Diffractive multifocal lens
AssigneeHoya Corporation
InventorTjundewo Lawu
Life of this patent
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Abstract
There is provided a diffractive multifocal lens, wherein a diffraction phase structure of a diffraction pattern has a structure expressed by the following formula: ϕ ( ξ ) = { p 1 ξ , 0 ≤ ξ < w p 2 ( ξ - 0.5 ) - q π , w ≤ ξ < 1 - w p 1 ( ξ - 1 ) , 1 - w ≤ ξ ≤ 1 ( 1 ) wherein ξ indicates a position in a radial direction of the lens in one period of the diffraction pattern, and φ(ξ) indicates a value (radian) of a phase shift amount of light passing through the position of ξ from the phase of light passing through a reference plane.
Claims8
A diffractive multifocal lens, having an annular diffraction pattern for exhibiting a light diffraction effect, which is formed concentrically repeatedly on a surface of a lens,
- wherein a diffraction phase structure of the diffraction pattern has a structure expressed by the following formula:
- ϕ
-
- (
- ξ
- )
- =
- {
- p
- 1
-
- ξ
- ,
- 0
- ≤
- ξ
- <
- w
- p
- 2
-
- (
- ξ
- -
- 0.5
- )
- -
- q
-
-
- π
- ,
- w
- ≤
- ξ
- <
- 1
- -
- w
- p
- 1
-
- (
- ξ
- -
- 1
- )
- ,
- 1
- -
- w
- ≤
- ξ
- ≤
- 1
- (
- 1
- )
- wherein each symbol is as follows:
- ξ indicates a position in a radial direction of the lens in one period of the diffraction pattern, having values from 0 to 1;
- w indicates a position where a form of the formula of φ(ξ) is changed;
- φ(ξ) indicates a value (radian) of a phase shift amount of light passing through the position of ξ from the phase of light passing through a reference plane;
- p1 indicates a value defining a gradient of a straight line φ(ξ), when satisfying 0≦ξ<w, and 1−w≦ξ≦1;
- p2 indicates a value defining the gradient of the straight line φ(ξ) when satisfying w≦ξ<1−w;
- and
- q indicates a parallel moving amount over the reference plane of the straight line φ(ξ) when satisfying w≦ξ<1−w.
Dependencies are inferred from the claim text.