# US 7,612,940 B2 · Diffractive optical element and method of fabricating diffractive optical element

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- Number: US 7,612,940 B2
- Document ID: US7612940B2
- Status: Granted
- Kind: B2
- Application number: 11/390,279
- Filed: 2006-03-28
- Published: 2006-08-03
- Granted: 2009-11-03
- Earliest claimed: 2003-09-30
- Assignees: Nikon Corporation
- Inventors: Kenzaburo Suzuki
- Web page: https://patentgrep.com/patent/US7612940B2

## CPC

- G02B 27/0037: {with diffracting elements (G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876)}
- G02B 1/04: made of organic materials, e.g. plastics (G02B1/08 takes precedence)
- G02B 5/1895: {such optical elements having dioptric power}
- G02B 27/4211: {correcting chromatic aberrations (G02B27/0056, G02B27/4222, G02B27/4227 take precedence)}
- G02B 27/4216: {correcting geometrical aberrations}
- G02B 27/4272: {having plural diffractive elements positioned sequentially along the optical path}
- G02B 27/4277: {being separated by an air space}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The present invention is a diffractive optical element 1 in which mutually different materials make contact with one another via the same diffraction grating groove 30. One of the mutually different materials is a first ultraviolet curing resin 10 and the other of the mutually different materials is a second ultraviolet curing resin 20 that is different from the first ultraviolet curing resin 10.

## Claims

### Claim 1

A diffractive optical element in which mutually different materials make contact with one another via the same diffraction grating groove, wherein one of the mutually different materials is a first ultraviolet curing resin and the other of the mutually different materials is a second ultraviolet curing resin that is different from the first ultraviolet curing resin,
wherein, when the refractive index at line d of the first ultraviolet curing resin is nd1, the dispersion value of the first ultraviolet curing resin is vd1, the refractive index at line d of the second ultraviolet curing resin is nd2, and the dispersion value of the second ultraviolet curing resin is vd2, the condition of expression
0.0015778≦(nd1−nd2)/(vd1−vd2)≦0.03
is satisfied.

### Claim 2 (depends on 1)

The diffractive optical element according to claim 1, wherein, when the refractive index at line d of the first ultraviolet curing resin is nd1 and the dispersion value of the first ultraviolet curing resin is vd1, the conditions of expressions
1.50≦nd1≦1.60
45≦vd1≦65
are satisfied and, when the refractive index at line d of the second ultraviolet curing resin is nd2 and the dispersion value of the second ultraviolet curing resin is vd2, the conditions of expressions
1.45≦nd2≦1.55
vd2≦45
are satisfied.

### Claim 3 (depends on 2)

The diffractive optical element according to claim 2, wherein, when the height of the diffraction grating groove is h, the condition of expression
h≦50 μm
is satisfied.

### Claim 4 (depends on 3)

The diffractive optical element according to claim 3, wherein the minimum pitch of the diffractive optical element is at least 80 μm.

### Claim 5 (depends on 4)

The diffractive optical element according to claim 4, wherein the sum of the thicknesses on the optical axis of the first ultraviolet curing resin and the second ultraviolet curing resin is no more than 1000 μm.

### Claim 6 (depends on 5)

The diffractive optical element according to claim 5, wherein the first ultraviolet curing resin and second ultraviolet curing resin both have a thickness of no more than 500 μm.

### Claim 7 (depends on 6)

The diffractive optical element according to claim 6, wherein, when the thickness of the first ultraviolet curing resin is t1 and the thickness of the second ultraviolet curing resin is t2, the condition of expression
0.2<t1/t2<5.0
is satisfied.

### Claim 8 (depends on 7)

The diffractive optical element according to claim 7, wherein, when the radius of curvature of a substrate that constitutes the diffractive optical element having the first ultraviolet curing resin is R, the condition of expression
0≦1/R<0.1(1/mm)
is satisfied.

### Claim 9 (depends on 2)

The diffractive optical element according to claim 2, wherein, when the refractive index at line d of the first ultraviolet curing resin is nd1, the refractive index at line C is nC1, and the refractive index at line F is nF1, and the refractive index at line d of the second ultraviolet curing resin is nd2, the refractive index at line C is nC2, the refractive index at line F is nF2, and Δnd=nd1 −nd2, Δ(nF−nC)={(nF1−nC1)−(nF2−nC2)}, the condition of expression
−10.0<Δnd/Δ(nF−nC)<−1.0
is satisfied.

### Claim 10 (depends on 9)

The diffractive optical element according to claim 9, wherein, when the height of the diffraction grating groove is h, the condition of expression
h≦50 μm
is satisfied.

### Claim 11 (depends on 1)

The diffractive optical element according to claim 1, wherein, when the height of the diffraction grating groove is h, the condition of expression
h≦50 μm
is satisfied.

### Claim 12 (depends on 1)

The diffractive optical element according to claim 1, wherein the minimum pitch of the diffractive optical element is at least 80 μm.

### Claim 13 (depends on 1)

The diffractive optical element according to claim 1, wherein the sum of the thicknesses on the optical axis of the first ultraviolet curing resin and the second ultraviolet curing resin is no more than 1000 μm.

### Claim 14 (depends on 1)

The diffractive optical element according to claim 1, wherein the first ultraviolet curing resin and second ultraviolet curing resin both have a thickness of no more than 500 μm.

### Claim 15 (depends on 1)

The diffractive optical element according to claim 1, wherein, when the thickness of the first ultraviolet curing resin is t1 and the thickness of the second ultraviolet curing resin is t2, the condition of expression
0.2<t1/t2<5.0
is satisfied.

### Claim 16 (depends on 1)

The diffractive optical element according to claim 1, wherein, when the radius of curvature of a substrate that constitutes the diffractive optical element having the first ultraviolet curing resin is R, the condition of expression
0≦1/R<0.1(1/mm)
is satisfied.

### Claim 17 (depends on 1)

The diffractive optical element according to claim 1, wherein, when the refractive index at line d of the first ultraviolet curing resin is nd1, the refractive index at line C is nC1, and the refractive index at line F is nF1, and the refractive index at line d of the second ultraviolet curing resin is nd2, the refractive index at line C is nC2, the refractive index at line F is nF2, and Δnd=nd1−nd2, Δ(nF−nC)={(nF1−nC1)−(nF2−nC2)}, the condition of expression
−10.0<Δnd/Δ(nF−nC)<−1.0
is satisfied.

### Claim 18 (depends on 17)

The diffractive optical element according to claim 17, wherein, when the height of the diffraction grating groove is h, the condition of expression
h≦50 μm
is satisfied.

### Claim 19 (depends on 1)

The diffractive optical element according to claim 1, wherein said first ultraviolet curing resin comprises an enthiol reaction product of an acrylate with a fat ring and a thiol compound, and said second ultraviolet curing resin comprises a mixture of an acrylate with a plurality of benzene skeletons in the molecule and an acrylate containing a fluorine atom in the molecule.

### Claim 20 (depends on 1)

The diffractive optical element according to claim 1, wherein said diffraction grating groove is formed in a flat face.

### Claim 21 (depends on 1)

The diffractive optical element according to claim 1, wherein said diffraction grating groove is formed in a curved face.

### Claim 22 (depends on 21)

The diffractive optical element according to claim 21, wherein said curved face comprises a convex shape.

### Claim 23 (depends on 21)

The diffractive optical element according to claim 21, wherein said curved face comprises a concave shape.