SPHERICAL ABERRATION
\sfˈɛɹɪkə͡l ˌabəɹˈe͡ɪʃən], \sfˈɛɹɪkəl ˌabəɹˈeɪʃən], \s_f_ˈɛ_ɹ_ɪ_k_əl ˌa_b_ə_ɹ_ˈeɪ_ʃ_ə_n]\
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By DataStellar Co., Ltd
By Willam Alexander Newman Dorland
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In the refraction of light by a lens, an inequality in the degree of convergence of the rays from different portions of the lens, producing a series of images at different focal distances, so called because the character of the a. is due to the fact that the surface of the lens is a segment of a sphere. [Lat.]
By Smith Ely Jelliffe
Word of the day
Olivopontocerebellar Atrophies
- group inherited disorders which share progressive ataxia combination with atrophy CEREBELLUM; PONS; inferior olivary nuclei. Additional features include RIGIDITY; NYSTAGMUS; RETINAL DEGENERATION; MUSCLE SPASTICITY; DEMENTIA; URINARY INCONTINENCE; OPHTHALMOPLEGIA. familial has an earlier onset (second decade) and may feature spinal cord atrophy. sporadic form tends to present in the fifth or sixth decade, is considered a clinical subtype MULTIPLE SYSTEM ATROPHY. (From Adams et al., Principles of Neurology, 6th ed, p1085)