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L3-12. Optical Board - Ray Diagram - Concave Mirror


To locate the image of a concave mirror by using the three principal rays.


Optical board with parabolic concave mirror, half-silvered and full-silvered mirros on mount, convex lens.




This is a short focal length concave parabolic mirror which produces a small image close to the mirror for the setup photographed. The central ray passes through a half-silvered mirror which deflects half of the light to the tip of the object arrow. The upper mirror can be rotated to create any of the three principal rays. Keep the mirror reasonably close to the mirror to produce a larger image. The convex lens keeps the light ray narrow. ◙◙The object can be moved within the focal point of the mirror to produce an anlarged virtual image behind the mirror.


Samuel Derman, Ray Tracing with Spherical and Parabolic Reflectors, TPT 28, 590-593 (1990).