Then an electrical technician, Cassagnes came upon the Etch A Sketch idea in the late 1950s when he peeled a translucent decal from a light switch plate and found pencil mark images transferred to the opposite face, the Toy Industry Association said.
To further hone the image, engineers use a technique called optical proximity correction, which uses oddly shaped bars, notches and other distortions that are cut into the chrome template on the quartz plate to trick light waves into making a more precise pattern (see left).
To further hone the image, engineers use a technique called optical proximity correction, which uses oddly shaped bars, notches and other distortions that are cut into the chrome template on the quartz plate to trick light waves into making a more precise pattern (see chart).