Tuesday, July 14, 2009
Failure of a lens or mirror to form an exact image of an object. It is a result of the natural laws of optics. Not all light rays entering a lens or mirror parallel to the principal axis focus at the same point; this phenomenon is spherical aberration. Coma astigmatism are aberrations produced by rays entering at an angel to the principal axis. Curvature of field is the tendency of a flat object to be imaged as a curved surface. Distortion is a nonuniformity in the scale of the image, some portions being magnified or reduced more than others. Chromatic aberration is the failure of the various wave length of light to come to the same focus.