JP2008242391A5

JP2008242391A5 -

Info

Publication number: JP2008242391A5
Application number: JP2007086843A
Authority: JP
Filing date: 2007-03-29
Publication date: 2010-05-06
Anticipated expiration: 2027-03-29

Claims

A diffractive optical element having a structure in which a first diffraction grating made of a first material and a second diffraction grating made of a second material are laminated so that the grating surfaces of the grating portions of each diffraction grating are in contact with each other,
The second material is made of a material obtained by mixing a fine particle material with a resin material,
The refractive index of the first material for the d-line, the Abbe number, the partial dispersion ratio for the g-line and the F-line, and the partial dispersion ratio for the g-line and the d-line are nd1, νd1, θg, F1, θg, d1,
The refractive index of the second material for the d-line, the Abbe number, the partial dispersion ratio for the g-line and the F-line, and the partial dispersion ratio for the g-line and the d-line are nd2, νd2, θg, F2, θg, d2,
When the refractive index and Abbe number of the fine particle material for d-line are ndb2 and νdb2, respectively.
nd1 ≧ 1.48
νd1 ≧ 40
(-1.665E-07 × νd1 ³ + 5.213E-05 × νd1 ² -5.656E-03 × νd1 + 0.700) ≦ θg, F1
≦ (-1.665E-07 × νd1 ³ + 5.213E-05 × νd1 ² -5.656E-03 × νd1 + 0.662)
(-1.687E-07 × νd1 ³ + 5.702E-05 × νd1 ² -6.603E-03 × νd1 + 1.425) ≦ θg, d1
≦ (−1.687E−07 × νd1 ³ + 5.702E-05 × νd1 ² −6.603E-03 × νd1 + 1.513)
nd2 ≦ 1.6
νd2 ≦ 30
θg, F2 ≦ (-1.665E-07 × νd2 ³ + 5.213E-05 × νd2 ² ‐5.656E-03 × νd2 + 0.675)
θg, d2 ≦ (-1.687E-07 × νd2 ³ + 5.702E-05 × νd2 ² -6.603E-03 × νd2 + 1.400)
nd1-nd2> 0
ndb2 ≧ 1.70
νdb2 ≦ 20
A diffractive optical element characterized by satisfying the following conditions:

The wavelengths of F-line, d-line and C-line are λF, λd, λC,
The value obtained by dividing the difference in optical optical path length between the convex part and concave part of the grating part of each diffraction grating with respect to the m-th order diffracted light at the wavelengths of F-line, d-line, and C-line by m (λF) , m (λd), m (λC), and d (μm) as the grating thickness of the grating part of the diffraction grating
d ≤ 20 (μm)
0.92 ≦ {m (λF) + m (λd) + m (λC)} / 3 ≦ 1.08
2. The diffractive optical element according to claim 1, wherein the following condition is satisfied.

3. The diffractive optical element according to claim 1, wherein the first material is a glass glass material.

4. The diffractive optical element according to claim 3, wherein the glass glass material is a glass glass material having a yield point temperature of 600 ° C. or less.

Wavelength 450nm, 550nm, 650nm in order λ1, λ2, λ3,
The diffraction efficiencies at the wavelengths λ1, λ2, and λ3 are sequentially expressed as η (λ1), η (λ2), η (λ3),
The internal transmittances of the first material at wavelengths λ1, λ2, and λ3 are sequentially expressed as T1 (λ1), T1 (λ2), T1 (λ3),
When the internal transmittance of the second material at wavelengths λ1, λ2, and λ3 is T2 (λ1), T2 (λ2), and T2 (λ3)
(T1 (λ1) * T2 (λ1) * η (λ1) + T1 (λ2) * T2 (λ2) * η (λ2) + T1 (λ3) * T2 (λ3) * η (λ3)) / 3 ≧ 0.70
The diffractive optical element according to claim 1, wherein the following condition is satisfied.

The second material is a resin material containing inorganic fine particles of any one of ITO, Ti, Nr, and Cr, or an oxide, composite, or mixture containing at least one of them. 6. The diffractive optical element according to any one of claims 1, 2, and 5, wherein:

Resin material for mixing inorganic fine particles of the second material, according to claim 6, an ultraviolet curable resin, and acrylic, fluorine, vinyl, characterized in that the one of the organic resin of epoxy Diffractive optical element.

8. The diffractive optical element according to claim 6, wherein an average particle diameter of the inorganic fine particles contained in the second material is 200 nm or less.

When the grating pitch and grating thickness of the grating parts of the first and second diffraction gratings are P and d, respectively.
d / P <1/7
The diffractive optical element according to claim 1, wherein the following condition is satisfied.

10. An optical system comprising the diffractive optical element according to claim 1.

11. An optical apparatus comprising the optical system according to claim 10.