OPTICS FOR KIDS: Science and Engineering

by Bruce Irving, Optical Research Associates

A NOTE TO PARENTS AND TEACHERS: Elementary school children might enjoy this quick look at some optical basics, especially if coupled with some experiments from the Optics Discovery Kit from OSA. There's also a bit of a pep talk on science and engineering as careers. Please share this with your kids!

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This presentation has two main points

Light Basics

Controlling Light

Why do we CARE about controlling light ANYWAY?

Lenses

Complex Lenses

Magnifying Glass: A simple optical device

White Light and Laser Light

What's Cool About Lasers?

Scientists and Engineers

Some Questions Scientists Might Ask About Light

Some Questions Engineers Might Ask About Light

Careers

Conclusions

Want to Learn More?

This presentation has two main points

FUN and LEARNING

Some fun and interesting things about OPTICS (the science of LIGHT, and one of the most important fields of PHYSICS)

SCIENTISTS and ENGINEERS

How do scientists and engineers see light? With their eyes? Yes, actually - but in other ways, too.

Light Basics

What is light?

It's a kind of energy called "electromagnetic (EM) radiation" (but this kind of radiation is not harmful, except for an occasional sunburn). There are other kinds of EM radiation too (radio waves, microwaves, x-rays, etc.), but light is the part WE can see, the part that makes the rainbow.

How does light travel?

FAST and STRAIGHT.

How FAST?

About 186,000 miles per second [300,000 kilometers per second], so light from the sun takes about 8 minutes to go 93 million miles [149 million kilometers] to earth. Does this seem SLOW? Well, if you could DRIVE to the sun at 60 mph [100 kph], it would take you 177 years to get there! In one second, light can go around the earth 7 times!

How STRAIGHT?

Perfectly straight, until something bends it. The straight paths of light are called LIGHT RAYS.

Controlling Light

There are THREE basic ways to control light:

 

1. Block it with something (this makes a shadow)

 

2. Reflect it (change its path with a mirror):

This is called REFLECTION, strangely enough

 

 

 

 

3. Bend it:

Change its direction by making it pass into another transparent material of different density, like glass or water. This is called REFRACTION, and it's how lenses work.

Why do we CARE about controlling light ANYWAY?

Well, some important, useful, and very cool "things" depend on being able to produce, control, and/or detect light in special ways:

Your eyes

Eyeglasses and contact lenses

Lenses for TV, movie, and photographic cameras

Photocopiers and fax machines

Binoculars and telescopes

Microscopes and magnifiers

Projectors (overhead, movie, slide, TV)

CD players

Supermarket product code laser scanners

Weather and spy satellites

Medical systems (to look inside the body)

Solar energy systems

...and many more (not to mention a little thing like PLANTS which use light to grow and to make the oxygen we breathe - but engineers don't make plants).

Lenses

What are lenses?

Lenses bend light in useful ways. Most devices that control light have one or more lenses in them (some use only mirrors, which can do most of the same things that lenses can do).

There are TWO basic simple lens types:

CONVEX or POSITIVE lenses will CONVERGE or FOCUS light and can form an IMAGE

CONCAVE or NEGATIVE lenses will DIVERGE (spread out) light rays

You can have mixed lens shapes too:

Complex Lenses

Simple or Complex?

Simple lenses can't form very sharp images, so lens designers or optical engineers figure out how to combine the simple types to make complex lenses that work better. We use special computer programs to help us do this because it can take BILLIONS and BILLIONS of calculations.

Camera lens

This complex lens has 6 simple lens elements - click the small picture to see the whole camera.

Zoom lens for home video camera (13 elements)

A professional TV zoom lens used to broadcast sports could have 40 elements and cost over $100,000!

Magnifying Glass: A simple optical device

This diagram (click it to see a bigger version) shows how a magnifying glass bends light rays to make things look bigger than they are. Many optical devices use the same basic idea of bending the light to fool your eye and brain so light LOOKS like it came from a different (usually larger or closer) object.

White Light and Laser Light

What is "White light?"

Regular light from the sun or from a light bulb really contains all the colors of the rainbow. But you have to split it up to see this.

Can light split???

YES! You can split up white light into its colors with a prism (raindrops act like tiny prisms when they make a rainbow in the sky, and a CD can break the light up into colors because it has fine grooves like a diffraction grating or a hologram)

So what's a laser?

A laser is a special source of light of only one pure color (or WAVELENGTH). You can't break up laser light into other colors.

What's Cool About Lasers?

FOCUS!

Lasers can be focused to a very small spot and can shine for long distances without spreading out very much (unlike a flashlight which spreads out a lot)

ENERGY!

The spot contains a lot of energy - so much that some lasers can cut through thick metal (and smaller ones are used as scalpels in some kinds of surgery)

INFORMATION!

Lower-power laser systems can be used to send and pick up information. For example,

the product code scanner in a supermarket uses a laser, lenses, rotating mirrors, and a computer to "read" bar codes from products. And the tiny laser in a CD player reads EVEN tinier bumps and holes that record the music like Morse Code (bumps and holes are used something like dots and dashes)

COMMUNICATION!

Lasers can also send information through long threads of glass called OPTICAL FIBERS. A single laser can send thousands of phone conversations through a fiber at the SAME TIME.

HOLOGRAMS!

Lasers are also used to make 3-D pictures called HOLOGRAMS (some engineers are working on moving holograms, so someday we may have AMAZING 3-D TV pictures - click here to learn more about holograms)

Scientists and Engineers

Aren't they the same thing?

Not quite. Though they use many of the same ideas and methods, scientists and engineers are somewhat different.

What do scientists want?

Scientists want to know how the universe works. They may see it as an enormous jigsaw puzzle to solve for its own sake. Some things they find are useful right away, others not (though much of what scientists have found in the past has turned out to be useful in some way). Though they certainly want to help people, their major goal is understanding, not usefulness.

What about engineers?

Engineers try to use the facts of science and math to do things that are useful to people. Many engineers are designers -- designing the many products that we use in the world, from computers to cars to camera lenses.

What do they have in common?

Quite a few things, actually. Scientists and engineers both use the facts and methods of science, and both often use MATH and COMPUTERS in their work.

Some Questions Scientists Might Ask About Light

What is light?

How is light produced by matter?

Why are things different colors?

Why is the sky blue?

Why do some things reflect lots of light and others very little?

Why are some things transparent?

How and why does light bend?

How fast does light travel?

Is light a particle, a wave, or something else?

Why does light change some materials?

Some Questions Engineers Might Ask About Light

Light lets us see things -- how can we control light to see better?

To correct poor vision? (Glasses)

To see things that are far away? (Telescopes)

To see very small things? (Microscopes)

To see in the dark? (Night vision goggles)

Light can change matter (e.g., sun turns skin red) -- can we use this fact?

To capture images of things to see later? (Photos, movies, TV, holograms)

To cut or shape things? (Laser surgery, laser drills, etc.)

To make electricity from light? (Solar cells and other solar energy systems)

Light moves fast and can carry information - how can we use this?

To get information from the world? (TV cameras, laser scanners, robot vision)

To communicate? (Optical fiber telephone systems)

To store a lot of information? (CDs, holograms)

Careers

The world needs scientists and engineers!

Scientists and engineers are important members of our society. We need science and technology to live in the modern world -- to have products we want, to communicate, to travel, to understand and protect the environment, and much more.

What do they do?

Scientists and engineers usually do a variety of things in their jobs and are usually well paid. It's not all math, computers, reading, and writing (though these are important skills). Many scientists and engineers travel for parts of their jobs (knowing a foreign language can be very useful). In the past, the majority of scientists and engineers have been men, but more and more women have been entering these fields in recent years, and there are good opportunities for anyone with a curious mind!

What about Math?

Math is important, but good reading and writing skills, common sense, curiosity, and general knowledge are also important. You need to have four or more years of college to be an engineer or scientist (most scientists and many engineers go to graduate school after college to increase their knowledge and get advanced degrees).

Other Options

Optics (optical science) and optical engineering are specialized but very useful and interesting fields, though there are many, many other areas too.

Science or engineering can be fun!

Conclusions

Optics is the science of light

Devices that control light are common and important in our daily lives

Many optical devices use lenses and lasers

Scientists and engineers use similar facts and methods (like math and computers), but their goals are different

Science or engineering can really be fun!

Want to Learn More? Books and experiments...

Your library or bookstore may have some of these books, as well as others on various aspects of optics.

LIGHT ACTION! by Vicki Cobb and Josh Cobb
(Illustrated by Theo Cobb, HarperCollins, 1993)

Subtitled "Amazing Experiments with Optics," this is a terrific book for continuing your exploration of optics. The experiments cover many of the points discussed here, but they go on to include more advanced topics such as polarization and diffraction. Experiments require only simple houshold materials and objects (suggested for grades 6 and up). Highly recommended!

LIGHT by David Burnie (Eyewitness Science Series, Dorling Kindersley, 1992)

Great photos and explanations!

Explorabook: A Kids' Science Museum in a Book by John Cassidy (Klutz Press, 1991)

Lens, mirror, diffraction grating and more for optics experiments, plus others on magnetism, bacteria, etc. -- a really cool book. This comes from the Exploratorium in San Francisco, a really great science museum.

How Science Works by Judith Hahn (Reader's Digest, 1991)

Very good optics (and other) experiments with simple home-built parts

Internet Webseum of Holography

This Web site has a lot of material on lasers and holography, with cool photos of holograms, and great information on how holograms are made. A fascinating site! The large amount of graphics may make some pages slow to load.

The Official Optics Discovery Kit (OSA)

Materials (lenses, filters, a hologram, optical fiber, diffraction grating, etc.) for various simple experiments with optics. Includes instruction booklet. Multi-kit classroom packages are also available. The Optical Society of America (OSA) can also provide information on careers in optics.

Order from:

Optical Society of America

Optics Kit Orders

2010 Massachusetts Ave. N.W.

Washington, DC 20036

Telephone: 202-416-1960

"Patterns in Nature" (Arizona State University) is an excellent Web site based largely on OSA's Optics Discovery Kit. Great graphics and explanations!

OR ASK YOUR FRIENDLY LIBRARIAN OR SCIENCE TEACHER TO HELP YOU FIND OTHER BOOKS ON OPTICS OR OTHER AREAS OF SCIENCE!

Go to Start of Optics for Kids

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