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THE SAGITTA OF A TOROIDAL SURFACE IN AN OBLIQUE MERIDIAN
Author(s) -
Churms P. W.
Publication year - 1981
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1981.tb00145.x
Subject(s) - oblique case , toroid , meridian (astronomy) , optics , physics , geometry , astronomy , mathematics , philosophy , linguistics , plasma , quantum mechanics
A method for the accurate calculation of the sagitta of a barrel‐form, toroidal surface in an oblique meridian is shown. The accurate oblique sagittae of barrel‐ and type‐form surfaces are compared with approximate sagittae derived from a method employing the concept of oblique cylindrical power. Differences between the values are examined in a range of toroidal surfaces common in ophthalmic lens manufacture. The implications of the data for lens volume and weight are discussed.