How to Magnify with a Fresnel Lens
The Fresnel lens was first developed and used in the early 1800s for use in lighthouses. Developed by French physicist and engineer Augustin-Jean Fresnel, this type of lens is a built-up array of specially shaped lenses designed to create a long light beam typical of those seen emulating from shoreline beacons. Fresnel lenses also can be used to magnify and project an image, but the image quality is not high. In recent years, Fresnel lenses have been used in traffic lights and to enhance solar collectors.
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Things You'll Need
- 12-inch-by-12-inch cardboard box
- Utility knife
- Plastic page reader
- Masking tape
- Aluminum foil
- Marshmallows
- Pointed wood stick or cooking skewer
Instructions
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1
Cut a square hole in one side of the cardboard box. The opening should be an inch smaller than the page reader, both in width and depth.
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2
Tape the page reader to the inside of the box. The smooth side should be located nearest the inside of the box, and the grooved side should point away from the box. When the box is set up, the grooved side will point toward the sun.
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3
Tape a piece of aluminum foil to the inside of the box opposite the page reader.
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4
Set the box up on a table in your backyard on a warm, sunny day. Try as close to noon as possible.
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5
Orient the box so the page reader lens is on top, facing the sun, and the aluminum foil is on the bottom. One part of the box will be left open. This was the original top of the box, but now it should be on the side.
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6
Slide a marshmallow onto a wooden skewer or pointed stick and place it directly under the center of the page reader near the aluminum foil.
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7
Cook the marshmallow in the beam of sunlight.
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Tips & Warnings
A plastic page reader is a reading device that contains a magnifying lens and is large enough to cover most of a page.
Make sure you cut the square opening on the side of the box and not the top or bottom of the box.
Do not make compound lenses like you would find in a lighthouse; just use one magnifying reader to perform this experiment.
A Fresnel-type magnifying lens has the potential to cause burns to the skin or inflict eye damage if a light beam is directed toward those parts of the body. Use caution when applying the beam of light.
References
- Photo Credit lighthouse image by jimcox40 from Fotolia.com
