Light control devices and methods implemented with kinoform diffusers having controllable diffusion characteristics

• US 20020034012A1
• Filed: 07/16/2001
• Published: 03/21/2002
• Est. Priority Date: 07/14/2000
• Status: Active Grant

• Current Assignee: Lumec Holding ULC
• Original Assignee: Lumec Holding ULC
• Inventors: Crenshaw, Melissa, Ashdown, Ian, Santoro, Scott
• Granted Patent: US 7,660,039 B2
• Time in Patent Office: Days
• US Class Current: 359/599
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: F21S 11/00 Non-electric lighting devices or systems using daylight roofs with sky-light opening E04D13/03; sun blinds for windows with means for redirecting light onto ceiling of a room E06B9/00; hybrid lighting devices combining artificial and natural light F21S19/00; solar heat collectors F24S; solar cells or solar cell modules H01L31/00
• 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 5/002 using microoptical elements for redirecting or diffusing light
• CPC Class Codes: G02B 5/021 the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/0257 creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G03H 1/2202 Reconstruction geometries or arrangements

Abstract

Kinoform diffusers (82) exhibit controllable diffusion characteristics that include off-axis transmittance and reflectance properties, elimination of zero-order beam, and freedom from spectral dispersion under achromatic illumination. Light control devices (76, 80, 82) implemented with kinoform diffusers having controllable diffusion characteristics provide anisotropic luminous intensity distributions and glare control at high viewing angles while maintaining high luminaire efficiency or daylight utilization.

Claims

1. A kinoform diffuser exhibiting off-axis bending of the propagation direction of incident light as it propagates from the kinoform diffuser, comprising:

a substrate having a surface relief pattern that includes scattering elements with a distribution of surface heights defining non-Gaussian statistical properties of a diffuser scattering mechanism, the surface relief pattern configured to resemble one or more laser speckle patterns such that the scattering elements cause off-axis bending of the propagation direction of incident light as it propagates from the kinoform diffuser.

2. The kinoform diffuser of claim 1, in which the surface relief pattern is formed in a photosensitive recording medium.

3. The kinoform diffuser of claim 1, in which the surface relief pattern constitutes a first substantially optically transparent, homogeneous medium having a first index of refraction, and further comprising a second substantially optically transparent, homogeneous medium having a second index of refraction and positioned adjacent the surface relief pattern, the first and second indices of refraction being different from each other.

4. The kinoform diffuser of claim 1, in which the surface relief pattern is configured to resemble a volumetric cross-section of a single laser speckle pattern.

5. The kinoform diffuser of claim 1, in which the surface relief pattern is configured to resemble a volumetric cross-section of multiple spatially autocorrelated laser speckle patterns.

6. The kinoform diffuser of claim 5, in which:

the incident light has a zero order component;

there is one laser speckle pattern; and

multiple spatial shifting of the photosensitive recording medium relative to the laser speckle pattern between successive exposures of the photosensitive recording medium forms the spatially autocorrelated laser speckle patterns for suppressing to a substantially imperceptible level the zero order component of the incident light.

7. The kinoform diffuser of claim 1, in which the surface relief pattern exhibits a luminous intensity distribution within a specified range of angles.

8. The kinoform diffuser of claim 6, in which the surface relief pattern exhibits negligible scattering of incident light outside of the specified range of angles.

9. The kinoform diffuser of claim 1, in which the surface relief pattern includes scattering elements forming a pebbled surface that provides a substantially uniform luminous intensity distribution.

10. The kinoform diffuser of claim 1, in which the surface relief pattern includes scattering elements forming a pitted surface that provides a substantially uniform luminous intensity distribution.

11. The kinoform diffuser of claim 1, in which the surface relief pattern includes scattering elements forming a corrugated surface that provides a substantially elliptical or linear luminous intensity distribution.

12. The kinoform diffuser of claim 1, in which the surface relief pattern includes scattering elements forming a granulated surface that provides a batwing luminous intensity distribution.

13. The kinoform diffuser of claim 1, in which the surface relief pattern is of a transmissive type and the substrate is of an optically transparent type having a refractive index, and further comprising an optically transparent protective layer covering the surface relief pattern and having a refractive index that is different from the refractive index of the substrate.

14. The kinoform diffuser of claim 1, in which the surface relief pattern is of a reflective type, and further comprising an optically transparent protective layer having a low index of refraction.

16. The light control device of claim 15, in which the kinoform diffuser includes first and second kinoform diffuser portions and the substrate includes first and second optically transparent substrate portions that have side margins located proximally to each other, the first substrate portion having a first major surface to which the first kinoform diffuser portion is applied and the second substrate portion having a second major surface to which the second kinoform diffuser portion is applied, and further comprising:

a linear light source from which the incident light propagates, the linear light source having a longitudinal axis and being positioned relative to the first and second substrate portions so that the proximally located side margins extend in directions generally along the longitudinal axis; and

the first and second kinoform diffuser portions cooperating to define a plane of diffusion that is oriented generally parallel to the longitudinal axis to provide for the light control device a luminous intensity distribution with a predetermined cutoff angle in multiple planes in each of which a common axis lies, the multiple planes set in different locations established by different angular displacements about the common axis in perpendicular disposition to the direction of the longitudinal axis.

17. The light control device of claim 16, in which the first and second substrate portions are inclined relative to each other in the general form of a V-shape to have outer surfaces and confronting inner surfaces, the linear light source and the substrate being positioned so that the outer surfaces are located nearer to the linear light source so that an image of the linear light source appears to decrease in width when the linear light source is viewed at increasing angles in a plane intersecting and perpendicular to the longitudinal axis.

18. The light control device of claim 17, in which the first and second major surfaces to which the first and second kinoform diffuser portions are applied are positioned nearer to the outer surfaces than to the confronting inner surfaces of the first and second substrate portions.

19. The light control device of claim 17, in which the first and second kinoform diffuser portions are of a linear or an elliptical luminous intensity distribution type.

20. The control device of claim 16, in which the first and second substrate portions are inclined relative to each other in the general form of a V-shape to have outer surfaces and confronting inner surfaces, linear light source and the substrate being positioned so that the confronting inner surfaces are located nearer to the linear light source so that an image of the linear light source appears as two spaced-apart images when the linear light source is viewed at increasing angles in a plane intersecting and perpendicular to the longitudinal axis.

21. The light control device of claim 20, in which the first and second major surfaces to which the first and second kinoform diffusers portions are applied are positioned nearer to the confronting inner surfaces than to the outer surfaces of the first and second substrate portions.

22. The light control device of claim 20, in which the first and second kinoform diffuser portions are of a linear or an elliptical luminous intensity distribution type.

23. The light control device of claim 16, in which the first and second substrate portions are curved and arranged in the general form of a U-shape to have outer surfaces and confronting inner surfaces, and further comprising first and second light shields positioned on either side of the linear light source and adjacent to the respective first and second curved substrate portions to provide for the light control device a luminous intensity distribution of a batwing shape.

24. The light control device of claim 23, in which the first and second major surfaces to which the first and second kinoform diffuser portions are applied are positioned nearer to the confronting inner surfaces than to the outer surfaces of the first and second substrate portions.

25. The light control device of claim 23, in which the first and second kinoform diffuser portions are of a linear or an elliptical luminous intensity distribution type.

26. The light control device of claim 16, in which the first and second substrate portions are curved and arranged in the general form of a U-shape to have outer surfaces and confronting inner surfaces, and further comprising first and second laterally extending substrates positioned adjacent to the respective first and second curved substrate portions, the first and second laterally extending substrates carrying respective first and second lateral kinoform diffusers each of which defining a plane of diffusion that is perpendicular to the longitudinal axis to provide for the light control device a luminous intensity distribution of a batwing shape.

27. The light control device of claim 26, in which:

the first and second major surfaces to which the first and second kinoform diffuser portions are applied are positioned nearer to the confronting inner surfaces than to the outer surfaces of the first and second curved substrate portions;

each of the first and second laterally extending substrates has opposed outer and inner major surfaces, the outer major surface and the inner major surface of the first laterally extending substrate positioned in proximity to, respectively, the outer surface and the confronting inner surface of the first curved substrate portion, and the outer major surface and the inner major surface of the second laterally extending substrate positioned in proximity to, respectively, the outer surface and the confronting inner surface of the second curved substrate portion; and

the first and second lateral kinoform diffusers are applied to the outer major surfaces of the respective first and second laterally extending substrates.

28. The light control device of claim 15, further comprising a linear light source from which the incident light propagates, the linear light source having a longitudinal axis.

29. The light control device of claim 28, in which the kinoform diffuser is of a generally circular luminous intensity distribution type.

30. The light control device of claim 28, in which the substrate is optically transparent.

31. The light control device of claim 30, in which the substrate is curved and the kinoform diffuser is of a linear or an elliptical luminous intensity distribution type and defines a plane of diffusion that is oriented generally perpendicular to the longitudinal axis to provide for the light control device a luminance intensity distribution in which the incident light diffuses in a plane generally perpendicular to the longitudinal axis and preferentially directs the diffused incident light toward a work plane positioned nearer to the substrate than to the linear light source.

32. The light control device of claim 30, in which the substrate is generally planar and the kinoform diffuser is of a linear or an elliptical luminous intensity distribution type and defines a plane of diffusion that is oriented generally parallel to the longitudinal axis to provide for the light control device a luminance intensity distribution in which the incident light diffuses in a plane generally parallel to the longitudinal axis and preferentially directs the diffused incident light toward a work plane positioned nearer to the substrate than to the linear light source.

33. The light control device of claim 30, in which the substrate is curved and the kinoform diffuser is of a linear or an elliptical luminous intensity distribution type and defines a plane of diffusion that is generally parallel to the longitudinal axis to provide for the light control device a luminous intensity distribution in which the incident light diffuses in a plane generally parallel to the longitudinal axis.

34. The light control device of claim 33, in which the light source includes two adjacent light emitting devices spaced apart by a separation distance in a direction along the longitudinal axis, and in which the diffused incident light is preferentially directed to a work plane positioned nearer to the light source than to the substrate to prevent formation of a dark area corresponding to the separation distance between the light emitting devices.

35. The light control device of claim 15, in which the substrate is optically reflective.

36. The light control device of claim 35, in which the kinoform diffuser is one of a circular, an elliptical, or a linear luminous intensity distribution type.

37. The light control device of claim 36, in which the substrate is generally planar and the kinoform diffuser is of an elliptical or a linear type and defines a plane of diffusion that provides for the light control device retroreflective luminous intensity distribution in which the incident light propagating from the light source is diffused by the kinoform diffuser and redirected back toward the light source.

38. The light control device of claim 15, in which the substrate is optically transparent, and further comprising a point source from which the incident light propagates.

39. The light control device of claim 38, in which the kinoform diffuser is of a circular or an elliptical luminous intensity distribution type.

40. The light control device of claim 39, in which the kinoform diffuser diffuses the incident light and preferentially directs the diffused incident light toward a work plane positioned nearer to the substrate than to the point light source.

41. The light control device of claim 38, in which the kinoform diffuser is of a linear or an elliptical luminous intensity type.

42. The light control device of claim 41, in which the substrate is generally planar and the kinoform diffuser is of a linear luminous intensity type that provides for the light control device an isotropic luminous intensity distribution on a work plane positioned nearer to the substrate than to the point light source.

43. The light control device of claim 41, in which the substrate is generally planar and has an effective center, and in which the kinoform diffuser includes multiple wedge-shaped segments, each of which having a plane of diffusion oriented radially to the local surface normal to the major surface of the substrate, the local surface normal positioned substantially at the effective center.

44. The light control device of claim 15, in which the substrate includes a generally centrally located optically transparent region, and further comprising a light source from which the incident light propagates, the light source positioned so that a portion of the incident light propagates through the optically transparent region without undergoing diffusion.

45. The light control device of claim 44, in which the optically transparent region is formed by an open aperture.

46. The light control device of claim 44, in which:

the kinoform diffuser includes first and second kinoform diffuser portions and the substrate includes first and second optically transparent portions separated by the optically transparent region, the first substrate portion having a first major surface to which the first kinoform diffuser portion is applied and the second substrate portion having a major surface to which the second diffuser portion is applied;

the light source from which the incident light propagates is of a linear light source type having a longitudinal axis; and

the first and second diffuser portions and the optically transparent region cooperate to provide for the light control device a batwing luminous intensity distribution in a plane that is perpendicular to the longitudinal axis.

47. The light control device of claim 44, in which:

the kinoform diffuser is of a generally circular luminous intensity distribution type;

the light source from which the incident light propagates is of a point source type; and

the kinoform diffuser and the optically transparent region cooperate to provide for the light control device a circular batwing luminous intensity pattern.

48. The light control device of claim 15, in which the substrate is optically transparent and in which the kinoform diffuser and the major surface of the substrate include a generally centrally located curved region, and further comprising a light source from which the incident light propagates, the light source positioned so that a portion of the incident light propagates through the curved region.

49. The light control device of claim 48, in which:

the light source is of a linear light source type having a longitudinal axis; and

the kinoform diffuser is of a linear or an elliptical luminous intensity distribution type with a plane of diffusion that is oriented generally perpendicular to the longitudinal axis of the linear light source to provide for the light control device a linear batwing luminous intensity distribution and prevention of light source image formation for essentially all viewing angles.

50. The light control device of claim 48, in which:

the light source is of a point source type; and

the kinoform diffuser is of a generally circular luminous intensity distribution type and is aligned with the point source to provide for the light control device a circular batwing luminous intensity distribution and prevention of light source image formation for essentially all viewing angles.

51. The light control device of claim 15, in which the substrate is optically transparent, and further comprising a light source from which the incident light propagates, the propagation direction of the incident light changing with time relative to the local surface normal of the major surface of the substrate, and the off-axis bending of the propagation direction of the incident light causing preferential diffusion of the incident light toward a diffuser reference direction in response to the changes in the propagation direction of the incident light.

52. The light control device of claim 51, in which the light source is the sun, the incident light is sunlight, and the propagation direction of the incident light changes with time as a consequence of traversal of the sun across the sky.

15. A light control device implemented with a kinoform diffuser exhibiting controllable luminous intensity distribution and imparting off-axis light propagation characteristics to incident light, comprising:

a substrate having a major surface with a local surface normal; and

a kinoform diffuser applied to the major surface of the substrate, the kinoform diffuser having a microscopic surface relief pattern of a character that diffuses incident light into a luminous intensity distribution pattern, the incident light propagating in a propagation direction and the luminous intensity exhibiting relative to the local surface normal off-axis bending of the propagation direction of the incident light as it propropates from the kinoform diffuser.