Optical lens, method for designing optical lens, and apparatus for manufacturing optical lens
An optical lens including, an object-side surface including an atoric surface element and an eyeball-side surface including an element that cancels a surface power shift produced by the atoric surface element, wherein the atoric surface element causes horizontal surface power at a fitting point to be greater than vertical surface power at the fitting point and causes a difference between the horizontal surface power and the vertical surface power to decrease along a horizontal reference line passing through the fitting point in a direction from the fitting point toward a periphery of the optical lens or causes a sign of the difference between the horizontal surface power and the vertical surface power to change along the horizontal reference line.
1. An optical lens comprising:
an object-side surface including an atoric surface element; and
an eyeball-side surface including an element that cancels a surface power shift produced by the atoric surface element, wherein
the atoric surface element of the object-side surface causes horizontal surface power at a fitting point to be greater than vertical surface power at the fitting point, the fitting point being a point through which a line of sight of a primary position of a user who is horizontally viewing a distant object in front of the user passes, and
the atoric surface element of the object-side surface
(i) causes a difference between the horizontal surface power and the vertical surface power to decrease along a horizontal reference line passing through the fitting point in a direction from the fitting point toward a periphery of the optical lens or
(ii) causes a sign of the difference between the horizontal surface power and the vertical surface power to change along the horizontal reference line.
2. The optical lens according to claim 1 , wherein the difference between the horizontal surface power and the vertical surface power at the fitting point is greater than or equal to 0.5 D but smaller than or equal to 3.5 D, where D represents dioptre.
3. The optical lens according to claim 1 , wherein an amount of decrease in the difference between the horizontal surface power and the vertical surface power is 0.3 D at maximum in an area within ±10 mm from the fitting point along the horizontal reference line.
4. The optical lens according to claim 1 , wherein an amount of decrease in the difference between the horizontal surface power and the vertical surface power in an area within ±25 mm from the fitting point along the horizontal reference line is greater than or equal to 0.3 times the difference between the horizontal surface power and the vertical surface power at the fitting point but smaller than or equal to 1.5 times of the difference between the horizontal surface power and the vertical surface power at the fitting point.
5. The optical lens according to claim 1 ,
further comprising a distance portion and a near portion having different power factors,
wherein the atoric surface element of the object-side surface includes at least one of the following elements: an element where horizontal surface power is greater than vertical surface power of the distance portion along a principal meridian or a vertical reference line passing through the fitting point and an element where horizontal surface power is greater than vertical surface power of the near portion along the vertical reference line passing through the fitting point or the principal meridian.
6. The optical lens according to claim 5 ,
wherein the object-side surface includes any of the following elements: a first element, a second element, and a third element,
the first element causes the vertical surface power of the distance portion to be greater than the vertical surface power of the near portion,
the second element causes the vertical surface power of the distance portion to be smaller than the vertical surface power of the near portion, and
the third element causes the vertical surface power of the distance portion to be equal to the vertical surface power of the near portion and the horizontal surface power of the distance portion to be equal to the horizontal surface power of the near portion.
7. A method for designing an optical lens having an object-side surface and an eyeball-side surface, the method comprising:
providing the object-side surface with an atoric surface element; and
providing the eyeball-side surface with an element that cancels a surface power shift produced by the atoric surface element of the object-side surface, wherein
the atoric surface element of the object-side surface causes horizontal surface power at a fitting point to be greater than vertical surface power at the fitting point, the fitting point being a point through which a line of sight of a primary position of a user who is horizontally viewing a distant object in front of the user passes, and
the atoric surface element of the object-side surface
(i) causes the difference between the horizontal surface power and the vertical surface power to decrease along a horizontal reference line passing through the fitting point in a direction from the fitting point toward a periphery of the optical lens or
(ii) causes the sign of the difference between the horizontal surface power and the vertical surface power to change along the horizontal reference line.
8. The optical lens according to claim 1 , wherein the optical lens is a spectacle lens.
9. The optical lens according to claim 8 , wherein the spectacle lens is a progressive lens.
10. The optical lens according to claim 1 , wherein the difference between the horizontal surface power and the vertical surface power is obtained by subtracting the horizontal surface power from the vertical surface power, or by subtracting the vertical surface power from the horizontal surface power.