Purpose:Demonstrate spherical aberration using rays.
Description:Rays from a point source are focused by a convex spherical lens. If the entire lens is used, considerable spherical aberration results. Reducing the aperture (equivalent to reducing the f-number of a lens) by sliding the slit baffle away from the source reduces the spherical aberration. Alternatively, spherical aberration can be eliminated entirely by using an aspherically corrected lens, such as the hyperbolic lens shown at the right.