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Spherical Aberration

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-455

2025-12-24

586

If the angular opening of the concave mirror is large, the principal focus for parallel rays near the axis will be farther from the mirror than that for those near its edge (Fig. 1). For this reason the out side of an image sometimes looks blurred. To prevent this spherical aberration the aperture should not exceed 10° or 12°. Spherical aberration can be avoided by the use of parabolic mirrors, such as are used in headlights for locomotives and electric cars. The rays of light coming from a lamp in the focus of such a mirror are sent off as parallel rays.