| 摘要 |
PURPOSE:To widen distant use and intermediate part areas, to improve visibility, and to eliminate the distortion and oscillation of an image by setting an astigmatism and an average refractive power of the near use area of the upper part than a line inclined to the lower part by a specified angle, and the difference between a refractive power of the distant use and near use part areas, to a prescribed value or below. CONSTITUTION:When a fitting point set in the vicinity of a boundary point of a distant use part area 1 and an intermediate part area 2 on the main meridian is set as a start point and both the left and right are installed and used, an astigmatism is less than 1.0 diopter and also an average refractive power is within D1+ or -0.5 diopter, in the whole surface on the upper refractive surface than a line inclined to the lower part by [K] degrees from the horizontal line, and in this state, by K=50-(ADDX20) and setting the difference ADD=D2-D1 between a refractive power D1 of a distant use part area 1 and a refractive power D2 of a near use part area 3, to ADD>=1.5, it is possible to obtain a progressive multifocus lens which has wide distant use and intermediate use fields of view, can reduce remarkably the distortion and oscillation of an image, and is optimum for uses such as sports such as golf, etc., driving of a car, going-out for shopping, etc. |
