G - Physics – 02 – C
Patent
G - Physics
02
C
G02C 7/02 (2006.01) G02B 3/02 (2006.01)
Patent
CA 2242477
In a single-vision aspherical spectacle lens having a pair of first and second refractive surfaces, the shape of the first refractive surface and/or the second refractive surface is defined by the following equation: (see figure I) where mi designates a real number which is not less than 2; n an integer which is not less than 1; X a length of a perpendicular dropped or drawn from a point, which is positioned on the aspherical surface and is located at a distance p from an optical axis to a tangent or tangential plane, which touches the aspherical surface at a vertex thereof; C curvature of a reference spherical surface at the vertex of the aspherical surface; .rho. a distance from the optical axis; k a conic constant; and Ami what is called an aspherical-surface coefficient of .rho. mi. Further, in a design stage of this aspherical lens, the shape of the lens is determined by taking an oblique astigmatic error and/or a mean oblique error into consideration when decentration is caused, in such a manner as to reduce degradation in performance of the lens, which is caused owing to the decentration.
On façonne l'un ou l'autre des premier et second plans, ou les deux plans, d'une lentille de contact asphérique comportant une paire de plans de réfraction, de telle manière que ces plans satisfassent l'équation (I) dans laquelle mi est un réel supérieur ou égal à 2, n est un entier supérieur ou égal à 1, X est la longueur d'une perpendiculaire issue d'un point du plan asphérique, à distance rho de l'axe optique, et aboutissant au plan nodal du sommet du plan asphérique, C est le rayon de courbure de la sphère de référence au niveau du sommet du plan asphérique, rho est la distance à l'axe optique, k est une constante de cône et Ami est le coefficient asphérique du terme rho <mi>. Lors de l'étape de conception de la lentille oculaire asphérique, on définit la forme de la lentille de façon à réduire la chute d'efficacité de la lentille due à l'excentricité associée à l'astigmatisme ainsi que l'erreur de puissance lorsque l'excentricité se produit.
Minato Atsuo
Qi Hua
Yamakaji Tetsuma
Dennison Associates
Hoya Corporation
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