From MAKE magazine’s series of weekend projects, build yourself a digital microscope by taking apart a basic webcam and turning it into an ultrafine ”shadow imager”. From the introduction of the PDF:
Behind the lens of a webcam is an imager chip with thousands of tiny light sensors, each about 1/10 the diameter of a human hair. If you replace the lens with an LED light source, and place tiny objects on the imager chip, shadows will project onto the sensor creating a lensless microscopic image. You can use the webcam’s regular software to save pictures and video or stream live images to the internet. Or use the imager chip from a security camera to see a colony of live plankton on TV.
In addition to the detailed printed description of the project, there is a nice video that shows you the basic steps. I love projects like this because you (or your kids) are not only exploring the world around you, but you are actually building your own tools to do it!
How-To:
