A Fresnel lens can be used for fun science projects.
Fresnel lenses were developed for lighthouses, but today they are used in many different applications and for school science projects. The National Aeronautics and Space Administration (NASA) is using Fresnel lens optics in space-based applications such as ray imaging detectors and solar power, according to the University of Alabama in Huntsville. Fresnel lenses are useful for education science projects.
Melt Pennies
Use a large projection TV screen to focus light from the sun and create enough heat to melt copper pennies.
Locate a discarded, or acquire a donated, projection screen TV. The screen of a projection TV is a large, acrylic Fresnel lens.
Projection screens can be as big as 3 or 4 ft. by 4 ft. Built a mounting frame slightly larger than the screen. Use any type of inexpensive wood and duct tape the edges of the projection lens inside the frame. Build a simple inverted L-shape or T-shape stand from wood to hold the frame so the frame can be rotated to adjust sunlight coming through the lens.
Demonstrate the Fresnel lens' ability to achieve high temperatures by melting objects placed approximately 2 ft. from the lens. The University of Hawaii used this technique with a Fresnel lens and was able to reach temperatures of 1300 Kelvin (1000 degrees Celsius or 2000 Fahrenheit). Wear safety goggles, perform the test in an open area away from flammables and use fire safety precautions.
Make Distilled Water
Use the sun's energy and a Fresnel lens to build a solar distillery that makes dirty water clean.
According to the Light-Science website, you can cut a 2-liter plastic bottle in half, but cut a hook shape on each side so you can hang the bottle on a pencil. Cut the top third off a 3-liter plastic bottle and punch a hole in each side, near the top, to insert the pencil.
Fill the 2-liter bottle almost to the top with seawater or salty water and hang it in the 3-liter bottle with the hooks on the pencil. Make a tent-like flap with plastic food wrap, drinking straws and masking tape, and extend the plastic wrap over the 3-liter bottle. Allow the bottom flaps of the plastic wrap to hang inside the 3-liter bottle.
Place the device in sunlight. Use a magnifying Fresnel lens, also called a page magnifier, to magnify the sunlight onto the plastic wrap. Page magnifiers are available at large retail stores and optical specialty stores. The plastic wrap tent will catch evaporated water, and the clean water will drip down into the 3-liter bottle. Use eye protection and perform the experiment in a clear, outdoor area away from flammable objects.
Test a Camera Flash
You can test a flash extender on a camera by using a Fresnel lens. Use a magnifying Fresnel lens, also called a page magnifier. Tape the lens to a flashlight with masking tape. Turn on the flashlight, and move the flashlight and lens about 5 to 6 feet from the object you are photographing.
Take a series of pictures with different aperture and flash settings, first with the flashlight on and then with the flashlight off. Compare the photographs from each set to determine the best illumination, depth of focus and exposure. Use safety precautions and eyewear when performing any experiments with a Fresnel lens.
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