| 摘要 |
An optical filter includes a first multilayer film structure including first and second optical layers which are constituted by materials different from each other, and a second multilayer film structure including third and fourth optical layers which are constituted by materials different from each other, the first multilayer film structure includes a first unit multilayer film with a width W1 including the first optical layer and the second optical layer, and a second unit multilayer film with a width W2 including the first optical layer and the second optical layer laminated alternately, the first and second unit multilayer films are shifted from each other in a lamination direction of the first and second optical layers, and constitute a unit structure in which the first and second unit multilayer films are arranged adjacent to each other in an arrangement direction orthogonal to the lamination direction. |
| 主权项 |
1. An optical filter comprising:
a first multilayer film structure including a first optical layer and a second optical layer which are constituted by materials different from each other; and a second multilayer film structure including a third optical layer and a fourth optical layer which are constituted by materials different from each other, wherein the first multilayer film structure includes:
a first unit multilayer film with a width W1 including the first optical layer and the second optical layer, the second optical layer having a refractive index lower than a refractive index of the first optical layer, the first optical layer and the second optical layer being laminated alternately, anda second unit multilayer film with a width W2 including the first optical layer and the second optical layer laminated alternately, wherein the first and second unit multilayer films are shifted from each other by a displacement D in a lamination direction of the first and second optical layers, and constitute a unit structure in which the first and second unit multilayer films are arranged adjacent to each other in an arrangement direction orthogonal to the lamination direction, wherein the second multilayer film structure includes a multilayer film including the third optical layer and the fourth optical layer, the fourth optical layer having a refractive index lower than a refractive index of the third optical layer, the third optical layer and the fourth optical layer being laminated alternately, and wherein expressions below are satisfied:
15 deg.<φ<55 deg., and1.5<nH1·dH1/nL1·dL1<5.0, where nH1 is the refractive index of the first optical layer, dH1 is an average layer thickness of the first optical layer, nL1 is the refractive index of the second optical layer, dL1 is an average layer thickness of the second optical layer, and φ is a tilt angle of the unit structure which is defined as φ=tan−1(|D|/0.5(W1+W2)) when |D| is not greater than 0.5(dL1+dH1) and is defined as φ=tan−1(((dL1+dH1)−|D|)/0.5(W1+W2)) when |D| is greater than 0.5(dL1+dH1). |
