The list of practical applications
for the laser is growing rapidly. Laser's properties have practical uses
in measurement and are used by many people from surveyors to machinists.
When engineers were constructing the Bay Area Rapid Transit system,
lasers were used to line up the dredging equipment for the underwater
tunnel in San Francisco Bay. Laser beams have also been bounced off
reflectors on the moon to provide information about the movement of the
Earth's crust. Eye surgeons use lasers to "weld" detached
retinas back into place without making an incision. The laser is simply
brought to focus in the region where the welding is to take place.
Lasers are used to measure the speed of light in a laboratory. They can
also measure distances on a street or movement along an earthquake
fault. In grocery stores, the bar code pattern is read by a laser to
decode the price of the product. Nearly all major sewer pipe and storm
drain pipe installations are aligned using helium-neon lasers. In the
auto business, lasers are used for wheel alignment. In biology, lasers
are used to measure blood cell diameter. The applications are unlimited.
Lasers are also used to make
holograms. Holograms are three-dimensional pictures, which when
illuminated, produce images so realistic that the sides of objects can
also be seen. Let students observe how a hologram is made when laser
light is used to take a picture of an object. Laser light is projected
on a photographic plate to produce these images.
Helium-neon lasers are the cheapest
visible light presently available and is used in a supermarket scanner.
The laser is scanned across a bar code on a package which is detected by
the laser as 0 and 1. This is a language the computer (cash register)
can interpret to represent the price of the package. Semiconductors are
also used to produce lasers with invisible light. Home entertainment
systems use the optical disc to provide digital audio or video signals.
Information is stored by using a laser beam to punch a series of holes
in reflecting layers. In the disc player, a semiconductor laser output
is reflected from the disc to a detector. The pattern of holes is
converted to a digital signal that contains the coded audio information.
Semiconductors also are used in laser printers. Carbon dioxide lasers
are used for cutting and heating. Argon lasers are used in the medical
profession.
PROCEDURE:
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Show students the
different holograms. These were all created by different lasers. If you
view them in natural light, the holograms stand out more.
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Talk about the
uses of lasers. Lasers are used in the grocery store to cutting steel.
Use the Internet to search for companies that use or produce lasers.
Search under "laser" for general information in the
"adult" search engine, like http://www.yahoo.com.
Students will find a host of products that use laser technology. Have
them list the products that they find on the worksheet. Laser technology
changes rapidly, with new products being developed all the time. Make
students as familiar with lasers as you can. They are in your students'
future.
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On the worksheet
it shows the how lasers are used in making holograms, which is just a
"3D" picture on a piece of holographic film. Taking the
picture is more involved than using a camera. The laser helps to define
the object better. Show students the different holograms, which are
created through different film.
