Comfortable road lighting luminaire with large vertical exit window

Abstract

The invention provides a light generating system (1000) comprising a lighting arrangement (2000), wherein the lighting arrangement (2000) comprises (a) an array (2200) of light sources (10), and (b) semitransparent mirrors (550), wherein: (A) the array (2200) of light sources (10) comprises a plurality of light sources (10) having (i) a first pitch (p1) along a first axis (A1), and (ii) a first array length (L1) along the first axis (A1), wherein the first pitch (p1) is at maximum 30 mm; (B) the light sources (10) are configured to generate visible light source light (11) along an optical axis (Ao); (C) the semitransparent mirrors (550) are configured parallel to the optical axis (Ao) and parallel to the first axis (A1), and are configured with the array (2200) of light sources (10) in between, such that each of the light sources (10) is configured between two semitransparent mirrors (550); the semitransparent mirrors (550) have (i) a mirror length (L2) parallel to the first array length (L1), (ii) a mirror height (Hm) parallel to the optical axis (Ao), and (iii) a mirror spacing (Dm); wherein L2≥L1, 0.25≤L2 / Hm≤10, and Hm≥1.5*Dm; and (D) the semitransparent mirrors (550) are both (i) specular reflective and (ii) transmissive for the light source light (11) irradiating the semitransparent mirrors (550) with an angle of incidence (α1) with a normal (N) selected to a semitransparent mirror (550) selected from the range of 5-35°, with on average over the semitransparent mirrors (550) a reflection percentage for the light source light (11) having the angle of incidence (α1) being higher than a transmission percentage for the light source light (11) having the angle of incidence (α1).

Description

[0001] COMFORTABLE ROAD LIGHTING LUMINAIRE WITH LARGE VERTICAL EXIT

[0002] WINDOW

[0003] FIELD OF THE INVENTION

[0004] The invention relates to a light generating system. Further, the invention relates to a lighting device. Further yet, the invention relates to a street lighting arrangement.

[0005] BACKGROUND OF THE INVENTION

[0006] Light generating systems are known in the art. For instance, US2011235335A1 describes a lighting apparatus including an optical unit and a body. The optical unit includes a light emitting module that has a light emitting element, a reflector that controls distribution of light from the light emitting module, and a unit supporting member that supports the light emitting module and the reflector. A plurality of optical units are mounted to the apparatus body such that each optical unit is detachable. The body includes an irradiating portion that has an opening through which the optical units irradiate light.

[0007] SUMMARY OF THE INVENTION

[0008] Outdoor lighting luminaires have a risk to be uncomfortably glary because the light sources are typically very bright (as much light as possible is concentrated in a luminaire to save cost on the number of required luminaires and poles) and the background is typically very dark (the night sky). To avoid glare (both discomfort and disability glare), the luminous intensity may be cut-off at large angles to the vertical direction (above -75-80° the luminous intensity may drop steeply), i.e. close to the horizontal direction. This avoids that people look into a very bright source when they look more or less straight ahead along the road (horizontally). Precisely tuned free-shape lenses may be designed to optimize this luminous intensity distribution. A method to reduce discomfort glare may be to improve the luminance uniformity of the glare source. Especially arrays of LEDs with lenses may provoke more glare than uniform sources with the same overall area and luminous intensity. This strategy may work well for outdoor lighting luminaires on lower poles (up to -6 m in height) that are typical for urban lighting (e.g. pedestrian areas, town squares, small streets). For the main roads and highways that use higher poles (>8m), the individual LEDs may not be visible on the high poles and no gain might be found by improving the luminous uniformity. Another method to reduce discomfort glare may be to introduce a “transition zone”, i.e. an area surrounding the bright glare source that has a luminance in between that of the glare source and the background. This transition zone may reduce the hard contrast at the transition from the glare source to the dark background, thereby reducing glare. Such a transition zone can be created in various ways. In embodiments, it may be possible to apply a white reflector around the glare source that reflects all stray light (unwanted uplight by Fresnel reflections off the glass cover plate or bowl for instance). Another way may be to apply a scattering texture on the glass cover or bowl. A drawback of this latter option may be that the texture may have a negative influence on luminaire efficacy and luminous intensity distribution. If the scattering is too strong, it may even lead to more glare due to the deterioration of the luminous intensity cut-off. Another drawback of the deteriorated intensity distribution may be the possible increase in uplight, which may be undesirable in view of local legislation. Yet another way to create a luminance transition zone may be to divide the glare source itself into two zones: one with a high flux density (LEDs driven at a higher current, or LEDs with a smaller pitch) and a transition zone around this area where the LEDs are either driven at a lower current or at a larger pitch (or both).

[0009] Current luminance-based solutions to prevent or reduce glare do not always seem to work. Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0010] The invention is set out in the appended set of claims. According to a first aspect, the invention provides a light generating system comprising a lighting arrangement. The lighting arrangement may comprise an array of light sources. Further, the lighting arrangement may comprise semitransparent mirrors, sometimes alternatively or also referred to as principle, semitransparent mirrors. The array of light sources may in embodiments comprise a plurality of light sources. The plurality of light sources may have a first pitch pi along a first axis Ai. Further, the plurality of light sources (in the array) may have a first array length Li along the first axis Ai. In embodiments, the first pitch pi may be at maximum 30 mm. Further, in embodiments, the light sources may be configured to generate visible light source light, such as especially along an optical axis Ao. In embodiments, the semitransparent mirrors may be configured parallel to the optical axis Aoand parallel to the first axis Ai, and may be configured with the array of light sources in between (viewed in a projection direction along the optical axis Ao), such that each of the light sources may be configured between two semitransparent mirrors. The semitransparent mirrors may have a mirror length L2 parallel to the first array length Li. Additionally, the semitransparent mirrors may have a mirror height Hmparallel to the optical axis Ao. Further, the semitransparent mirrors may have a mirror spacing Dm. In embodiments, L2>LI, 0.25<L2 / Hm<10, and Hm>1.5*Dm. The semitransparent mirrors may (further) be both (i) specular reflective and (ii) transmissive for the light source light irradiating the semitransparent mirrors with an angle of incidence (ai) with a normal (N) selected to a (respective) semitransparent mirror selected from the range of 5-35°. Further, on average, over the semitransparent mirrors a reflection percentage for the light source light having the angle of incidence (ai) may be higher than a transmission percentage for the light source light having the angle of incidence (ai). Hence, in specific embodiments, the invention may provide a light generating system comprising a lighting arrangement, wherein the lighting arrangement comprises (a) an array of light sources, and (b) semitransparent (such as transflective) mirrors, which may be mutually oppositely arranged, wherein: (A) the array of light sources comprises a plurality of light sources having (i) a first pitch pi along a first axis Ai, and (ii) a first array length Li along the first axis Ai, wherein the first pitch pi is at maximum 30 mm; (B) the light sources are configured to generate visible light source light along an optical axis Ao; (C) the semitransparent mirrors are configured parallel to the optical axis Aoand parallel to the first axis Ai, and are configured with the array of light sources (e.g. centrally or symmetrically arranged with respect to the first axis Ai) in between (viewed in a projection direction along the optical axis Ao), such that each of the light sources is configured between two semitransparent mirrors; the semitransparent mirrors have (i) a mirror length L2 parallel to the first array length Li, (ii) a mirror height Hmparallel to the optical axis Ao, and (iii) a mirror spacing Dm; wherein L2>LI, 0.25<L2 / Hm<10, and Hm>1.5*Dm; and (D) the semitransparent mirrors are both (i) specular reflective and (ii) transmissive for the light source light irradiating the semitransparent mirrors with an angle of incidence (ai) with a normal (N) selected to a semitransparent mirror selected from the range of 5-35°, with on average over the semitransparent mirrors a reflection percentage for the light source light having the angle of incidence (ai) being higher than a transmission percentage for the light source light having the angle of incidence (ai).

[0011] With such a light generating system, it may be possible to provide (outdoor) lighting with reduced or substantially no discomfort glare. Further, with such system it may be possible on the one hand to more efficiently use the light source(s), and on the other hand to reduce discomfort glare. Especially, with such a light generating system, a transition zone may be created without having to drive (any of) the light sources at a lower current. That is, the semitransparent mirrors may be configured to create (multiple rows of) virtual images of the light sources upon irradiation with light source light (under the angle of incidence (ai)), wherein the virtual images are configured to appear on opposite sides of the array of light sources, and wherein the virtual images may have a decreasing intensity upon increasing distance from the array, providing a transition zone. As such, it may be possible to maintain glare at a level similar to known systems, but increase the luminous flux of the array. Further, with such a light generating system, uplight may be reduced or prevented, as the light source light may be directed in a generally downwards direction (e.g. by lenses).

[0012] The light generating system may comprise an array of light sources. The array of light sources may comprise a plurality of light sources. Especially, the array of light sources may comprise > 3 light sources, such as > 5 light sources, especially > 10 light sources. Additionally or alternatively, in embodiments, the array of light sources may comprise < 1000 light sources, such as < 750 light sources, especially < 600 light sources. Further, in embodiments, the array of light sources may comprise < 100 light sources, such as < 75 light sources, especially < 50 light sources. In embodiments, the light sources may especially comprise light emitting diode (LED) light sources. However, other (types of) light sources are also possible (see further below). In embodiments, the array of light sources may have a first axis Ai. The first axis Ai may be parallel to a longitudinal direction of the array. That is, the array may have dimensions length and width, wherein the first axis Ai may be parallel to the length. Hence, in embodiments, the array may have a first array length Li along the first axis Ai. The first array length Li may especially be defined by a heart-to-heart (or “center-to-center”) distance of outer light sources in a row (see below) of the array, wherein said row is configured parallel to the first axis Ai. Hence, the first array length Li may be measured from the center of a first outer light source to the center of a second outer light source arranged in the same row of the array (configured parallel to the first axis Ai). In embodiments, the first array length Li may be selected from the range of > 3 cm, such as from the range of > 5 cm, especially from the range of > 10 cm. Additionally and alternatively, in embodiments, the first array length Li may be selected from the range of < 100 cm, such as from the range of < 50 cm, especially from the range of < 30 cm. Further, in embodiments, the array of light sources may have a first pitch pi along the first axis. A pitch may especially indicate a repetitive center-to-center distance between a first light source in the array and a second light source in the array (wherein for the first pitch pi the second light source may be configured in a direction along the first axis Ai with respect to the first light source). Hence, the array may comprise a plurality of light sources configured evenly spaced (with a first pitch pi) along the first axis Ai. In embodiments, the first pitch pi may be selected from the range of at maximum 60 mm, such as from the range of at maximum 50 mm, especially from the range of at maximum 40 mm. Further, in embodiments, the first pitch pi may be selected from the range of at maximum 30 mm, such as from the range of at maximum 25 mm, especially from the range of at maximum 20 mm. Additionally or alternatively, the first pitch pi may be selected from the range of at minimum 1 mm, such as from the range of at minimum 2.5 mm, especially from the range of at minimum 4 mm. Further, in embodiments, the first pitch pi may be selected from the range of at minimum 5 mm, such as from the range of at minimum 7.5 mm, especially from the range of at minimum 10 mm. However, pitches smaller than 5 mm are herein not excluded. Hence, in embodiments, 5 mm < pi < 30 mm, such as 7.5 mm < pi < 25 mm, especially 10 mm < pi < 20 mm. In specific embodiments, 7.5 mm < pi < 25 mm. Such a first pitch pi may be small enough to provide a compact lighting arrangement. Additionally or alternatively, such a first pitch pi may be large enough that, when e.g. a (respective) lens is placed downstream of each light source, neighboring light sources may (essentially) not interact with neighboring lenses. Further, with such a first pitch pi, the light sources may not be individually discernable when the lighting arrangement is viewed (in peripheral view) from a distance of > 2 m, such as from a distance of > 3 m, especially from a distance of > 4 m, and an (apparently) single homogeneous light source may be provided.

[0013] In embodiments, the plurality light sources may be configured in a linear (ID) array. That is, the array may comprise the plurality of light sources configured in a single row (along the first axis Ai). Alternatively, the plurality of light sources may be configured in a 2D array. Hence, the array of light sources may comprise a 2D array of light sources. The 2D array of light sources may especially be configured symmetrical relative to the first axis Ai. That is, the 2D array of light sources may comprise n rows of m light sources, wherein the first axis Ai may be configured in the center of the n rows. For instance, the 2D array may comprise 3 rows, wherein the middle row is configured along the first axis Ai and the outer rows are configured on either side of (and equidistant from) the first axis Ai. Yet, in other embodiments, the 2D array of light sources may be configured asymmetrical relative to the first axis AL That is, the first axis Ai may be located off-center with respect to the 2D array. In embodiments, the number of rows n may be selected from the range of 1-8, such as 1-6, like 1-4, especially 1-3, though larger numbers are herein not excluded. Additionally or alternatively, the number of light sources in each (of the n) row(s) m may be selected from the range of 3-100, such as from the range of 5-75, especially from the range of 5-30. Hence, in embodiments, a 2D array of light sources may have a smaller number of rows (n) than the number of light sources in those respective rows (m). In embodiments, m > 1.5*n, such as m > 2*n, especially m > 3*n. In embodiments, the number of light sources m in a respective row may be equal for all n rows. Alternatively, the number of light sources m in a respective row may be individually selected (from the range of 3-100) for each respective row. Yet, in specific embodiments, the number of light sources in an outer row (of the 2D array) may be at least twice as large as the number of rows in the 2D array (i.e., m > 2*n).

[0014] In embodiments, the 2D array of light sources may have a second pitch p2 in a direction perpendicular to the first axis Ai. That is, (the centers of) light sources in neighboring rows may be separated by the second pitch p2. In embodiments, the second pitch P2 may be equal to the first pitch pi, i.e., pi = p2. Alternatively, the second pitch may be (individually) selected from the range of 5-30 mm, such as from the range of 7.5-25 mm, especially from the range of 10-20 mm. In embodiments, the rows in the 2D array may be aligned (in a direction perpendicular to the first axis Ai), such that the light sources in the array are arranged according to (the intersections in) a square lattice. Alternatively, in embodiments, the light sources in the array may be arranged according to (the intersections in) a hexagonal lattice, wherein alternating rows in the 2D array may be aligned, and the interspersed rows may have an offset, wherein the offset has an equal magnitude and direction for each of the interspersed rows. Hence, especially the array of light sources is a regular array, such as an array with perpendicularly configured pitches (which may have the same values).

[0015] In embodiments, the outer rows in the (2D) array of light sources may be separated by a heart-to-heart distance d4. Especially, light sources configured in outer rows (of the 2D array) and configured symmetrically relative to the first axis Ai may have heart- to-heart distances d4. That is, the first axis Ai may indicate, when measuring the heart-to- heart distances d4 between light sources configured in outer rows (and configured symmetrically relative to the first axis Ai), the position of 0.5*d4. In embodiments, the heart- to-heart distances d4 may be equal for each pair of light sources configured in (opposite) outer rows, though this need not be the case. Further, in embodiments, (each of) the heart-to- heart distances d4 may be (individually) selected from the range of > 0.25 cm, such as from the range of > 0.5 cm, especially from the range of > 1 cm, like from the range of > 3 cm. Additionally and alternatively, in embodiments, (each of) the heart-to-heart distances d4 may be (individually) selected from the range of < 50 cm, such as from the range of < 30 cm, especially from the range of < 15 cm, like from the range of < 7.5 cm. Further, in embodiments, the heart-to-heart distances d4 may be provided by (n-l)*p2 (with n the number of rows in the 2D array). In embodiments, the heart-to-heart distances d4 may define a width of the array of light sources. In embodiments, the mirror spacing Dmmay be larger than a width of the array, such that the semitransparent mirrors may be configured on either side of the array (i.e., with the array of light sources in between). Hence, in embodiments, (all of) the heart-to-heart distances d4 may be smaller than the mirror spacing Dm. That is, in embodiments, the heart-to-heart distances d4 may be selected from the range of d4 < Dm< (d4+5*p2), such as from the range of d4 < Dm< (d4+3.5*p2), especially from the range of d4 < Dm< (d4+2*p2), like from the range of (d4+0.5*p2) < Dm< (c +1.5*p2) (such as Dm=d4+p2). Hence, in specific embodiments, the array of light sources may comprise a 2D array of light sources, configured symmetrical relative to the first axis Ai, wherein heart-to-heart distances d4 of light sources configured in outer rows and configured symmetrically relative to the first axis Ai may be smaller than the mirror spacing Dm, and wherein the number of light sources in an outer row may be at least twice as large as the number of rows in the 2D array. A 2D array of light sources wherein the heart-to-heart distances d4 are smaller than the mirror spacing Dmmay provide the advantage that the array of light sources may be fully configured in between the semitransparent mirrors. Hence, the light generating system may provide reduced glare, as the semitransparent mirrors may provide a transition zone between the area illuminated by the light sources and an unilluminated area (e.g. the night sky), yet only for light sources configured in between the semitransparent mirrors.

[0016] In embodiments, the light sources (in the array) may be configured to generate light source light. Especially, the light sources may be configured to generate light source light along an optical axis Ao. In embodiments, the optical axis Aomay be an average optical axis for (all of) the light sources in the array. That is, each light source may be configured to generate light source light along a respective optical axis, (i.e., a first light source may have a first optical axis Ao,i, a second light source may have a second optical axis Ao, 2, etc.) wherein an average optical axis of the respective optical axes A0,i of the light sources determines the optical axis Ao. In embodiments, the light source light may be visible light source light. The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. Hence, the light sources may be configured to generate visible light source light having one or more wavelengths in the range of 380-780 nm. In embodiments, the light source light may be colored light, such as blue light, or such as yellow light. Alternatively, the light sources may be configured to generate white light. Hence, in specific embodiments, the light source light may be white light. The term “white light”, and similar terms, herein, is known to the person skilled in the art. It may especially relate to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700 K and 6500 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL. In embodiments, the light source light may have a CCT selected from the range of 1800-6500 K and / or a color rendering index of at least 60, such as at least 70, especially at least 80. Further, in embodiments, the light source light from each of the light sources may have the same optical properties. Alternatively, in embodiments, at least one of the light sources may be configured to generate light source light differing (from the light source light generated by at least one other light source) in one or more of a spectral power distribution, a color point, a CCT, a color rendering index, and an intensity (and / or luminous flux). In embodiments, the light generating system may be configured to generate system light, wherein the system light may comprise the light source light. Hence, in embodiments, the light generating system may especially be configured to generate system light along the optical axis Ao. In embodiments, the light source light may be (at least partially) incident on the semitransparent mirrors. Hence, the light sources may be configured to (at least partially) irradiate the semitransparent mirrors. Especially, in embodiments, a peak intensity of the light sources may be configured to irradiate the semitransparent mirrors with (at least) an angle (y) to a surface normal to a (light escape) surface of the light sources, wherein in embodiments the surface normal to the (light escape) surface of the light sources may be configured perpendicular to the first axis Ai (and parallel to the optical axis Ao). In embodiments, the angle (y) may be selected from the range of 20-88°, such as from the range of 45-87°, especially from the range of 55-85°, like from the range of 60-80°, though smaller and larger angles are herein not excluded. Such an angle (y) may provide the benefit that, would the light generating system be mounted (on a pole) as a streetlight, wherein the first axis Ai would be configured parallel to a surface of the street (and the angle (y) may correspond to an angle of the light source light to a surface normal of the street), the light source light (irradiating the semitransparent mirrors) would be directed in a downwards direction, thereby preventing uplight. Further, at angles (y) of < 80°, glare may be reduced for observers walking along the street. In embodiments, at least 70% of the radiant flux of the light sources light may be within angles (y) selected from the range of 20-88°, like at least about 80%.

[0017] Hence, the light source light may be incident on semitransparent mirrors. In embodiments, the light generating system may comprise > 2 semitransparent mirrors, such as > 4 semitransparent mirrors, especially > 6 semitransparent mirrors. Additionally or alternatively, in embodiments, the light generating system may comprise < 10 semitransparent mirrors, such as < 8 semitransparent mirrors, especially < 6 semitransparent mirrors. Yet, in embodiments, the light generating system may comprise only two semitransparent mirrors. A principle semitransparent mirror may consist of a single semitransparent mirror or may consist of subsets of semitransparent mirror, for example a principle semitransparent mirror may be formed by the subset of semitransparent mirrors arranged in a row along / parallel to the row of light sources and thus may build up a contiguous surface of the single, principle semitransparent mirror. Hence, when at a side of the light sources there is more than one semitransparent mirror, these semitransparent mirrors are considered subsets of as single, principal semitransparent mirror that define essentially a contiguous surface of the single, principal semitransparent major mirror face (having the below indicated first area). Mirror spacing, mirror heights, mirror lengths may especially be defined relative to two semitransparent mirrors (with the light sources configured in between), even when one or both semitransparent mirrors may consist of subsets of semitransparent mirrors. In these embodiments, the two semitransparent mirrors are configured (at least partially) surrounding the array of light sources. That is, each of the light sources, such as especially the array of light sources, is configured between the two semitransparent mirrors. The semitransparent mirrors are arranged only around all the (array of) light sources means that all the (array of) light sources are sandwiched by the two semitransparent mirrors, hence that there are no semitransparent mirrors arranged / positioned between light sources. Especially, the semitransparent mirrors may in embodiments be planar. Alternatively, the semitransparent mirrors may be curved, such as especially along the mirror length L2.

[0018] In specific embodiments, the array of light sources may be centered between the semitransparent mirrors. Further, (at least two of) the semitransparent mirrors may be configured (essentially) parallel to the first axis AL Further yet, in embodiments, (at least two of) the semitransparent mirrors may be configured on opposite sides of the first axis Ai, wherein the semitransparent mirrors may be configured equidistant from the first axis Ai. Additionally or alternatively, in embodiments, (at least two of) the semitransparent mirrors may be configured on opposite sides of the first axis Ai, and configured at an angle with the first axis Ai (selected from the range of 1-80°), wherein in further embodiments the (at least two of the) semitransparent mirrors may be configured mirrored (and / or symmetrical) around the first axis Ai. In such embodiments, wherein the (at least two) semitransparent mirrors are configured at an angle with the first axis Ai, the light sources may especially be configured to provide a rotationally symmetrical beam of (light source) light, i.e., the intensity distribution of the light source light may in such cases be (essentially) the same at every angle around the optical axis Aoof the light sources. In embodiments, the semitransparent mirrors may comprise pairs of semitransparent mirrors, wherein the pairs of semitransparent mirrors may be configured symmetrical (or mirrored) about the first axis Ai (and wherein a (first) major (mirror) face of the semitransparent mirrors is parallel to a symmetry plane of the intensity distribution of the light source light (from the array)).

[0019] In embodiments, the semitransparent mirrors may be configured at least partially transmissive for light source light. Hence, in embodiments, the semitransparent mirrors may comprise a light transmissive material. The light transmissive material may in embodiments be selected from the group comprising a glass, a light transmissive polymer (e.g. PMMA, a polycarbonate (PC), etc.), a light transmissive ceramic, and a light transmissive sapphire. Additionally or alternatively, in embodiments, the semitransparent mirrors may be configured at least partially reflective for light source light. That is, in specific embodiments, the semitransparent mirrors may be both partially transmissive and partially reflective for light source light (see also further below). Hence, in embodiments, the semitransparent mirrors may be transflective mirrors. In embodiments, the semitransparent mirrors may thus (further) comprise a light reflective material. Especially, the light reflective material may comprise a specular reflective light reflective material. Herein, the term “specular reflective” may indicate that, upon reflection of a beam of light by a surface (such as a light reflective material), the angle of the (incident) beam with the surface is maintained in the reflected beam, yet the reflected beam may be located on an opposite side of a surface normal (of the surface) from the incident beam. The light reflective material may be selected from the group comprising a dielectric material, a reflective metal (e.g. configured as a metal layer coating), and a reflective polymer (e.g. a (cholesteric) liquid crystal polymer). In embodiments, the dielectric material may be configured as a coating on e.g. a light transmissive material. Yet, in other embodiments, the dielectric material may be configured as a layer, such as between two layers of light transmissive material. In further embodiments, the semitransparent mirrors may comprise a multilayer comprising dielectric layers. In such embodiments, the dielectric layers may especially (each) have an index of refraction, wherein at least two of the dielectric layers may have a different index of refraction (or “refractive index”). Especially, in embodiments, the index of refraction may be different for adjacent (dielectric) layers, wherein a difference between the index of refraction of the adjacent layers may be selected from the range of > 0.05, such as from the range of > 0.1, especially from the range of > 0.25, like in specific embodiments from the range of > 0.5. In embodiments, each of the dielectric layers may have a different index of refraction. Alternatively, the multilayer may comprise a first type of dielectric layers having a first index of refraction, and a second type of dielectric layers having a second index of refraction (differing by > 0.05 from the first index of refraction), wherein the first type and second type of dielectric layers may be alternated in the multilayer. Additionally or alternatively, the dielectric layers may comprise birefringent material and / or be birefringent. In such embodiments, adjacent dielectric layers may have a different orientation (of the birefringent material), such that light (with a certain polarization) is refracted to a different extent and / or in a different direction at each layer. Additionally or alternatively, the semitransparent mirrors may comprise a metal layer mirror comprising a metal layer coating. In such embodiments, the metal layer coating may especially have a smaller thickness than is needed to reflect (and / or absorb) at least 98% of the light source light. That is, the metal layer coating may have a thickness selected such, that the metal layer coating may transmit at least part of the light source light. Alternatively, in embodiments, the metal layer coating may have a thickness selected such, that (essentially) all of the light source light may be reflected (and / or absorbed) by the metal layer coating. In such embodiments, the metal layer coating may e.g. comprise openings (see below) to facilitate (partial) transmission of the light source light. Hence, in specific embodiments, the light sources may comprise LED light sources, and the semitransparent mirrors may comprise one or more of (i) a multilayer comprising dielectric layers with different indices of refraction, and (ii) a metal layer mirror comprising a metal layer coating having a thickness allowing transmission of light source light. Such semitransparent mirrors may facilitate simultaneous transmission and reflection of light source light. Hence, with such semitransparent mirrors, the light source light may be (at least partially) reflected back-and- forth between the semitransparent mirrors, wherein with each reflection part of the light source light is (also) transmitted through the semitransparent mirrors, to facilitate the appearance of rows of (virtual) light sources providing a transition zone between a dark background (e.g. the night sky) and an area of highest light intensity in the beam of light source light.

[0020] In embodiments, the semitransparent mirrors may be configured closest to light sources in the outer rows of the (2D) array of light sources. Especially, (each) semitransparent mirror may have a third distance ds to a center of a closest light source. That is, a closest light source may have a third distance ds to (a first major face of) a closest semitransparent mirror. In embodiments, the third distance ds may be selected from the range of > 5 mm, such as from the range of > 7.5 mm, especially from the range of > 10 mm. Further, the third distance ds may be selected from the range of < 40 mm, such as from the range of < 30 mm, especially from the range of < 20 mm, like from the range of < 15 mm. Additionally or alternatively, the third distance ds may be selected from the range of 0.1 *p2 - 3*p2, such as from the range of 0.2*p2 - 2*p2, especially from the range of 0.25 *p2 - p2. In specific embodiments, the third distance ds may especially be 0.5*p2. A third distance ds of 0.5*p2 may provide the benefit that the first virtual light source may be configured at a distance of p2 from the light source nearest to the mirror (and providing the virtual light source). Hence, the (real) light sources and virtual light sources may form a larger array having a constant pitch p2. In yet further embodiments, the third distance ds may be selected from the range of ds / pi < 3, such as from the range of ds / pi < 2, especially from the range of ds / pi < 1. Additionally or alternatively, the third distance ds may be selected from the range of 0.1 < ds / pi < 1, such as from the range of 0.2 < dis / pi < 0.8, especially from the range of 0.3 < ds / pi < 0.7. Hence, in specific embodiments, a third distance ds between a center of a closest light source to a closest semitransparent mirror may be selected from the range of ds / pi < 1. Such a third distance ds may facilitate the formation of virtual rows of light sources having - in a direction perpendicular to the first axis Ai - a similar pitch to the first pitch pi. Further, with such a third distance ds, a relatively larger number of rows of virtual light sources may be provided, as this number may partially depend on the third distance ds. Additionally or alternatively, with such a distance ds, the (virtual) light sources may not be individually discernable when the lighting arrangement is viewed (in peripheral view) from a distance of > 2 m, such as from a distance of > 3 m, especially from a distance of > 4 m.

[0021] In embodiments, the semitransparent mirrors may be configured parallel to the optical axis Aoand parallel to the first axis AL Further, the semitransparent mirrors may have a mirror length L2 parallel to the first array length Li. Hence, the semitransparent mirrors may have a mirror length L2 (in a direction) parallel to the first axis Ai. In embodiments, the mirror length may be selected from the range of > 3.5 cm, such as from the range of > 7 cm, especially from the range of > 15 cm. Additionally and alternatively, in embodiments, the first array length Li may be selected from the range of < 250 cm, such as from the range of < 100 cm, especially from the range of < 50 cm. Further, in embodiments, the mirror length L2 may be larger than the first array length Li, i.e., L2 > Li. Especially, in embodiments, L2 > 1.05*Li, such as L2 > l.l*Li, especially L2 > 1.25*Li, like L2 > 1.3*Li. Additionally or alternatively, in embodiments, L2 < 2*Li, such as L2 < 1.75*Li, especially L2 < 1.5*Li, like L2 < 1.4*Li. Hence, in specific embodiments, L2 < 1.5*Li. A mirror length L2 selected from the range of < 1.5*Li may ensure that the semitransparent mirrors extend (slightly) beyond the array of light sources. As such, the light source light from each of the light sources may be at least partially incident on the semitransparent mirrors (to provide a transition zone), and glare may be reduced. In embodiments, each of the semitransparent mirrors may have the same mirror length L2. Alternatively, the mirror lengths L2 from (at least) two semitransparent mirrors may differ, such as by < 50%, like by < 30%, especially by < 10%. Yet, in embodiments, the mirror lengths L2 from (at least) two semitransparent mirrors may differ by at most 8%, such as by at most 5%, especially by at most 2.5%, like by at most 1%.

[0022] Further, in embodiments, the semitransparent mirrors may (each) have a mirror height Hm. The mirror height Hmmay especially be determined in a direction parallel to the optical axis Ao. Further, in embodiments, the mirror height Hmmay (for each semitransparent mirror) be defined by a (respective) mirror first side and a (respective) mirror second side. In embodiments, the (respective) mirror first side may be the side of the semitransparent mirror configured closest to the light sources. For instance, the light sources and semitransparent mirrors may be configured (mounted) on a printed circuit board (PCB), wherein the side of the semitransparent mirrors with which they are configured (mounted) on the PCB may be the mirror first side. Alternatively, for instance, the light sources may be mounted on a first support structure, and the semitransparent mirrors may be configured on a second support structure, remote from the light sources (in a direction parallel to the optical axis Ao). In such embodiments, the side of the semitransparent mirrors for which the (average) distance to the light sources is smallest may be the mirror first side. In embodiments, the mirror second side may be configured opposite the mirror first side. Hence, the mirror second side may be configured remote from the light sources. That is, in embodiments, the mirror second side may be the side of the semitransparent mirrors having the largest (average) distance to the light sources. The distance between the mirror first side and the mirror second side may define the mirror height Hm. In embodiments, the mirror height Hmmay be selected from the range of > 5 cm, such as from the range of > 10 cm, especially from the range of > 12.5 cm. Additionally or alternatively, in embodiments, the mirror height Hmmay be selected from the range of < 50 cm, such as from the range of < 40 cm, especially from the range of < 30 cm. In (other) embodiments, the mirror height Hmmay be related to the mirror length L2, such as be selected from the range of 0.1 < I Hm < 20, like from the range of 0.25 < I Hm < 10, especially from the range of 0.35 < I Hm < 5, such as from the range of 0.5 < I Hm < 2. Further yet, in (alternative) embodiments, the mirror height Hmmay be at least partially determined by the mirror spacing Dm. That is, with a (relatively) large mirror spacing Dmand a (relatively) small mirror height Hm, the transition zone provided by the semitransparent mirrors may be narrow, thereby having little impact on the glare. Conversely, with a (relatively) small mirror spacing Dmand a (relatively) large mirror height Hm, the light source light may be distributed (or “spread out”) relatively more over the mirror height Hm, creating a broad transition zone and reducing the efficiency of the lighting arrangement. Hence, in embodiments, the mirror height Hmmay be selected from the range of Hm> 1.25*Dm, such as from the range of Hm> 1.5*Dm, especially from the range of Hm> 2*Dm, like from the range of Hm> 2.5*Dm. Further, in embodiments, the mirror height Hmmay be selected from the range of Hm< 50*Dm, such as from the range of Hm< 35*Dm, especially from the range of Hm< 20*Dm, like from the range of Hm< 15*Dm. Additionally or alternatively, the mirror height Hmmay be selected from the range of 1.25 < Hm / Dm< 50, such as from the range of 1.5 < Hm / Dm< 35, especially from the range of 2 < Hm / Dm< 20, like from the range of 2.5 < Hm / Dm< 15. Hence, in specific embodiments, one or more of the following may apply: (i) 0.5 < I Hm < 2 and (ii) 2 < Hm / Dm< 20. As indicated, such a mirror height Hmmay provide a balance between a width of the transition zone, providing decreased glare, and an efficiency of the light sources in providing (direct) bright light in a direction around the optical axis Ao(providing visibility for e.g. traffic). In embodiments, the mirror height Hmfor each of the semitransparent mirrors may be equal, that is, each of the semitransparent mirrors may have the same mirror height Hm. Alternatively, the mirror height Hmmay for each of the semitransparent mirrors be selected individually. The mirror area of the respective mirror areas may be defined by Hmand L2, i.e. especially Hm* L2.

[0023] (At least two of) the semitransparent mirrors may be configured at a distance from each other provided by the mirror spacing Dm. The mirror spacing Dmmay in embodiments especially be the distance between a first major face of a first semitransparent mirror and a first major face of a second semitransparent mirror, wherein the first major faces may especially be the faces of the (respective) semitransparent mirrors configured facing the array of light sources (and configured parallel the first axis Ai and optionally to the optical axis Ao). In embodiments, the mirror spacing Dmmay be selected from the range of > 5 mm, like from the range of > 10 mm, such as from the range of > 12.5 mm, especially from the range of > 15 mm. Additionally or alternatively, in embodiments, the mirror spacing Dmmay be selected from the range of < 100 mm, such as from the range of < 75 mm, especially from the range of < 50 mm. In (other) embodiments, the mirror spacing Dmmay be provided by (n- l)*p2+2*ds, wherein n is the number of rows in the (2D) array of light sources(, and wherein optionally it may apply that ds = 0.5*p2). Further, as indicated above, the semitransparent mirrors may be configured equidistant from the first axis Ai. Hence, in embodiments, the semitransparent mirrors may have a mirror spacing Dm, wherein the distance from a first semitransparent mirror to the first axis Ai is provided by 0.5*Dm(and consequently the distance from a second semitransparent mirror to the first axis Ai is also provided by 0.5*Dm). Further, as indicated above, the semitransparent mirrors may comprise pairs of semitransparent mirrors. In such embodiments, the mirror spacing Dmmay be individually selected for each pair of semitransparent mirrors.

[0024] In embodiments, the semitransparent mirrors may be (at least partially) reflective for the light source light. Especially, the semitransparent mirrors may be (at least partially) specular reflective for the light source light. Hence, in embodiments, the semitransparent mirrors may be configured to (specularly) reflect at least part of the light source light incident on the semitransparent mirrors. Especially, the semitransparent mirrors may be (at least partially) specular reflective for light source light irradiating the semitransparent mirrors with an angle of incidence (ai), wherein the angle of incidence (ai) may especially be the angle of the incident light source light with a normal (N) of the (respective) semitransparent mirror (on which the light source light is incident). In embodiments, the angle of incidence (ai) may be selected from the range of 2-70°, such as from the range of 3-55°, especially from the range of 5-35°, like from the range of 10-30°, though smaller and larger angles are herein not excluded. In embodiments, the specular reflection of the light source light (having the angle of incidence (ai)) may be characterized by a reflection percentage (R). The reflection percentage (R) may especially indicate the percentage (on a power basis) of the incident beam of light source light (having the angle of incidence (ai)) that is reflected by the semitransparent mirror. Hence, each time the light source light is incident on a semitransparent mirror with the angle of incidence (ai), a percentage of the light source light may be reflected by the semitransparent mirror, wherein the percentage of light source light reflected is equal to the reflection percentage (R) of the (respective) semitransparent mirror. In embodiments, the reflected light source light may have an (essentially) equal spectral power distribution to the incident light source light (and the transmitted light source light), but a lower (total) luminous flux. Further, in embodiments, the reflection percentage (R) may indicate a local reflection percentage (R), determined at a local area of the (first major face of the) semitransparent mirror having a size of 5 mm2, such as especially a size of 10 mm2. In embodiments, the semitransparent mirror may be configured to (locally) reflect (essentially) all of the light source light, that is, the (local) reflection percentage (R) may be (essentially) 100%. Yet, in (other) embodiments, the (local) reflection percentage (R) of (each of) the semitransparent mirrors may be selected from the range of < 99.5%, such as from the range of < 98%, especially from the range of < 97%, like from the range of < 95%. Additionally or alternatively, in embodiments, the (local) reflection percentage (R) of (each of) the semitransparent mirrors may in embodiments be selected from the range of > 0.5%, such as from the range of > 2.5%, especially from the range of > 5%, like from the range of > 10%. Further, in embodiments, the (local) reflection percentage (R) of (each of) the semitransparent mirrors may in embodiments be selected from the range of > 15%, such as from the range of > 20%, especially from the range of > 30%, like from the range of > 40%. In embodiments, the reflection percentage (R) may be constant over the mirror height Hmand / or mirror length L2 of the respective semitransparent mirror.

[0025] Alternatively, the reflection percentage (R) may vary over the mirror height Hmand / or mirror length L2 of the respective semitransparent mirror (see also below).

[0026] In (such) embodiments, the semitransparent mirrors may (further) have an average reflection percentage (Ra) over (the height and / or length of) the semitransparent mirror. The average reflection percentage (Ra) may in embodiments be selected from the range of 30-99.5%, such as from the range of > 50-99%, especially from the range of 65- 98%, like from the range of 80-95%. Hence, in embodiments, the semitransparent mirrors may (each) have an average reflection percentage for light source light irradiating the (respective) semitransparent mirror with the angle of incidence (ai), wherein the average reflection percentage may be selected from the range of 15-90%, such as from the range of 20-85%, especially from the range of 30-80%. Especially, the average reflection percentage may be based on local reflection percentages, averaged over the (mirror) area of the semitransparent mirror (having a mirror height Hmand mirror length L2).

[0027] Further, in embodiments, the semitransparent mirrors may be (at least partially) transmissive for light source light. In embodiments, the semitransparent mirrors may especially be configured to transmit (essentially) all of the light source light (with the angle of incidence (ai)) not reflected by the semitransparent mirrors (i.e., R+T ~ 100%). In embodiments, the semitransparent mirrors may be configured to transmit (at least part of) the light source light irradiating the semitransparent mirrors, especially with the angle of incidence (ai). The transmission of light source light by the semitransparent mirrors may be characterized by a transmission percentage (T). The transmission percentage (T) may especially indicate the percentage (on a power basis) of the incident beam of light source light (having the angle of incidence (ai)) that is transmitted by the semitransparent mirror. Hence, each time the light source light is incident on a semitransparent mirror with the angle of incidence (ai), a percentage of the light source light may be transmitted by the semitransparent mirror, wherein the percentage of light source light transmitted is equal to the transmission percentage (T) of the (respective) semitransparent mirror. In embodiments, the transmission percentage (T) may indicate a local transmission percentage (T), determined at a local area of the (first major face of the) semitransparent mirror having a size of 5 mm2, such as especially a size of 10 mm2. In embodiments, the semitransparent mirror may be configured to (locally) transmit (essentially) none of the light source light, that is, the (local) transmission percentage (T) may be (essentially) 0%. In (other) embodiments, the (local) transmission percentage (T) of (each of) the semitransparent mirrors may in embodiments be selected from the range of < 99.5%, such as from the range of < 97.5%, especially from the range of < 95%, like from the range of < 90%. Further, in embodiments, the (local) transmission percentage (T) of (each of) the semitransparent mirrors may in embodiments be selected from the range of < 85%, such as from the range of < 80%, especially from the range of < 70%, like from the range of < 60%. Additionally or alternatively, in embodiments, the (local) transmission percentage (T) of (each of) the semitransparent mirrors may in embodiments be selected from the range of > 0.5%, such as from the range of > 2%, especially from the range of > 3%, like from the range of > 5%. In embodiments, the transmission percentage (T) may be constant over the mirror height Hmand / or mirror length L2 of the respective semitransparent mirror. Alternatively, the transmission percentage (T) may vary over the mirror height Hmand / or mirror length L2 of the respective semitransparent mirror (see also below).

[0028] In (such) embodiments, the semitransparent mirrors may (further) have an average transmission percentage (Ta) over (the height and / or length of) the semitransparent mirror. The average transmission percentage (Ta) may in embodiments be selected from the range of 0.5-70%, such as from the range of 1-50%, especially from the range of 2-35%, like from the range of 5-20%. Hence, in embodiments, the semitransparent mirrors may (each) have an (average) transmission percentage for light source light irradiating the (respective) semitransparent mirror with the angle of incidence (ai), wherein the (average) transmission percentage may be selected from the range of 5-85%, such as from the range of 15-80%, especially from the range of 20-70%. In embodiments, the average reflection percentage (Ra) may (for at least one semitransparent mirror) be higher than the average transmission percentage (Ta). That is, on average over the semitransparent mirror, a reflection percentage (R) for the light source light (having the angle of incidence (ai)) may be higher than a transmission percentage (T) for the light source light (having the angle of incidence (ai)) (“transmission and reflection condition”). In embodiments, the difference between the (average) reflection percentage and the (average) transmission percentage (i.e., R-T) may be selected from the range of > 5%, such as from the range of > 10%, especially from the range of > 15%. Additionally or alternatively, the difference between the (average) reflection percentage and the (average) transmission percentage may be selected from the range of < 80%, such as from the range of < 70%, especially from the range of < 60%. Especially, the average transmission percentage may be based on local transmission percentages, averaged over the (mirror) area of the semitransparent mirror (having a mirror height Hmand mirror length L2).

[0029] In embodiments, the light source light may be (at least partially) reflected back-and-forth between the semitransparent mirrors (configured on opposite sides of the first axis Ai). Especially, in embodiments, each time a beam of light source light is incident on (one of) the semitransparent mirrors (with the angle of incidence (ai)), a percentage of the luminous flux density of the (beam of) light source light may be transmitted through the semitransparent mirror, and a (second) percentage of the luminous flux density of the (beam of) light source light may be reflected by the semitransparent mirror. In embodiments, the transmission percentage (T) and reflection percentage (R) of the semitransparent mirror (at the location where the beam of light is incident) may determine the percentage of the luminous flux density of the (beam of) light source light that is transmitted and reflected, respectively. That is, the beam of light source light incident on the semitransparent mirror (with the angle of incidence (ai)) may have a luminous flux density Ls, and the beam of light transmitted through the semitransparent mirror may have a luminous flux density L of Ti*Ls, wherein Ti is the transmission percentage (T) at the location of incidence. Further, the beam of light reflected by the semitransparent mirror may have a luminous flux density L of Ri*Ls, wherein Ri is the reflection percentage (R) at the location of incidence. In embodiments, the reflected beam of light from a first semitransparent mirror may be incident on a second (opposite) semitransparent mirror. In embodiments, at the second semitransparent mirror, again a part of the luminous flux L density of the (reflected) beam of light may be transmitted. Especially, the luminous flux density of the beam of light reflected by a first semitransparent mirror and transmitted by a second semitransparent mirror may be provided by L = RI*T2*LS, wherein T2 is the transmission percentage (T) at the location of incidence for the reflected beam. In embodiments, part of a beam of light source light may be reflected a plurality of x times before being transmitted. In such embodiments, the luminous flux density of the beam of light transmitted after x (prior) reflections may be provided by L = RI*R2* . . . *Rx*Tx+i*Ls. In embodiments, each time a (part of a) beam of light is (reflected) transmitted through a semitransparent mirror, a virtual (image of a) light source may be provided on the side of the array opposite to the side at which the semitransparent mirror (through which the beam of light is transmitted) is configured (and thus at the side of the array at which the semitransparent mirror at which the beam of light was (last) reflected). Hence, in embodiments, a (partially) virtual 2D array of light sources may be provided. In embodiments, the size of the virtual 2D array may depend on the maximum number of reflections (on either mirror) possible between the mirrors. For example, for a single row of 10 light sources, emitting light source light which is reflected up to 5 times between the mirrors, a virtual 2D array of 6 by 10 light sources may be provided (when viewing the lighting arrangement from an angle with the normal (N) equal to the angle of incidence (ai)). As can be inferred from the previous sentence, the number of rows of virtual light sources observed may depend on the angle (with the normal (N)) from which the lighting arrangement is observed, with a larger angle providing a lower number of rows. Further, the number of rows of virtual light sources may depend on the mirror height Hmand / or the mirror spacing Dm(and the related third distance ds). That is, with a larger mirror height Hm, a larger number of reflections is possible before reaching the end of the semitransparent mirror (thus increasing the number of rows of virtual light sources). Conversely, with a larger mirror spacing Dm, a reflected beam of light source light may travel further along the mirror height Hmbefore being incident on the opposite semitransparent mirror, decreasing the number of reflections possible (and thus the number of rows of virtual light sources). In embodiments, at least 20% of the radiant flux of the light source light is reflected at least once by each of the two semitransparent mirrors.

[0030] As indicated above, in embodiments, the reflection percentage (R) may be constant over the mirror height Hmof the semitransparent mirrors. Further, in embodiments, the transmission percentage (T) may (also) be constant over the mirror height Hmof the semitransparent mirrors. That is, when drawing a (virtual) line from the mirror first side to the mirror second side, (both) the reflection percentage (R) and the transmission percentage (T) may (essentially) not vary over that line. In other words, the reflection percentage (R) and / or the transmission percentage (T) may be uniform across the semitransparent mirrors. It is herein not excluded that local variations in the reflection percentage (R) and / or the transmission percentage (T) may be present, yet on a larger scale (e.g. considering areas of > 5 mm2) the reflection percentage (R) and / or the transmission percentage (T) in one area (along the virtual line) may be the same as (i.e., deviate within the range of (R-2) -(R+2)% and / or (T-2) - (T+2)% from) the reflection percentage (R) and / or the transmission percentage (T) in another area (along the virtual line). Hence, in embodiments, at each point along the mirror height Hm, the same percentage of an incident beam of (light source) light may be reflected and transmitted by the semitransparent mirror (provided the light source light irradiates the semitransparent mirror with the angle of incidence (ai)). In embodiments, the light transmitted through the semitransparent mirrors and emanating away therefrom (i.e., emanating away from the semitransparent mirrors) may have a (transmitted) luminous flux density (L). The (transmitted) luminous flux density (L) may be defined as the total transmitted luminous flux in any direction from a given area divided by the size of that area (with units lumen per square meter, i.e., lm / m2). In embodiments, the semitransparent mirrors may (each) have an (overall) average (transmitted) luminous flux density (La). Further, the semitransparent mirrors may (each) have a plurality of (local) (transmitted) luminous flux densities (L). Especially, the semitransparent mirrors may (each) be divided into a plurality of x bands over the (respective) mirror height Hm, such that each band has a length equal to the (local) mirror length L2, and a height equal to Hm / x, and wherein each band has a respective luminous flux density (Lx). In embodiments, the (local) (transmitted) luminous flux density (Li) of the transmitted light source light for the first band irradiated by light source light with the angle of incidence (ai) may be provided by Li = Ls*Ti), wherein Ls is the luminous flux density of the light source light irradiating the first band (with the angle of incidence (ai)), and Ti is the transmission percentage at the first band. Further, in embodiments, the (local) (transmitted) luminous flux density (Lx) of the transmitted light source light (irradiating with the angle of incidence (ai)) for each subsequent band may be provided by Lx= (Lx-i / Tx-i)*Rx-i*Tx), wherein Lx-i is the luminous flux density of the previous band, Txis the transmission percentage at the previous band, Rx-i is the reflection percentage at the previous band, and Tx-i is the transmission percentage at the irradiated band. In embodiments wherein the transmission percentage (T) (and the reflection percentage (R)) are constant over the mirror height Hm, i.e., Tx-i = Tx(= T) and Rx-i = Rx(= R), the formula Lx= (Lx-i / Tx-i)*Rx-i*Tx) may be simplified to Lx= Lx-i*R= Ls*T*Rx-1(wherein the x-1 in Rx lindicates the number of bands before the xthband). Hence, in embodiments, the (local) luminous flux density (L) may decrease along the semitransparent mirror with increasing distance from the array of light sources (with a factor related to the reflection percentage (R)). That is, when moving from a first band configured at the mirror first side to a last band configured at the mirror second side, the (local) luminous flux density (Lx) in each band may be (slightly) lower than the luminous flux density (Lx-i) in a previous band. In embodiments, the decrease in (transmitted) luminous flux density (L) may be gradual, i.e., a graph displaying the luminous flux density (L) as a function of the mirror height Hmmay display a smooth (downwards) line. Further, in embodiments, the decrease in luminous flux density (L) may be an exponential decrease, i.e., the magnitude with which the luminous flux density (L) decreases (when moving from a former band to a latter band) may decrease with increasing distance from the array. In embodiments, the luminous flux density (L) may (gradually) decrease along the semitransparent mirror (height Hm) with an (average) magnitude selected from the range of > 1% / cm, like from the range of > 2% / cm, such as from the range of > 3.5% / cm, especially from the range of > 5% / cm. Herein, the percentage may be a percentage of a largest luminous flux density (Lmax) (measured) along the semitransparent mirrors. Hence, for example, starting from the largest luminous flux density (Lmax), and gradually decreasing the luminous flux density (L) with 5% / cm, the luminous flux density (L) would be (essentially) zero after a mirror height Hmof 20 cm. In embodiments, the luminous flux density (L) may (further) (gradually) decrease with an (average) magnitude selected from the range of < 20% / cm, such as from the range of < 15% / cm, especially from the range of < 10% / cm. Hence, in specific embodiments, the reflection percentage and the transmission percentage may be constant over the mirror height Hmof the semitransparent mirrors, and a luminous flux density of the light source light transmitted through the semitransparent mirrors and emanating away therefrom may gradually decrease along the semitransparent mirrors with increasing distance from the array of light sources. With such a configuration, the highest luminous flux density (Lmax) (of the transmitted light source light) may be provided close to the mirror first side (such as at the first band), and the lowest luminous flux density (Lmin) may be provided close to the mirror second side. Hence, with such a configuration, a transition zone (wherein the luminous flux density gradually fades to (essentially) zero) may be created on one side of the lighting arrangement, reducing glare on that side. In (alternative) embodiments, the reflection percentage (R) may vary over the mirror height Hmof the semitransparent mirrors (i.e., RxRx-i). Additionally or alternatively, the transmission percentage (T) may vary over the mirror height Hmof the semitransparent mirrors (i.e., TxTx-i). In embodiments, the reflection percentage (R) and / or the transmission percentage (T) may especially decrease and / or increase (respectively) along the mirror height Hm. Further, in embodiments, the magnitude with which the reflection percentage (R) and / or the transmission percentage (T) decreases and / or increases (respectively) along the mirror height Hmmay increase along the mirror height Hm. That is, for example, a difference between the transmission percentages (Tx-Tx.i) for a pair of adjacent bands located near the mirror first side may be smaller than a difference between the transmission percentages (Tx-Tx-i) for a pair of adjacent bands located near the mirror second side. In embodiments, the reflection percentage (R) and / or the transmission percentage (T) may vary such over the mirror height Hmof the semitransparent mirrors, that a (transmitted) luminous flux density (L) of the light source light transmitted through the semitransparent mirrors (and emanating away therefrom) may have a maximum deviation along the semitransparent mirrors with increasing distance from the array of light sources. Especially, the (transmitted) luminous flux density (L) of the light source light transmitted through the semitransparent mirrors may have the maximum deviation along the semitransparent mirrors in the luminous flux density (in lm / m2) of the light source light transmitted within an angular range selected from the range of 15-30°, especially from the range of 15-20° with the normal (N) of the (respective) semitransparent mirror. In embodiments, the maximum deviation may be a maximum deviation (either positive or negative) from a mean and / or average (transmitted) luminous flux (density) of the light source light (transmitted through the semitransparent mirrors). That is, a graph showing the luminous flux density (L) over the mirror height Hmmay display a line fluctuating (with an amplitude equal to the maximum deviation) around a mean and / or average (transmitted) luminous flux density (L). In embodiments, the maximum deviation may be selected from the range of < 50%, such as from the range of < 33%, especially from the range of < 20%. Hence, in specific embodiments, the reflection percentage and the transmission percentage may vary over the mirror height Hmof the semitransparent mirrors, such that a luminous flux density of the light source light transmitted through the semitransparent mirrors and emanating away therefrom may deviate at most 33% along the semitransparent mirror with increasing distance from the array of light sources. Such a configuration may facilitate the lighting arrangement providing a roughly even light distribution over the semitransparent mirrors (when viewing the lighting arrangement from an angle of 15-30° with the normal (N) of a semitransparent mirror). As such, a more homogeneous illumination may be provided.

[0031] Further, in embodiments, the reflection percentage (R) and / or the transmission percentage (T) may vary such over the mirror height Hmof the semitransparent mirrors, that a (transmitted) luminous flux density (L) of the light source light transmitted through the semitransparent mirrors (and emanating away therefrom) may firstly gradually increase along the semitransparent mirrors with increasing distance from the array of light sources, and secondly gradually decrease along the semitransparent mirrors with further increasing distance from the array of light sources. That is, over a first part of the mirror height Hm, oriented closer to the mirror first side than the mirror second side, the luminous flux density (L) of the light source light transmitted through the semitransparent mirrors may gradually increase with increasing distance from the array of light sources (i.e., in a direction towards the mirror second side). Further, over a second part of the mirror height Hm, oriented closer to the mirror second side than the mirror first side, the luminous flux density (L) of the light source light transmitted through the semitransparent mirrors may gradually decrease with increasing distance from the array of light sources (i.e., in a direction towards the mirror second side). In embodiments, the transition from the gradual increase to the gradual decrease (in luminous flux density) may be gradual. That is, in embodiments, a graph depicting the luminous flux density (L) over the mirror height Hmmay display a Gaussian curve, wherein the maximum of the Gaussian curve represents the transition from the gradual increase to the gradual decrease. In such embodiments (wherein the graph would display a Gaussian curve), the reflection percentage (R) and / or the transmission percentage (T) may especially decrease and / or increase (respectively) along the mirror height Hm, wherein the magnitude with which the reflection percentage (R) and / or the transmission percentage (T) decreases and / or increases (respectively) along the mirror height Hmmay increase along the mirror height Hm. Hence, in specific embodiments, the reflection percentage and the transmission percentage may vary over the mirror height Hmof the semitransparent mirrors, such that a luminous flux density of the light source light transmitted through the semitransparent mirrors and emanating away therefrom may firstly gradually increase along the semitransparent mirrors with increasing distance from the array of light sources, and may secondly gradually decrease along the semitransparent mirrors with further increasing distance from the array of light sources. With such a configuration, the highest luminous flux density (Lmax) (of the transmitted light source light) may be provided close to the center of the semitransparent mirrors (at ~ 0.5*Hm), and the lowest luminous flux densities (Lmin) may be provided at the sides of the semitransparent mirrors (close to the mirror first side and the mirror second side). Hence, with such a configuration, a transition zone may be created on either side of the lighting arrangement, reducing glare in (at least) two directions from the lighting arrangement.

[0032] In embodiments, the light source light transmitted through (each of) the semitransparent mirrors and emanating away therefrom may further have a (transmitted) luminous flux density. Especially, the light source light (transmitted through the semitransparent mirrors and emanating away therefrom) may have first (transmitted) luminous flux densities Lvi in first areas Amiof the semitransparent mirrors. The first areas Ami may especially be configured at the mirror first side (i.e., closest to the array of light sources). Further, the first areas Amimay have a first area height Haiof 0.99*Hm. Hence, when labelling the mirror first side as 0*Hm, and labelling the mirror second side as l*Hm, the first areas Amimay span from 0*Hm(i.e., the mirror first side) to 0.99*Hm. That is, the first areas Amimay span the first 99% of the mirror height Hm(when looking from the mirror first side). Further, in embodiments, the first areas Amimay span the full mirror lengths L2 of the semitransparent mirrors. Hence, the first areas Amimay (each) have an area of the first area Amiprovided by (0.99*Hm)*L2. Additionally or alternatively, in embodiments, the light source light (transmitted through the semitransparent mirrors and emanating away therefrom) may have second (transmitted) luminous flux densities Lv2 in second areas Am2 of the semitransparent mirrors. The second areas Am2 may especially be configured adjacent to the (respective) first areas Ami. Further, the second areas Am2 may be configured at the mirror second side (i.e., furthest from the array of light sources). Additionally, in embodiments, the second areas Am2 may have a second area height EL2 of 0.01 *Hm. Hence, when labelling the mirror first side as 0*Hm, and labelling the mirror second side as l*Hm, the second areas Am2 may span from 0.99*Hmto l*Hm(i.e., the mirror second side). That is, the second areas Am2 may span the last 1% of the mirror height Hm(when looking from the mirror first side). Further, in embodiments, the second areas Am2 may span the full mirror lengths L2 of the semitransparent mirrors, such that an area of (each) second area Am2 may be provided by (0.01*Hm)*L2. In embodiments, (at least one of) the second (transmitted) luminous flux densities Lv2 may be smaller than the (the corresponding first luminous flux density Lvi of the) first (transmitted) luminous flux densities Lvi. Especially, in embodiments, the second (transmitted) luminous flux densities Lv2 and the first (transmitted) luminous flux densities Lvi may have a ratio of LV2 / Lvi < 0.01, such as a ratio of LV2 / Lvi < 0.005, especially a ratio of LV2 / LVI < 0.0025, like a ratio of LV2 / Lvi < 0.002. Further, in embodiments, the second (transmitted) luminous flux densities Lv2 and the first (transmitted) luminous flux densities Lvi may have a ratio of Lv? / Lvi < 0.0001, such as a ratio of Lv? / Lvi < 0.0005, especially a ratio of Lv? / LVI < 0.00025. Additionally or alternatively, in embodiments, the second (transmitted) luminous flux densities Lv2 and the first (transmitted) luminous flux densities Lvi may have a ratio of LV2 / Lvi > 0.00001, such as a ratio of LV2 / Lvi > 0.000025, especially a ratio of LV2 / Lvi > 0.00005. In embodiments, the first areas Amiof the respective (at least) two semitransparent mirrors may have an average first area transmission percentage Tai. Additionally, in embodiments, the second areas Am2 of the respective (at least) two semitransparent mirrors may have an average second area transmission percentage Ta2. In such embodiments, a ratio between a first internal flux density Lvi / Taibetween the first areas Ami of the respective (at least) two semitransparent mirrors and a second internal flux density v2 / Ta2 present between the second areas Am2 of the respective (at least) two semitransparent mirrors may be selected from the range of (Lv2 / Ta2) / Lvi / Tai) < 0.01, such as from the range of Lv2 / Ta2) / (Lvi / Tai) < 0.0025, especially from the range of (Lv2 / Ta2) / (Lvi / Tai) < 0.001, like from the range of (Lv2 / Ta2) / (Lvi / Tai) < 0.0002. In embodiments, a relatively low second (transmitted) luminous flux density Lv2 (and / or a relatively low second internal flux density v2 / Ta2) may be provided by selecting a lower transmission percentage (T) (e.g., T < 2%) of the respective semitransparent mirror in the second area Am2. Additionally or alternatively, in embodiments, a relatively low second (transmitted) luminous flux density Lv2 (and / or a relatively low second internal flux density Lv2 / Ta2) may be provided by a higher (average) transmission percentage (T) (e.g., T > 10%) of the respective semitransparent mirror in the first area Ami. Especially, with a higher (average) transmission percentage (T) of the semitransparent mirror in the first area Ami, the majority of the luminous flux density of the light source light emitted by the light sources may be transmitted through the semitransparent mirror in the first area Ami, such that only a minor percentage (e.g. < 5%) of the luminous flux density remains to be (partially) transmitted through the semitransparent mirror in the second area Am2. Hence, in specific embodiments, the mirror height Hmmay be defined by a mirror first side and a mirror second side, wherein the mirror first side may be configured closest to the light sources, wherein the mirror second side may be configured opposite the mirror first side and remote from the light sources, wherein first luminous flux densities Lvi of the light source light transmitted through the semitransparent mirrors and emanating away therefrom in first areas Amiof the semitransparent mirrors, configured at the mirror first side and having a first area height Haiof 0.99*Hm, and second luminous flux densities Lv2 of the light source light transmitted through the semitransparent mirrors and emanating away therefrom in second areas Am2 of the semitransparent mirrors, configured at the mirror second side and having a second area height Ha2 of 0.01 *Hm, may have a ratio of LV2 / LV1 < 0.005. Such a ratio between the second luminous flux densities Lv2 and the first luminous flux densities Lvi may provide the benefit that, at the mirror second side, the luminous flux density may be relatively low, providing a more gradual transition from a (brightly) illuminated area (by the light transmitted through the first area Ami) to an unilluminated area (e.g. the night sky). As such, a transition zone may be provided, and glare may be reduced. Note that here the mirror area of the respective semitransparent mirrors may be Ami+ Am2.

[0033] In embodiments, the light source light may be at least partially transmitted (through the semitransparent mirrors) through openings in the semitransparent mirrors. Hence, (each of) the semitransparent mirrors may comprise openings. The openings may be through openings, spanning from a first major face of the semitransparent mirror to a second major face of the semitransparent mirror (in a direction perpendicular to the mirror length L2 and the mirror height Hm). Alternatively, the semitransparent mirrors may (each) comprise a multilayer (comprising dielectric layers), wherein the openings may be (through) openings in at least one of the layers from the multilayer (such as especially in a dielectric layer). Additionally or alternatively, in embodiments, the semitransparent mirrors may (each) comprise a metal layer mirror comprising a metal layer coating, wherein the openings may be (through) openings in at least the metal layer coating of the metal layer mirror. In embodiments, the openings (of each semitransparent mirror) may be arranged in an array.

[0034] The array may be regular, random, or quasi random. Especially, in embodiments, the array of openings may be a regular (2D) array. Hence, in embodiments, the array may comprise one or two constant pitches. However, other arrays, like a phyllotaxis tessellation or a sunflower tessellation, may also be possible. The term “tessellation” may herein especially refer to a pattern of (repeated) shapes, especially polygons, that fit together closely without gaps or overlapping. In embodiments, the tessellation may comprise a translation tessellation of the entrance shape. The term “translation tessellation” may herein especially refer to a tessellation wherein the tessellated shape, such as a polygon, may be moved without rotation or mirroring thereof. In embodiments wherein the array comprises a phyllotaxis tessellation or a sunflower tessellation, the openings may especially be arranged on comers of the (repeated) shape. Yet, in specific embodiments, the array may be a first regular array. In embodiments, the (regular) array may be an n*m array, wherein n and m may each individually be selected from the range of at least 3. In specific embodiments, n and m may each be individually selected from the range of 3-5000. In embodiments, especially at least 80%, such as at least about 90%, like at least about 95% (such as e.g. up to about 99%, or higher) of the total number of openings, may be configured in a phyllotaxis tessellation.

[0035] Hence, in embodiments, a part (like in embodiments selected from the range of 1-20%) of the total number of the openings may be arranged in a first regular array. Yet, in embodiments, a percentage (of a total number) of the openings may be offset from the first regular array (i.e., the array may be a quasi-random array). Especially, at least 10%, such as at least 20%, especially at least 25% of a total number of openings may be offset from the first regular array. Further, in embodiments, at least 30%, such as at least 40%, especially at least 50% of a total number of openings may be offset from the first regular array. Additionally or alternatively, at most 99%, such as at most 90%, especially at most 80% of a total number of openings may be offset from the first regular array. In embodiments, the offset openings may (each) have a uniquely selected offset from the first regular array. In such embodiments, the offset openings may especially not form a (secondary) regular array (yet may form a random array). A combination of openings having the same offset and openings having a uniquely selected offset may also be possible. That is, a percentage of (a total number of) the offset openings may (together) be arranged in a secondary regular array, while the rest of the (total number of) offset openings may be arranged in a random array. Especially, in embodiments, at most 60%, such as at most 50%, especially at most 40%, like at most 30%, of the total number of offset openings may be arranged in a secondary regular array. In further embodiments, at most 20%, such as at most 10%, especially at most 5%, like at most 1%, of the total number of offset openings may be arranged in a secondary regular array. Further, in embodiments subsets of at most 20%, such as at most 10%, like at most 5%, of the total number of openings may form a regular array. In (alternative) embodiments, the openings may be arranged in a random array, especially at least 80%, such as at least about 90%, like at least about 95% (such as e.g. up to about 99%, or higher) of the total number of openings.

[0036] Hence, in embodiments at least 20% of a total number of openings may be (configured) offset from a first regular array, and especially at most 50% of a total number of (these) offset openings is arranged in a secondary regular array.

[0037] In (other) embodiments, the openings may be arranged in a regular array, wherein at least 20% of a total number of openings is offset from the regular array, and at most 50% of a total number of offset openings is arranged in a secondary regular array.

[0038] Therefore, in embodiments the openings, or especially at least 80%, such as at least about 90% of the total number of openings, may not be positioned along horizontal or vertical lines. Especially, the offset may essentially not be the same vector displacement of the openings.

[0039] In embodiments, the openings may have a (cross-sectional) shape in a plane parallel to the mirror length L2 and the mirror height Hm. The shape of the openings may be (for each opening individually) selected from the group comprising a circular shape, an elliptical shape, a (rounded) rectangular shape, and an n-gonal shape, wherein n > 2, like n > 4, such as n > 6, especially n > 8, more especially n > 12, like up to n < 24, and wherein the side faces (of the respective opening) may be curved and / or (substantially) planar. Further, in embodiments, the openings may have cross-sectional equivalent circular diameters Deq,0(in a plane parallel to the mirror length L2 and the mirror height Hm). The equivalent circular diameter (or ECD) (or “circular equivalent diameter”) of an (irregularly shaped) two- dimensional shape is the diameter of a circle of equivalent area. For instance, the equivalent circular diameter of a square with side a is 2a / SQRT(7t). For a circle, the diameter D is the same as the equivalent circular diameter D. Would a circle in an xy-plane with a diameter D be distorted to any other shape (in the xy-plane), without changing the area size, then the equivalent circular diameter of that shape would be D. In embodiments, the openings may have cross-sectional equivalent circular diameters Deq,0selected from the range of > 10 pm, such as from the range of > 50 pm, especially from the range of > 100 pm, like from the range of > 125 pm. Additionally or alternatively, in embodiments, the openings may have cross-sectional equivalent circular diameters Deq,0selected from the range of < 15 mm, such as from the range of < 12.5 mm, especially from the range of < 10 mm, like from the range of < 5 mm. Hence, in embodiments, the openings may have cross-sectional equivalent circular diameters Deq,0selected from the range of 10 pm - 15 mm, such as from the range of 50 pm - 12.5 mm, especially from the range of 100 pm - 10 mm, like from the range of 125 pm - 5 mm. In embodiments, each of the openings may have the same equivalent circular diameter Deq,0. Alternatively, each of the openings may have an individually selected equivalent circular diameter Deq,0. In embodiments, the openings (in each semitransparent mirror) may further have a total cross-sectional area Ao, wherein the total cross-sectional area Aomay be the sum of the cross-sectional area of each individual opening. Further, in embodiments, the semitransparent mirror (comprising the openings) may have a total cross-sectional area At (in a plane parallel to the mirror length L2 and the mirror height Hm). In embodiments, the total cross-sectional area At of the semitransparent mirror may include the total cross-sectional area Aoof the openings. Further, in embodiments, the total cross-sectional area Aoof the openings may be selected from the range of > 0.1%, such as from the range of > 0.5%, especially from the range of > 1%, like from the range of > 5%, of the total cross-sectional area At of the semitransparent mirror. Additionally or alternatively, in embodiments, the total cross-sectional area Aoof the openings may be selected from the range of < 50%, such as from the range of < 35%, especially from the range of < 25%, like from the range of < 15%, of the total cross-sectional area At of the semitransparent mirror. Further, in embodiments, the total cross-sectional area Aoof the openings may be selected from the range of 0.1-50%, such as from the range of 0.5-35%, especially from the range of 1-25%, like from the range of 5-15%, of the total cross-sectional area At of the semitransparent mirror. In embodiments, the openings may not be evenly distributed over (the total cross-sectional area At of) the semitransparent mirror. That is, an opening density (or number of openings per unit area) may be higher in one part of the semitransparent mirror compared to another part of the semitransparent mirror. In embodiments, the opening density may increase with an increasing transmission percentage (T) of the semitransparent mirror. Additionally or alternatively, the opening density may increase and / or decrease over the mirror height Hm. Hence, in specific embodiments, each of the semitransparent mirrors may comprise openings having cross- sectional equivalent circular diameters Deq,0selected from the range of 100 pm - 10 mm; wherein a total cross-sectional area Aoof the openings may be selected from the range of 1- 25% of a total cross-sectional area At of the semitransparent mirror; wherein the openings may be arranged in a first regular array, wherein at least 20% of a total number of openings may be offset from the first regular array, and wherein at most 50% of the total number of offset openings may be arranged in a secondary regular array. Such a configuration of openings may prevent the appearance of moire patterns on an illuminated area (i.e., the appearance of an interference pattern by the overlaying of two (different) (regular) arrays) upon the transmission of light source light (from the array) through the (array of) openings. Further, the use of openings in the semitransparent mirrors may provide a facile method for the tailoring of the transmission percentage (T) of the semitransparent mirror. That is, in embodiments, the semitransparent mirrors may comprise a multilayer comprising dielectric layers, wherein the dielectric layers have a reflection percentage (R) selected from the range of > 90%, and wherein the openings are configured as through openings through the dielectric layers. In such embodiments, the transmission percentage (T) may be adjusted (over the mirror height Hm) by adjusting an opening density of the openings across the (mirror height Hmof the) semitransparent mirror.

[0040] In embodiments, the semitransparent mirrors may define two side openings. The two side openings may in embodiments especially be configured along the first axis Ai, and on either side of the array of light sources. Further, in embodiments, the semitransparent mirrors may define a remote opening. The remote opening may especially be configured remote from the array of light sources (e.g., at the mirror second side). Further, the remote opening may be configured bridging the two side openings (and the respective mirror second sides of the semitransparent mirrors defining the remote opening). In embodiments, the light generating system, especially the lighting arrangement, may further comprise a beam expander. The beam expander may in embodiments be configured in at least one of the (two) side openings and the remote opening. Alternatively, in embodiments, the beam expander may be configured downstream of at least one of the (two) side openings and the remote opening. The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light sources), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is “downstream”. In embodiments, the light generating system may comprise a plurality of beam expanders, such as two beam expanders, especially three beam expanders. Hence, in embodiments, the light generating system may comprise two beam expanders, (each) configured downstream of (one of) the side openings. Alternatively, the light generating system may comprise three beam expanders, configured downstream of the two side openings and the remote opening. Additionally or alternatively, in embodiments, the light generating system may especially comprise a beam expander configured downstream of the remote opening. The beam expander may be configured to broaden a beam of light escaping from the (respective) at least one of the (two) side openings and the remote opening. Especially, the beam expander may be configured to broaden said beam of light in a direction perpendicular to the semitransparent mirrors (i.e., in a direction perpendicular to the first axis Ai and / or to the optical axis Ao). Additionally or alternatively, the beam expander may be configured to broaden the beam of light in a direction parallel to the semitransparent mirrors (i.e., in a direction parallel to the first axis Ai and / or to the optical axis Ao). In embodiments, the beam expander may be configured to broaden and / or increase (a full width half maximum (FWHM) of) an angular scattering distribution of the beam of light (escaping from the at least one of the (two) side openings and the remote opening). Hence, the beam of light may have an angular scattering distribution in a direction perpendicular to the semitransparent mirrors. An angular scattering distribution of a beam of light may especially relate to a distribution of a light intensity of said beam of light as a function of an angle to an optical axis (of said beam of light). For a standard light source (e.g. a flashlight) providing a rotationally symmetrical (i.e., circular) beam of light, the angular scattering distribution (in a single direction perpendicular to the optical axis) may generally appear as a Gaussian curve, with a maximum at the optical axis (angle is zero), and a gradual decrease in light intensity with an increasing angle to the optical axis. In embodiments, the (curve of the) angular scattering distribution may have a full width half maximum (FWHM), defined as the width of the angular scattering distribution (in degrees °) at half of the maximum (light) intensity of the angular scattering distribution. In embodiments, the angular scattering distribution and the corresponding FWHM of a light source may be independent of the distance at which the angular scattering distribution (and FWHM) is measured (yet may be measured at a distance of at least 5, such as at least 10, times the diameter of the light source). Returning to the beam expander, the beam expander may thus be configured to increase a full width half maximum of an angular scattering distribution of the beam of light (escaping from the at least one of the (two) side openings and the remote opening) incident on the beam expander. Hence, the broadening of the beam (of light escaping from the at least one of the (two) side openings and the remote opening) (by the beam expander) may be defined by an increase in the full width half maximum of an angular scattering distribution of the beam of light. In embodiments, the increase in the FWHM of the angular scattering distribution of the beam of light may be selected from the range of > 0.25*atan(Dm / (2*Hm)), such as from the range of > 0.5*atan(Dm / (2*Hm)), especially from the range of > 0.75*atan(Dm / (2*Hm)), wherein atan indicates the arctangent, or the inverse of the tangent (tan-1) in the interval of (0,7t / 2). Additionally or alternatively, in embodiments, the increase in the FWHM of the angular scattering distribution of the beam of light may be selected from the range of < 5*atan(Dm / (2*Hm)), such as from the range of < 3*atan(Dm / (2*Hm)), especially from the range of < 2.5*atan(Dm / (2*Hm)). Hence, in embodiments, the increase in the FWHM of the angular scattering distribution of the beam of light may be selected from the range of (0.25*atan(Dm / (2*Hm))) - (5*atan(Dm / (2*Hm))), such as from the range of (0.5*atan(Dm / (2*Hm))) - (3*atan(Dm / (2*Hm))), especially from the range of (0.75*atan(Dm / (2*Hm))) - (2.5*atan(Dm / (2*Hm))).

[0041] In embodiments, the beam expander may comprise scattering elements to facilitate the broadening of a beam of light. For instance, the beam expander may comprise a light transparent support material (e.g. a plate or foil) with scattering elements imbedded therein and / or deposited thereon. Additionally or alternatively, the beam expander may comprise refractive elements. In (further) embodiments, the beam expander may comprise one or more of scattering elements, refractive elements, (divergent) lenses, prisms, holographic diffusers, and reflective elements. In embodiments, the beam expander may comprise the light transparent support material, wherein the light transparent support material may comprise a surface structure facilitate the broadening of the (incident) beam of light. Hence, in specific embodiments, the semitransparent mirrors may define two side openings and a remote opening, remote from the array of light sources and bridging the two side openings; wherein in or downstream of at least one of these openings, a beam expander may be configured, wherein the beam expander may be configured to broaden a beam of light escaping from the respective opening in a direction perpendicular to the semitransparent mirrors; wherein the broadening of the beam may be defined by an increase in a full width half maximum of an angular scattering distribution of the beam of light selected from the range of (0.5*atan(Dm / (2*Hm))) - (3*atan(Dm / (2*Hm))); and wherein the beam expander may comprise one or more of scattering elements and refractive elements. The broadening of the beam of light may facilitate homogenizing the beam of light (downstream of the beam expander), such that bright spots originating from the (virtual) light sources may be reduced. Further, in embodiments, the edges of the semitransparent mirrors (defining the side openings and the remote opening) may induce the formation of an intensity modulation (i.e., the appearance of stripes) upon irradiation with light source light. By configuring a beam expander configured to increase the FWHM of an angular scattering distribution of the beam of light source light by an angle selected from the range of (0.5*atan(Dm / (2*Hm))) - (3*atan(Dm / (2*Hm))) downstream of said side openings and / or remote opening, the beam of light may be broadened by an angle larger than an angular pitch of the intensity modulation, thereby reducing the observed intensity modulation.

[0042] In embodiments, the light generating system, especially the lighting arrangement, may (further) comprise a lens. The lens may be configured downstream of the light sources. Further, in embodiments, the light generating system may comprise a plurality of lenses. Especially, the number of lenses (comprised by the light generating system) may be equal to a number of light sources (in the array), though this need not be the case. Yet, in embodiments, each light source may have a related lens. That is, downstream of each light source, a (respective) lens may be configured. Hence, in specific embodiments, the light generating system may further comprise lenses, wherein downstream of each light source a lens may be configured. In embodiments, the lenses may be configured to one or more of (i) shape the beam of light originating from the (respective) light source, and (ii) steer the beam of light originating from the (respective) light source. In embodiments, the lenses may comprise one or more of concave lenses (diverging lenses), convex lenses (converging lenses), compound lenses, Fresnel lenses, lenticular lenses, bifocal lenses, axicon lenses, gradient index lenses, freeform lenses, meta lenses, and super lenses, though other options are herein not excluded. The lenses may in embodiments be configured (directly) on top of (such as in physical contact with) the light sources. Alternatively, the lenses may be configured at a non-zero distance from (a surface of) the light sources. In embodiments, the non-zero distance may be selected from the range of < 20 mm, such as from the range of < 10 mm, especially from the range of < 5 mm. In embodiments, the beam of light from each light source may (essentially) be incident on (only) one of the lenses. Especially, at least 80%, such as at least 85%, especially at least 90%, like at least 95%, of a luminous flux from a light source may irradiate the same lens. In embodiments, the beam of light emanating from the lens may have a beam shape. The beam shape may in embodiments be selected from group comprising a circular beam, an oval (or elliptical) beam, a batwing-shaped beam, and a (rounded) rectangular beam. Alternatively, the beam shape may be an irregular shape. Yet, in embodiments, the beam shape may especially comprise a plane of symmetry. Especially, the beam shape of a beam of light source light (incident on the semitransparent mirror) may comprise a plane of symmetry (in a plane parallel to the semitransparent mirror). That is, the beam shape may be symmetrical about a (virtual) axis, wherein the (virtual) axis (indicating the plane of symmetry) may be configured parallel to a plane of the semitransparent mirrors. A symmetrical beam shape may prevent distortion of the beam shape (upon reflection) by the semitransparent mirrors. Further, in embodiments, the beam of light source light (from the array of light sources) may have an angular scattering distribution in a plane parallel to the remote opening (and / or the array of light sources) and perpendicular to the semitransparent mirrors. Further, the beam of light source light may have a peak intensity, defined as the angle for which a maximum intensity is found in a graph of the angular scattering distribution (in said plane) (wherein an angle of 0° denotes the optical axis Ao). In embodiments, the peak intensity of the beam of light source light may be configured at an angle selected from the range of 2-70°, such as from the range of 3-55°, especially from the range of 5-35°, like from the range of 10-30°, though smaller and larger angles are herein not excluded. In specific embodiments, the peak intensity of the beam of light source light may be configured at an angle equal to the angle of incidence (ai). Additionally or alternatively, the peak intensity of the beam of light source light may be configured at the angle (y) to the optical axis Ao(and / or to a surface normal to a (light escape) surface of the light sources) selected from the range of 20-88°, such as from the range of 45-87°, especially from the range of 55-85°, like from the range of 60-80° (see also above). Further, the beam of light source light may have a plurality of peak intensities, such as especially two peak intensities. In such embodiments, the two peak intensities may both be configured at the same (absolute) angle, wherein the first peak intensity (of the two peak intensities) may be configured on an opposite side of the optical axis Ao from the second peak intensity (of the two peak intensities). Alternatively, the angle may for each of the two (or plurality of) peak intensities be individually selected from the range of 2-70°, such as from the range of 3-55°, especially from the range of 5-35°, like from the range of 10-30°. Yet, especially, in embodiments, the two (or plurality of) peak intensities may (both) be configured at an (absolute) angle equal to the angle of incidence (ai) (and on opposite sides of the optical axis Ao). Such a beam of light source having two peak intensities may facilitate irradiating the (at least two) semitransparent mirrors (simultaneously) with a peak intensity at the angle of incidence (ai). Hence, the majority of the luminous flux (density) of the light source light may irradiate the semitransparent mirrors under the angle of incidence (ai), facilitating the formation of an array of (partially) virtual light sources.

[0043] Hence, the angle of incidence (ai) with a normal (N) selected to a (respective) semitransparent mirror selected from the range of 5-35° may refer to embodiments wherein at least part, or even a substantial part, of the light source light is provided within that angle. For instance, the peak intensity may be under that angle of incidence. However, as the angle of incidence (ai) with a normal (N) selected to a (respective) semitransparent mirror selected from the range of 5-35° is used for definition purposes, this is not necessarily the case (as long as the transmission and reflection condition(s) is (are) met.

[0044] In embodiments, at least part of the light generating system, such as especially at least part of the lighting arrangement, may be configured in an enclosure. Especially, the array of light sources may be configured in an enclosure. Further, in embodiments, the lenses may be configured in an enclosure. Additionally or alternatively, the semitransparent mirrors may be configured in the enclosure. The enclosure may be light transmissive for the light source light, such as (light) transparent for the light source light. That is, in embodiments, the enclosure may be configured to transmit at least 60%, such as at least 70%, especially at least 80%, like at least 90%, including (essentially) 100%, of (a spectral power (distribution) of) the light source light. Hence, in embodiments, the lighting arrangement may be (at least partially) configured in a light transmissive enclosure. Additionally or alternatively, the semitransparent mirrors may define part of the enclosure. For instance, the enclosure may comprise a plurality of enclosure sides and / or enclosure walls, wherein at least one, such as at least two, of the enclosure sides and / or enclosure walls comprise (at least one of) the semitransparent mirrors. In embodiments, the enclosure sides and / or enclosure walls may (further) comprise the beam expander. That is, in embodiments, the beam expander may define part of the enclosure. In embodiments, the (light transmissive) enclosure (comprising the semitransparent mirrors and / or the beam expander) may be configured to protect the lighting arrangement, especially the light sources, against one or more of ingress, moisture, and damage. Additionally or alternatively, the (light transmissive) enclosure (comprising the semitransparent mirrors and / or the beam expander) may be one or more of watertight and gastight. Hence, in specific embodiments, one or more of the following may apply: (i) the semitransparent mirrors may define part of an enclosure, and (ii) the lighting arrangement may be configured in a light transmissive enclosure. Configuring the semitransparent mirrors to define part of an enclosure may provide a compact system, and may reduce the amount of material needed in the construction of the light generating system. Further, configuring the lighting arrangement in a light transmissive enclosure may protect especially the light sources (and optionally other electronics) against one or more of ingress, moisture, and damage, thereby extending the lifetime of the light generating system.

[0045] Returning to general embodiments of the light sources, the term “light source” may in principle relate to any light source known in the art. In a specific embodiment, the light source comprises a solid state light source (such as an LED (light emitting diode) or laser diode (or “diode laser”)). The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 (solid state) (LED) light sources. The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid- state light sources selected from the same bin. Hence, the term LED may also refer to a plurality of LEDs. Further, the term “light source” may in embodiments also refer to a so- called chip-on-board (COB) light source. The term “COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of light emitting semiconductor light source may be configured on the same substrate. In embodiments, a COB is a multi LED chip configured together as a single lighting module. The term “light source” may also refer to a chip scale package (CSP) and / or a chip scale packaged (CSP) LED. A CSP may comprise a single solid state die (such as a LED) with provided thereon a luminescent material comprising layer. The term “light source” may also refer to a midpower package. A midpower package may comprise one or more solid state die(s). The die(s) may be covered by a luminescent material comprising layer. The die dimensions may be equal to or smaller than 2 mm, such as in the range of e.g. 0.2-2 mm. Herein, the term “light source” may also especially refer to a small solid state light source, such as having a mini size or micro size. For instance, the light sources may comprise one or more of mini LEDs and micro LEDs, such as especially micro LEDs or “microLEDs” or “pLEDs”. Herein, the term mini size or mini LED especially refers to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm - 1 mm. Herein, the term p size or micro LED especially refers to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm and smaller.

[0046] The light source may have a light escape surface. For LEDs it may for instance be the LED die, or when a resin is applied to the LED die, the outer surface of the resin. The term escape surface especially relates to that part of the light source, where the light actually leaves or escapes from the light source. The beam of light source light (thus) escapes from the light exit surface of the light source. Likewise, a light generating system may comprise a light escape surface, such as an end window. The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term “light source” may also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In an embodiment, the light source comprises an LED. The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED). Especially, the term “solid state light source”, or “solid state material light source”, and similar terms, may refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, or a superluminescent diode. In embodiments, the light source may comprise one or more micro-optical elements (array of micro lenses) downstream of a single solid-state light source, such as an LED. In embodiments, the light source may comprise an LED with on-chip optics. In embodiments, the light source comprises pixelated single LEDs (with or without optics) (offering in

[0047] In specific embodiments, the light source may be selected from the group of laser diodes and superluminescent diodes. In other embodiments, the light source may comprise an LED. The term “light source” may refer to a light generating element as such, like e.g. a solid state light source, or e.g. to a package of the light generating element, such as a solid state light source, and one or more of a luminescent material comprising element and (other) optics, like a lens, a collimator. In embodiments, the term “light source” may thus also refer to a combination of a light source, like an LED, and an optical filter, which may change the spectral power distribution of the light generated by the light source.

[0048] In embodiments, the light generating system may (further) comprise a control system. The control system may be configured to (individually) control the light sources. Further, the control system may be configured to control the array of light sources. Additionally or alternatively, in embodiments, the control system may be configured to control one or more of the semitransparent mirrors and the beam expander. For instance, the control system may be configured to control a position of the one or more of the semitransparent mirrors and the beam expander. In (other) embodiments, the control system may (further) be configured to control the extent to which the beam expander broadens the beam of light. In (yet further) embodiments, the control system may be configured to control one or more of a spectral power distribution, a luminous flux, a color point, a color rendering index, and a correlated color temperature of the system light (e.g. by controlling a luminous flux from individual light sources). In embodiments, the control system may control (the light generating system) in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and / or a predetermined time scheme. The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior on the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface. The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

[0049] The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or “mode of operation” or “operational mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed. However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability).

[0050] The light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting.

[0051] As indicated above, the lighting arrangement may comprise a plane of symmetry (symmetry plane). This symmetry plane may be parallel to the semitransparent mirrors. Further, this plane of symmetry may include the first axis Al and / or the optical axis Ao. Light emanating from the lighting arrangement may be indicated as system light. As indicated above, the light generating system may be configured to generate system light, wherein the system light may comprise the light source light. Hence, at least part of the light source light emanates from the lighting arrangement and provides thereby the system light. At least part of the system light is provided by transmission of light source light via the semitransparent mirrors. Optionally, part of the system light may be provided by escape through the remote opening (optionally via (transmission through) a beam expander), and optionally part of the system light may be provided by escape through the side opening(s) (optionally via (transmission through) a beam expander). All light source light escaping from the arrangement may be indicated as system light. Especially, the angular distribution of the system light may be substantially symmetrical relative to the plane of symmetry.

[0052] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc.. The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In embodiments, the light widow may comprise the (light transmissive) enclosure (comprising the semitransparent mirrors). In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, an optical wireless communication device, and a street lighting device, comprising the light generating system as defined herein. Especially, in an aspect the invention provides a lighting device selected from the group of a lamp, a luminaire, a disinfection device, an optical wireless communication device, and a street lighting device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support the lighting arrangement.

[0053] In a further aspect, the invention may provide a lighting arrangement, especially a street lighting arrangement, comprising the light generating system as defined herein. Additionally or alternatively, the street lighting arrangement may comprise the lighting device as defined herein (such as especially the street lighting device). The street lighting arrangement may further comprise an elongated way. The elongated way may be selected from the group comprising a street, a railway, a highway, an alley, an avenue, a bike path, a waterway, a field, a race track, a parking lot, an outdoor industrial and logistics area, a tunnel, and a landing strip, though other options are herein not excluded. In embodiments, the elongated way may comprise an axis of elongation Aw(wherein the elongated way is elongated along the axis of elongation Aw). Further, in embodiments, the lighting arrangement may be configured over the (elongated) way. That is, in embodiments, the lighting arrangement may be configured (mounted) on a support, such that the lighting arrangement is configured elevated and / or suspended above the elongated way. In embodiments, the support may be selected from the group comprising a post, a pole, a wall, a pillar, a bridge, a tunnel ceiling and / or wall, and a roof (structure), though other options are herein not excluded. Hence, in embodiments, the lighting arrangement may be configured at a non-zero distance (i.e., remote) from (a surface of) the elongated way. Especially, in embodiments, the semitransparent mirrors may be configured at an arrangement height H3 over the way. The arrangement height H3 may be the distance between a (top) surface of the elongated way and the mirror second side of the (closest of the) semitransparent mirrors. In embodiments, the arrangement height H3 may be selected from the range of > 0.35 m, such as from the range of > 0.4 m, especially from the range of > 0.5 m, like from the range of > 1 m. Further, in embodiments, the arrangement height H3 may be selected from the range of > 1.5 m, such as from the range of > 2 m, especially from the range of > 2.5 m, like from the range of > 3 m. Additionally or alternatively, in embodiments, the arrangement height H3 may be selected from the range of < 10 m, such as from the range of < 9 m, especially from the range of < 8 m, like from the range of < 7.5 m. Further, in embodiments, the arrangement height H3 may be selected from the range of < 7 m, such as from the range of < 6.5 m, especially from the range of < 6 m,. Hence, in embodiments, the arrangement height H3 may be selected from the range of 0.35-10 m, such as from the range of 0.4-9 m, especially from the range of 0.5-8 m, like from the range of 1-7.5 m, such as 2.5-6 m. In embodiments, the light generating system (comprising the lighting arrangement) may be configured at an angle with the elongated way. Especially, in embodiments, the semitransparent mirrors may have an angle (P) with the axis of elongation Aw(of the elongated way). The angle (P) may especially be determined between the axis of elongation Awand a (first) major face of the semitransparent mirrors (defined by the mirror length L2 and the mirror height Hm). In embodiments, as indicated above, the (first) major face of the semitransparent mirrors may be configured parallel to the first axis Ai (of the array of light sources) and the optical axis Ao. Hence, in embodiments, the angle (P) may (further) be the angle between the first axis Ai and the axis of elongation Aw. In embodiments, the angle (P) may be selected from the range of 60-130°, such as from the range of 70-120°, especially from the range of 80-110°, like from the range of 80-100°. In specific embodiments, the angle (P) may be selected from the range of 85-95°, i.e., from the range of around 90°. Hence, in an aspect, the invention provides a street lighting arrangement comprising (i) the light generating system as defined herein, and (ii) an elongated way, comprising an axis of elongation Aw; wherein the lighting arrangement is configured over the way, with the semitransparent mirrors at an arrangement height H3 over the way, wherein the arrangement height H3 is selected from the range of 0.5-8 m, and wherein the semitransparent mirrors have an angle (P) with the axis of elongation Awselected from the range of 80-110°. Such a street lighting arrangement may provide an illuminated elongated way, wherein, in a direction along the axis of elongation Aw, the illumination may have a transition zone of gradually decreasing light intensity surrounding the lighting arrangement, providing reduced glare by decreasing the contrast between the illuminated area and the unilluminated area (e.g., a night sky). Further, an angle (P) selected from the range of 80-110° may facilitate that the semitransparent mirrors may be configured roughly perpendicular to the axis of elongation Aw. Hence, the side openings may be configured parallel to the axis of elongation Aw, while the virtual light sources may be visible to an observer (e.g. a pedestrian) moving in a direction along the axis of elongation Aw. Hence, amongst others, the invention also provides an assembly of a (street) pole and lighting arrangement.

[0054] In embodiments, the street lighting arrangement may comprise a plurality of light generating systems. The plurality of light generating systems may in such embodiments especially be configured along (yet not necessarily on) the axis of elongation Aw. For instance, the elongated way may be a street (having an axis of elongation Awalong the center of the street), wherein the plurality of light generating systems may be configured (in a row parallel to the axis of elongation Aw) at a (regular) interval along (a side of) the street. Further, in embodiments, the street lighting arrangement may comprise a plurality of elongated ways (such as e.g. a street grid) each comprising a (respective) axis of elongation Aw, wherein at least one light generating system may be configured over each of the plurality of elongated ways.

[0055] BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0057] Fig. 1 schematically depicts an embodiment of the light generating system; Figs. 2A-C schematically depicts an embodiment of the luminous flux density of the light source light transmitted through the semitransparent mirrors;

[0058] Fig. 3 schematically depicts an embodiment of the light generating system;

[0059] Fig. 4A schematically depicts an embodiment of the semitransparent mirrors;

[0060] Fig. 4B schematically depicts an embodiment of the light generating system comprising a beam expander; and

[0061] Figs. 5A-B schematically depict an embodiment of a street lighting arrangement. The schematic drawings are not necessarily to scale.

[0062] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] Fig. 1 schematically depicts an embodiment of the light generating system 1000. Fig. l(I-III) shows (partly) bottom views, while Fig. l(IV-VI) shows (partly) side views of the light generating system 1000. The light generating system may comprise a lighting arrangement 2000. The lighting arrangement 2000 may especially comprises (a) an array 2200 of light sources 10, and (b) semitransparent mirrors 550. The array 2200 of light sources 10 may comprises a plurality of light sources 10. The plurality of light sources 10 may be arranged to have a first pitch pi along a first axis Ai. In embodiments, the first pitch pi may be at maximum 30 mm. Further, the plurality of light sources 10 may have a first array length Li along the first axis Ai. The first array length Li may especially be defined by a heart-to-heart distance of outer light sources 10 in a row of the array 2200 parallel to the first axis AL In embodiments, the light sources 10 may be configured to generate visible light source light 11 along an optical axis Ao. The light source light 11 may especially be white light. Further, in embodiments, the optical axis Ao may be an average optical axis Aofor the light sources 10 in the array 2200. As depicted in Fig. 1(IV), each light source 10 may be configured to generate light source light 11 along a respective optical axis Ao. That is, a first light source 10 may have a first optical axis A0,i, a second light source 10 may have a second optical axis Ao, 2, etc., wherein an average optical axis of the respective optical axes A0,i of the light sources 10 determines the optical axis Ao. As schematically depicted in Fig. 1 (III) and Fig. 1(IV), the light generating system 1000 may further comprise lenses 560. Especially, downstream of each light source 10, a lens 560 may be configured. The semitransparent mirrors 550 may be configured parallel to the optical axis Aoand parallel to the first axis Ai. Especially, the semitransparent mirrors 550 may be configured with the array 2200 of light sources 10 in between, such that each of the light sources 10 is configured between two semitransparent mirrors 550. In embodiments, the semitransparent mirrors 550 may be configured in one or more pairs, wherein the semitransparent mirrors 550 in each pair may be configured on opposite sides of (and equidistant from) the first axis Ai. Hence, the array 2200 of light sources 10 may be configured centered between the semitransparent mirrors 550. The semitransparent mirrors 550 may have a mirror length L2 parallel to the first array length Li. Further, the semitransparent mirrors 550 may have a mirror height Hmparallel to the optical axis Ao. Additionally, the semitransparent mirrors 550 may have a mirror spacing Dm, wherein the mirror spacing Dmmay especially be the distance between a (first) major face of a first semitransparent mirror 550 and a (first) major face of a second semitransparent mirror 550, configured on the opposite side of the first axis Ai from the first semitransparent mirror 550. In embodiments, L2 > Li, 0.25 < I Hm < 10, and Hm> 1.5*Dm. The semitransparent mirrors 550 may be both (i) specular reflective and (ii) transmissive for the light source light 11 irradiating the semitransparent mirrors 550 with an angle of incidence (ai) with a normal (N) selected to a (respective) semitransparent mirror 550 selected from the range of 5-35°. This is schematically depicted in Fig. 1(V), wherein a first part of the light source light 11 incident on the semitransparent mirror 550 (with the angle of incidence (ai)) is transmitted through the semitransparent mirror 550 (indicated by the dashed arrow), and a second part of said light source light 11 is reflected by the semitransparent mirror 550 (indicated by the solid arrow). In embodiments, the semitransparent mirrors 550 may have a reflection percentage (R) and a transmission percentage (T). The reflection percentage (R) and transmission percentage (T) may vary over the mirror height Hmof the semitransparent mirrors 550. Yet, on average over the semitransparent mirrors 550, a reflection percentage (R) for the light source light 11 having the angle of incidence (ai) may be higher than a transmission percentage (T) for the light source light 11 having the angle of incidence (ai).

[0064] Further, a peak intensity of the light sources 10 may be configured to (at least partially) irradiate the semitransparent mirrors 550 with an angle (y) to a surface normal to the (light escape) surface of the light sources 10, wherein the surface normal to the (light escape) surface of the light sources 10 may be configured perpendicular to the first axis Ai (and parallel to the optical axis Ao). In embodiments, the angle (y) may be selected from the range of 55-85°. In embodiments, the light generating system 1000 may be configured to (in an operational mode of the light generating system) generate system light 1001, wherein the system light 1001 may comprise the light source light 11. Especially, the system light 1001 may comprise the light source light 11 exiting the light generating system 1000, either by transmission through the semitransparent mirrors 550, or by emission from the side openings 551 (see Fig. 4B) and / or the remote opening 552 (optionally via the beam expander 554, see Fig. 4).

[0065] As depicted in Fig. 1(V), all the (array of) light sources 10 are sandwiched by the only two semitransparent mirrors 550 (as shown there are no semitransparent mirrors 550 positioned in between the light sources 10) and the light source light 11 may be (at least partially) reflected back-and-forth between the two semitransparent mirrors 550 (configured on opposite sides of the first axis Ai), with a general direction of propagation of the light source light 11 indicated by x. Especially, in embodiments, each time a beam of light source light 11 is incident on (one of) the semitransparent mirrors 550 (with the angle of incidence (ai)), a percentage of the luminous flux density of the (beam of) light source light 11 may be transmitted through the semitransparent mirror 550, and a (second) percentage of the luminous flux density of the (beam of) light source light 11 may be reflected by the semitransparent mirror 550. Especially, the beam of light source light 11 incident on the semitransparent mirror 550 (with the angle of incidence (ai)) may have a luminous flux Ls, and the beam of light transmitted through the semitransparent mirror 550 (depicted as the dashed line indicated by 1 in Fig. 1(V)) may have a luminous flux density L of Ti*Ls, wherein Ti is the transmission percentage (T) at the location of incidence. Further, the beam of light reflected by the semitransparent mirror 550 may have a luminous flux density L of Ri*Ls, wherein Ri is the reflection percentage (R) at the location of incidence. In embodiments, the reflected beam of light from a first semitransparent mirror 550 may be incident on a second (opposite) semitransparent mirror 550. In embodiments, at the second semitransparent mirror 550, again a part of the luminous flux density L of the (reflected) beam of light may be transmitted. Especially, the luminous flux density of the beam of light reflected by a first semitransparent mirror 550 and transmitted by a second semitransparent mirror 550 (depicted as the dashed line indicated by 2 in Fig. 1(V)) may be provided by L = RI*T2*LS, wherein T2 is the transmission percentage (T) at the location of incidence for the reflected beam. In embodiments, part of a beam of light source light may be reflected a plurality of x times before being transmitted. In such embodiments, the luminous flux density of the beam of light transmitted after x (prior) reflections may be provided by L = RI*R2* . . . *Rx*Tx+i*Ls. As can be seen in Fig. 1(V), for a single row of light sources 10, and up to x reflections (of the light source light 11) between the two mirrors 550, a virtual 2D array with a width of x+1 (virtual) light sources may be provided (when viewing the lighting arrangement 2000 from an angle with the normal (N) equal to the angle of incidence (ai)). Yet, as depicted in Fig. l(II-IV), the array 2200 of light sources 10 may comprise a 2D array of light sources 10. The 2D array of light sources 10 may especially be configured symmetrical relative to the first axis Ai. Further, the 2D array of light sources 10 may have a second pitch p2 in a direction perpendicular to the first axis Ai. The 2D array of light sources 10 may especially be a first regular array comprising n rows of m light sources 10. In embodiments, light sources 10 configured in the outer rows of the 2D array may be separated from each other by heart-to-heart distances d4. Especially, light sources 10 configured in the outer rows of the 2D array and configured symmetrically relative to the first axis Ai may be separated by distances d4. The heart-to-heart distances d4may be smaller than the mirror spacing Dm. Further, the number of light sources 10 in an outer row (and / or in any row of the 2D array) may be at least twice as large as the number of rows in the 2D array (i.e., the 2D array may be an elongated array). The semitransparent mirrors 550 may be configured at a distance from the (2D) array 2200. Especially, a center of a closest light source 10 (e.g. a light source in an outer row of the array 2200) may be separated from a (major face of a) closest semitransparent mirror 550 by a third distance ds. In embodiments, the third distance ds may be selected from the range of ds / pi < 1, such as from the range of 0.2 < ds / pi < 0.8.

[0066] Returning to the semitransparent mirrors 550, the mirror height Hmof the semitransparent mirrors 550 may especially be defined by a mirror first side 5501 and a mirror second side 5502. The mirror first side 5501 may be configured closest to the light sources 10. Meanwhile, the mirror second side 5502 may be configured opposite the mirror first side 5501, and remote from the light sources 10. Further, the semitransparent mirrors 550 may have first areas Ami, configured at the mirror first side 5501 and having a first area height Hai of 0.99*Hm. Additionally, the semitransparent mirrors 550 may have second areas Am2, configured at the mirror second side 5502 (and adjacent to the first areas Ami) and having a second area height Ha2 of 0.01 *Hm. In embodiments, first (transmitted) luminous flux densities Lvi of the light source light 11 transmitted through the semitransparent mirrors 550 and emanating away therefrom in the first areas Ami, and second (transmitted) luminous flux densities Lv2 of the light source light 11 transmitted through the semitransparent mirrors 550 and emanating away therefrom in the second areas Am2 may have a ratio of LV2 / LV1 < 0.005.

[0067] Mirror spacing, mirror heights, mirror lengths may especially be defined relative to the only two semitransparent mirrors (with the light sources configured in between, i.e. the mirrors are arranged only around all the (array of) light sources, hence all the (array of) light sources are sandwiched by the two mirrors meaning that there are no mirrors arranged / positioned between light sources), even when one or both semitransparent mirrors may consist of subsets of semitransparent mirrors. Note that in the embodiments schematically depicted, both semitransparent mirrors may consist of a single semitransparent mirror.

[0068] Fig. 2 schematically depicts several embodiments of a (transmitted) luminous flux density (L) of the light source light 11 transmitted through the semitransparent mirrors 550 and emanating away therefrom. Further, Fig. 2 schematically depicts several embodiments of the (values of the) transmission percentage (T) and reflection percentage (R) over the mirror height Hm, starting from the mirror first side 5501 and moving in the direction as indicated by the x in Fig. 1(V) and Fig. 1(VI). Note that in the graphs on the right, the transmission percentage (T) and reflection percentage (R) are provided as fractions, rather than percentages. Hence, a number of 0.1 in the right graphs of Fig. 2 may correspond to a percentage of 10%.

[0069] Fig. 2A schematically depicts an embodiments wherein the transmission percentage (T) and reflection percentage (R) of the semitransparent mirrors 550 are (both) constant over the mirror height Hm. In such embodiments, a (transmitted) luminous flux density (L) of the light source light 11 transmitted through the semitransparent mirrors 550 and emanating away therefrom may gradually decrease along the semitransparent mirrors 550 with increasing distance from the array 2200 of light sources 10 (i.e., in the direction of x, towards the mirror second side 5502).

[0070] Fig. 2B schematically depicts an embodiments wherein the transmission percentage (T) and reflection percentage (R) of the semitransparent mirrors 550 vary over the mirror height Hm. Especially, the transmission percentage (T) may increase over the mirror height Hm, and the reflection percentage (R) may decrease over the mirror height Hm, wherein the magnitude with which the transmission percentage (T) increases and the reflection percentage (R) decreases may increase over the mirror height Hm. In such embodiments, a (transmitted) luminous flux density (L) of the light source light 11 transmitted through the semitransparent mirrors 550 and emanating away therefrom may deviate at most 33% along the semitransparent mirrors 550 with increasing distance from the array 2200 of light sources 10.

[0071] Fig. 2C schematically depicts a similar embodiment to the embodiment of Fig. 2B. Yet, here, the magnitude with which the transmission percentage (T) increases and the reflection percentage (R) decreases over the mirror height Hmvaries from the embodiment in Fig. 2B. As such, in this embodiment, a (transmitted) luminous flux density (L) of the light source light 11 transmitted through the semitransparent mirrors 550 and emanating away therefrom may firstly gradually increase along the semitransparent mirrors 550 with increasing distance from the array 2200 of light sources 10, and secondly gradually decrease along the semitransparent mirrors 550 with further increasing distance from the array 2200 of light sources 10. Especially, in such embodiments, the graph of the luminous flux density (L) over distance from the array 2200 of light sources 10 may display a Gaussian curve.

[0072] Fig. 3 schematically depicts two (further) embodiments of the light generating system 1000 with all the light sources 10 centrally arranged (viewed in a projection direction along the optical axis Ao) in between the only two semitransparent mirrors 550. In the embodiment schematically depicted on the left of Fig. 3, the lighting arrangement 2000 is configured in a light transmissive enclosure 1250. In embodiments, the semitransparent mirrors 550 may therefore be configured in the light transmissive enclosure 1250. Yet, as depicted on the right of Fig. 3, in embodiments, the semitransparent mirrors 550 may define part of an enclosure 570, e.g., the semitransparent mirrors 550 may be comprised by one or more walls of the enclosure 570. The light sources 10 may be configured to (at least partially) irradiate the semitransparent mirrors 550 with an angle (y) to a surface normal to the (light escape) surface of the light sources 10, wherein the surface normal to the (light escape) surface of the light sources 10 may be configured perpendicular to the first axis Ai (and parallel to the optical axis Ao).

[0073] Fig. 4A schematically depicts an embodiment of the semitransparent mirrors 550. Each of the semitransparent mirrors may comprise openings 555. The openings 555 may have cross-sectional equivalent circular diameters Deq,0selected from the range of 100 pm - 10 mm. Further, the openings 555 may be arranged in a first regular array, wherein at least 20% of a total number of openings 555 is offset from the first regular array. From the offset openings 555, at most 50% of the total number of offset openings 555 may be arranged in a secondary regular array. Alternatively, the openings 555 may be arranged in a random array. The openings 555 may further (each) have a cross-sectional area, wherein a total cross- sectional area Aoof the openings 555 may be selected from the range of 1-25% of a total cross-sectional area At of the semitransparent mirror 550.

[0074] Fig. 4B schematically depicts an embodiment of the light generating system 1000 viewed in two side views, i.e. respectively viewed along the first axis Ai (depicted on the left of Fig. 4B) and viewed perpendicular to the first axis Ai (depicted on the right of Fig. 4B). The semitransparent mirrors 550 may define two side openings 551 (depicted on the right of Fig. 4B) and a remote opening 552. The side openings 551 may be configured perpendicular to the first axis Ai, and bridging the semitransparent mirrors 550. The remote opening 552 may be configured remote from the array 2200 of light sources 10 and bridging the two side openings 551 (and the semitransparent mirrors 550). A beam expander 554 may be configured in or downstream of at least one of these openings 551,552. The beam expander 554 may comprise one or more of scattering elements and refractive elements. Further, the beam expander 554 may be configured to broaden a beam of light escaping from the respective opening 551,552 in a direction perpendicular to the semitransparent mirrors 550. In embodiments, the broadening of the beam may be defined by an increase in a full width half maximum of an angular scattering distribution of the beam of light selected from the range of (0.5*atan(Dm / (2*Hm))) - (3*atan(Dm / (2*Hm))).

[0075] Fig. 5 schematically depicts an embodiment of a lighting device 1200 of the invention. Fig. 5A schematically depicts the lighting device 1200 in a top view, wherein the dashed oval line may indicate (an outline of) a housing of the lighting device 1200. Meanwhile, Fig. 5B schematically depicts a side view of the (same) lighting device 1200. The lighting device 1200 may be selected from the group of a lamp, a luminaire, a disinfection device, an optical wireless communication device, and a street lighting device 4. Further, the lighting device 1200 may comprise the light generating system 1000 as defined herein. In Fig. 5A and Fig. 5B, especially the embodiments of a street lighting device 4 is (schematically) depicted. Fig. 5 further schematically depicts an embodiment of a street lighting arrangement 3000 of the invention. The street lighting arrangement 3000 may especially comprise (i) the light generating system 1000 as defined herein, and (ii) an elongated way 3005. Further, the street lighting arrangement 3000 may comprise the lighting device 1200 as defined herein. In the embodiment depicted in Fig. 5, the elongated way 3005 is a street, and the light generating system 1000 (of the lighting device 1200) may be configured as a street lighting device 4, though other options are also possible. The elongated way 3005 may comprise an axis of elongation Aw. Further, the lighting arrangement 2000 may be configured over the way 3005, with the semitransparent mirrors 550 at an arrangement height H3 over the way 3005 (see Fig. 5B). In embodiments, the arrangement height H3 may be selected from the range of 0.5-8 m. Further, (a major face of) the semitransparent mirrors 550 may have an angle (P) with the axis of elongation Awselected from the range of 80-110°.

[0076] The term “plurality” refers to two or more. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’. The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species". Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0077] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0078] 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.

[0079] Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0080] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system 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. In yet a further aspect, the invention (thus) provides a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein. The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system. The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings.

[0081] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) comprising a lighting arrangement (2000), wherein the lighting arrangement (2000) comprises (a) an array (2200) of light sources (10), and (b) only two semitransparent mirrors (550), wherein: the array (2200) of light sources (10) comprises a plurality of light sources (10) having (i) a first pitch (pi) along a first axis (Ai), and (ii) a first array length (Li) along the first axis (Ai), wherein the first pitch (pi) is at maximum 30 mm; the light sources (10) are configured to generate visible light source light (11) along an optical axis (Ao); the semitransparent mirrors (550) are configured parallel to the optical axis (Ao) and parallel to the first axis (Ai), and are configured with the array (2200) of light sources (10) in between, such that each of the light sources (10) is configured between the only two semitransparent mirrors (550); the semitransparent mirrors (550) have (i) a mirror length (L2) parallel to the first array length (Li), (ii) a mirror height (Hm) parallel to the optical axis (Ao), and (iii) a mirror spacing (Dm); wherein L2>LI, 0.25<L2 / Hm<10, and Hm>1.5*Dm; and the semitransparent mirrors (550) are both (i) specular reflective and (ii) transmissive for the light source light (11) irradiating the semitransparent mirrors (550) with an angle of incidence (ai) with a normal (N) selected to a semitransparent mirror (550) selected from the range of 5-35°, with on average over the semitransparent mirrors (550) a reflection percentage for the light source light (11) having the angle of incidence (ai) being higher than a transmission percentage for the light source light (11) having the angle of incidence (ai).

2. The light generating system (1000) according to claim 1, wherein the light sources (10) comprise LED light sources; and wherein the semitransparent mirrors (550) comprise one or more of (i) a multilayer comprising dielectric layers with different indices of refraction, and (ii) a metal layer mirror comprising a metal layer coating having a thickness allowing transmission of light source light (11).

3. The light generating system (1000) according to any one of the preceding claims, wherein: each of the semitransparent mirrors (550) comprises openings (555) having cross-sectional equivalent circular diameters (Deq,0) selected from the range of 100 pm - 10 mm; wherein a total cross-sectional area (Ao) of the openings (555) is selected from the range of 1-25% of a total cross-sectional area (At) of the semitransparent mirror (550); wherein at least 20% of a total number of openings (555) is offset from a first regular array, and wherein at most 50% of a total number of offset openings (555) is arranged in a secondary regular array; and the semitransparent mirrors (550) define two side openings (551) and a remote opening (552), remote from the array (2200) of light sources (10) and bridging the two side openings (551); wherein in or downstream of at least one of these openings (551,552), a beam expander (554) is configured, wherein the beam expander (554) is configured to broaden a beam of light escaping from the respective opening (551,552) in a direction perpendicular to the semitransparent mirrors (550); wherein the broadening of the beam is defined by an increase in a full width half maximum of an angular scattering distribution of the beam of light selected from the range of (0.5*atan(Dm / (2*Hm))) - (3*atan(Dm / (2*Hm))); and wherein the beam expander (554) comprises one or more of scattering elements and refractive elements.

4. The light generating system (1000) according to any one of the preceding claims, wherein one or both semitransparent mirrors consist of subsets of semitransparent mirrors.

5. The light generating system (1000) according to any one of the preceding claims, further comprising lenses (560), wherein downstream of each light source (10) a lens (560) is configured.

6. The light generating system (1000) according to any one of the preceding claims, wherein one or more of the following applies:7.5 mm < pi < 25 mm;L2< 1.5*LI;0.5 < L2 / Hm< 2; and2 < Hm / Dm< 20.

7. The light generating system (1000) according to any one of the preceding claims, wherein a third distance (ds) between a center of a closest light source (10) to a closest semitransparent mirror (550) is selected from the range of ds / pi < 1.

8. The light generating system (1000) according to any one of the preceding claims 1-7, wherein the reflection percentage and the transmission percentage are constant over the mirror height (Hm) of the semitransparent mirrors (550), and wherein a luminous flux density of the light source light (11) transmitted through the semitransparent mirrors (550) and emanating away therefrom gradually decreases along the semitransparent mirrors (550) with increasing distance from the array (2200) of light sources (10).

9. The light generating system (1000) according to any one of the preceding claims 1-7, wherein the reflection percentage and the transmission percentage vary over the mirror height (Hm) of the semitransparent mirrors (550), such that a luminous flux density of the light source light (11) transmitted through the semitransparent mirrors (550) and emanating away therefrom deviates at most 33% along the semitransparent mirrors (550) with increasing distance from the array (2200) of light sources (10).

10. The light generating system (1000) according to any one of the preceding claims 1-7, wherein the reflection percentage and the transmission percentage vary over the mirror height (Hm) of the semitransparent mirrors (550), such that a luminous flux density of the light source light (11) transmitted through the semitransparent mirrors (550) and emanating away therefrom firstly gradually increases along the semitransparent mirrors (550) with increasing distance from the array (2200) of light sources (10), and secondly gradually decreases along the semitransparent mirrors (550) with further increasing distance from the array (2200) of light sources (10).

11. The light generating system (1000) according to any one of the preceding claims 8-10, wherein the mirror height (Hm) is defined by a mirror first side (5501) and a mirror second side (5502), wherein the mirror first side (5501) is configured closest to the light sources (10), wherein the mirror second side (5502) is configured opposite the mirror first side (5501) and remote from the light sources (10), wherein first luminous flux densities Lvi of the light source light (11) transmitted through the semitransparent mirrors (550) andemanating away therefrom in first areas (Ami) of the semitransparent mirrors (550), configured at the mirror first side (5501) and having a first area height Haiof 0.99*Hm, and second luminous flux densities Lv2 of the light source light (11) transmitted through the semitransparent mirrors (550) and emanating away therefrom in second areas (Am2) of the semitransparent mirrors (550), configured at the mirror second side (5502) and having a second area height Ha2 of 0.01 *Hm, have a ratio of LV2 / LV1 < 0.005.

12. The light generating system (1000) according to any one of the preceding claims, wherein the array (2200) of light sources (10) comprises a 2D array of light sources (10), configured symmetrical relative to the first axis (Ai), wherein heart-to-heart distances (d4) of light sources (10) configured in outer rows and configured symmetrically relative to the first axis (Ai) are smaller than the mirror spacing (Dm), and wherein the number of light sources (10) in an outer row is at least twice as large as the number of rows in the 2D array.

13. The light generating system (1000) according to any one of the preceding claims, wherein one or more of the following applies: (i) the semitransparent mirrors (550) define part of an enclosure (570), and (ii) the lighting arrangement (2000) is configured in a light transmissive enclosure (1250).

14. A lighting device (1200) selected from the group of a lamp, a luminaire, a disinfection device, an optical wireless communication device, and a street lighting device (4), comprising the light generating system (1000) according to any one of the preceding claims.

15. A street lighting arrangement (3000) comprising (i) the light generating system (1000) according to any one of the preceding claims 1-13, and (ii) an elongated way (3005), comprising an axis of elongation (Aw); wherein the lighting arrangement (2000) is configured over the way (3005), with the semitransparent mirrors (550) at an arrangement height (H3) over the way (3005), wherein the arrangement height (H3) is selected from the range of 0.5-8 m, and wherein the semitransparent mirrors (550) have an angle (P) with the axis of elongation (Aw) selected from the range of 80-110°.

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