( ( ( ( Spherical Aberration ) , ) ( Where ( ( ( the surface ) ( of ( a ( convex lens ) ) ) ) ( in ( ( ( not ( perfectly spherical ) ) and ) ( ( all ( the rays ) ) ( of light ) ) ) ) ) ) ) ( ( ( do not ) ( focus ( at ( the ( same point ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Spherical) (NNP Aberration)) (, ,) (SBAR (WHADVP (WRB Where)) (S (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (DT a) (NN convex) (NN lens)))) (PP (IN in) (UCP (ADJP (RB not) (RB perfectly) (JJ spherical)) (CC and) (NP (NP (PDT all) (DT the) (NNS rays)) (PP (IN of) (NP (NN light))))))))) (VP (VBP do) (RB not) (VP (VB focus) (PP (IN at) (NP (DT the) (JJ same) (NN point))))) (. .)))
Spherical Aberration, Where the surface of a convex lens in not perfectly spherical and all the rays of light do not focus at the same point.
(ROOT (S (NP (NNP Convex) (NNS lenses)) (VP (VBP are) (NP (NP (JJR thicker)) (PP (IN in) (NP (DT the) (NN middle)))) (PP (IN than) (PP (IN at) (NP (DT the) (NNS edges)))) (SBAR (IN so) (S (NP (PRP they)) (VP (VBP cause) (S (NP (NP (NNS rays)) (PP (IN of) (NP (NN light)))) (VP (TO to) (VP (VB converge) (, ,) (CC or) (VB meet) (, ,) (PP (IN at) (NP (NP (DT a) (NN point)) (VP (VBN called) (NP (NN focus)))))))))))) (. .)))