, or all of the waves are traveling out of the tube in a very controlled and uniform manner.
The bottom line is that lasers are very simple tools. Especially the lasers that are used to make most holograms. 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 (called reflection). The other mirror, while reflecting MOST of the light back into the tube, lets SOME of the light pass through. And the light that passes through, comes out as the laser beam. Very simple, huh?
Why do you need a LASER to make a HOLOGRAM?
Right now, we still need lasers to MAKE holograms, because only a laser can provide the special light that is 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 a hologram, and you also needed a laser to see most holograms.
Recently, you can now make holograms with a little laser pointer. The same laser pointers that you see selling in stores. 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.
In ClosingYou are the generation that will see holograms become an everyday experience. They will be present from entertainment, to saving someone's life through holographic medical imaging. Perhaps one day you will become involved with holograms yourself. If you do, I hope that you remember your short time here at the HoloKids web page! However, regardless of what it is that you choose to do, I want to wish you the very best of luck in your journey through life. I always like to remember a quote by President Abraham Lincoln. It goes like this: "Whatever you are, be a good one."
One last VERY important message . . .It is very important that you realize that the Internet is filled with misinformation about holograms and what they are. Not just a little bit of misinformation, but a LOT of misinformation. Just because something is 3D, does not mean that it is a hologram. The ONLY time that something can be called a TRUE hologram, is when it is created using the science and technology of HOLOGRAPHY, a Nobel Prize-winning field of study. Then, and only then, can it be a hologram. So . . . beware, okay?
Are You Ready for the Hologram Challenge Quiz?!?!
Well, that's it for now. I hope you learned some cool things about lasers and holograms! If you would like to receive an online certificate that you can print out, you may now take the 10-question HOLOKIDS ONLINE QUIZ. You do not need to provide ANY personal information at all. Good luck!
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