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Ask your parents if they can show you a
laser pointer. Get them to shine it on a wall
on the far side of a room.
Watch the spot that the laser makes on the
surface. Can you see little “speckles” of
light and dark areas? This is called a speckle
pattern and it is created by the interference
of the laser light as it bounces off the
surface.
Move around. Does the speckle pattern move
too? If you wear glasses, take them off and
view the spot. Which way is the speckle
pattern moving now?
Supermarket
Sweep
Blip! Blip! When you are next
in the supermarket, find the
barcodes on your shopping.
At the checkout, watch how a
cashier uses a Barcode Scanner.
Barcode scanners use a laser light
that is scanned back and forth very
quickly so that it appears as a red
line or curved pattern to your eyes.
A sensor measures the strength of the
light reflected back from the black and
white barcode pattern, generating a signal
that is used to measure the widths of the bars
NA SA /JPL- altech
C
and spaces in the barcode.
SPARK
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