Any type of projector, whether it projects still or video images, works by shining light and the image through lenses to project and focus the image. If you know the basic principles of refracting light, you can build a still-frame or video projector at home. Once you know the images you want to project, you'll need a light source, lenses to focus the light and a projection frame to contain everything and project the image in a fixed direction. The types of lenses and light source you need depend on whether you are making a still-image or video projector.
Instructions
1. Choose a source of light for the projector. If you are making a video projector, you also need a video source like a TV set with a video player. In this case, the TV set provides the light source for you. A flashlight works for a slide projector, while a light bulb fixture (taken from a lamp) can be used for larger still images like transparencies.
2. Get lenses that will focus the light for the projector's images (see Resources). They should be close to the size of your light source. For a still-image projector, you need a glass convex and a concave lens, like the ones used in magnifying glasses and telescopes. A fresnel lens, which is used in stage lighting, will work for a video projector.
3. Cut out a set of frames from cardboard or wood to hold the lens(es). For a video projector, make the frames the same size as your video screen. For a still projector, make them as big as your lenses and light source. Cut holes in the frames and fit the lenses inside them. If using a flashlight, make another frame and fit the flashlight in it with its lens removed.
4. Construct a box-like frame to contain the light source and lenses. It should be as high and wide as your lens frames and about 45 cm long. The frame is made of four pieces with the two ends that are the size of the lens frames left open. Make the top piece removable.
5. Connect one end of the box frame to your light source. Tape it onto the TV screen, glue the frame with the flashlight to it or place the light bulb near the end and close the end up with another wood/cardboard piece (leave a small hole for its power cord).
6. Insert the lenses into the box frame. With glass lenses, the convex lens (which curves inward) is placed closest to the light source,and the concave (curves outward) goes near the box's open end. If using a fresnel lens with a monitor, you can use just one, but you must turn the monitor upside down.
7. Cut a hole in the top of the box frame if you are making a still projector. This is to insert the still pictures (like slides) into the projector The hole must have the light source on one side and all lenses on the other.
8. Activate the light source (plug in the light bulb or turn on the TV/flashlight) and provide the image (turn on the video player or insert a slide) to start the projector. Reach in and adjust the position of the lenses to focus the image that projects on the wall (opening the top of the box helps).
Tags: light source, video projector, light bulb, focus image, focus light, frame contain