USRE48601EActiveUtilityPatentIndex 60
Optical sky-sun diffuser
Est. expiryJun 24, 2028(~2 yrs left)· nominal 20-yr term from priority
H10H 20/882H10H 20/851F21V 9/30F21K 9/00F21Y 2115/10F21V 9/40F21W 2121/00F21W 2131/103G02B 6/0041F21K 9/61F21V 3/00G02B 27/30G02B 6/001F21S 8/033F21V 9/02F21Y 2115/30F21V 9/08G02B 19/0071G02B 19/0047G02B 6/0096G02B 5/0242H01L 33/50H01L 2933/0091
60
PatentIndex Score
0
Cited by
38
References
41
Claims
Abstract
An embodiment of a solid optical sky-sun diffuser, which comprises a transparent solid matrix embedding a dispersion of transparent nanoparticles having an average size d in the range 10 nm≤d≤240 nm; wherein: the ratio between the blue and red scattering optical densities γ≡Log [T(450 nm)]/Log [T(630 nm)] of said diffuser falls in the range 5≥γ≥2.5, where T(λ) is the Monochromatic Normalized Collinear Transmittance; in at least one propagation direction, said Monochromatic Normalized Collinear Transmittance is T(450 nm)≥0.4; in at least one propagation direction said Monochromatic Normalized Collinear Transmittance is T(450 nm)≤0.9, said propagation direction being the same or different from that at which said Monochromatic Normalized Collinear Transmittance is T(450 mm)≥0.4.
Claims
exact text as granted — not AI-modifiedThe invention claimed is:
1. A solid optical diffuser which comprises a transparent solid matrix embedding a dispersion of transparent nanoparticles, wherein:
said nanoparticles have an average size d in the range 10 nm≤d≤240 nm; the ratio between the blue and red scattering optical densities γ≡Log └T (450 nm)┘/Log └T(630 nm)┘ of said solid optical diffuser falls in the range 5≥γ≥2.5, where T(λ) is the monochromatic normalized collinear transmittance of the solid optical diffuser, which is the ratio between the transmittance of the solid optical diffuser, without the contribution of scattered light, and the transmittance of a reference sample identical to the solid optical diffuser except for the fact that it does not contain nanoparticles; along at least a first propagation direction, the monochromatic normalized collinear transmittance of the solid optical diffuser is T(450 nm)≥0.4; and along at least a second propagation direction, the monochromatic normalized collinear transmittance of the solid optical diffuser is T(450 nm)≤0.9.
2. The solid optical diffuser according to claim 1 , wherein the relative refraction index
m
≡
n
p
n
h
,
where n p is the refractive index of said nanoparticles and n h is the refractive index of said transparent solid matrix, falls in the range 0.7≤m≤2.1, and the effective particle diameter, D≡dn h , fulfills D[nm]≤132 m+115 if 0.7≤m<1; D[nm]≤240 if 1<m<1.35 and D[nm]≤−135 m+507 if 1.35≤m≤2.1.
3. The solid optical diffuser according to claim 2 , wherein, along at least the first propagation direction, the number of nanoparticles per unit area is
N
≤
N
max
=
3.7
×
1
0
-
28
D
6
m
2
+
2
m
2
-
1
2
[
meters
-
2
]
,
D being given in meters.
4. The solid optical diffuser according to claim 3 , wherein, along at least the second propagation direction, the number of nanoparticles per unit area is
N
≥
N
min
=
4.24
×
10
-
29
D
6
m
2
+
2
m
2
-
1
2
[
meters
-
2
]
,
D being given in meters.
5. The solid optical diffuser according to claim 1 , wherein the maximum filling fraction is f≤10 −2 .
6. The solid optical diffuser according to claim 1 , moreover being shaped as a parallelepiped panel where the ratio between the largest dimension, L, and the smallest dimension, W, is L/W≥20.
7. The solid optical diffuser according to claim 1 , wherein the ratio between the blue and red scattering optical densities γ is comprised in the range 3.5≤γ≤5, and wherein:
along said first propagation direction, the monochromatic normalized collinear transmittance of the solid optical diffuser is T(450 nm)≥0.6; and
along said second propagation direction, the monochromatic normalized collinear transmittance of the solid optical diffuser is T(450 nm)≤0.7.
8. The solid optical diffuser according to claim 1 , wherein said second propagation direction is the same as said first propagation direction.
9. The solid optical diffuser according to claim 1 , wherein said second propagation direction is orthogonal to said first propagation direction, and wherein along said second propagation direction the monochromatic normalized collinear transmittance of the solid optical diffuser is T(λ)≤0.5 for λ≤570 nm.
10. The solid optical diffuser according to claim 9 , wherein along said second propagation direction the monochromatic normalized collinear transmittance of the solid optical diffuser is T(λ)≤0.1 for λ≤570 nm.
11. The solid optical diffuser according to claim 9 , wherein the relative refraction index
m
≡
n
p
n
h
,
where n p is the refractive index of said nanoparticles and n h is the refractive index of said transparent solid matrix, falls in the range 0.7≤m≤2.1, and the effective particle diameter, D≡dn h , fulfills D[nm]≤132m+115 if 0.7≤m<1; D[nm]≤240 if 1<m<1.35 and D[nm]≤−135 m+507 if 1.35≤m≤2.1.
12. The solid optical diffuser according to claim 11 , wherein, along at least the first propagation direction, the number of nanoparticles per unit area is
N
≤
N
max
=
3.7
×
1
0
-
28
D
6
m
2
+
2
m
2
-
1
2
[
meters
-
2
]
,
D being given in meters.
13. The solid optical diffuser according to claim 12 , wherein, along at least the second propagation direction, the number of nanoparticles per unit area is
N
≥
N
min
=
4.24
×
10
-
29
D
6
m
2
+
2
m
2
-
1
2
[
meters
-
2
]
,
D being given in meters.
14. The solid optical diffuser according to claim 9 , wherein the maximum filling fraction is f≤10 −3 .
15. The solid optical diffuser according to claim 9 , moreover being shaped as a parallelepiped panel where the ratio between the largest dimension, L, and the smallest dimension, W, is L/W≥10.
16. The solid optical diffuser according to claim 15 , configured to be side-lit by a light source so that the light generated by the light source is partially guided inside the parallelepiped panel by total internal reflection and partially scattered out of the parallelepiped panel because of the action of the nanoparticles dispersed in the panel.
17. An illumination system comprising a solid optical diffuser according to claim 9 and a light source, the solid optical diffuser and the light source being configured so that the light emitted by the light source is at least partially guided inside the solid optical diffuser.
18. An optical diffuser comprising:
a matrix embedding a dispersion of nanoparticles having an average size d in the range 10 nm≤d≤240 nm; wherein the optical diffuser has a geometric shape that has a length L extending along an axial propagation direction and an extent E along an orthogonal propagation direction that is orthogonal to the axial direction; wherein T(λ) is a monochromatic normalized collinear transmittance at wavelength λ and is, for a given propagation direction, a ratio between the transmittance of the optical diffuser, without the contribution of scattered light, and the transmittance of a reference sample identical to the solid optical diffuser except containing no nanoparticles; wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the axial propagation direction is less than or equal to 0.9; and wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the orthogonal propagation direction is greater than or equal to 0.4.
19. The optical diffuser of claim 18, wherein a ratio γ between scattering optical densities of the optical diffuser at blue and red wavelengths falls in the range 5≥γ≥2.5, the ratio γ is equal to Log [T(λ 1 )]/Log [T(λ 2 )], λ 1 is a wavelength of blue light, and λ 2 is a wavelength of red light.
20. The optical diffuser of claim 19, wherein λ 1 is 450 nm and λ 2 is 630 nm.
21. The optical diffuser of claim 18, wherein the geometric shape of the optical diffuser is a parallelepiped, a cylinder, a tube, a lens, or a fiber.
22. The optical diffuser of claim 18, wherein L>10E.
23. The optical diffuser of claim 18, wherein the monochromatic normalized collinear transmittance T(λ) of the optical diffuser for λ=570 nm is in the range T(570)≤0.5 along the axial propagation direction.
24. The optical diffuser of claim 18, wherein the monochromatic normalized collinear transmittance T(λ) of the optical diffuser for λ=570 nm is in the range T(λ)≤0.3.
25. The optical diffuser of claim 18, wherein the monochromatic normalized collinear transmittance T(λ m ) of the optical diffuser at a measurement wavelength λ m is given by a ratio between first and second ratios,
wherein the first ratio is a ratio between a first radiant power of a measurement light beam impinging on the optical diffuser and a second radiant power of the measurement light beam propagating beyond the optical diffuser, along a measurement direction, the measurement light beam being a non-polarized quasi-monochromatic light beam having a central wavelength equal to the measurement wavelength λ m , a spectral bandwidth lower than 10 nm, and an angular divergence lower than 5 mrad; and
the second ratio is a ratio between a first radiant power of a measurement light beam impinging on a reference specimen and a second radiant power of the measurement light beam propagating beyond the reference specimen, along a measurement direction, the measurement light beam being a non-polarized quasi-monochromatic light beam having a central wavelength equal to the measurement wavelength λ m , a spectral bandwidth lower than 10 nm, and an angular divergence lower than 5 mrad, the reference specimen identical to the optical diffuser except that the reference specimen lacks transparent nanoparticles.
26. The optical diffuser of claim 18, wherein a relative refraction index m≡n p /n h , where n p is a refractive index of the nanoparticles and n h is a refractive index of the matrix, falls in the range 0.7≤m≤2.1 with the exclusion of the values falling in the range 0.95≤m≤1.05, and the effective particle diameter, D≡dn h , fulfills D[nm]≤132m+115 if 0.7≤m≤0.95, D[nm]≤240 if 1.05≤m≤1.35; and D[nm]≤−135m+507 if 1.35≤m≤2.1.
27. The optical diffuser of claim 26, wherein, along at least the orthogonal propagation direction, the number of nanoparticles per unit area is
N
≤
Nmax
=
3.7
×
1
0
-
28
D
6
m
2
+
2
m
2
-
1
2
[
meters
-
2
]
,
D being given in meters.
28. The optical diffuser of claim 26, wherein, along at least the axial propagation direction, the number of nanoparticles per unit area is
N
≥
Nmin
=
4.24
×
10
-
29
D
6
m
2
+
2
m
2
-
1
2
[
meters
-
2
]
,
D being given in meters.
29. The optical diffuser of claim 18, wherein a maximum filling fraction f is less than or equal to 10 −2 or less than or equal to 10 −3 .
30. The optical diffuser of claim 18, wherein the nanoparticles have a core-shell morphology comprising a core and a shell either covalently bonded or physically bonded by entanglement.
31. The optical diffuser of claim 18, wherein the nanoparticles are homogenously dispersed in an embedding matrix or the dispersion of nanoparticles includes gradients in filling fractions.
32. The optical diffuser of claim 18, wherein the nanoparticles are transparent.
33. The optical diffuser of claim 18, wherein the matrix is transparent.
34. The optical diffuser of claim 18, wherein the matrix has an absorption in the visible range of less than 0.05% for a 3 mm thickness.
35. The optical diffuser of claim 18, wherein the matrix has an absorption of light that is less than 50% of a scattering produced by the nanoparticle dispersion.
36. An optical system comprising:
an optical diffuser comprising:
a transparent matrix embedding a dispersion of transparent nanoparticles having an average size d in the range 10 nm≤d≤240 nm;
wherein the optical diffuser has a geometric shape that has a length L extending along an axial propagation direction and an extent E along an orthogonal propagation direction that is orthogonal to the axial direction;
wherein T(λ) is a monochromatic normalized collinear transmittance at wavelength λ and is, for a given propagation direction, a ratio between the transmittance of the optical diffuser, without the contribution of scattered light, and the transmittance of a reference sample identical to the solid optical diffuser except containing no nanoparticles;
wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the axial propagation direction is less than or equal to 0.9; and
wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the orthogonal propagation direction is greater than or equal to 0.4; and
a light source coupled to one side of the optical diffuser such that the light produced by the light source is partially guided inside the optical diffuser by total internal reflection and partially scattered out of the diffuser because of the action of the dispersed nanoparticles.
37. The optical system of claim 36, wherein a ratio γ between scattering optical densities of the optical diffuser at blue and red wavelengths falls in the range 5≥γ≥2.5, the ratio γ is equal to Log [T(λ 1 )]/Log [T(λ 2 )], λ 1 is a wavelength of blue light, and λ 2 is a wavelength of red light.
38. An optical system comprising:
a mirror; and an optical diffuser applied to a surface of the mirror, the optical diffuser comprising:
a transparent matrix embedding a dispersion of transparent nanoparticles having an average size d in the range 10 nm≤d≤240 nm;
wherein the optical diffuser has a geometric shape that has a length L extending along an axial propagation direction and an extent E along an orthogonal propagation direction that is orthogonal to the axial direction;
wherein T(λ) is a monochromatic normalized collinear transmittance at wavelength λ and is, for a given propagation direction, a ratio between the transmittance of the optical diffuser, without the contribution of scattered light, and the transmittance of a reference sample identical to the solid optical diffuser except containing no nanoparticles;
wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the axial propagation direction is less than or equal to 0.9; and
wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the orthogonal propagation direction is greater than or equal to 0.4.
39. The optical system of claim 38, wherein a ratio γ between scattering optical densities of the optical diffuser at blue and red wavelengths falls in the range 5≥γ≥2.5, the ratio γ is equal to Log [T(λ 1 )]/Log [T(λ 2 )], λ 1 is a wavelength of blue light, and λ 2 is a wavelength of red light.
40. An optical system comprising:
an optical diffuser comprising two largest faces, the optical diffuser comprising:
a transparent matrix embedding a dispersion of transparent nanoparticles having an average size d in the range 10 nm≤d≤240 nm;
wherein the optical diffuser has a geometric shape that has a length L extending along an axial propagation direction and an extent E along an orthogonal propagation direction that is orthogonal to the axial direction;
wherein T(λ) is a monochromatic normalized collinear transmittance at wavelength λ and is, for a given propagation direction, a ratio between the transmittance of the optical diffuser, without the contribution of scattered light, and the transmittance of a reference sample identical to the solid optical diffuser except containing no nanoparticles;
wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the axial propagation direction is less than or equal to 0.9; and
wherein the monochromatic normalized collinear transmittance at a wavelength of 450 nm T(450 nm) of the optical diffuser along the orthogonal propagation direction is greater than or equal to 0.4; and
a high-reflectivity coating deposited on at least one of the two largest faces of the optical diffuser.
41. The optical system of claim 40, wherein a ratio γ between scattering optical densities of the optical diffuser at blue and red wavelengths falls in the range 5≥γ≥2.5, the ratio γ is equal to Log [T(λ 1 )]/Log [T(λ 2 )], λ 1 is a wavelength of blue light, and λ 2 is a wavelength of red light.Cited by (0)
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