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Title:
A LIGHTING SYSTEM FOR EMITTING A SHAPED LIGHT BEAM AND A LUMINAIRE
Document Type and Number:
WIPO Patent Application WO/2013/046081
Kind Code:
A1
Abstract:
A lighting system 100 for emitting a shaped light beam 112, a luminaire and a method of manufacturing the lighting system is provided. The lighting system 100 comprises a housing 102, a light redirection means 114, 106, a plurality of light sources 124, and a beam- shaping structure 118. The housing 102 comprises at least a base 107 and a light exit window 104 which is arranged opposite to the base 107. The base 107 is reflective. Between the base 107 and the light exit window 104 a light transmitting space 122 is present. The light redirection means 114, 106 redirects impinging light in an angular domain to improve outcoupling of light via the light exit windowl04. The light redirection means 114, 106 is arranged in the light transmitting space 122. The plurality of light sources 124 are arranged at light source positions P-L1, P-L2, P-L3 within the light transmitting space 122. The light sources 124 emit at least a part of the emitted light towards the redirection means 106, 114. The beam-shaping structure 118 is arranged at the light exit window 104. The beam-shaping structure shapes a beam of light emitted by the lighting system. The beam-shaping structure 118 comprises a plurality of micro beam-shaping elements (110) which are arranged in a pattern. The light source positions P-L1, P-L2, P-L3 of at least a subset of the light sources 124 are unaligned with respect to positions of the micro beam-shaping elements 110 in the pattern.

Inventors:
KRIJN MARCELLINUS PETRUS CAROLUS MICHAEL (NL)
VERSCHUREN COEN ADRIANUS (NL)
JAGT HENDRIK JOHANNES BOUDEWIJN (NL)
KLEIJNEN CHRISTIAN (NL)
VDOVIN OLEXANDR VALENTYNOVYCH (NL)
Application Number:
PCT/IB2012/054733
Publication Date:
April 04, 2013
Filing Date:
September 12, 2012
Export Citation:
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Assignee:
KONINKL PHILIPS ELECTRONICS NV (NL)
KRIJN MARCELLINUS PETRUS CAROLUS MICHAEL (NL)
VERSCHUREN COEN ADRIANUS (NL)
JAGT HENDRIK JOHANNES BOUDEWIJN (NL)
KLEIJNEN CHRISTIAN (NL)
VDOVIN OLEXANDR VALENTYNOVYCH (NL)
International Classes:
F21V11/14; F21V8/00
Domestic Patent References:
WO2001053744A12001-07-26
WO2005078487A12005-08-25
WO2005083317A12005-09-09
Foreign References:
US7806547B22010-10-05
US3351753A1967-11-07
US20020097354A12002-07-25
US7806547B22010-10-05
Attorney, Agent or Firm:
VAN EEUWIJK, Alexander Henricus Walterus et al. (AE Eindhoven, NL)
Download PDF:
Claims:
CLAIMS:

1. Lighting system (100, 200, 500, 550, 802) for emitting a shaped light beam

(112, 214), the lighting system (100, 200, 500, 550, 802) comprising

a housing (102) comprising at least a base (107, 212) and a light exit window (104) being arranged opposite to the base (107, 212), the base (107, 212) being reflective, and a light transmitting space (122, 218, 553) being present between the base (107, 212) and the light exit window (104),

a light redirection means (106, 202, 206, 502, 504, 554) for redirecting impinging light in an angular domain to improve outcoupling of light via the light exit window (104), the light redirection means (106, 202, 206, 502, 504, 554) being arranged in the light transmitting space (122, 218, 553),

a plurality of light sources (124) being arranged at light source positions (P- Ll, P-L2, P-L3) within the light transmitting space (122, 218, 553), the light sources (124) are configured to emit at least a part of the emitted light towards the light redirection means (106, 202, 206, 502, 504, 554),

- a beam-shaping structure (118, 215, 551, 602, 620, 660) being arranged at the light exit window (104), the beam-shaping structure (118, 215, 551, 602, 620, 660) being configured for shaping a beam of light (112, 214) emitted by the lighting system (100, 200, 500, 550, 802), the beam-shaping structure (118, 215, 551, 602, 620, 660) comprising a plurality of micro beam-shaping elements (110, 302, 304, 306, 604, 622, 640, 670) being arranged in a pattern,

wherein the light source positions (P-Ll, P-L2, P-L3) of at least a subset of the light sources (124) are unaligned with respect to positions (pi, ..., pi 3) of the micro beam- shaping elements (110, 302, 304, 306, 604, 622, 640, 670) in the pattern.

2. A lighting system (100, 200, 500, 550, 802) according to claim 1, wherein the micro beam-shaping elements (110, 302, 304, 306, 604, 622, 640, 670) are arranged in two directions at a predefined pitch, and specific distances between the light sources (124) of the subset differ from the predefined pitch, the specific distances are measured in at least one of the two directions.

3. A lighting system (100, 200, 500, 550, 802) according to claim 2, wherein the predefined pitch is not an integer multiple of any one of the specific distances and any one of the specific distances is not an integer multiple of the predefined pitch.

4. A lighting system (100, 200, 500, 550, 802) according to claim 1, wherein the housing (102) further comprises walls (103, 204) being interposed between the base (107, 212) and a side of the housing (102) which comprises the light exit window (104), the walls (103, 204) are reflective.

5. A lighting system (100, 200, 500, 550, 802) according to claim 1, wherein the beam-shaping structure (118, 215, 551, 602, 620, 660) is a plate which comprises light transmitting funnels (108, 223) enclosed by a nontransparent material. 6. A lighting system (100, 200, 500, 550, 802) according to claim 5, wherein the light transmitting funnels (108, 223) are arranged in an array, the light transmitting funnels (108, 223) have a certain funnel length h, a funnel entrance characteristic size of light input windows of the light transmitting funnels has a value a, a funnel exit window characteristic size of light exit windows of the light transmitting funnels (108, 223) has a value b, and \l2{bla) < h/b < 3(b/a)-2.

7. A lighting system (100, 200, 500, 550, 802) according to claim 1, wherein the beam-shaping structure (118, 215, 551, 602, 620, 660) transmits a first portion of light impinging on the beam-shaping structure (118, 215, 551, 602, 620, 660), and the beam- shaping structure (118, 215, 551, 602, 620, 660) is configured to reflect back a second portion of the impinging light that is not being transmitted through the beam-shaping structure (118, 215, 551, 602, 620, 660).

8. A lighting system (100, 200, 500, 550, 802) according to claim 7, wherein the beam-shaping structure (118, 215, 551, 602, 620, 660) is configured to diffusely reflect back the second portion of the impinging light.

9. A lighting system (100, 200, 500, 550, 802) according to claim 1, wherein the beam-shaping structure (118, 215, 551, 602, 620, 660) comprises a transparent plate and the micro beam-shaping elements (110, 302, 304, 306, 604, 622, 640, 670) are protrusions at or recesses in a surface of the transparent plate,

or

wherein the beam-shaping structure (118, 215, 551, 602, 620, 660) comprises a first layer (662) and a second layer (664) arranged on top of each other, wherein the first layer (662) comprises an array of elongated micro-prisms (666) and the second layer (664) comprises another array of elongated micro-prisms (674), the elongated micro-prisms (674) of the second layer (664) are arranged perpendicular to the elongated micro-prisms (666) of the first layer (662).

10. A lighting system (100, 200, 500, 550, 802) according to claim 1 or 4, wherein portions of the base (107, 212) that are not covered by the light sources (124) are diffusely reflective, or, when referring to claim 4, at least one of: i) the portions of the base (107, 212) that are not covered by the light sources (124) and ii) portions of the walls (103, 204) are diffusely reflective.

11. A lighting system (100, 200, 500, 550, 802) according to claim 1 or 4,

wherein an average absorption coefficient of the combination of the base (107, 212) and the light sources (124) is lower than 0.2, the average absorption coefficient being defined as a ratio between an absorbed amount of light of an amount of impinging light and the amount of the impinging light, or

when referring to claim 4, wherein the average absorption coefficient of the combination of the base (107, 212), the walls (103, 204) and the light sources (124) is lower than 0.2.

12. A lighting system (100, 200, 500, 550, 802) according to claim 1, wherein the light sources (124) comprise a light emitter (210) and a light conversion element (202, 504, 554) for converting the color the light emitted by the light emitter (210).

13. A lighting system (100, 200, 500, 550, 802) according to claim 5 and 12, wherein the light conversion elements (202, 504, 554) of the light sources (124) are only provided at least at a subset of light input windows of the light transmitting funnels (108, 223).

14. A luminaire (800) comprising a lighting system (100, 200, 500, 550, 802) according to claim 1. 15. A method (900) of manufacturing a lighting system for emitting a shaped light beam, the method comprises the steps of

providing (902) a housing which comprises at least a base and a light exit window opposite the base, the base is light reflective, and a light transmitting space is present between the base and the light exit window,

- arranging (904) a light redirection means in the light-transmitting space, the light redirection means being configured to randomly redirect impinging light in an angular domain to improve outcoupling of light via the light exit window,

arranging (906) a plurality of light sources at light source positions within the light transmitting space, the light sources are configured to emit at least a part of the emitted light towards the light re-direction means,

arranging (908) a beam-shaping structure at the light exit window, the beam- shaping structure is configured for shaping a beam of light emitted by the lighting system, the beam-shaping structure comprises a plurality of micro beam-shaping elements that are arranged in a pattern,

wherein, in at least one of the steps of arranging of the plurality of light sources and arranging of the beam-shaping structure, the arranging is performed in a unadjusted manner to obtain light sources positions for the light sources of a subset of light source that are unaligned with respect to positions of the micro beam-shaping element in the pattern.

Description:
A lighting system for emitting a shaped light beam and a luminaire

FIELD OF THE INVENTION

The invention relates to lighting systems for emitting a shaped light beam.

BACKGROUND OF THE INVENTION

Many light sources have a Lambertian light emission profile, which means that light is emitted in all directions into the ambient of the light sources and the light intensity in a given direction is proportional to the cosine angle with the surface normal. For lighting of workplaces in offices and industry this is undesirable and lighting has to comply with glare norms. Glare is the sensation produced by bright areas and may be uncomfortable. According to specific glare norms, the lighting systems should emit the light with angular intensity distributions having a cut off angle at about 60 degrees, which means that only a little amount of light is emitted at light emission angles larger than 60 degrees, wherein the light emission angle is measured with respect to an axis perpendicular to the (imaginary) light emission surface of the lighting system. Light emission at relatively large light emission angles is often prevented by the use of parabolic reflectors which shape the light emitted by the light source to a light beam which has a shape with a cut off angle at about 60 degrees.

Published patent US7806547 discloses a brightness-enhancing film. In specific embodiments of the patent document, specific lighting systems are disclosed which comprise a light mixing chamber having reflective walls and comprise light sources. At one side of the light mixing chamber a plurality of small light exit windows are available which allow the transmission of light from the light mixing chamber into collimating structures. The lighting systems emit via the collimating structures collimated light into the ambient of the lighting systems.

In the presented embodiments in the cited patent, the positions of the light sources are directly related to the positions of the light exit windows with their collimating structures. Either the light sources are provided in front of a light exit window, or the light sources are provided at a position somewhere in the middle of two light exit windows. Thus, during manufacturing, the light exit window and the light sources must be positioned very accurately with respect to each other, which results in a significant increase of manufacturing costs. Also a number of light sources need to be based on the number of light exit windows or vice versa. Further, the flexibility of the use of specific layers of collimating structures and the use of a specific cavity comprising light sources at a specific position is limited. In one of the embodiments, the light sources are provided within two collimating structures, which means that the size of the light source is limited with respect to the size of the collimating structures: the diameter of the light sources are at least smaller than the pitch of the collimating structures. This size limitation is another characteristic which limits the flexibility and which results in smaller light sources which are often more expensive if the pitch between the collimating structures is relatively small.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a lighting system for emitting a shaped light beam which is less expensive than the known lighting systems.

A first aspect of the invention provides lighting as claimed in claim 1. A second aspect of the invention provides a luminaire as claimed in claim 14. A third aspect of the invention provides a method of manufacturing a lighting system as claimed in claim 15. Advantageous embodiments are defined in the dependent claims.

A lighting system for emitting a shaped light beam in accordance with the first aspect of the invention comprises a housing, a light redirection means, a plurality of light sources, and a beam-shaping structure. The housing comprises at least a base and a light exit window which is arranged opposite to the base. The base is reflective. Between the base and the light exit window a light transmitting space is present. The light redirection means redirects impinging light in an angular domain to improve outcoupling of light via the light exit window. The light redirection means is arranged in the light transmitting space. The plurality of light sources are arranged at light source positions within the light transmitting space. The light sources emit at least a part of the emitted light towards the redirection means. The beam-shaping structure is arranged at the light exit window. The beam-shaping structure shapes a beam of light emitted by the lighting system. The beam-shaping structure comprises a plurality of micro beam-shaping elements which are arranged in a pattern. The light source positions of at least a subset of the light sources are unaligned withrespect to positions of the micro beam-shaping elements in the pattern.

The light redirection means changes the light emission angles of a part of the light emitted by the light sources such that light rays of this portion of light are distributed along a plurality of light emission directions. The light redirection means facilitate the redirection of light in the angular domain by reflecting in a plurality of directions, by diffuse reflection mechanisms and/or by scattering impinging light. Further, the base of the light transmitting space reflects light rays which impinge on the base. As such, light rays arrive at the light exit window at a plurality of directions and an angular distribution is relatively broad. Especially, if the distance from the light exit window towards the base has an appropriate value, a light output at the light exit window is relatively homogenous. The light direction means at least contributes to obtaining a more homogeneous light output. Thus, the light redirection means and the reflective base allow that the light sources are not positioned very accurately with respect to the positions of the micro beam-shaping elements because the light redirection means and the reflective base contribute to a relatively homogenous light output at the light exit window. Further, they prevent that light is absorbed before the light is outcoupled via the beam-shaping structure. The base being reflective means that the base reflects a relatively large part of impinging light, for example, more than 80% of the impinging light.

At least the light source positions of the light sources of the subset are unaligned with respect tothe positions of the micro beam-shaping elements and, as such, the lighting systems may be manufactured at a lower price. Light source positions which are unaligned with respect to positions of micro beam-shaping elements are light source positions which are unadjusted and/or unrelated to the positions of the micro beam-shaping elements. It allows, for example, the use of a plurality of beam-shaping structures which are not specifically designed for the position of the light sources and, thus, a cheaper beam-shaping structure may be selected and the manufacturing process is more flexible. Or, it allows, for example, a manufacturing process which places the light sources with a lower accuracy at specific positions and, consequently, the manufacturing process is cheaper. Further, the number of light sources doesn't need to be related to the number of micro beam-shaping elements which also increases the flexibility in the manufacturing process. Finally, the size of the light sources is not really important, and the light sources may have a size which is larger than a pitch of the micro beam-shaping elements. The light sources may be provided on the base. Optionally, the housing comprises walls and one or more of the light sources are provided on the walls.

It is to be noted that in the cited patent US7806547 all disclosures teach the skilled person that the light emitted by the light sources must be reflected once or twice before being emitted through the collimating structures into the ambient of the disclosed lighting systems and, therefore, the cited patent teaches that one has to align the positions of light sources with the positions of the collimating structures. Thus, the cited patent points the skilled person into a direction which is different from the claimed invention and, as such, it is not obvious for the skilled person how to obtain the claimed invention.

The positions of the light sources of the subset are unaligned with respect to the positions of the micro beam-shaping elements. In other words, the positions of the light source of the subset are unadjusted, unadapted and/or unrelated to the positions of the micro beam-shaping elements. Or, optionally, the light sources of the subset are positioned according to a first pattern, while the micro beam-shaping elements are positioned according to a second pattern, and the first pattern is not a subpattem of the second pattern and the first pattern cannot be obtained by a combination of translating, scaling with an integer factor and/or rotating the subpattem of the second pattern. It is to be noted that the subpattem of the second pattern is formed by more than two micro beam- shaping elements. Optionally, the relative positions of the light sources with respect to the micro beam-shaping elements are randomly distributed.

The micro beam- shaping elements have a relatively small size which is indicated by the term "micro". It means, in an embodiment, that a specific size of the micro beam-shaping elements, measured along a plane parallel to the light exit window, is smaller than 5 mm. In another embodiment, the diameter of the micro beam-shaping elements is smaller than 1 mm. The specific size is a diameter of the micro beam-shaping element if the micro beam-shaping element has a circular cross-section along the plane. The specific size is a distance between two parallel edges of the micro beam-shaping element if the micro beam- shaping element has a square cross-section along the plane. If the micro beam-shaping element has a rectangular cross-section along the plane, the specific size is the largest distance of the two distances between two parallel edges of the rectangle. Optionally, the specific size of the micro beam-shaping elements is smaller than a specific size of the light sources.

The micro beam-shaping elements shape the light beam emitted by the lighting system. Shaping the light beam means that the light emissions angles (measured with respect to a normal to the beam-shaping structure) and the amount of energy at specific light emission angles is influenced to obtain the shaped light beam. In other words, the micro beam-shaping elements modify an angular intensity distribution of the light beam which impinges from the light transmitting space onto the beam-shaping element to a desired angular distribution. As discussed before, the light which arrives at the light exit window from the light transmitting space has about all possible light transmission directions. Optionally, the micro beam-shaping elements reduce the light emission to a less wide light beam, when the micro beam-shaping elements are used as a collimator, and as such less energy will be emitted at relatively large light emission angles (measured with respect to a normal to the light exit window). The reduction of light emission angles may be symmetrical, such that the emitted shaped light beam is a collimated light beam, or the reduction of light emission angles may be asymmetrical such that the angular intensity distribution of the shaped light beam is different in different cross sections of the shaped light beam.

Alternatively, the light shaping of the light beam may also be such that the amount of energy at light emission angles close to the normal to the beam-shaping structure is relatively small - this is often termed a batwing shaped light emission.

Optionally, the light redirection means diffusely reflects light that impinges on the light redirection means.

Optionally, the micro beam-shaping elements are arranged in two directions at a predefined pitch. Specific distances between the light sources of the subset differ from the predefined pitch. The specific distances are measured in at least one of the two directions.

Optionally, the predefined pitch is not an integer multiple of any one of the specific distances and any one of the specific distances is not an integer multiple of the predefined pitch. Thus, the light source positions of light sources of at least the subset are not adjusted to the positions of the micro beams-shaping elements in the pattern. It is to be noted that the micro beam-shaping element may be arranged in a matrix pattern and that, as such, the two directions are orthogonal. The micro beams-shaping element may also be arranged in a honeycomb pattern and, then, an angle between the two directions is 60 degrees.

Optionally, the housing further comprises walls which are interposed between the base and a side of the housing which comprises the light exit window. The walls are reflective. Reflective walls assist in the recycling of light which is reflected back from the light exit window towards the walls and assist in the outcoupling of light if light is transmitted from the base towards the walls or which is transmitted from the light redirection means towards the walls. Thus, the walls do not contribute to a possible inefficiency and the walls contribute to the fact that light arrives at a plurality of light emission angles at the light exit window.

Optionally, a thickness of the beam-shaping structure measured in a direction following the light emission direction from the light sources towards the light exit window is smaller than 1 cm. It is advantageous to have a thin beam-shaping structure in the light emission direction, because it allows the manufacturing of a thin lighting system, for example, for use in thin display devices. Optionally, the thickness is smaller than 5 mm. Optionally the thickness is smaller than 1 mm.

Optionally, the beam-shaping structure is a plate which comprises light transmitting funnels that are enclosed by a nontransparent material. The plate with funnels is a beam-shaping structure that is not expensive. It may be a nontransparent plate in which holes are drilled, or a nontransparent plate in which funnels of a specific shape are etched. Further, grooves may be sawed in two orthogonal directions in a transparent plate and the grooves may be filled with the non-transparent material. Funnels may have the shape of (tapered) cylinder, a (partial) cone, compound-parabolic-concentrator, or any other shape which results in the beam shaping of the light emitted by the light sources.

Optionally, the light transmitting funnels are enclosed by a reflective material. Optionally, the funnels are arranged in an array. The funnels have a certain funnel length h. A funnel entrance characteristic size of light input windows of the funnels has a value a. A funnel exit window characteristic size of light exit windows of the funnels has a value b. And the relation \l2(bld) < h/b < 3(b/a)-2 applies. It has been observed that if the parameters of the funnel length, the funnel entrance diameter, the funnel exit window diameter fulfill the relation of this option, an optimum is obtained between the thickness of the beam-shaping structure and the efficiency of the lighting system. It is to be noted that the light input windows of the funnels are an end of the funnels which are facing the light sources and that the light exit windows of the funnels are an end of the funnels which are facing the ambient of the lighting system. Further, the diameter of a non-circular light input window of a funnel or of a non-circular light exit window of a funnel is the longest linear distance between two points of the envelope of the respective light input window or the light exit window. Thus, if the light input window has a square shaped light input window, the diameter is the length of a diagonal of the square shaped light input window.

The characteristic sizes of the light input window and the light output window are sizes which characterize the size of the respective light input window and light output window. It means that, for circular light input windows and light output windows the characteristic size is a diameter of the circle. For square light input windows and light output windows the characteristic size is a distance between two parallel edges of the square.

It is to be noted that the optional feature of the above discussed relation between different characteristics of the funnels may also be applied in a lighting system independently of the feature of the invention in which the light source positions of at least a subset of the light sources is unaligned with the positions of the micro beam-shaping elements. The above discussed relation between different characteristics of the funnels also result in the advantageously effect of having a lighting system which is relatively thin and which is relatively efficient independently of this feature.

Optionally, the funnels are arranged in the array at a certain funnel array pitch p and p equals b. In this case the micro beam- shaping elements are arranged as close as possible to each other, such that the beam-shaping structure has a maximum number of micro beam-shaping elements, and, thus, the efficiency of the beam-shaping structure is as high as possible.

Optionally, the beam-shaping structure transmits a first portion of light impinging on the beam-shaping structure, and the beam-shaping structure is configured to reflect back a second portion of the impinging light that is not being transmitted by the beam- shaping structure. It is advantageous that the beam-shaping structure reflects back light that is not transmitted through the beam-shaping structure because it allows the recycling of this light. The light transmitting space may, for example, reflect the light back towards the beam- shaping structure. Further, the light is, thus, not absorbed by the beam-shaping structure and as such the temperature of the beam-shaping structure does not rise above undesirable values as the result of the absorption of light. It is to be noted that still a small amount of light may be absorbed. Optionally, the beam-shaping structure is configured to absorb not more than 5% of the light which impinges from the light transmitting space on the beam- shaping structure.

Optionally, the beam-shaping structure is configured to diffusely reflect back the second portion of the impinging light. Thus, the portions of the beam-shaping structure, which reflect back the light in a diffuse manner, become part of the light redirection means of the lighting system. A diffuse reflection is advantageous because the light emission directions of the diffusely reflected light rays is randomized and, thus, the light, which arrives at the light exit window, is more homogeneous and, therefore, a total light output of the lighting system is more homogenous. If the light sources of the lighting system emit light of different colors, the back reflection, and the reflection of the light by the base and/or walls of the housing result in a better mixing of color and consequently in a more homogeneous color of light which arrives at the light exit window. Note that the beam-shaping structure which diffusely reflects back the second portion of the impinging light becomes a part of the light redirection means.

Optionally, the beam-shaping structure comprises a transparent plate and the micro beam-shaping elements are protrusions at or recesses in a surface of the transparent plate. The shape of the protrusions or recesses may be the shape of pyramid, a cone, or any other shape that provides a beam-shaping characteristic (such as, for example, disclosed in WO2005083317). Beam-shaping structures according to this option may be manufactured relatively cheap and they provide an advantageous beam-shaping characteristic. Further, the beam- shaping structure has a relatively low absorption characteristic: the transparent plate does not absorb light, and the interfaces between the transparent plate and the ambient either transmit (and refract) light beams, or reflect light beams.

Optionally, the beam-shaping structure comprises a first and a second layer arranged on top of each other, wherein the first layer comprises an array of elongated micro- prisms and the second layer comprises another array of elongated micro-prisms, the elongated micro-prisms of the second layer are arranged perpendicular to the elongated micro-prisms of the first layer. The manufacturing of such a beam-shaping structure is relatively cheap because two equal layers have to be arranged on top of each other and only one layer must be rotated 90 degrees with respect to the other layer. Optionally, the first layer comprises an array of elongated lenses and the second layer comprises an array of elongated lenses which are arranged perpendicular to the lenticular lenses of the first layer.

Optionally, at least one of i) portions of the base that are not covered by the light sources and ii) portions of the walls are diffusely reflective. If the base and/or the walls of the light transmitting space are diffusely reflective, light, which impinges on the base and/or the walls, is reflected such that the reflected light is directly transmitted to the light exit window or arrives after a few more reflections at the light exit window. Thus, this light is recycles and may also be used for emission through the beam-shaping structure. If the light is reflected diffusely, a plurality of light emission directions are obtained which increases the probability that the diffusely reflected light is emitted through the beam-shaping structure into the ambient of the lighting system. The base and/or the walls which diffusely reflect light that impinges on the base and/or the walls are part of the light redirection means of the invention.

Optionally, an average absorption coefficient of the combination of the base and the light sources is lower than 0.2 or an average absorption coefficient of the

combination of the base, the walls and the light sources is lower than 0.2. The average absorption coefficient is defined as a ratio between an absorbed amount of light of an amount of the impinging light and the amount of impinging light. Thus, if light is reflected back by the beam-shaping structure, this light is reflected with a high probability by the wall and, thus, a significant amount of light is recycled within the light transmitting space. Optionally, the average absorption coefficient of the combinations is lower than 0.1. Optionally, the average absorption coefficient of the combinations is lower than 0.05.

Optionally, the light sources comprise a light emitter and a light conversion element for converting the color of the light emitted by the light emitter. Optionally the light conversion element comprises luminescent material for absorbing a part of the light emitted by the light emitter and converting a part of the absorbed light to light of another color. The light conversion element may be arranged directly on top of the light emitter. If the light conversion element is arranged at a certain distance away from the light emitter, one often refers to this configuration by "a remote phosphor configuration". In other advantageous optional arrangements a small gap is present between the light emitter and the light converting element. The gap has a depth of, for example, 100 micrometer to 10 millimeter. The configuration with the gap is often called a vicinity phosphor configuration. Often the luminescent material emits light of the another color in all directions. Further, specific luminescent materials such as, for example, inorganic phosphors, scatter light or diffusely reflect which impinges on it and which is not being absorbed. Thus, the light conversion element may be part of the light redirection means of the lighting system of the invention. It is to be noted that different light sources may comprises different types of luminescent elements, for example, comprising different luminescent materials to obtain different colors of light.

Optionally, the light conversion elements of the light sources are only provided at least at a subset of light input windows of the funnels. It is advantageous to provide the light conversion elements only at the light input windows because it saves material. The material used in light conversion elements is often relatively expensive.

Further, in this option, the light conversion elements provided at the light input windows are shared by at least a subset of the light emitters. Because the position of a subset of the light sources is unadjusted to the positions of the micro beam-shaping elements, in this option the number of light conversion elements may differ from the number of light emitters. If different light sources have different light conversion elements, different light input windows may comprise different light conversion elements.

Optionally, the light conversion elements of the light sources are provided within light input windows of the funnels.

According to a second aspect of the invention, a luminaire is provided which comprises a lighting system according to the first aspect of the invention. The luminaire according to the second aspect of the invention provides the same benefits as the lighting system according to the first aspect of the invention and has similar embodiments with similar effects as the corresponding embodiments of the system.

According to a third aspect of the invention, a method of manufacturing a lighting system for emitting a shaped light beam has been provided. The method comprises the steps of: i) providing a housing which comprises at least a base and a light exit window opposite the base, the base is light reflective, and a light transmitting space is present between the base and the light exit window, ii) arranging a light re-direction means in the light-transmitting space, the light re-direction means being configured to randomly re-direct impinging light in an angular domain to improve outcoupling of light via the light exit window, iii) arranging a plurality of light sources at light source positions within the light transmitting space, the light sources are configured to emit at least a part of the emitted light towards the light re-direction means, iv) arranging a beam-shaping structure at the light exit window, wherein the beam-shaping structure is configured for shaping a beam of light emitted by the lighting system, and wherein the beam-shaping structure comprises a plurality of micro beam- shaping elements that are arranged in a pattern. In at least one of the steps of arranging of the plurality of light sources and arranging of the beam-shaping structure, the arranging is performed in a unadjusted manner to obtain light sources positions for the light sources of a subset of light source that are unaligned with respect to positions of the micro beam-shaping element in the pattern.

The method according to the third aspect of the invention provides the same benefits as the lighting system according to the first aspect of the invention and has similar embodiments with similar effects as the corresponding embodiments of the system.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

It will be appreciated by those skilled in the art that two or more of the above- mentioned options, implementations, and/or aspects of the invention may be combined in any way deemed useful.

Modifications and variations of the system, the method, and/or of the computer program product, which correspond to the described modifications and variations of the system, can be carried out by a person skilled in the art on the basis of the present description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings: Fig. 1 schematically shows a cross-section of an embodiment of a lighting system according to the first aspect of the invention,

Fig. 2 schematically shows a cross-section of another embodiment of a lighting system inclusive an enlargement of a specific detail of the lighting system,

Fig. 3 schematically shows three cross-sections of different embodiments of the beam-shaping structure,

Fig. 4a schematically shows a chart in which a range of favorable combinations of a collimation angle and efficiency of the lighting system is selected from and related to two ratios of geometrical characteristics of funnels of micro beam-shaping elements,

Fig. 4b schematically shows a chart in which, for a compound-parabolic- concentrator, the collimation angle and the efficiency of the lighting system is related to the two ratios of Fig. 4a,

Fig. 5a schematically shows a cross-section of a lighting system in which the light sources comprises a light conversion element,

Fig. 5b schematically shows a cross-section of a lighting system in which the light sources, together with a diffusing element, form a side-emitting light source,

Fig. 6 schematically shows different embodiments of the beam-shaping structure,

Fig. 7 schematically shows the effect of the beam-shaping structure on the beam shape of the emitted light,

Fig. 8 schematically shows a luminaire according to the second aspect of the invention, and

Fig. 9 schematically shows a method of manufacturing a lighting system for emitting a shaped light beam.

It should be noted that items denoted by the same reference numerals in different Figures have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item have been explained, there is no necessity for repeated explanation thereof in the detailed description.

The Figures are purely diagrammatic and not drawn to scale. Particularly for clarity, some dimensions are exaggerated strongly.

DETAILED DESCRIPTION A first embodiment is shown in Fig. 1. A lighting system 100 is presented which is configured to emit a shaped light beam 112. The lighting system 100 comprises a housing 102 which encloses a light transmitting space, which is in the embodiment of Fig. 1 a cavity 122. The cavity 122 has a light exit window 104. The housing 102 has walls 103 and a base 107 and surfaces 106 of the walls 103 and base 107 which face the interior of the cavity are at least light reflective. A plurality of light sources 124 are arranged within the cavity 122. The light sources 124 are arranged at light source positions P-Ll, P-L2, P-L3. The light sources 124 emit light towards the light exit window 104. As seen in Fig. 1 the light rays 120 emitted by the light sources 124 form relatively wide light beams. A beam- shaping structure 118 is provided at the light exit window 104 and, as such, the beam- shaping structure 118 is arranged within the light rays 120 emitted by the light sources 124. The beam- shaping structure 118 shapes the light rays 120 emitted by the light sources 124 into the shaped light beam 112. The beam-shaping structure 118 comprises a plurality of micro beam-shaping elements 110. Surfaces 114 of the micro beam- shaping elements 110, which face the cavity and do not allow the transmission of light into the ambient of the lighting system 100, are reflective. The surfaces 114 of the micro beam- shaping elements and/or the surfaces 106 of the base 107 and walls 103 are diffusely reflective and form a light redirection means. The micro beam-shaping elements 110 are arranged in a pattern. In Fig. 1 the micro beam- shaping elements 110 have positions pi to pl3. The light source positions P-Ll to P-L3 are unadjusted to the positions pi to pl3 of the micro beam- shaping elements 110. It is seen in Fig. 1 that one light source 124, which is the most left light source 124 at position P-Ll, is exactly positioned in between two micro beam-shaping elements 110, while, for example, another light source, which is the most right light source 124 at position P-L3, is arranged at a position in front of a specific micro beam-shaping element 110. Thus, the positions P-Ll, P-L2, P-L3 of the light sources 124 are not aligned with respect to the positions pi ...pi 3 of the micro beam- shaping elements 110. In other words, the light sources 124 are randomly positioned with respect to the micro beam-shaping elements 110.

The light of the relatively wide light beams (formed by light rays 120) which is not directly transmitted into the ambient is (diffusely) reflected by surface 114 of the micro beam-shaping elements 110 and/or the surfaces 106 of the base 107 and/or walls 103 and, as such, the light which arrives at the light exit window 104 comprises light rays in a plurality of light emission angles and is, as such, a wide light beam. The light is collimated by the micro beam-shaping elements 110. The micro beam-shaping elements 110 comprise a transparent channel 108, which becomes wider in a direction away from the light exit window 104. The transparent channel 108 is formed in between two opaque structures 116 which have a triangular cross-section. In a three dimensional view, the transparent channel 108 may be enclosed by four pyramids of a nontransparent material.

According to the invention, the positions P-Ll, P-L2, P-L3 of the light sources 124 are not adjusted to the positions pi ...pi 3 of the micro beam- shaping elements 110. This means, in the embodiment of the lighting system 100, the light sources 124 need not to be positioned accurately, because the positions P-Ll, P-L2, P-L3 of the light source 124 are unadjusted to the positions of the micro beam-shaping elements 110 of the beam-shaping structure 118. In other words, the beam- shaping structure 118 may be arranged to the housing with a certain inaccuracy, because such an inaccuracy is acceptable because of the presence of light redirection means and reflective surfaces. As such, the manufacturing costs of the lighting system 100 are relatively low. Further, it provides flexibility: if, for example, the beam-shaping structure 118, which is normally arranged at the light exit window 104, is not available anymore, and a similar beam-shaping structure, which provides the same beam- shaping characteristics, is available, the similar beam-shaping structure may be arranged at the light exit window 104.

The housing 102 of lighting system 100 comprises the walls 103. However, in an alternative embodiment, the lighting system is relatively large and has no walls at its edges. In that case the space between the base and the light exit window is a light

transmitting space which may, for example, be filled with a light transmitting material.

Especially, when the effect of possible light loss at the edges may be neglected compared to the total amount of light that is emitted (because of the surface of the walls are small compared to the size of the lighting system), the walls do not have a very important function in the efficiency of the lighting system.

In the embodiment of Fig. 1, the light sources 124 are provided on the base

107. Alternatively, in another embodiment, one or more of the light sources 124 are provided on the walls 103.

Fig. 2 schematically shows a cross-section of another embodiment of a lighting system 200 inclusive an enlargement of a specific detail of the lighting system. A part of the lighting system 200, which is encircled in the top part of Fig. 2, is enlarged at the bottom end of Fig. 2. The lighting system 200 has a housing which comprises walls 204 and a base 212. The housing encloses a cavity 218 which is filled with air or with a transparent material. The housing has a light exit window 104. On the base 212 are provided Light Emitting Diode (LEDs) 210 which are arranged to emit a substantial part of their light emission towards the light exit window 104. A part of the light emission of the LEDs 210 may also be transmitted directly towards the walls 204. Surfaces of the walls 204 and of the base 212 that face the cavity (and are not covered by the LEDs 210) comprise a layer 206 of a diffusely reflective material. Light which impinges on this layer 206 is diffusely reflected. Thus, light from the LEDs 210 which is directly transmitted to the walls 204 is diffusely reflected back such that it has another chance of leaving the cavity 218 via the light exit window 104. Further, light which is reflected by other surfaces around the cavity may also impinge on the layer 206.

The layer 206 of a diffusely reflective material may also comprise material which is specular reflective, as long as at least a part of the reflected light is diffusely reflected. Further, the layer 206 may be relatively thin, however, in an optional embodiment the layer 206 is relatively thick. Diffusely reflective means that after reflection the light emission angles are distributed over a plurality of light emission angles (preferably randomly distributed), thus, the angular distribution of the light becomes wider.

At the light exit window 104 is provided a light conversion element 202 which comprises a luminescent material for absorbing a part of the light received from the LEDs 210 and converting a part of the absorbed light into a light emission of another color. The luminescent material may be any type of luminescent material, such as, for example, organic phosphors or inorganic phosphors. If inorganic phosphors are used, the inorganic phosphor particles have also to some extent the function to diffusely reflect light. In a specific embodiment of the light conversion element 202, the light conversion element 202 also comprises particles, such as, for example, Ti0 2 particles for scattering and/or diffusely reflecting light which impinges on the particles. Thus, the light conversion element 202 may be part of the light redirection means of the lighting system 200.

The lighting system 200 further comprises a beam- shaping structure 215 which comprises micro beam-shaping elements 110. The micro beam-shaping elements 110 are embedded in a light transmitting layer 208 of a transparent material. The micro beam- shaping elements 110 are formed by neighboring opaque structures 216 which enclose a funnel 223. The neighboring opaque structures 216 have in a cross-sectional view a triangular shape. In a three-dimensional view the micro beam- shaping elements 110 are formed in between three or four conical shaped structures or structures having the shape of a pyramid. Surfaces 220 of the triangular shaped structures 216, which face the funnel 223, are reflective and reflect impinging light 222 according to the law of "the angle of reflection equals the angle of incidence". This reflection effect may be the result of reflection by reflection coating or result from total internal reflection. A bottom surface of the triangular shaped structures 216 is provided with a layer 206 of a diffusely reflective material, which means that, if light 224 impinges on the bottom surface, the light is reflected in a plurality of directions. The bottom surface of the triangular shaped structures 216 faces the light conversion element 202 and, thus, the cavity 218, and the diffusely reflected light is recycled via the cavity.

In a specific embodiment, the LEDs 210 emit blue light. The light conversion element 202 comprises inorganic luminescent material which absorbs a part of the blue light and converts the absorbed light towards yellow light. A mix of blue and yellow light is emitted in an upwards direction at the top surface of the light conversion element 202 (wherein the orientation of the presented cross-section of Fig. 2 defines which direction is upwards and which surface is the top surface). Because light arrives at the light exit window 104 in a plurality of directions, and the light conversion element 202 also redirects light (via scattering and emitting light in a diffuse manner), the beam-shaping structure 215 receives a light beam which also has relatively wide light emission angles. The funnels 223 collimate the light beam into the shaped light beam 214. The reflective surface 220 which faces the funnels 223 reflects light rays 222 at relatively large light incidence angles into a direction within the shaped light beam 214.

The lighting system 200 is very efficient because absorption of light in the cavity and by the beam-shaping structure is minimized by using highly reflective materials and coatings. Thus, the operational costs of the lighting system 200 are relatively low.

Further, the LEDs 210 are larger than the beam- shaping elements 110 and the position of the LEDs 210 are not adjusted to the pattern in which the beam-shaping elements 110 are arranged. Thus, during manufacturing, the LEDs can be positioned with some inaccuracy and/or the beam-shaping structure 215 may be arranged within the lighting system 200 with some inaccuracy. This reduces the manufacturing costs of the lighting system 200.

In another embodiment (not drawn), the light conversion element 202 of the lighting system 200 does not cover the whole light exit window 104, but covers only the entrance windows of the funnels 223. In yet another embodiment, sections of the light conversion element 202 are provided within the funnels 223 near the entrance window of the funnels 223.

Fig. 3 schematically shows three cross-sections of different embodiments of the beam-shaping structures. The beam-shaping structure presented at (a) has beam-shaping elements 302 which have, in a cross-sectional view, a triangular shaped funnel through an opaque material. In a three dimensional view, the funnel has a conical or pyramid shape. As seen at (a) the top of the cone or pyramid is cut off in order to obtain a light input window for receiving light into the funnel. In the cross-section presented at (a) four different parameters of the beam-shaping structure are presented. The beam-shaping elements 302 are arranged in an array at a certain pitch p. The funnels have a length (height) h. The light entrance window of the funnels (which faces the cavity) has a diameter a and the light exit window of the funnels (which faces the ambient) has a diameter b. Advantageous relations between these parameters are discussed in the discussion of Fig. 4.

The beam-shaping structure presented at (b) has beam-shaping elements 304 which are arranged in an array at a certain pitch. The beam- shaping elements 304 have also a light transmitting funnel through an opaque material similar to the beam-shaping elements 302 of beam- shaping structure (a), however, the walls of the funnels are arranged in a specific profile as presented in the Figure. The light transmitting funnels are, for example conical shaped or have the shape of a pyramid.

The beam-shaping structure presented at (c) has beam-shaping element 306 which have a funnel in the shape of a compound-parabolic-concentrators.

Fig. 4a schematically shows a chart in which the collimation angle and the efficiency of the lighting system are related to two ratios of geometrical characteristics of funnels of micro beam-shaping elements. In Fig. 3, at beam-shaping structure (a), four different characteristics of the funnels of the beam-shaping elements (a) have been indicated. The x-axis of the chart represents the ratio h/b and the y-axis represents the ratio b/a. The presented chart of Fig. 4a has been obtained with a simulation by means of ray-tracing software. A lighting system, similar to the lighting system of Fig. 2 was simulated with different beam-shaping structures which have a design similar to the design the beam-shaping structure (a) of Fig. 3. The simulations were performed with a beam-shaping structure in which the pitch p of the array of micro beam-shaping elements is equal to the characteristic size b of the light exit window of the funnel. The simulated different beam-shaping structures have different have different values for the characteristics a, b and h. The reflectively value of a metal coating which is applied to surface of the micro beam-shaping elements that face the funnels was 95%, and the reflectivity of the diffusely reflective layers 206 (of the surfaces facing the cavity) was 97%.

In the chart of Fig. 4a the dark lines, such as for example line 408, represent borders of regions with a specific collimation angle. Thus, in order words, all lighting systems that have h/b and b/a ratios such that they would be projected on a point on the line, emit a shaped light beam which has the same beam angle (measured as a Half Width Half Maximum angle). Line 408 represents the lighting systems which have a beam angle of 11 degrees.

The background grey of the chart of Fig. 4a represents different levels of energy efficiency of the lighting system. The darker the grey is, the more energy efficient the lighting system is. The efficiency is defined as a ratio of an amount light output with the beam-shaping structure and an amount of light output without the beam-shaping structure.

Further, two white lines 404, 412 are drawn which form a border between three different regions 402, 410, 414. The center region 410, which is the region in between the white lines 404, 412, may be described by the relation 1/2 (b/a) < h/b < 3(b/a)-2. Lighting systems, which have beam-shaping elements with geometrical characteristics within the center region 410, are advantageous lighting systems because they can be made relatively thin and are relatively efficient. The bottom-right region 414 represents beam- shaping elements which have a too large height and are as such not thin enough. The top-left region 420 represents lighting systems which are not efficient enough. It is to be noted that, in specific advantageous embodiments of a lighting system, the characteristics of the micro beam-shaping elements fulfill the relations 1/2 (b/a) < h/b < 3(b/a)-2 independently of the fact that the positions of the light sources of the lighting system are adjusted or unadjusted to the positions of the micro beam-shaping elements.

In an embodiment, the micro-collimating structures have the subsequent dimensions: the funnels have a funnel length A of 21 mm, a funnel entrance characteristic size of light input windows of the funnels has a value a of 1 mm, a funnel exit window

characteristic size of light exit windows of the funnels has a value b of 4.2 mm. This results in a 10 degrees HWFM collimating angle of the shaped light beam.

In a chart of Fig. 4b the background grey color represents the efficiency of the lighting system. The line 432 represents configurations of a lighting system with a beam- shaping structure that comprises compound parabolic concentrator (CPC) beam-shaping elements, such as the beam- shaping elements of the beam-shaping structure (c) of Fig. 3. For CPCs there is a unique relation between the ratios b/a and h/b and, as such, lighting systems comprising CPC shaped beam-shaping elements are only present on the line 432 drawn in Fig. 4b. The dots with values on line 432 represent the collimation angle of the shaped light beam by the CPCs.

Fig. 5a schematically shows a cross-section of a lighting system 500 in which the light sources 210 comprise a light conversion element 504. In a previously discussed embodiment of a lighting system 200 of Fig. 2, the light conversion element 202, which comprises luminescent material, was arranged at the light exit window 102 of the lighting system 200. In the presented lighting system 500, the light conversion element 202 is replaced by a diffusing layer 502 which diffuses light which impinges on the layer. The diffusing layer 502 partially transmits light and partially reflects light and the light emission angles are randomly changed by the diffusing layer 502 via scattering light in the

transmission direction and the reflection direction. The diffusing layer 502 is part of the light redirection means of the lighting system 500. Further, in the lighting system 500 are provided light conversion elements 504 that are in direct contact with a light emitting surface of the dies of the LEDs 210. The LEDs 210 emit blue light and a luminescent material of the light conversion elements 504 absorbs a part of the blue light and converts the absorbed part to light of another color, which is, for example, yellow. The total light emission of the LEDs 210 with their light conversion element 504 is the combination of light emitted by the LEDs 210 that is not absorbed by the light conversion element 504 and light of another spectral range that is generated by the light conversion element 504 (after absorbing a part of the light received from the LEDs 210). If the LEDs 210 emit blue light and the light conversion element 504 converts some blue light towards yellow light, the total light emission may be white light.

It is to be noted that the invention is not limited to the use of LEDs which emit blue light. The emission of UV light and the conversion of UV light to light in another spectral range may also be advantageous.

Fig. 5b schematically shows a cross-section of a lighting system 550 in which the light sources 210 together with a diffusing element 554 form a side-emitting light source. The lighting system 550 comprises a cavity 553 which is filled with a transparent material. Recesses 556 in the transparent material comprise the diffusing element 554 and a LED 210 on which a light conversion element 504 is provided. The LED 210 with light conversion element 504 are configured to emit light towards the diffusing element 554. A gap is present between the diffusing element 554 and the LED 210 with light conversion element 504. Because of the specific configuration, light can only leave the recess 556 and enter the transparent material of the cavity 553 at side-wards oriented directions (wherein the term side-wards is used in relation to the orientation of the presented cross-section of Fig. 5b).

Surfaces of the walls 204 and the base 212 are covered with a specular reflecting coating 552, and, consequently, light which impinges on the surfaces is reflected according to the law of "angle of reflection equals the angle of incidence". This means that light rays within the cavity 553 have a direction which has mainly a side- wards orientation and the direction is slightly oriented downwards or upwards.

The beam-shaping structure 551 is made of a layer of a transparent material 208 which has grooves 558. In the presented cross-section, the grooves have a triangular cross-section and only the grooves with an orientation perpendicular to the plane of the cross- section are shown. The beam-shaping structure 551 has also grooves in a direction parallel to the plane of the presented cross-section. The layer 208 of the transparent material is the same as the layer 208 of the transparent material of the lighting system 200 of Fig. 2; however, the beam-shaping structure 551 differs from the beam-shaping structure 215 of the lighting system 200 of Fig. 2 with respect to the material which is put into the recesses 558. In the beam-shaping structure 552 the recesses 558 are filled with air or a gas which has a refractive index that is at least lower than the reflective index of material of the layer 208 such that light rays which impinge on this surface are subject to total internal reflection. In an embodiment, the refractive index of the gas has a value of about 1. The transparent material has a higher refractive index and, as such, the surfaces of the recesses, which face funnels in between the recesses, are reflective for most light beams which impinge the surfaces as the result of total internal reflection. This is shown at position 562.

Further, the transparent material which fills the cavity 553 has also a higher refractive index than the material which is provided in recesses 558. Consequently, interfaces between transparent material of the cavity 553 and the recesses 558 of the beam-shaping element 551 are also reflective for light beams which impinge on the interfaces at relatively large light incidence angles (measured with respect to a normal of the interface). This is shown at position 560 where a light ray which impinges at a large angle on the interface is reflected due to total internal reflection

The transparent material which fills the cavity 553 and the transparent material of the layer 208 have about the same refractive index. This results in a transmission of light rays which impinge on the interface between both transparent materials without significant refraction or reflection. The transmitted light rays impinge on the surfaces of the recesses in the layer 208 and are, as discussed above, reflected. This reflection is shown at position 562.

The advantage of the embodiment of the lighting system 550 is that the beam- shaping structure 551 may be manufactured relatively cheap. The walls of the funnels need not to be coated with a specular coating, the recesses 558 need not to be filled by a specific material, and the bottom surfaces of the recesses 558 need not to be coated with a diffusely reflective material. Fig. 6 schematically shows, in addition to the already presented beam-shaping structure, different embodiments of possible beam-shaping structures 602, 620, 660 and an embodiment of a micro beam-shaping element 640. Beam-shaping structure 602 comprises beam-shaping elements 604 which comprise a protrusion in a surface of a transparent layer. Beam-shaping structure 620 comprise beam-shaping element 622 which comprise a recess in a surface of a transparent layer. In part (iii) of Fig. 6 a beam-shaping element is presented which is made of a conical protrusion which comprises a recess in the top of the cone. Beam- shaping structure 660 comprises two layers. A first layer 662 comprises an array of elongated pyramids 666 of a first transparent material which has a first refractive index. In between the elongated pyramid 666 a second transparent material 668 is provided which has a second refractive index. The first refractive index is substantially different from the second refractive index such that light rays passing the interface between the first material and the second material are refracted. The second layer 664 also comprises an array of elongated pyramids 674 of the first transparent material which has the first refractive index. In between the elongated pyramid 674 the second transparent material 672 is provided which has the second refractive index (in an embodiment, the first refractive index is larger than the second refractive index). At the interface between the first material and the second material light rays are refracted. The orientation of the elongated pyramids 666 of the first layer 662 is perpendicular to the orientation of the elongated pyramids 674 of the second layer 664. A beam-shaping element 670 comprises a part of the first layer 662 and a part of the second layer 664 which is above the part of the first layer 662. Every crossing of a single elongate pyramid in the first layer 662 and a single elongated pyramid of the second layer 664 form a beam- shaping element 670. The borders of the beam- shaping element 670 are defined by borders of the single elongated pyramid in the first layer 662 and borders of the single elongated pyramid in the second layer 664. It is to be noted that, in other embodiments, the elongated pyramid 666, 674 of both layers are elongated lenses, like lenticular lenses.

Fig. 7 schematically shows the effect of a specific beam-shaping structure on the beam shape of the emitted light. A polar plot 700 of angular distribution of beam intensity is presented.

The specific beam-shaping structure for which the polar plot 700 was made is a beam-shaping element which is similar to the beam-shaping element 215 of Fig. 2. The beam-shaping element was made from a Perspex layer (Polymethylmethacrylate, PMMA) in which in two perpendicular directions grooves were slotted at one of its surfaces. The surfaces of the grooves were coated with aluminum or silver. Subsequently, the grooves were filled with Ti0 2 particles in a sol-gel solution or with an epoxy material filled with Ti0 2 particles. Subsequently, the entrance windows of funnels in between the grooves were opened by planarizing the surface of the beam-shaping structure at which the grooves were made. The height of the funnels was 0.475 mm, the entrance openings of the funnels have a size of 0.125 mm and the exit openings have size of 0.250 mm.

In the polar plot 700 the angular distribution of beam intensity at the entrances and at the exit planes of the micro beam-shaping elements is presented. A drawn circle 702 represents a Lambertian light source which is similar to the angular distribution of beam intensity at the entrances of the micro beam-shaping elements. Within the circle two curves have been drawn. Curve 704 represents the measured angular distribution of beam intensity of a lighting system which comprises the above discussed beam-shaping structure and, thus, is the actual angular distribution of beam intensity at the exit planes of the micro beam- shaping elements. Another curve 706 represents the simulated angular distribution of beam intensity of the lighting system which comprises the above discussed beam-shaping structure. It is seen in the polar plot that the light beam emitted by the lighting system is shaped towards a relatively narrow light beam. The half-width-at-half-maximum angle of the emitted light beam is about 26 degrees.

It is to be noted that the shaped light beam, which is emitted by the lighting system, has a substantially symmetrical shape. The invention is not limited to beam-shaping structures which shape the beam symmetrical. The beam-shaping structure may also be configured to obtain an asymmetrical shaped light beam, or in another embodiment, a light beam which has a very limited intensity of light in, , for example, light emission angles close to a normal to the beam-shaping structure - such a light emission distribution is called a batwing-type distribution.

Fig. 8 schematically shows a luminaire 800 according to the second aspect of the invention. The luminaire 800 comprises a lighting system 802 according to the first aspect of the invention. The lighting system 802 emits a shaped light beam of which a footprint 804 is schematically indicated on a surface 804 on which the luminaire 800 is arranged. The luminaire 800 is, for example, a luminaire 800 for lighting a desk or a specific area of a room. In other embodiments, the luminaire is a ceiling luminaire, or a wall luminaire for lighting an area of a room.

Fig. 9 schematically shows a method of manufacturing a lighting system for emitting a shaped light beam. The method comprises the steps of: i) providing 902 a housing which comprises at least a base and a light exit window opposite the base, the base is light reflective, and a light transmitting space is present between the base and the light exit window, ii) arranging 904 a light re-direction means in the light-transmitting space, the light re-direction means being configured to randomly re-direct impinging light in an angular domain to improve outcoupling of light via the light exit window, iii) arranging 906 a plurality of light sources at light source positions within the light transmitting space, the light sources are configured to emit at least a part of the emitted light towards the light re-direction means, iv) arranging 908 a beam-shaping structure at the light exit window, wherein the beam- shaping structure is configured for shaping a beam of light emitted by the lighting system, and wherein the beam-shaping structure comprises a plurality of micro beam-shaping elements that are arranged in a pattern. In at least one of the steps of arranging of the plurality of light sources and arranging of the beam-shaping structure, the arranging is performed in a unadjusted manner to obtain light sources positions for the light sources of a subset of light source that are unaligned with respect to positions of the micro beam-shaping element in the pattern.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.