Optical sky-sun diffuser

• US 8,469,550 B2
• Filed: 12/23/2010
• Issued: 06/25/2013
• Est. Priority Date: 06/24/2008
• Status: Expired

• Current Assignee: CoeLux S.R.L.
• Original Assignee: Light in Light S.r.l.
• Inventors: Di Trapani, Paolo, Pigazzini, Marta Cecilia, Averchi, Alessandro
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): SANTONOCITO, MICHAEL P
• Application Number:
  US12/977,070
• Publication Number:
  US 20110216542A1
• Time in Patent Office: 915 Days
• Field of Search: 362/311.01
• US Class Current: 362/311.01
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: F21S 8/033 the surface being a wall or like vertical structure, e.g. building facade
• CPC Class Codes: F21V 3/00 Globes; Bowls; Cover glasses with refracting properties F21V5/00; with reflecting properties F21V7/00; characterised by cooling arrangements F21V29/506
• CPC Class Codes: F21V 9/02 for simulating daylight F21V9/04, F21V9/06 take precedence
• CPC Class Codes: F21V 9/08 for producing coloured light, e.g. monochromatic; for reducing intensity of light with provision for controlling the colour F21V9/40
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: F21V 9/40 with provision for controlling spectral properties, e.g. colour, or intensity
• CPC Class Codes: F21W 2121/00 Use or application of lighting devices or systems for decorative purposes, not provided for in codes F21W2102/00 – F21W2107/00
• CPC Class Codes: F21W 2131/103 of streets or roads
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 Semiconductor lasers
• CPC Class Codes: G02B 19/0047 for use with a light source G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005
• CPC Class Codes: G02B 19/0071 adapted to illuminate a complete hemisphere or a plane extending 360 degrees around the source
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre
• CPC Class Codes: G02B 6/0041 provided in the bulk of the light guide
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/50 : Wavelength conversion elements

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

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

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

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

5. The solid optical diffuser according to claim 1, wherein the maximum filling fraction is f≦

10<sup>−

2</sup>.

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

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

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

14. The solid optical diffuser according to claim 9, wherein the maximum filling fraction is f≦

10<sup>−

3</sup>.

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.