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US07712897B2 Varifocal lens 有权
变焦镜头

Varifocal lens
Abstract:
A method for constructing a progressive varifocal lens having a far vision area, a near vision area and an intermediate progression area. the method comprises the steps of a) determining the x- and y-coordinates of a first point in the closed interval between the far vision reference point of the far vision area and the center point; b) determining the x and y coordinates of a second point as the near vision reference point of the near vision area; c) determining a mathematical function D(y) which obeys the following conditions: it contains the first and second points as local extrema and comprises exactly one point of inflection in the open interval between the two points; distributing the addition according to the said function along a principal meridian of progression connecting the first and second points; and d) forming the varifocal lens.
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