Linear collimator optics for a linear array of omnidirectional LED filament

Abstract

The invention provides a light generating system (1000) comprising an elongated light generating device (100), and an elongated collimator lens (4000) that comprises a light transparent material and that is configured in a light receiving relationship with the elongated light generating device (100); wherein the elongated collimator lens (4000) comprises an axis of elongation (A1) and an elongated cavity (400) along the axis of elongation (A1), wherein the elongated light generating device (100) is configured in the elongated cavity (400), wherein the elongated light generating device (100) is configured to generate a first beam (5) of device light (101) with a non-zero light intensity over the entire range of 30-150° and 210-330° around the axis of elongation (A1), wherein the light transparent material encloses the axis of elongation (A1) over an angle (γ) of at least 260°, thereby defining the elongated cavity (400); and wherein the elongated collimator lens (4000) comprises in a cross-sectional view perpendicular to the axis of elongation (A1): (i) a light exit face (4010), (ii) a first total internal reflection face (4020), and (iii) a second total internal reflection face (4030); and (B) the elongated collimator lens (4000) is configured such that for device light (101) provided by an elongated light generating device (100) configured in the elongated cavity (400) and having an omnidirectional light distribution around the axis of elongation (A1) applies that: (i) a reflected part (12) escapes from the elongated collimator lens (4000) via the light exit face (4010) after a single total internal reflection at the first total internal reflection face (4020), and (ii) a double reflected part (13) escapes from the elongated collimator lens (4000) via the light exit face (4010) after a first total internal reflection at the second total internal reflection face (4030) and subsequently a second total internal reflection at the first total internal reflection face (4020).

Description

[0001] Linear collimator optics for a linear array of omnidirectional LED filament

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating system comprising an elongated collimator lens. Further, the invention relates to a lighting device comprising the light generating system.

[0004] BACKGROUND OF THE INVENTION

[0005] Collimator lenses are known in the art. For instance, US6819505B1 describes an optical lens for capturing, homogenizing and transmitting substantially all of the light emitted by a light source, such as a light emitting diode. The optical lens includes a light transmitting structure having a TIR collector portion, a projector portion and a transition portion disposed between the TIR and projector. The structure is characterized by the length of the transition portion being longer than the focal length of the TIR portion. The light source is disposed within a recess in one end of the TIR portion. The light output from the light source is captured by the TIR portion and homogenized to form a uniform, circular near field image within the transition portion. The projector portion then projects the circular near field image into a uniform, circular far field image.

[0006] SUMMARY OF THE INVENTION

[0007] Conventional light generating systems (e.g. incandescent or fluorescent lamps) are rapidly being replaced by light emitting diode (LED) based lighting solutions. Especially LED filaments may be used, as LED filaments may have a relatively high efficiency. Due to their omnidirectional light emittance, LED filaments may be especially suited to replace conventional filaments in filament (light) bulbs. However, in luminaires, the LED light source may be mounted near (or on) an opaque surface (such as a luminaire housing), wherein emission of light in all directions may lead to a drop in efficiency, as light emitted towards the opaque surface is absorbed and converted into heat. Prior art may describe collimator lenses capable of reducing a width of a beam of LED light, yet such collimator lenses may only be suitable to collimate light originating from one (half-sphere) side of the LED light source. As such, there is a need and desire for a collimator lens that may especially be suitable to collimate an omnidirectional light beam into a narrow beam of fixed width. Hence, it is an aspect of the invention to provide an alternative collimator lens, 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.

[0008] According to a first aspect, the invention provides a light generating system comprising an elongated light generating device, and an elongated collimator lens. The elongated collimator lens comprises a light transparent material and it is configured in a light receiving relationship with the elongated light generating device. Further, the elongated collimator lens comprises an axis of elongation (Ai) and an elongated cavity along the axis of elongation (Ai). The elongated light generating device is configured in the elongated cavity. The elongated light generating device (100) is further configured to generate a first beam (5) of device light (101) with a non-zero light intensity over the entire range of 30-150° and 210- 330° around the axis of elongation (Ai). The light transparent material encloses the axis of elongation (Ai) over an angle y of at least 260°, thereby defining the elongated cavity. Further, the elongated collimator lens comprises, in a cross-sectional view perpendicular to the axis of elongation (Ai): (i) a light exit face, (ii) a first total internal reflection face, and (iii) a second total internal reflection face. The elongated collimator lens is configured such that for device light provided by the elongated light generating device applies that: (i) a reflected part escapes from the elongated collimator lens via the light exit face after a single total internal reflection at the first total internal reflection face, and (ii) a double reflected part escapes from the elongated collimator lens via the light exit face after a first total internal reflection at the second total internal reflection face and subsequently a second total internal reflection at the first total internal reflection face.

[0009] Hence, the elongated collimator lens comprises a light transparent material; wherein the elongated collimator lens comprises an axis of elongation (Ai) and an elongated cavity along the axis of elongation (Ai), wherein the light transparent material encloses the axis of elongation (Ai) over an angle y of at least 260°, thereby defining the elongated cavity; and wherein the elongated collimator lens comprises in a cross-sectional view perpendicular to the axis of elongation (Ai): (i) a light exit face, (ii) a first total internal reflection face, and (iii) a second total internal reflection face.

[0010] The elongated collimator lens is configured such that for device light provided by an elongated light generating device configured in the elongated cavity and having an omnidirectional light distribution around the axis of elongation (Ai) applies that: (i) a reflected part escapes from the elongated collimator lens via the light exit face after a single total internal reflection at the first total internal reflection face, and (ii) a double reflected part escapes from the elongated collimator lens via the light exit face after a first total internal reflection at the second total internal reflection face and subsequently a second total internal reflection at the first total internal reflection face.

[0011] Such an elongated collimator lens (“collimator lens”) may especially be configured to collimate an omnidirectional beam of light. Hence, such an elongated collimator lens may provide the benefit that a relatively highly efficient omnidirectional light generating device (e.g. a LED filament) may be used in applications requiring a narrow beam of light. Further, such a collimator lens may protect a light generating device from damage by at least partially hosting (and covering) the light generating device in the elongated cavity.

[0012] The elongated light generating device (configured in the cavity of the elongated collimator lens) may be a virtual light generating device. Alternatively, the elongated light generating device may be any (known) elongated light generating device providing an omnidirectional light distribution, such as an elongated light generating device selected from the group comprising a LED filament, an optical fiber, and a (LED-based or fluorescent) tube. The elongated collimator lens may in embodiments not comprise the elongated light generating device. Especially, the elongated light generating device may serve to explain the function of the elongated collimator lens, yet may not be comprised by (or form a part of) the elongated collimator lens. The term “omnidirectional light distribution” may refer to a light distribution having a non-zero light intensity over the entire range of 0-360° around the axis of elongation (Ai). Said light distribution may be homogeneous around the axis of elongation (Ai), wherein a radiant flux at every angle in the range of 0-360° may be identical. Alternatively, said light distribution may have a relatively larger radiant flux at some subranges in the range of 0-360°. Yet, especially, the term “omnidirectional light distribution” may refer to a light distribution having a non-zero light intensity in all four quadrants (each spanning 90°) around the axis of elongation (Ai), wherein for at least two opposite quadrants may apply that the light distribution may have a non-zero light intensity over the entire (range of the) quadrant.

[0013] The elongated collimator lens comprises a light transparent material. Herein, the term “light transparent” material indicates the material may be (specular) transmissive for one or more wavelengths selected from the range of 190-1500 nm, such as from the range of 200-1000 nm, especially from the range of 380-780 nm (i.e. visible light). In embodiments, the light transparent material may comprise one or more materials selected from the group comprising glass, polycarbonate (PC), polyethylene (PE), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), (clear) polyvinyl chloride (PVC), cyclic olefin copolymers (COC), fluorinated ethylene propylene (FEP), styrene methyl methacrylate (SMMA), polysiloxanes, and poly(methyl methacrylate) (PMMA). In specific embodiments, the light transparent material may comprise, such as consist of, one or more of PC, PE, PS, PP, PET, and PMMA. Especially, the light transparent material may comprise, such as consist of, PMMA. Additionally or alternatively, the light transparent material may comprise, such as consist of, PC. Hence, in specific embodiments, the light transparent material may comprise one or more of PMMA and PC. PMMA and PC may especially be light transparent, and have a suitable refractive index (for visible light). The term “visible light”, and similar terms, refers to light having one or more wavelengths in the range of about 380-780 nm. Further, PMMA and PC may be relatively cheap, easy to process, and easy to mold into complex shapes.

[0014] The elongated collimator lens is elongated along an axis of elongation (Ai). Further, the light transparent material may encircle, especially enclose, the axis of elongation Ai over an angle y. Hence, in embodiments, the axis of elongation (Ai) may not intersect the light transparent material, yet may be at least partially surrounded by the light transparent material. Especially, the elongated collimator lens may comprise an elongated cavity (“cavity”), wherein the axis of elongation (Ai) may be configured (and / or located) in the elongated cavity, and wherein the elongated cavity may be defined by the light transparent material enclosing the axis of elongation (Ai) (over the angle y). The angle y may be selected from the range of > 230°, such as from the range of > 260°, especially from the range of > 300°. Further, the angle y may be selected from the range of > 330°, such as from the range of > 340°, especially from the range of > 350°, including (essentially) 360°. Hence, in specific embodiments, the light transparent material may enclose the axis of elongation (Ai) over 360°. In such embodiment, the cavity may especially be a closed cavity. A closed cavity may provide the benefit that the cavity may not comprise a gap through which light may escape from the elongated collimator lens without being collimated. Yet, in alternative embodiments, the angle y may be selected from the range of < 360°, such as from the range of < 350°, especially from the range of < 340°. Hence, in specific embodiments, the light transparent material may enclose the axis of elongation (Ai) over < 360°. In such embodiments, the cavity may especially be an open cavity. An open cavity may facilitate improving thermal management, as heat may escape through the gap in the cavity. Further, an open cavity may provide the benefit that e.g. electrical connections may be provided to any point along the length of a light generating device configured in the cavity.

[0015] The (edges of the) light transparent material may define a length, width, and height of the elongated collimator lens. Especially, the elongated collimator lens may have a collimator width Wc in a cross-sectional view perpendicular to the axis of elongation (Ai). The collimator width Wc may be selected from the range of > 3 mm, such as from the range of > 5 mm, especially from the range of > 10 mm. Additionally or alternatively, the collimator width Wc may be selected from the range of < 90 mm, such as from the range of < 60 mm, especially from the range of < 50 mm. Hence, in embodiments, 3 mm < Wc < 90 mm, such as 5 mm < Wc < 60 mm, especially 10 mm < Wc < 50 mm. Further, the elongated collimator lens may have a collimator height He in a cross-sectional view perpendicular to the axis of elongation (Ai), wherein the collimator height He may be (determined) perpendicular to the collimator width Wc. In embodiments, the elongated collimator lens may be configured such that (essentially) all device light provided by a (virtual) elongated light generating device configured in the elongated cavity may be reflected at least once before escaping from the elongated collimator lens (via the light exit face). In such embodiments, Wc < He, such as Wc < 0.8*Hc, especially, Wc < 0.6*Hc, like Wc < 0.5*Hc. Additionally or alternatively, in such embodiments, Wc > 0.1 *Hc, such as Wc > 0.25*Hc, especially Wc > 0.3 *Hc. In other embodiments, the elongated collimator lens may be configured such that at least part of said device light may escape from the elongated collimator lens (via the light exit face) without internal reflection (as a directly escaping part, see below). In such embodiments, He < Wc, such as He < 0.8*Wc, especially, He < 0.6*Wc, like He < 0.5*Wc. Additionally or alternatively, in such embodiments, He > 0.1 *Wc, such as He > 0.25*Wc, especially He > 0.3 *Wc. Alternatively, the collimator height He may be selected from the range of 0.3-75 mm, such as from the range of 1-50 mm, especially from the range of 5-30 mm. Further, the elongated collimator lens may have a collimator length Lc along the axis of elongation (Ai). The collimator length Lc may be selected from the range of 30-900 mm, such as from the range of 40-600 mm, especially from the range of 50-400 mm. Further, in embodiments, Lc > Wc, such as Lc > 1.5*Wc, especially Lc > 2*Wc, like Lc > 3*Wc. Additionally or alternatively, in embodiments, Lc < 50*Wc, such as Lc < 40*Wc, especially Lc < 30*Wc. Hence, in specific embodiments, the elongated collimator lens may have a collimator width Wc in a cross-sectional view perpendicular to the axis of elongation (Ai); wherein 5 mm < Wc < 60 mm; wherein the elongated collimator lens may have a collimator height He in the cross-sectional view perpendicular to the axis of elongation (Ai); wherein He < 0.6*Wc; and wherein the elongated collimator lens may have a collimator length Lc along the axis of elongation (Ai); wherein Lc > 2*Wc. An elongated collimator lens having such dimensions may be small enough to allow installation in most luminaires. Yet, an elongated collimator lens having such dimensions may be large enough to fit a wide range of elongated light generating devices (in the elongated cavity).

[0016] The elongated collimator lens may have a cross-sectional perimeter (in a cross-sectional view perpendicular to the axis of elongation (Ai)). The cross-sectional perimeter may be defined by the (outside) edges of the light transparent material. Further, the cross-sectional perimeter may be at least defined by the light exit face, the first total internal reflection face, and the second total internal reflection face. The cross-sectional perimeter may have a perimeter length Lp. In embodiments, the perimeter length Lpmay be selected from the range of > 7 mm, such as from the range of > 15 mm, especially from the range of > 30 mm. Additionally or alternatively, the perimeter length Lpmay be selected from the range of < 200 mm, such as from the range of < 150 mm, especially from the range of < 100 mm. However, other sizes are herein not excluded. Further, in embodiments, 2*Wc < Lp< 5*Wc, such as 2*Wc < Lp< 4*Wc, especially 2*Wc < Lp< 3*Wc.

[0017] The cross-sectional perimeter may be partially defined by the light exit face. Hence, in a cross-sectional view perpendicular to the axis of elongation (Ai), the elongated collimator lens may comprise a light exit face. The light exit face may have a first length Li along the perimeter. In embodiments, Li > 0.05*Lp, such as Li > 0.1 *LP, especially Li > 0.2*Lp. Additionally or alternatively, in embodiments, Li < 0.7*Lp, such as Li < 0.6*Lp, especially Li < 0.5*Lp. Hence, in embodiments, 0.05*Lp< Li < 0.7*Lp, such as 0.1 *LP< Li < 0.6*Lp, especially 0.2*Lp< Li < 0.5*Lp. In (other) embodiments, the elongated collimator lens may be configured such that at least part of device light provided by a (virtual) elongated light generating device configured in the elongated cavity may escape from the elongated collimator lens (via the light exit face) without internal reflection (as the directly escaping part). In such embodiments, Li > 0.25*Lp, such as Li > 0.3*Lp, especially Li > 0.4*Lp. Hence, in embodiments, 0.25*Lp< Li < 0.7*Lp, such as 0.3*Lp< Li < 0.6*Lp, especially 0.4*Lp< Li < 0.5*Lp. Further, the light exit face may at least partially span across (such as define) the collimator width Wc. Especially, the light exit face may span over at least 0.7*Wc, such as over at least 0.8*Wc, especially over at least 0.9*Wc, including (essentially) 1*WC.

[0018] The light exit face may be (essentially) planar. That is, across the first length

[0019] Li, the light exit face may deviate from a straight line by < 0.05*Li, such as by < 0.03 *Li, especially by < 0.02*Li. Alternatively, the light exit face may be curved (i.e., deviate > 0.05*Li from a straight line across the first length Li). Further, the light exit face may comprise a collimator lens element. The collimator lens element may be configured to shape (especially (further) collimate) a beam of device light passing through the collimator lens element (from the elongated cavity). The collimator lens element may have a shape selected from the group comprising a (semi-)circular shape, a (semi-)elliptical shape, and a (regular) (semi-)polygonal shape (in the light exit face). Further, the collimator lens element may be configured as a protrusion in the light exit face. Especially, with respect to a (virtual) line of a light exit face not comprising the collimator lens element, the collimator lens element may protrude from the light exit face with an amplitude di. Hence, the collimator lens element may have an amplitude di. The amplitude di may be selected from the range of > 0.5 mm, such as from the range of > 1 mm, especially from the range of > 2 mm. Additionally or alternatively, the amplitude di may be selected from the range of < 7 mm, such as from the range of < 5 mm, especially from the range of < 4 mm. That is, the amplitude di may be selected from the range of 0.5-7 mm, such as from the range of 1-5 mm, especially from the range of 2-4 mm. Hence, in specific embodiments, the light exit face may comprise a collimator lens element, wherein the collimator lens element may have an amplitude di selected from the range of 1-5 mm. A collimator lens element may facilitate further shaping (especially collimating) a beam of device light transmitted through the elongated collimator lens. In embodiments, the collimator lens element may be configured centered in the light exit face, wherein a highest point of the collimator lens element (defining the amplitude di) may be located at 0.5*Li. Alternatively, the collimator lens element may be configured offset from a mid-point (0.5*Li) of the light exit face, such as by an offset distance doff of 0.01 *Li < doff < 0.2*Li, especially 0.02*Li < doir < 0.1 *Li.

[0020] The light exit face may comprise the light transparent material. Hence, the light exit face may be light transmissive. Especially, the light exit face may be specular transmissive. Alternatively, the light exit face may be at least partially diffuse transmissive, such as especially at least partially diffuse transmissive for visible light. Hence, in embodiments, one or more may apply of: (a) at least part of the light exit face may be diffuse transmissive, and (b) the light exit face may be configured to diffuse at least part of a light received by the light exit face (from the elongated cavity). The light exit face may have a surface roughness, wherein light may be scattered upon interaction with (such as refraction at) the irregularities on the light exit face. Alternatively, the light exit face may comprise light scattering particles (e.g. at least one of BaSCU, A12O3, and TiCE particles) embedded in the light transparent material. Further, (at least part of) the light exit face may be configured to scatter (at least part of) incident light according to a gaussian distribution (gaussian scattering). Especially, (at least part of) the light exit face may be configured to scatter (at least part of) incident light, wherein a full width at half maximum (FWHM) of a beam of light (directly) downstream of the at least partially diffuse transmissive light exit face may be increased by 1-30°, such as 2-20°, especially 3-15° in a plane perpendicular to the axis of elongation (Ai), compared to a beam of light (directly) downstream of a light transparent light exit face. Hence, in specific embodiments, the light exit face may be at least partially diffuse transmissive for visible light.

[0021] As indicated above, a light generating device is configured in the elongated cavity (i.e., the elongated cavity may be configured to host a light generating device). Said light generating device may especially be configured to generate device light having an omnidirectional light distribution, wherein said device light may be at least partially transmitted through (and escape from) the elongated collimator lens. Especially, a directly escaping part of the device light may (directly) escape from the elongated collimator lens via the light exit face. In such embodiments, the directly escaping part of the device light may be refracted twice before escaping from the light exit face: once upon entering the light transparent material (via the cavity wall (first section), see below), and once upon escaping from the light exit face. Especially, the directly escaping part of the device light may escape from the elongated collimator lens without internal reflection (at either the light exit face, the first total internal reflection face, or the second total internal reflection face). Hence, in specific embodiments, a directly escaping part of the device light may escape from the elongated collimator lens via the light exit face without internal reflection. An elongated collimator lens configured to transmit at least part of the incident light (originating in the elongated cavity) without internal reflection may facilitate reducing the collimator height He of the elongated collimator lens (see also above).

[0022] The directly escaping part (of the device light) may comprise > 20%, such as > 25%, especially > 30%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Additionally or alternatively, the directly escaping part may comprise < 80%, such as < 70%, especially < 60%, of a radiant flux of the device light escaping from the elongated collimator lens. That is, the directly escaping part (of the device light) may comprise 20-80%, such as 25-70%, especially 30-60%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Hence, in specific embodiments, the directly escaping part may comprise 25-70% of a radiant flux of the device light escaping from the elongated collimator lens.

[0023] Further, a reflected part of the device light may escape from the elongated collimator lens via the light exit face after a single total internal reflection at the first total internal reflection face. That is, in embodiments, the light transparent material (comprised by the first total internal reflection face) may have a critical angle 0C, wherein (at least) the reflected part (of the device light) may be incident on the first total internal reflection face with a primary second light angle 02, i, wherein 02, i > 0C, and wherein the (at least) reflected part may (thus) be reflected at the first total internal reflection face. The reflected light comprising (at least) the reflected part may next be incident on the light exit face with a secondary second light angle 02,2, wherein 02,2 < 0c, and wherein the reflected part may (thus) be transmitted at the light exit face to escape from the elongated collimator lens. In embodiments, (essentially) all of the device light may escape from the elongated collimator lens after at least one total internal reflection. In such embodiments, the reflected part (of the device light) may comprise > 60%, such as > 70%, especially > 80%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Additionally or alternatively, in such embodiments, the reflected part may comprise < 99%, such as < 98%, especially < 95%, of a radiant flux of the device light escaping from the elongated collimator lens. That is, the reflected part may comprise 60-99%, such as 70-98%, especially 80-95%, of a radiant flux of the device light escaping from the elongated collimator lens. Alternatively, as indicated above, the elongated collimator lens may be configured to provide the directly escaping part. In such embodiments, the reflected part (of the device light) may comprise > 10%, such as > 15%, especially > 20%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Additionally or alternatively, in such embodiments, the reflected part may comprise < 60%, such as < 50%, especially < 40%, of a radiant flux of the device light escaping from the elongated collimator lens. That is, the reflected part may comprise 10-60%, such as 15-50%, especially 20-40%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Hence, in specific embodiments, the reflected part may comprise 15-50% of a radiant flux of the device light escaping from the elongated collimator lens. A double reflected part of the device light may escape from the elongated collimator lens via the light exit face after a first total internal reflection at the second total internal reflection face and subsequently a second total internal reflection at the first total internal reflection face. That is, in embodiments, (at least) the double reflected part (of the device light) may be incident on the second total internal reflection face with a primary third light angle 03, i, wherein 03, i > 0C, and the (at least) double reflected part may (thus) be reflected at the second total internal reflection face. The reflected light comprising (at least) the double reflected part may next be incident on the first total internal reflection face with a secondary third light angle 03,2, wherein 03,2 > 0c, and wherein the reflected light comprising at least the double reflected part may (thus) be reflected again at the first total internal reflection face. Next, the double reflected light comprising (at least) the double reflected part may be incident on the light exit face with a tertiary third light angle 03,3, wherein 03,3 < 0c, and the double reflected part may (thus) be transmitted at the light exit face to escape from the elongated collimator lens. In embodiments, the double reflected part (of the device light) may comprise > 1%, such as > 2%, especially > 5%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Additionally or alternatively, the double reflected part may comprise < 40%, such as < 30%, especially < 25%, of a radiant flux of the device light escaping from the elongated collimator lens. That is, the double reflected part may comprise 1-40%, such as 2-30%, especially 5-25%, of a radiant flux of the device light escaping from the elongated collimator lens (via the light exit face, the first total internal reflection face, and the second total internal reflection face). Hence, in specific embodiments, the double reflected part may comprise 2-30% of a radiant flux of the device light escaping from the elongated collimator lens.

[0024] Hence, in specific embodiments, (essentially) all device light escaping from the elongated collimator lens may escape after at least one total internal reflection in the elongated collimator lens, wherein: (i) a reflected part may comprise 60-99%, such as 70- 98%, especially 80-95%, of a radiant flux of the device light escaping from the elongated collimator lens; and (ii) a double reflected part may comprise 1-40%, such as 2-30%, especially 5-25%, of a radiant flux of the device light escaping from the elongated collimator lens. In such embodiments, especially Wc < He (see also above) may apply. Alternatively, at least some of the device light may escape from the elongated collimator lens (via the light exit face) without internal reflection, wherein: (i) a directly escaping part may comprise 20- 80%, such as 25-70%, especially 30-60%, of a radiant flux of the device light escaping from the elongated collimator lens; (ii) a reflected part may comprise 10-60%, such as 15-50%, especially 20-40%, of a radiant flux of the device light escaping from the elongated collimator lens; and (iii) a double reflected part may comprise 1-40%, such as 2-30%, especially 5-25%, of a radiant flux of the device light escaping from the elongated collimator lens. In such embodiments, especially He < Wc (see also above) may apply.

[0025] The first total internal reflection face may have a second length L2 along the perimeter. In embodiments, L2 > 0.15*Lp, such as L2 > 0.25*Lp, especially L2 > 0.35*Lp. Further, in embodiments, (essentially) all of device light provided by a (virtual) elongated light generating device configured in the elongated cavity may escape from the elongated collimator lens after at least one total internal reflection. In such embodiments, L2 < 0.9*Lp, such as L2 < 0.8*Lp, especially L2 < 0.7*Lp. Hence, in embodiments, 0.15*Lp< L2 < 0.9*Lp, such as 0.25*Lp< L2 < 0.8*Lp, especially 0.35*Lp< L2 < 0.7*Lp. Alternatively, at least part of said device light may escape from the elongated collimator lens (via the light exit face) as the directly escaping part, i.e., without internal reflection. In such embodiments, L2 < 0.6*Lp, such as L2 < 0.5*Lp, especially L2 < 0.4*Lp. Hence, in such embodiments, 0.15*Lp< L2 < 0.6*Lp, such as 0.25*Lp< L2 < 0.5*Lp, especially 0.35*Lp< L2 < 0.4*Lp. The first total internal reflection face may at least partially span across the collimator height He. Especially, the first total internal reflection face may span over at least 0.4*Hc, such as over at least 0.5*Hc, especially over at least 0.75*Hc, including (essentially) He. Further, the first total internal reflection face may span over at least 0.4*Wc, such as over at least 0.5*Wc, especially over at least 0.6*Wc. Hence, in embodiments, the first total internal reflection face may comprise one or more slanted faces.

[0026] The first total internal reflection face may comprise a primary first face and a secondary first face, wherein the primary first face and the secondary first face may be configured physically separated and on opposite sides of (the cross-sectional view of) the elongated collimator lens. In embodiments, the primary first face may have a primary second length L2,I, and the secondary first face may have a secondary second length L2,2, wherein L2,I and L2.2 may be individually selected from the range of 0.4*L2 - 0.6*L2, such as from the range of 0.45*L2 - 0.55*L2, especially from the range of 0.48*L2 - 0.52*L2, and wherein L2,I + L2,2 = L2. Further, the primary first face may be configured in physical contact with the light exit face at a first end of the light exit face, and the secondary first face may be configured in physical contact with the light exit face at a second (opposite) end of the light exit face. In embodiments, the primary (and / or secondary) first face may be configured at a sharp angle with respect to the light exit face at the point of physical contact. Alternatively, the primary (and / or secondary) first face may transition into the light exit face, wherein the primary (and / or secondary) first face and the light exit face may (gradually) curve towards each other at the point of physical contact. In such embodiments, the point where the derivative of the curve may be (essentially) zero indicates the transition from the light exit face to the first total internal reflection face, and thus the point of physical contact.

[0027] In embodiments, a continuous subsection of the light exit face may be configured at a (smallest) second mutual angle at2 with a continuous subsection of the first total internal reflection face. The continuous subsection of the light exit face may have length

[0028] > 0.2*Li, such as length > 0.25*Li, especially length > 0.3*Li. Further, the continuous subsection of the light exit face may be located closer towards an end of the light exit face than a center (or mid-point) of the light exit face. The continuous subsection of the first total internal reflection face may have length > 0.35*L2, such as length > 0.4*L2, especially length

[0029] > 0.45 *L2. In embodiments, one (or more) of the primary first face and the secondary first face may comprise the continuous subsection (of the first total internal reflection face). Further, the second mutual angle a.f2 may be selected from the range of > 20°, such as from the range of > 30°, especially from the range of > 40°. Additionally or alternatively, the second mutual angle a.f2 may be selected from the range of < 80°, such as from the range of < 70°, especially from the range of < 60°. Further, in embodiments, 20° < at2 < 80°, such as 30°

[0030] < at2 < 70°, especially 40° < at2 < 60°. Hence, in specific embodiments, a continuous subsection of the light exit face with length > 0.25 *Li may be configured at a second mutual angle at2 with a continuous subsection of the first total internal reflection face with length > 0.4*L2; wherein 30° < ai2 < 70°. Such an angle between (continuous subsections of) the light exit face and the first total internal reflection face may facilitate that (device) light incident on the first total internal reflection face with an angle of > 9Cmay be reflected towards the light exit face, wherein the light may be incident on the light exit face with an angle of < 0C.

[0031] Turning to the second total internal reflection face, the second total internal reflection face may have a third length L3 along the perimeter. In embodiments, L3 > 0.03*Lp, such as L3 > 0.05*Lp, especially L3 > 0.1*Lp. Additionally or alternatively, in embodiments, L3 < 0.25*Lp, such as L3 < 0.2*Lp, especially L3 < 0.15*Lp. Further, in embodiments, 0.03*Lpf L3 < 0.25*Lp, such as 0.05*Lpf L3 < 0.2*Lp, especially 0.1*Lp< Ls

[0032] < 0.15*LP. In embodiments, Li + L2 + L3 > 0.95 *LP, such as especially Li + L2 + L3 = Lp. Hence, in specific embodiments, the elongated collimator lens may have a cross-sectional perimeter, wherein the cross-sectional perimeter may be at least defined by the light exit face, the first total internal reflection face, and the second total internal reflection face; wherein the perimeter may have a perimeter length (Lp); wherein: (A) the light exit face may have a first length Li along the perimeter, wherein 0.1 *LP< Li < 0.6*Lp; (B) the first total internal reflection face may have a second length L2 along the perimeter, wherein 0.25 *LP< L2 < 0.8*Lp; and (C) the second total internal reflection face may have a third length L3 along the perimeter, wherein 0.05*Lp< L3 < 0.2*Lp. A light exit face having a length of > 0.3*Lpmay facilitate that (most of) the light reflected at the first total internal reflection face may be incident on the light exit face, especially with an angle of < 0C. Further, an elongated collimator lens wherein L3 < L2 may facilitate that (most of) the light reflected at the second total internal reflection face may be incident on the first total internal reflection face. In embodiments, at least part of device light provided by a (virtual) elongated light generating device configured in the elongated cavity may escape from the elongated collimator lens as the directly escaping part, i.e., without internal reflection. In such embodiments, especially the first length Li may be relatively larger, and the second length L2 may be relatively shorter. Hence, in specific embodiments, the elongated collimator lens may have a cross- sectional perimeter, wherein the cross-sectional perimeter may be at least defined by the light exit face, the first total internal reflection face, and the second total internal reflection face; wherein the perimeter may have a perimeter length (Lp); wherein: (A) the light exit face may have a first length Li along the perimeter, wherein 0.3 *LP< Li < 0.6*Lp; (B) the first total internal reflection face may have a second length L2 along the perimeter, wherein 0.25 *LP< L2 < 0.5*Lp; and (C) the second total internal reflection face may have a third length L3 along the perimeter, wherein 0.05*Lp< L3 < 0.2*Lp.

[0033] The second total internal reflection face may at least partially span across the collimator height He, such as over at least 0.1 *Hc, especially over at least 0.2*Hc. Yet, the second total internal reflection face may span over at most 0.5*Hc, such as over at most 0.4*Hc, especially over at most 0.3 *Hc. Further, the second total internal reflection face may span over a distance selected from the range of 0.05 *Wc - 0.45 *Wc, such as the range of 0.1*Wc - 0.4*Wc, especially the range of 0.15*Wc - 0.35*Wc. Hence, in embodiments, the second total internal reflection face may comprise one or more slanted faces. Especially, the second total internal reflection face may comprise a primary second face and a secondary second face, wherein the primary second face and the secondary second face may be configured at an angle with respect to each other over at least 80%, such as at least 90%, of a length of the primary second face and the secondary second face. In embodiments, the cavity may be a closed cavity, and the primary second face may be configured in physical contact with the secondary second face. Alternatively, the cavity may be an open cavity, and the primary second face may be configured physically separated from the secondary second face. Further, the primary second face may have a primary third length Lsj, and the secondary second face may have a secondary third length Ls,2, wherein Ls,i and 1 / 3,2 may be individually selected from the range of 0.4*L3 - 0.6*L3, such as from the range of 0.45*L3 - 0.55*1 / ?, especially from the range of 0.48*1 3 - 0.52*1 / 3, and wherein I / ?,i + 1 / 3,2 = 1 / 3. Further, the primary second face may be configured in physical contact with the primary first face, and the secondary second face may be configured in physical contact with the secondary second face. In embodiments, the primary (and / or secondary) second face may be configured at a sharp angle with respect to the respective primary (and / or secondary) first face at the point of physical contact. Alternatively, the primary (and / or secondary) second face may transition into the respective primary (and / or secondary) first face, wherein the primary (and / or secondary) second face and the respective primary (and / or secondary) first face may (gradually) curve towards each other at the point of physical contact. In such embodiments, the point where the derivative of the curve may be (essentially) zero indicates the transition from the primary (and / or secondary) second face to the respective primary (and / or secondary) first face, and thus the point of physical contact.

[0034] In embodiments, a continuous subsection of the first total internal reflection face may be configured at a (smallest) first mutual angle an with a continuous subsection of the second total internal reflection face. The continuous subsection of the first total internal reflection face may have length > 0.35*L2, such as length > 0.4*L2, especially length > 0.45 *L2. In embodiments, one (or more) of the primary first face and the secondary first face may comprise the continuous subsection (of the first total internal reflection face). Further, the continuous subsection of the second total internal reflection face may have length > 0.35*1 / 3, such as length > 0.4*1 / 3, especially length > 0.45*1 / 3. In embodiments, one (or more) of the primary second face and the secondary second face may comprise the continuous subsection (of the second total internal reflection face). In embodiments, the first mutual angle an may be selected from the range of > 80°, such as from the range of > 90°, especially from the range of > 100°. Additionally or alternatively, the first mutual angle an may be selected from the range of < 130°, such as from the range of < 120°, especially from the range of < 110°. Further, in embodiments, 80° < an < 130°, such as 90° < an < 120°, especially 100° < an < 110°. Hence, in specific embodiments, a continuous subsection of the first total internal reflection face with length > 0.4*L2 may be configured at a first mutual angle an with a continuous subsection of the second total internal reflection face with length > 0.4*1 / 3; wherein 90° < an < 120°. Such an angle between (continuous subsections of) the first total internal reflection face and the second total internal reflection face may facilitate that (device) light incident on the second total internal reflection face with an angle of > 0Cmay be reflected towards the first total internal reflection face, wherein the light may again be incident on the first total internal reflection face with an angle of > 0C.

[0035] The elongated collimator lens may be symmetrical (in a cross-sectional view perpendicular to the axis of elongation (Ai)). Especially, the elongated collimator lens may have bilateral (or reflection) symmetry. Hence, the elongated collimator lens may comprise a plane of symmetry Ps. The plane of symmetry Psmay especially be (configured) parallel to the axis of elongation (Ai) (and the collimator height He), and intersecting at least the light exit face. In embodiments wherein the cavity is a closed cavity, the plane of symmetry Psmay further intersect the second total internal reflection face. Hence, in specific embodiments, the elongated collimator lens may comprise a plane of symmetry Ps, wherein the plane of symmetry Psmay be parallel to the axis of elongation (Ai) and intersecting at least the light exit face. An elongated collimator lens having a plane of symmetry Psmay facilitate providing a symmetrical beam of (device) light. Further, a symmetrical elongated collimator lens may be more decorative. The plane of symmetry Psmay intersect the light exit face, wherein half of the light exit face is located on one side of the plane of symmetry Ps, and half of the light exit face is located on the other side of the plane of symmetry Ps. Further, the primary first face and primary second face may be located on one side of the plane of symmetry Ps(and have the first mutual angle an), while the secondary first face and the secondary second face may be located on the other side of the plane of symmetry Ps(and have the first mutual angle an).

[0036] As indicated above, the light exit face may have a first length Li along the perimeter. Note that effectively the light exit face may also comprise of a primary part and a secondary part. These may be configured on opposite sides of (the cross-sectional view of) the elongated collimator lens, but may essentially not be configured physically separated (but form a continuous length).

[0037] In embodiments, the primary light exit face may have a primary first length Li,i, and the secondary light exit face may have a secondary first length LI,2, wherein Li,i and LI,2 may be individually selected from the range of 0.4*Li - 0.6*Li, such as from the range of 0.45*Li - 0.55*Li, especially from the range of 0.48*L2 - 0.52*Li, and wherein Li,i + LI,2 = Li.

[0038] Hence, in embodiments the primary light exit face and the secondary light exit face may be configured mirror-symmetric relative to the plane of symmetry Ps. In embodiments the primary first face and the secondary first face may be configured mirror- symmetric relative to the plane of symmetry Ps. Yet, in embodiments the primary second face and the secondary second face may be configured mirror-symmetric relative to the plane of symmetry Ps.

[0039] Further, the elongated collimator lens may comprise a center plane Pcparallel to the axis of elongation (Ai) (and the collimator height He) and intersecting at least the light exit face. In specific embodiments, the center plane Pcmay be the plane of symmetry Ps, such as define the plane of symmetry Ps. Hence, in specific embodiments, the center plane Pcmay define a plane of symmetry Psof the elongated collimator lens. Alternatively, the elongated collimator lens may be asymmetrical, and the center plane Pcmay not be a plane of symmetry Ps. Hence, in embodiments, the elongated cavity may be symmetrical or asymmetrical. Further, the elongated cavity may comprise a cavity wall. In embodiments, (the elongated collimator lens may be configured to provide the directly escaping part of (device) light, wherein) on each side of the center plane Pc, the cavity wall may comprise a cavity wall first section, a cavity wall second section, and a cavity wall third section. The cavity wall first section may especially be configured over a first angle ai with respect to the axis of elongation (Ai) (in a cross-sectional view perpendicular to the axis of elongation (Ai)). That is, a first line connecting a first end point of the cavity wall first section to the axis of elongation (Ai) may be configured at a first angle ai with a second line connecting a second end point of the cavity wall first section to the axis of elongation (Ai). In embodiments, ai > 2°, such as ai > 5°, especially ai > 10°. Additionally or alternatively, in embodiments, ai < 100°, such as ai < 90°, especially ai < 80°. Hence, in embodiments, 2° < ai < 100°, such as 5° < ai < 90°, especially 10° < ai < 80°. Further, the cavity wall first section may be configured to receive at least the directly escaping part (of the device light). Hence, in embodiments, the light exit face may be configured in a light receiving relationship with the cavity wall first section.

[0040] The cavity wall second section may be configured over a second angle 012 with respect to the axis of elongation (Ai) (in a cross-sectional view perpendicular to the axis of elongation (Ai)). In embodiments, a.2 > 30°, such as a.2 > 50°, especially a.2 > 70°. Additionally or alternatively, in embodiments, a.2 < 180°, such as a.2 < 160°, especially a.2 < 140°. Hence, in embodiments, 30° < 012 < 180°, such as 50° < 012 < 160°, especially 70° < 012 < 140°. Further, the cavity wall second section may be configured to receive at least the reflected part (of the device light). Hence, in embodiments, the first total internal reflection face may be configured in a light receiving relationship with the cavity wall second section. The cavity wall third section may be configured over a third angle as with respect to the axis of elongation (Ai) (in a cross-sectional view perpendicular to the axis of elongation (Ai)). In embodiments, as > 5°, such as as > 10°, especially as > 20°. Additionally or alternatively, in embodiments, as < 70°, such as as < 60°, especially as < 50°. Hence, in embodiments, 5° < as < 70°, such as 10° < as < 60°, especially 20° < as < 50°. Further, in embodiments, 120° < ai+a2+as < 180°, such as 140° < ai+a2+as < 180°, especially 160° < ai+a2+as < 180°. In embodiments, the cavity wall third section may be configured to receive at least the double reflected part (of the device light). Hence, the second total internal reflection face may be configured in a light receiving relationship with the cavity wall third section. Hence, in specific embodiments, the elongated collimator lens may comprise a center plane Pcparallel to the axis of elongation (Ai) and intersecting at least the light exit face; and the elongated cavity may comprise a cavity wall; wherein on each side of the center plane Pcthe cavity wall may comprise a cavity wall first section, a cavity wall second section, and a cavity wall third section, wherein: (A) the cavity wall first section may be configured over a first angle ai with respect to the axis of elongation (Ai); wherein 5° < ai < 90°; wherein the cavity wall first section may be configured to receive at least the directly escaping part; (B) the cavity wall second section may be configured over a second angle a2 with respect to the axis of elongation (Ai); wherein 50° < a.2 < 160°; wherein the cavity wall second section may be configured to receive at least the reflected part; (C) the cavity wall third section may be configured over a third angle as with respect to the axis of elongation (Ai); wherein 10° < as < 60°; wherein the cavity wall third section may be configured to receive at least the double reflected part; and (D) 140° < ai+a2+as < 180°. A cavity wall comprising cavity wall first sections, cavity wall second sections, and cavity wall third sections (spanning the angles ai, a2, and as, respectively) may facilitate refracting (and / or guiding) the incident device light towards respectively the light exit face, the first total internal reflection face, and the second total internal reflection face.

[0041] The cavity wall first section may be planar or curved. Further, the cavity wall second section may be planar or curved. Similarly, the cavity wall third section may be planar or curved. The term “planar” may indicate that along the length L of a wall section, the wall section may deviate from a straight line by < 0.05*L, such as by < 0.03*L, especially by < 0.02*L. Further, the term “curved” may indicate that along the length L of a wall section, the wall section may deviate from a straight line by > 0.05 *L, such as by > 0.07*L, especially by > 0.1 *L. In embodiments wherein one or more of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be curved, said cavity wall section may especially be convex. That is, the end points of said cavity wall section may be located further away from the axis of elongation (Ai) than a mid-point of said cavity wall section. Alternatively, one or more of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be concave. Yet, especially, at least one of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be convex. Additionally or alternatively, at least one of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be planar. Hence, in specific embodiments, in a cross-sectional view perpendicular to the axis of elongation (Ai) one or more of the following may apply: (a) at least one of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be planar; and (b) at least one of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be convex. A convex cavity wall section may better refract the incident (device) light towards the desired (light exit, first total internal reflection, and / or second total internal reflection) face on the perimeter of the elongated collimator lens, thereby improving efficiency of the elongated collimator lens. Alternatively, a planar cavity wall section may be relatively easier to produce. In specific embodiments, all of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be planar. Alternatively, in specific embodiments, all of the cavity wall first section, the cavity wall second section, and the cavity wall third section may be convex. Further, in embodiments, the elongated cavity may be closed at one or both ends of the elongated collimator lens. Yet, especially, the elongated cavity may be open on both ends of the elongated collimator lens, i.e., the elongated cavity may be a through opening along the collimator length Lc.

[0042] The elongated collimator lens may comprise one or more (elongated) prismatic structures, especially (configured) on the light exit face. In embodiments, the one or more (elongated) prismatic structures may be configured to collimate the device light in a plane parallel to the axis of elongation (Ai) and the collimator height He. In embodiment, the one or more (elongated) prismatic structures may have a largest dimension prism length Lpr. Further, in a cross-section perpendicular to the prism length Lpr, the one or more (elongated) prismatic structures may have a regular polygonal shape, such as especially a triangular shape. The triangular shape may be selected from the group comprising an equilateral triangular shape, an isosceles triangular shape, a scalene triangular shape, an acute triangular shape, an obtuse triangular shape, and a right triangular shape. Further, a base of the triangular shape may be configured in physical contact with the light exit face, wherein a point of the triangular shape may be configured pointing away from the light exit face. Hence, the (triangular shape of the) one or more (elongated) prismatic structures may comprise (at least) one contact face configured in physical contact with the light exit face, and (at least) two protruding faces configured extending away from the light exit face. The (at least) two protruding faces may be configured at a mutual angle aprwith respect to each other. In embodiments, the mutual angle aprmay be selected from the range of 70-110°, such as from the range of 80-100°, especially from the range of 85-95°. Further, the one or more (elongated) prismatic structures may have a prism width Wprin a cross-section perpendicular to the prism length Lpr. Especially, the contact face may define the prism width Wpr. In embodiments, the prism width Wprmay be selected from the range of > 0.03 mm, such as from the range of > 0.05 mm, especially from the range of > 0.08 mm. Additionally or alternatively, the prism width Wprmay be selected from the range of < 6 mm, such as from the range of < 5 mm, especially from the range of < 4 mm. Hence, the one or more (elongated) prismatic structures may have a prism width Wprselected from the range of 0.03- 6 mm, such as from the range of 0.05-5 mm, especially from the range of 0.08-4 mm.

[0043] As indicated above, the one or more prismatic structures may be configured to collimate the device light in a plane parallel to the axis of elongation (Ai) and the collimator height He. That is, the one or more prismatic structures may be configured to collimate device light in a length direction of the elongated collimator lens. Especially, device light emitted from the light generating device and diverging in a length direction of the elongated collimator lens (i.e., having a vector parallel to the axis of elongating (Ai)) may be incident on the light exit face with an angle < 0C, and incident on the one or more prismatic structures with an angle > 0C, wherein said device light may be reflected (through total internal reflection) at the one or more prismatic structures. The thus reflected light may be reflected again by one or more of the cavity wall, the perimeter (of the elongated collimator lens), the light generating device (comprising e.g. a reflective carrier), and a housing (see below), after which the twice-reflected light may propagate towards the one or more prismatic structures with a smaller (or no) vector parallel to the axis of elongation (Ai). Said twice-reflected light may then be incident on the one or more prismatic structures with an angle < 0C, wherein the twice-reflected light may be transmitted through the one or more prismatic structures as (part of) a collimated beam. In embodiments, the cycle of reflection at the one or more prismatic structures and reflection at one or more of the cavity wall, the light generating device, and a housing may be repeated a plurality of times before the (diverging part of the) device light is transmitted through the one or more prismatic structures. The prism length Lprmay be configured (essentially) parallel to the collimator length Lc. In such embodiments, the prism length Lprmay (for each prismatic structure individually) be selected from the range of > 0.8*Lc, such as from the range of > 0.9*Lc, especially from the range of > 0.95*Lc, including (essentially) Lc. Alternatively, the prism length Lprmay be configured (essentially) parallel to the collimator width Wc (and on the light exit face). In such embodiments, the prism length Lprmay (for each prismatic structure individually) be selected from the range of > 0.8*Wc, such as from the range of > 0.9*Wc, especially from the range of > 0.95*Wc, including (essentially) Wc. Especially, in such embodiments, the prism length Lprmay (for each prismatic structure individually) be selected from the range of > 0.8*Li, such as from the range of > 0.9* Li, especially from the range of > 0.95* Li, including (essentially) Li. In embodiments wherein the prism length Lpris configured (essentially) parallel to the collimator width Wc, collimation in the length direction may further be facilitated by refraction of (diverging) device light at the one or more prismatic structures. Further, the elongated collimator lens may comprise a plurality of (elongated) prismatic structures. The plurality of (elongated) prismatic structures may be configured in physical contact (with each other) on the light exit face. Especially, at least one edge of the contact face of a first (elongated) prismatic structure may be configured in physical contact with an edge of a contact face of at least one adjacent (elongated) prismatic structure. Further, the plurality of (elongated) prismatic structures may (cover and / or) be configured over at least 80%, such as at least 90%, especially at least 95%, including (essentially) 100% of a surface area of the light exit face (defined by Lc*Li). Hence, in specific embodiments, the elongated collimator lens may comprise one or more prismatic structures on the light exit face; wherein the one or more prismatic structures may be configured to collimate the device light in a plane parallel to the axis of elongation (Ai) and the collimator height He. Such (a) prismatic structure(s) may facilitate collimating a beam of light in two directions, thereby providing a more focused beam of light. Hence, an elongated collimator lens comprising one or more prismatic structures may be suitable for luminaires comprising a relatively small light escape surface, or for applications requiring higher intensity light in smaller spot sizes.

[0044] The elongated light generating device that is configured in the elongated cavity (of the elongated collimator lens) is configured to generate a first beam of device light. The first beam of device light has a non-zero light intensity over the entire (angular) range of 30-150° around the axis of elongation (Ai). Further, the first beam of device light has a nonzero light intensity over the entire (angular) range of 210-330° around the axis of elongation (Ai). A reflected part of the device light may escape from the elongated collimator lens via the light exit face after a single total internal reflection at the first total internal reflection face. Further, a double reflected part of the device light may escape from the elongated collimator lens via the light exit face after a first total internal reflection at the second total internal reflection face and subsequently a second total internal reflection at the first total internal reflection face.

[0045] The light generating system may be configured to generate a second beam of system light having a second beam angle otb2, defined by a full width half maximum of the second beam in a plane perpendicular to the axis of elongation (Ai). In embodiments, the second beam angle ab2 may be selected from the range of < 100°.

[0046] Hence, in specific embodiments, the invention provides a light generating system comprising the elongated collimator lens as defined herein and an elongated light generating device, wherein: (A) the elongated collimator lens is configured in a light receiving relationship with the elongated light generating device; (B) the elongated light generating device is configured in the elongated cavity, wherein the elongated light generating device is configured to generate a first beam of device light with a non-zero light intensity over the entire range of 30-150° and 210-330° around the axis of elongation (Ai); (C) (i) a reflected part of the device light escapes from the elongated collimator lens via the light exit face after a single total internal reflection at the first total internal reflection face, and (ii) a double reflected part of the device light escapes from the elongated collimator lens via the light exit face after a first total internal reflection at the second total internal reflection face and subsequently a second total internal reflection at the first total internal reflection face; and (D) the light generating system is configured to generate a second beam of system light having a second beam angle ab2, defined by a full width half maximum of the second beam in a plane perpendicular to the axis of elongation (Ai); wherein the second beam angle ab2 is selected from the range of < 100°.

[0047] Such a light generating system may facilitate providing a relatively narrow beam of system light using a light generating device (with a relatively high efficiency) providing device light over a combined angular range of > 240° around the axis of elongation (Ai). Hence, especially, such a light generating system may be more energy-efficient than a light generating system comprising a light generating device providing a narrow beam of system light. Further, the light generating system of the present invention may facilitate adjusting the beam shape and beam angle of the system light by altering the location of the light generating device within the elongated cavity. The light generating system comprises an elongated light generating device (“light generating device”). The elongated light generating device may comprise an optical fiber. Alternatively, the elongated light generating device may comprise one or more (solid state) light sources, especially configured on an elongated carrier. The light generating device may be any (elongated) light generating device (having a non-zero light intensity over the entire range of 30-150° and 210-330°) known in the art. The elongated light generating device may be an elongated light generating device providing an omnidirectional light distribution (see above). Especially, the elongated light generating device may be an elongated light generating device (providing device light) at least approximating an omnidirectional light distribution. Hence, the elongated light generating device may at least provide a light distribution having a non-zero light intensity in all four quadrants (each spanning 90°) around the axis of elongation (Ai), wherein for at least two opposite quadrants may apply that the light distribution may have a non-zero light intensity over the entire (range of the) quadrant. Especially, the elongated light generating device may provide device light having a non-zero light intensity over the entire range of 30-150° and 210-330° (see also below), wherein the range of 45-135° indicates a first quadrant, and the range of 225-315° indicates a second opposite quadrant in which the device light has a non-zero light intensity. In specific embodiments, the elongated light generating device may comprise a LED filament. A LED filament may be especially energy-efficient.

[0048] LED filaments as such are known, and are e.g. described in US 8,400,051 B2, W02020016058, WO2019197394, etc., which are hereby herein incorporated by reference. In general, a LED filament may comprise (i) a plurality of light emitting diodes (LEDs), arranged on (at least a first major surface of) an elongated carrier, and (ii) an elongated encapsulant covering (and / or at least partially enclosing) the plurality of LEDs and at least part of the elongated carrier. In embodiments, the LED filament may be straight. Alternatively, the LED filament may be curved. For instance, the filament may have a (2D or 3D) spiraling shape, (like) a helical shape. The LED filament may in embodiments be defined by a filament length LF, a filament width WF, and a filament thickness TF. The LED filament may have relatively high aspect ratios (LF / WF or LF / TF), such as > 10, especially > 15, such as > 20. Large aspect ratios may better mimic a filament. Yet, in embodiments, the aspect ratio (LF / WF and / or LF / TF) may be < 900, such as < 650, especially < 500. Hence, in specific embodiments, 10*WF < LF < 900*WF, and 10*TF < LF < 900*TF.

[0049] As indicated, the LED filament may comprise an elongated carrier, solid state light sources, and an encapsulant. Especially, the elongated carrier may support the solid state light sources. The elongated carrier may e.g. comprise glass, quartz, metal, or sapphire. In other embodiments, the elongated carrier may e.g. comprise a polymeric material or (flexible) metal, e.g., a film or foil. The elongated carrier may be rigid (self-supporting), but may (in polymeric embodiments) also be flexible. In embodiments, the elongated carrier may be light transmissive, translucent, or transparent for light, especially visible light. Alternatively, in embodiments, the carrier may be light reflective, especially reflective for one or more of the light source light (see below) and the device light, such as reflective for at least the light source light and the device light. In specific embodiments, the carrier may be diffuse reflective. The carrier may especially be configured to reflect at least 80%, such as at least 90%, especially at least 95%, including (essentially) 100% of the (visible) light received by the carrier. The (elongated) carrier may comprise a first major surface at a first side of the carrier and a second major surface at a second side of the carrier, opposite to the first side. In embodiments, the solid state light sources may be arranged on at least one of these surfaces. Hence, at least part of, such as all of, the solid state light sources may be mounted onto the first major surface. Additionally or alternatively, at least part of the solid state light sources may be mounted onto the second major surface. Hence, the solid state light sources may be arranged, mounted and / or mechanically coupled on / to the carrier, wherein the carrier may especially be configured to mechanically and / or electrically support the LEDs.

[0050] In embodiments, the solid state light sources may comprise LEDs. Alternatively or additionally, the solid state light sources may comprise diode lasers. Further, the LED filament may comprise one or more of LEDs, laser diodes, superluminescent diodes, and multi -junction light emitting diodes. Especially, the LED filament comprises a plurality of LEDs. The (plurality of) solid state light sources may be arranged in an array (on the elongated carrier), especially over (at least part of) the filament length LF. The number of solid state light sources in the array may be > 4, such as > 8, even more especially > 12. Especially, the number of solid state light sources in the array may be selected from the range of 10-2000, such as from the range of 10-1500, especially from the range of 10-1000. In embodiments, the solid state light sources may be configured in a ID (linear) array over at least part of the filament length LF. Further, in embodiments, the solid state light sources may be configured in two ID arrays, one on the first major surface of the elongated carrier and one on the second major surface. A 2D array of solid state light sources of n*m LEDs may also be possible. In embodiments, n may be selected from the range of 1-4, such as 1-3, like 1-2, such as in embodiments 1 or in embodiments 2, and m may be selected from the range of larger than n, such as especially selected from the range of > 4 (when n<4), like > 6, such as > 8. Hence, a 2D array of solid state light sources may especially have a (much) smaller number of rows (n) than the number of solid state light sources in those respective rows (m), such as n / m <0.2, like n / m <0.1, especially n / m <0.05. In embodiments, the plurality of solid state light sources may be configured on (only) the first major surface of the carrier, wherein the first major surface may be configured facing the light exit face (and wherein the second major surface may be configured facing the second total internal reflection face). In such embodiments, the carrier may especially be light transparent. Alternatively, the plurality of solid state light sources may be configured on the first major surface and the second major surface of the carrier, wherein one of the first major surface and second major surface may be configured facing the light exit face (and wherein the other of the first major surface and the second major surface may be configured facing the second total internal reflection face). In such embodiments, the carrier may be light transmissive or light reflective. Especially, in embodiments, an optical axis of light source light generated by the plurality of solid state light sources (see below) may be configured parallel to the center plane Pc.

[0051] In embodiments, the LED filament may comprise an encapsulant. The encapsulant may especially (at least partly) enclose the plurality of solid state light sources. Further, the encapsulant may cover at least part of the elongated carrier, such as at least (part of) one of the first major and second major surfaces. In general, the encapsulant may be in contact with the elongated carrier and may enclose all of the solid state light sources. The encapsulant may be a continuous coating along the filament length LF, at one or both of the first major and the second major surface. Further, the encapsulant may at least partly cover (and / or enclose) the solid state light sources, such as at least 50% of the total number of solid state light sources in the array, such as > 75%, especially > 95%, up to 100%. The encapsulant may comprise one or more of a luminescent material and a light scattering material. The one or more of the luminescent material and the light scattering material may be configured embedded in an encapsulant material, e.g. a (flexible) polymer material (such as a silicone). In embodiments, the luminescent material may be configured to convert at least part, such as all, of the light source light (generated by the solid state light sources) into luminescent material light. In specific embodiments, the luminescent material may comprise a phosphor such as an inorganic phosphor and / or quantum dots or rods. Further, the light scattering material may be configured to scatter (or “diffuse”) the light source light, especially in a direction transverse to a normal of the (first and / or second) major surface. In embodiments, the light scattering material may comprise light scattering particles, such as e.g. at least one of BaSCU, A12O3 and TiCE particles. In embodiments, the LED filament may be configured to generate filament light. In embodiments, the device light may comprise the filament light, such as (essentially) consist of the filament light. Further, the solid state light sources may be configured to generate light source light. In embodiments, at least two, such as all, of the solid state light sources may be configured to emit light source light having different spectral power distributions. In other embodiments, at least two, such as all, of the solid state light sources may be configured to provide light source light having essentially the same spectral power distribution. In embodiments, the filament light may comprise the light source light, or may essentially consist of (scattered) light source light. However, in embodiments wherein the encapsulant may comprise a luminescent material, the filament light may comprise luminescent material light, or may essentially consist of luminescent material light. Further, the filament light may comprise luminescent material light and at least part of the (nonconverted and / or scattered) light source light. In embodiments, the LED filament may provide filament light with a desired spectral light distribution, e.g., white light having a correlated color temperature (CCT) selected from the range of 1500-3000 K. In such embodiments, the filament light may comprise luminescent material light and optionally transmitted light source light. Further, the filament light may at least comprise light at a wavelength selected from the range of 380-780 nm, i.e., visible light. In embodiments, the filament light may comprise white light. The term “white light”, and similar terms, is known to the person skilled in the art. It may especially relate to light having a CCT between 1800 K and 20000 K, such as between 2000 K and 20000 K, especially between 2700 K and 20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700-6500 K. The CCT may especially be within 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within 10 SDCM from the BBL, such as within 5 SDCM from the BBL. Especially, the filament light may be relatively warm (white) light, such as selected from the range of 1500 - 3000 K, especially selected from 1500 - 2700 K, most especially selected from the range of 1800-2700 K. Hence, the device light may be white light.

[0052] Alternatively, the filament light may be colored light, such as one or more of violet light, blue light, green light, yellow light, orange light, and red light. The term “violet light”, and similar terms, may especially relate to light having a wavelength in the range of about 380-440 nm. The term “blue light”, and similar terms, may especially relate to light having a wavelength in the range of about 440-490 nm. The term “green light”, and similar terms, may especially relate to light having a wavelength in the range of about 490-560 nm. The term “yellow light”, and similar terms, may especially relate to light having a wavelength in the range of about 560-590 nm. The term “orange light”, and similar terms, may especially relate to light having a wavelength in the range of about 590-620 nm. The term “red light”, and similar terms, may especially relate to light having a wavelength in the range of about 620-780 nm. Hence, the device light may be colored light.

[0053] In embodiments, the LED filament may comprise multiple sub-filaments.

[0054] Further, the elongated light generating device may comprise a plurality of LED filaments. In such embodiments, at least two, such as all, of the LED filaments may be configured to emit filament light having different spectral power distributions. Alternatively or additionally, at least two, such as all, of the LED filaments may be configured to provide filament light having essentially the same spectral power distribution. The (plurality of) LED filaments may be configured in an array, such as an n*m array, wherein n and m are as described above. In embodiments, the array of LED filaments may be elongated, such as especially elongated in a direction of the axis of elongation (Ai). Hence, in specific embodiments, the elongated light generating device may comprise an elongated array of LED filaments. An array of (individually controllable) LED filaments may facilitate adjusting the intensity of the system light. Further, at least two of the LED filaments may provide filament light having different spectral power distributions. In such embodiments, the array of (individually controllable) LED filaments may further facilitate adjusting the color point, CCT, and / or color rendering index of the system light. Further, such an array may provide decorative lighting effects.

[0055] The elongated light generating device may be configured in the elongated cavity of the elongated collimator lens. In specific embodiments, the elongated light generating device may be configured in a geometrical center of the cavity. Such a configuration may facilitate distributing the device light evenly over the cavity wall. Alternatively, the elongated light generating device may be configured at an offset distance d? with respect to a geometrical center of the elongated cavity. That is, a distance between the geometrical center of the elongated cavity and a geometrical center of the elongated light generating device may be the offset distance d2. In embodiments, d2 > 0.3 mm, such as d2 > 0.5 mm, especially d2 > 0.7 mm. Additionally or alternatively, in embodiments, d2 < 4 mm, such as d2 < 3 mm, especially d2 < 2 mm. Further, in embodiments, 0.3 mm < d2 < 4 mm, such as 0.5 mm < d2 < 3 mm, especially 0.7 mm < d2 < 2 mm. Hence, in specific embodiments, the elongated light generating device may be configured at an offset distance d2 with respect to a geometrical center of the elongated cavity; wherein 0.5 mm < d2 < 3 mm. Configuring the elongated light generating device at an offset from the geometrical center of the elongated cavity may facilitate adjusting the angles with which the device light is incident on (the cavity wall, and) the first and second total internal reflection faces, thereby facilitating adjusting the shape and FWHM of the second beam.

[0056] The elongated light generating device (configured in the elongated cavity) may have a first diameter Di in a cross-sectional view perpendicular to the axis of elongation (Ai). The first diameter Di may especially be an equivalent circular diameter of the elongated light generating device. 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 first diameter Di may be selected from the range of > 0.5 mm, such as from the range of > 0.7 mm, especially from the range of > 1 mm. Additionally or alternatively, the first diameter Di may be selected from the range of < 5 mm, such as from the range of < 4 mm, especially from the range of < 3 mm.

[0057] Further, as indicated above, the elongated collimator lens may have a collimator width Wc and a collimator height He in a cross-sectional view perpendicular to the axis of elongation (Ai). The collimator width Wc may be selected from the ranges provided above. Further, in embodiments, Wc / Di > 3, such as Wc / Di > 5, especially Wc / Di > 10. Additionally or alternatively, in embodiments, Wc / Di < 60, such as Wc / Di < 50, especially Wc / Di < 30. Hence, in embodiments, 3 < Wc / Di < 60, such as 5 < Wc / Di < 50, especially 10 < Wc / Di < 30. Further, as indicated above, in embodiments Wc < 0.8*Hc, such as Wc < 0.6*Hc, especially Wc < 0.5*Hc. Alternatively, a directly escaping part of the device light may escape from the elongated collimator lens (via the light exit face) without internal reflection. In such embodiments, He < 0.8*Wc, such as He < 0.6*Wc, especially He < 0.5*Wc. Further yet, the elongated collimator lens may have a collimator length Lc along the axis of elongation (Ai). As indicated above, in embodiments, Lc > Wc, such as Lc > 1.5*Wc, especially Lc > 2*Wc, like Lc > 3*Wc. Hence, in specific embodiments, the elongated light generating device may have a first diameter Di in a cross-sectional view perpendicular to the axis of elongation (Ai), and the elongated collimator lens may have a collimator width Wc in a cross-sectional view perpendicular to the axis of elongation (Ai); wherein 5 < Wc / Di < 50; wherein the elongated collimator lens may have a collimator height He in the cross-sectional view perpendicular to the axis of elongation (Ai); wherein He < 0.6*Wc; and wherein the elongated collimator lens may have a collimator length Lc along the axis of elongation (Ai); wherein Lc > 2*Wc. A ratio Wc / Di > 5 may facilitate providing system light with a relatively broad second beam angle ab2 (i.e., closer to 100°). Further, a ratio Wc / Di > 5 may provide a more compact light generating system. Alternatively, a ratio Wc / Di < 50 may facilitate providing system light with a relatively narrow second beam angle ab2. Hence, such a ratio may be suitable to provide a more focused beam of system light.

[0058] The elongated light generating device may be configured to generate a first beam of device light. In embodiments, at least 70%, such as at least 80%, especially at least 90%, including (essentially) 100%, of a spectral power (and / or radiant flux) of the (first beam of) device light may be in a first angular range around the axis of elongation (Ai). The (first) angular range may especially be selected from the range of 0-300°, such as from the range of 0-330°, especially from the range of 0-360°. Hence, in embodiments, at least 90% of a spectral power of the device light may be in an angular range of 0-300°, such as in an angular range of 0-330°, especially in an angular range of 0-360°, around the axis of elongation (Ai). In embodiments, the (first) angular range may be determined in a cross-section of the elongated light generating device perpendicular to the axis of elongation (Ai), wherein a (center of a) first side face of the elongated carrier (bridging the first and second major surfaces) may denote both 0° and 360°, and wherein a (center of a) second opposite side face of the elongated carrier may denote 180°. In such embodiments, the angular range of 0-180° may especially be configured on a side of the first major surface (especially facing the light exit face), and an angular range of 180-360° may especially be configured on a side of the second major surface (especially facing the second total internal reflection face). Further, the device light may have a non-zero light intensity over the entire (angular) range of 40-140°, such as the entire range of 30-150°, especially the entire range of 20-160° (in the first angular range). That is, at every angle in the (angular) range of 40-140°, such as the range of 30-150°, especially the range of 20-160°, around the axis of elongation (Ai), the device light may have at least some intensity (or radiant flux). Especially, at least 10%, such as at least 20%, especially at least 30%, of a spectral power of the device light may be in the (angular) range of 40-140°, such as the range of 30-150°, especially the range of 20-160°, around the axis of elongation (Ai). Additionally, the device light may have a non-zero light intensity over the entire range of 220-320°, such as the entire range of 210-330°, especially the entire range of 200-340° (in the first angular range). That is, at every angle in the (angular) range of 220- 320°, such as the range of 210-330°, especially the range of 200-340°, around the axis of elongation (Ai), the device light may have at least some intensity (or radiant flux). Especially, at least 10%, such as at least 20%, especially at least 30%, of a spectral power of the device light may be in the (angular) range of 220-320°, such as the range of 210-330°, especially the range of 200-340°, around the axis of elongation (Ai). In embodiments, the elongated light generating device may comprise a LED filament comprising solid state light sources on (only) the first major surface of the elongated carrier, wherein the elongated carrier may be light transmissive, and wherein at least 50% of a spectral power of the device light may be in the angular range of 30-150°, and at least 10% of the spectral power may be in the angular range of 210-330°, with a non-zero light intensity over the entire range of 30- 150° and 210-330°. Alternatively, said LED filament may comprise solid state light sources on (both) the first major surface and the second major surface of the elongated carrier, wherein the elongated carrier may be light transmissive or opaque, and wherein at least 30% of a spectral power of the device light may be in the angular range of 30-150°, and at least 30% of the spectral power may be in the angular range of 210-330°, with a non-zero light intensity over the entire range of 30-150° and 210-330°. At least 70%, such as at least 80%, especially at least 90%, of a spectral power of the device light may be in the angular ranges of 30-150° and 210-330°. Additionally or alternatively, at most 98%, such as at most 95%, especially at most 90%, of a spectral power of the second device light may be in the angular ranges of 30-150° and 210-330°. Hence, looking along the axis of elongation Ai, the elongated light generating device may be configured to provide device light over at least two circle sections (especially a full circle) around the axis of elongation Ai. In specific embodiments, the elongated light generating device may provide an omnidirectional light distribution, with a non-zero light intensity over the entire range of 0-360° (e.g., the elongated light generating device may be an optical fiber).

[0059] The first beam of device light may be incident on (the cavity wall of) the elongated collimator lens. Especially, the first beam of device light may be at least partially transmitted through (and escape from) the elongated collimator lens. Hence, the elongated collimator lens may be configured in a light receiving relationship with the elongated light generating device. In embodiments, the device light may comprise a directly escaping part, wherein the directly escaping part may escape from the elongated collimator lens via the light exit face without internal reflection. Hence, in specific embodiments, a directly escaping part of the device light may escape from the elongated collimator lens via the light exit face without internal reflection. An light generating system wherein at least part of the device light is transmitted through the elongated collimator lens without internal reflection may facilitate reducing the collimator height He of the elongated collimator lens (see also above). The directly escaping part of the device light may especially comprise 20-80%, such as 25- 70%, especially 30-60%, of a radiant flux of the device light (see also above).

[0060] Further, a reflected part of the device light may escape from the elongated collimator lens via the light exit face after a single total internal reflection at the first total internal reflection face. That is, in embodiments, the light transparent material (of the elongated collimator lens) may have a critical angle 0C, and the reflected part (of the device light) may be incident on the first total internal reflection face with a primary second light angle 02, i, wherein 02, i > 0C, and wherein the (at least) reflected part may be reflected at the first total internal reflection face. The reflected light comprising the reflected part may next be incident on the light exit face with a secondary second light angle 02,2, wherein 02,2 < 0c, and wherein the reflected part may be transmitted through (and thus escape from) the light exit face. In embodiments, the reflected part of the device light may comprise 10-60%, such as 15-50%, especially 20-40%, of a radiant flux of the device light (see also above). Alternatively, the reflected part may comprise 60-99%, such as 70-98%, especially 80-95%, of a radiant flux of the device light.

[0061] Further, a double reflected part of the device light may escape from the elongated collimator lens via the light exit face after a first total internal reflection at the second total internal reflection face and subsequently a second total internal reflection at the first total internal reflection face. That is, (at least) the double reflected part (of the device light) may be incident on the second total internal reflection face with a primary third light angle 03, i, wherein 03, i > 0C, and wherein (at least) the double reflected part may be reflected at the second total internal reflection face. The reflected light comprising the double reflected part may next be incident on the first total internal reflection face with a secondary third light angle 03,2, wherein 03,2 > 0c, and wherein the reflected light comprising the double reflected part may again be reflected at the second total internal reflection face. Next, the double reflected light comprising the double reflected part may next be incident on the light exit face with a tertiary third light angle 03,3, wherein 03,3 < 0c, and wherein the double reflected part may be transmitted through (and thus escape from) the light exit face. In embodiments, the double reflected part of the device light may comprise 1-40%, such as 2-30%, especially 5- 25%, of a radiant flux of the device light (see also above). Hence, in specific embodiments, (a) the directly escaping part of the device light may comprise 25-70% of a radiant flux of the device light, (b) the reflected part of the device light may comprise 15-50% of a radiant flux of the device light, and (c) the double reflected part of the device light may comprise 2-30% of a radiant flux of the device light. Such a distribution of radiant fluxes may facilitate that most of the device light may escape from the elongated collimator lens after one or no reflections. As some device light may be lost with each reflection, such a distribution may especially improve the efficiency of the light generating system.

[0062] The light generating system may be configured to generate a second beam of system light. The second beam of system light may comprise, especially consist of, the directly escaping part, reflected part, and double reflected part of the device light escaping from the elongated collimator lens. In embodiments, the second beam of system light may have a second beam angle a.b2, defined by a full width half maximum of the second beam in a plane perpendicular to the axis of elongation (Ai). The second beam angle ab2 may be selected from the range of < 120°, such as from the range of < 100°, especially from the range of < 80°. Further, the second beam angle ab2 may be selected from the range of < 70°, such as from the range of < 60°, especially from the range of < 40°, like from the range of < 25°. Additionally or alternatively, in embodiments, the second beam angle ab2 may be selected from the range of > 5°, such as from the range of > 10°, especially from the range of > 15°. Further, in embodiments, the second beam angle ab2 may be selected from the range of 5-80°, such as from the range of 10-70°, especially from the range of 10-60°, like from the range of 15-40°. Hence, in specific embodiments, the second beam angle ab2 may be selected from the range of 10-70°. Such a second beam angle ab2 may especially indicate a highly- collimated beam of system light.

[0063] The second beam of system light may have a light (intensity) distribution in a cross-sectional view perpendicular to the axis of elongation (Ai). In embodiments, the light distribution may be selected from the group comprising a linear light distribution and a batwing light distribution. Hence, in embodiments the second beam of system light may have a linear light distribution, wherein ab2 < 40°, such as ab2 < 30°, especially ab2 < 20°. Alternatively, the second beam of system light may have a batwing light distribution comprising two maxima in the light distribution, wherein the two maxima may be separated (within the second beam) by a mutual angle P selected from the range of > 5°, such as from the range of > 7°, especially from the range of > 10°. In such embodiments, 15 < otb2 < 80°, such as 20 < ab2 < 70°, especially 25 < ab2 < 60°.

[0064] As indicated above, the elongated collimator lens may comprise one or more (elongated) prismatic structures, especially (configured) on the light exit face. The one or more (elongated) prismatic structures may be configured to collimate the device light in a plane parallel to the axis of elongation (Ai) and the collimator height He. Hence, the second beam of system light may have a third beam angle a.b3, defined by a full width half maximum of the second beam in a plane parallel to the axis of elongation (Ai) and the collimator height He. In embodiments, the third beam angle ab3 may be selected from the range of < 80°, such as from the range of < 70°, especially from the range of < 60°. Additionally or alternatively, the third beam angle a.b3 may be selected from the range of > 20°, such as from the range of > 30°, especially from the range of > 40°. Hence, in specific embodiments, the elongated collimator lens may comprise one or more prismatic structures on the light exit face; wherein the one or more prismatic structures may be configured to collimate the device light in a plane parallel to the axis of elongation (Ai) and the collimator height He; wherein the second beam of system light may have a third beam angle ab3, defined by a full width half maximum of the second beam in a plane parallel to the axis of elongation (Ai) and the collimator height He; wherein the third beam angle ab3 may be selected from the range of < 70°. An elongated collimator lens comprising one or more prismatic structures may facilitate providing a second beam of system light collimated in two directions. Hence, a more focused beam of system light may be provided with such an elongated collimator lens. Further, such a light generating system may especially provide system light adhering to office glare requirements, e.g. having a unified glare ratio (UGR) of < 19.

[0065] The light generating system may comprise a housing, such as e.g. a luminaire housing. The housing may especially be elongated along the axis of elongation (Ai). Further, the housing may (at least) partially enclose the elongated collimator lens, such as over > 180°, especially over > 220°, like over > 270°, around the axis of elongation (Ai). In embodiments, the (elongated) housing may enclose the elongated collimator lens over (essentially) 360° around the axis of elongation (Ai), wherein the housing may comprise a (light transparent) light exit window configured facing and in a light receiving relationship with the light exit face. Alternatively, the housing may partially enclose the elongated collimator lens, wherein the housing may at least not enclose (i.e., be in a light receiving relationship with) the light exit face. Further, in embodiments, the housing (with the exception of the optional light exit window) may be at least partially reflective, such as at least partially reflective for the device light and / or system light. Especially, the second total internal reflection face may be configured facing a first housing part, wherein the first housing part may be reflective for the device light and / or system light.

[0066] The elongated collimator lens may be configured (directly or indirectly) physically coupled with the housing. Further, the elongated collimator lens may be configured in physical contact with the housing. Especially, the elongated collimator lens, such as especially the second total internal reflection face, may be configured physically coupled (such as in physical contact) with the housing over at least part of an outside surface area of the elongated collimator lens (defined by Lp*Lc). In embodiments, the elongated collimator lens (especially the second total internal reflection face) may be configured physically coupled and / or in physical contact with the housing over < 10%, such as over < 5%, especially over 0.1-5%, like over 0.1-2%, of the outside surface area. In embodiments, the elongated collimator lens may be indirectly physically coupled with the housing, wherein the elongated collimator lens may be in physical contact with one or more support elements, and wherein the one or more support elements may be configured to physically couple (and / or fixate) the elongated collimator lens to the housing. The one or more support elements may for instance be selected from the group comprising brackets, screws, bolts, an adhesive layerjoints, and clamps.

[0067] The term “luminescent material” may herein refer to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation, especially visible light. Herein, UV (ultraviolet) may especially refer to a wavelength selected from the range of 190-380 nm, such as 200-380 nm, though other wavelengths may also be possible. In general, the first radiation and second radiation have different spectral power distributions, with the second radiation especially having a spectral power distribution at larger wavelengths than the first radiation (i.e. “down-conversion”). Hence, upon excitation with radiation, the luminescent material may emit radiation. Further, the term “luminescent material” may refer to phosphorescence and / or fluorescence. The term “luminescent material” may also refer to a plurality of different luminescent materials. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition. Examples of possible luminescent materials are indicated below. Instead of the term “luminescent material” also the term “phosphor” may be applied, as is known to the person skilled in the art.

[0068] In embodiments, luminescent materials may be selected from garnets and nitrides, especially doped with trivalent cerium or divalent europium, respectively. The term “nitride” may also refer to oxynitride or nitridosilicate, etc. Alternatively or additionally, the luminescent material(s) may be selected from silicates, especially doped with divalent europium. The luminescent material may comprise a divalent europium comprising oxynitride luminescent material. Further, in embodiments, the luminescent material may comprise a divalent europium comprising nitride luminescent material.

[0069] The luminescent material may comprise a cerium comprising garnet luminescent material of the type AsBsOnUe, wherein A comprises one or more of yttrium (Y), lanthanum (La), gadolinium (Gd), terbium (Tb) and lutetium (Lu), and wherein B comprises one or more of aluminum (Al), gallium (Ga), indium (In), and scandium (Sc); and wherein the light source light may comprise blue light. Embodiments of garnets especially include A3B5O12 garnets, wherein A comprises at least Y or Lu, and wherein B comprises at least Al. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of Ce and Pr. Further, B and O may at least partly be replaced by Si and N. The term “:Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the “A” ions) in the luminescent material is replaced by Ce. This is known to the person skilled in the art.

[0070] The luminescent material may comprise a luminescent material of the type AsSieNiuCe3, wherein A comprises one or more of Y, La, Gd, Tb and Lu, such as in embodiments one or more of La and Y. The luminescent material may alternatively or additionally comprise one or more of MS:Eu2+and / or NfcSis Eu2and / or MAlSiNvEu2and / or Ca2AlSi3O2Ns:Eu2+, etc., wherein M comprises one or more of Ba, Sr and Ca, especially in embodiments at least Sr.

[0071] The term “luminescent material” herein especially relates to inorganic luminescent materials. Alternatively or additionally, also other luminescent materials may be applied. For instance quantum dots and / or organic dyes may be applied and may optionally be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc..

[0072] The luminescent material may comprise a tetravalent manganese-comprising luminescent material, i.e., a luminescent material doped with tetravalent manganese. Especially, in embodiments, the luminescent material may comprise a luminescent material of the type M M2-2xAXe:Mn4+, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x may be selected from the range of 0-1, wherein A comprises a tetravalent cation, for instance comprising one or more of silicon and titanium, and wherein X comprises a monovalent anion, at least comprising fluorine. The alkaline earth cation M’ may comprise one or more of magnesium (Mg), strontium (Sr), calcium (Ca), and barium (Ba), especially one or more of Sr and Ba. Further, the alkaline cation M may comprise one or more of sodium (Na), potassium (K), rubidium (Rb), ammonium (NFLC), lithium (Li), and cesium (Cs), such as at least K, or such as at least Rb. In embodiments, A may comprise a tetravalent cation, and preferably at least comprises silicon. A may (further) comprise one or more of titanium (Ti), germanium (Ge), stannum (Sn) and zinc (Zn). The monovalent anion X may comprise fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), such as at least F. The luminescent material may be coated, as described in WO2013121355A1. The term “light source” may in principle relate to any light source known in the art. In a specific embodiment, the light source may comprise a solid state light source (such as a LED or laser diode). 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), optionally covered by a luminescent material comprising layer. The die dimensions may be < 2 mm, such as in the range of e.g. 0.2-2 mm. Herein, the term “light source” may also refer to mini LEDs or micro LEDs, such as especially micro LEDs or “microLEDs”. Herein, the term mini LED refers to solid state light sources having (die) dimensions, especially length and width, selected from the range of 0.1- 1 mm. Further, the term micro LED refers to solid state light sources having (die) dimensions, especially length and width, selected from the range of < 100 pm.

[0073] The term “light source” may refer to a semiconductor light-emitting device, such as an LED, a resonant cavity LED (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term “light source” may also refer to an organic LED (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In an embodiment, the light source a LED, a laser diode, a superluminescent diode, or a multi -junction LED.

[0074] The light source may be configured to provide primary radiation, which is used as such, such as e.g. a blue light source, like a blue LED. Such LEDs may be indicated as direct color LEDs. In other embodiments, the light source may be configured to provide primary radiation and part of the primary radiation may converted into secondary radiation (e.g. by a luminescent material). The luminescent material may be comprised by the light source, such as an LED with a luminescent material layer or dome. Such LEDs may be indicated as phosphor converted LEDs or PC LEDs. In other embodiments, the light source may be configured to provide primary radiation and part of the primary radiation is converted into secondary radiation. Secondary radiation may be based on conversion by a luminescent material. The luminescent material may in embodiments be comprised by the light source, such as an LED with a luminescent material layer or dome comprising luminescent material. Such LEDs may be indicated as phosphor converted LEDs or PC LEDs.

[0075] 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. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems.

[0076] 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 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 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, and an optical wireless communication device, comprising the light generating system as defined herein. Especially, in a second aspect, the invention provides a lighting device selected from the group of a lamp and a luminaire, 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.

[0077] The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

[0078] BRIEF DESCRIPTION OF THE DRAWINGS

[0079] 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: Fig. 1-3 schematically depict embodiments of the elongated collimator lens and the light generating system;

[0080] Figs. 4A-B schematically depict an embodiment of the light generating system;

[0081] Figs. 5A-B schematically depict an embodiment of the elongated light generating device and the device light; and

[0082] Fig. 6 schematically depicts an embodiment of the lighting device.

[0083] The schematic drawings are not necessarily to scale.

[0084] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0085] Fig. 1 A schematically depicts an embodiment of the elongated collimator lens 4000. The elongated collimator lens 4000 may comprise a light transparent material. The light transparent material may comprise one or more of PMMA and PC. Further, the elongated collimator lens 4000 may comprise an axis of elongation (Ai) and an elongated cavity 400 along the axis of elongation (Ai). The light transparent material may enclose the axis of elongation (Ai) over an angle y of at least 260°, thereby defining the elongated cavity 400. Further, in a cross-sectional view perpendicular to the axis of elongation (Ai) the elongated collimator lens 4000 may comprise: (i) a light exit face 4010, (ii) a first total internal reflection face 4020, and (iii) a second total internal reflection face 4030. The elongated collimator lens 4000 may be configured such that for device light 101 provided by a (virtual) elongated light generating device 100 configured in the elongated cavity 400 and having an omnidirectional light distribution around the axis of elongation (Ai) applies that:

[0086] (i) a reflected part 12 escapes from the elongated collimator lens 4000 via the light exit face 4010 after a single total internal reflection at the first total internal reflection face 4020, and

[0087] (ii) a double reflected part 13 escapes from the elongated collimator lens 4000 via the light exit face 4010 after a first total internal reflection at the second total internal reflection face 4030 and subsequently a second total internal reflection at the first total internal reflection face 4020. Further, a directly escaping part 11 of the device light 101 may escape from the elongated collimator lens 4000 via the light exit face 4010 without internal reflection.

[0088] The double reflected part 13 (of the device light 101) may especially comprise 2-30% of a radiant flux of the device light 101 escaping from the elongated collimator lens 4000. Further, the reflected part 12 (of the device light 101) comprises 15-50% of a radiant flux of the device light 101 escaping from the elongated collimator lens 4000. Additionally, the directly escaping part 11 may comprise 25-70% of a radiant flux of the device light 101 escaping from the elongated collimator lens 4000.

[0089] The elongated collimator lens 4000 may comprise a center plane Pc. The center plane Pcmay be (configured) parallel to the axis of elongation (Ai) and intersecting the light exit face 4010. Further, the elongated collimator lens 4000 may be symmetrical about the center plane Pc. Hence, center plane Pcmay define a plane of symmetry Psof the elongated collimator lens 4000. The light exit face 4010 may have a first exit face part 4011 on a first side of the center plane Pc, and a second exit face part 4012 on a second (opposite) side of the center plane Pc. Further, the light exit face 4010 may comprise a collimator lens element 4015. The collimator lens element 4015 may have an amplitude di selected from the range of 1-5 mm (with respect to a (virtual) line of the light exit face 4010 without the collimator lens element 4015). Further, the first total internal reflection face 4020 may have a primary first face 4021 on the first side of the center plane Pc, and a secondary first face 4022 on the second side of the center plane Pc. Similarly, the second total internal reflection face 4030 may have a primary second face 4031 on the first side of the center plane Pc, and a secondary second face 4032 on the second side of the center plane Pc.

[0090] The elongated collimator lens 4000 may have a cross-sectional perimeter 4001 (perpendicular to the axis of elongation (Ai)). The cross-sectional perimeter 4001 may be at least defined by the light exit face 4010, the first total internal reflection face 4020, and the second total internal reflection face 4030. Further, the perimeter 4001 may have a perimeter length Lp. The light exit face 4010 may have a first length Li along the perimeter 4001, wherein 0.1 *LP< Li < 0.6*Lp. Further, the first total internal reflection face 4020 may have a second length L2 along the perimeter 4001, wherein 0.25*Lp< L2 < 0.8*Lp(and wherein the primary first face 4021 and secondary first face 4022 have lengths L2,I and 1,2,2, respectively). Similarly, the second total internal reflection face 4030 may have a third length L3 along the perimeter 4001, wherein 0.05*Lp< L3 < 0.2*Lp(and wherein the primary second face 4031 and secondary second face 4032 have lengths 1,3,1 and 1,3,2, respectively). As depicted in Fig. 1, the transition from e.g. the primary first face 4021 to the primary second face 4031 may be a gradual curve. In such embodiments, the point where the derivative of the gradual curve may be (essentially) zero indicates the transition from the primary first face 4021 to the primary second face 4031.

[0091] A continuous subsection of the first total internal reflection face 4020 with length > 0.4*1,2 (e.g. the primary first face 4021) may be configured at a first mutual angle an with a continuous subsection of the second total internal reflection face 4030 with length > 0.4*Ls (e.g. the primary second face 4031). In embodiments, 90° < an < 120°. Additionally or alternatively, a continuous subsection of the light exit face 4010 with length > 0.25 *Li may be configured at a second mutual angle an with a continuous subsection of the first total internal reflection face 4020 with length > 0.4*L2 (e.g. the primary first face 4021). In embodiments, 30° < an < 70°.

[0092] Turning to the elongated cavity 400, the light transparent material may enclose the axis of elongation (Ai) over 360° (thereby forming a closed cavity 400). Alternatively, the light transparent material may enclose the axis of elongation (Ai) over < 360° (thereby forming an open cavity 400). Further, the elongated cavity 400 may comprise a cavity wall 450. On each side of the center plane Pcthe cavity wall 450 may comprise a cavity wall first section 451, a cavity wall second section 452, and a cavity wall third section 453. The cavity wall first section 451 may be configured over a first angle ai with respect to the axis of elongation (Ai). In embodiments, 5° < ai < 90°. Further, the cavity wall first section 451 may be configured to receive at least the directly escaping part 11 (of the device light 101). The cavity wall second section 452 may be configured over a second angle a? with respect to the axis of elongation (Ai). In embodiments, 50° < a < 160°. Further, the cavity wall second section 452 may be configured to receive at least the reflected part 12 (of the device light 101). The cavity wall third section 453 may be configured over a third angle as with respect to the axis of elongation (Ai). In embodiments, 10° < as < 60°. Further, the cavity wall third section 453 may be configured to receive at least the double reflected part 13 (of the device light 101). In embodiments, 140° < ai+a2+as < 180°. In a cross-sectional view perpendicular to the axis of elongation (Ai), at least one of the cavity wall first section 451, the cavity wall second section 452, and the cavity wall third section 453 may be planar. Additionally or alternatively, in a cross-sectional view perpendicular to the axis of elongation (Ai), at least one of the cavity wall first section 451, the cavity wall second section 452, and the cavity wall third section 453 may be convex.

[0093] The elongated collimator lens 4000 may have a collimator width Wc in a cross-sectional view perpendicular to the axis of elongation (Ai). In embodiments, 5 mm < Wc < 60 mm. Further, the elongated collimator lens 4000 may have a collimator height He in the cross-sectional view perpendicular to the axis of elongation (Ai), wherein He < 0.6*Wc. Further yet, the elongated collimator lens 4000 may have a collimator length Lc along the axis of elongation (Ai) (see Fig. 3). In embodiments, Lc > 2*Wc.

[0094] Fig. 1 further schematically depicts an embodiment of the light generating system 1000. The light generating system 1000 may comprise the elongated collimator lens 4000 as defined herein, and an elongated light generating device 100. The elongated collimator lens 4000 may be configured in a light receiving relationship with the elongated light generating device 100. Further, the elongated light generating device 100 may be configured in the elongated cavity 400. Additionally, the elongated light generating device 100 may be configured to generate a first beam 5 of device light 101 with a non-zero light intensity over the entire range of 30-150° and 210-330° around the axis of elongation (Ai). A reflected part 12 of the device light 101 may escape from the elongated collimator lens 4000 via the light exit face 4010 after a single internal reflection at the first total internal reflection face 4020. Further, a double reflected part 13 of the device light 101 may escape from the elongated collimator lens 4000 via the light exit face 4010 after a first internal reflection at the second total internal reflection face 4030 and subsequently a second total internal reflection at the first total internal reflection face 4020. As such, the light generating system 1000 may be configured to generate a second beam 6 of system light 1001 having a second beam angle ab2, defined by a full width half maximum of the second beam 6 in a plane perpendicular to the axis of elongation (Ai). The second beam angle ab2 may especially be selected from the range of < 100°, such as from the range of 10-70°.

[0095] A directly escaping part 11 of the device light 101 may escape from the elongated collimator lens 4000 via the light exit face 4010 without internal reflection. Further, the elongated light generating device 100 may have a first diameter Di in a cross- sectional view perpendicular to the axis of elongation (Ai). In embodiments, 5 < Wc / Di. Further, the elongated light generating device 100 may be configured in a geometrical center of the cavity 400.

[0096] Fig. 2 schematically depicts a further embodiment of the elongated collimator lens 4000 and the light generating system 1000. The elongated collimator lens 4000 of Fig. 2 may especially be configured to provide a second beam 6 of system light 1001 having a batwing light distribution. As depicted in Fig. 2, the elongated light generating device 100 may be configured at an offset distance d2 with respect to a geometrical center of the cavity 400. In embodiments, 0.5 mm < d2 < 3 mm.

[0097] Fig. 3 schematically depicts a further embodiment of the elongated collimator lens 4000 and the light generating system 1000. The elongated collimator lens 4000 may comprise one or more (elongated) prismatic structures 4050 on the light exit face 4010. The one or more prismatic structures 4050 may be configured to collimate the device light 101 in a plane parallel to the axis of elongation (Ai) and the collimator height He. In such embodiments, the second beam 6 of system light 1001 may have a third beam angle ab3, defined by a full width half maximum of the second beam 6 in a plane parallel to the axis of elongation (Ai) and the collimator height He. The third beam angle ab3 may be selected from the range of < 70°. In the embodiment depicted in Fig. 3, the one or more (elongated) prismatic structures 4050 may have prism lengths Lprconfigured parallel to the collimator width Wc, though this need not be the case (see Fig. 4). Further, as depicted in Fig. 3, the one or more (elongated) prismatic structures 4050 may comprise openings along the prism length Lpr, wherein the light exit face 4010 may be exposed at the openings. Reference abi indicates the angular range over which the first beam 5 of device light 101 has a non-zero light intensity. In Fig. 3, said angular range may be (essentially) 360°, though this need not be the case (see e.g. Fig. 5).

[0098] Fig. 4 schematically depicts an embodiment of the light generating system 1000 comprising a housing 5000. Fig. 4A schematically depicts a front view, along the axis of elongation (Ai), and Fig. 4B schematically depicts a perspective view. The housing 5000 may have a light exit window 5100, through which the second beam 6 system light 1001 may escape from the housing 5000. The elongated collimator lens 4000 may be (directly or indirectly) physically coupled with the housing 5000. In Fig. 4, the elongated collimator lens 4000 is physically coupled with the housing 5000 via one or more support elements 5200. The elongated collimator lens 4000 (especially the second total internal reflection face 4030) may be configured physically coupled with the housing 5000 over < 10%, such as over < 5%, especially over 0.1-5%, like over 0.1-2%, of an outside surface area of the elongated collimator lens 4000 (defined by Lp*Lc). Further, the second total internal reflection face 4030 may be configured facing a first housing part 5010 (of the housing 5000). The first housing part 5010 may especially be reflective for the device light 101 and / or system light 1001. In the embodiment depicted in Fig. 4, the one or more prismatic structures 4050 may have prism lengths Lprconfigured parallel to the collimator length Lc.

[0099] Fig. 5A schematically depicts an embodiment of the first beam 5 of device light 101. The square markers indicate the light distribution of the device light 101 along the axis of elongation (Ai), and the circular markers indicate the light distribution of the device light 101 around the axis of elongation (Ai) (i.e., in a plane perpendicular to the axis of elongation (Ai)). The first beam 5 of device light 101 may have a non-zero light intensity over two angular ranges around the axis of elongation (Ai): a first angular range (indicated with reference abi,i) spanning from 30-150°, and a second angular range (indicated with reference 01,1,2) spanning from 210-330°. Hence, the elongated light generating device 100 may be configured to generate a first beam 5 of device light 101 with a non-zero light intensity over the entire range of 30-150° and 210-330° around the axis of elongation (Ai). Such a light distribution may apply for a LED filament 500. Hence, the elongated light generating device 100 may comprise a LED filament 500. Further, the first beam 5 of device light 101 may have a non-zero light intensity over two oppositely arranged quadrants around the axis of elongation (Ai), with a first quadrant spanning from 45-135°, and a second opposite quadrant spanning from 225-315°. Hence, the elongated light generating device 100 may provide an omnidirectional light distribution.

[0100] Fig. 5B schematically depicts an embodiment of the elongated light generating device 100 in a cross-section perpendicular to the axis of elongation (Ai). The elongated light generating device 100 may comprise a LED filament 500. The LED filament 500 may comprise an elongated carrier 550 with a first major surface 551 and a second major surface 552. Solid state light sources 10 may be configured on the first major surface 551, wherein the elongated carrier 550 may be light transparent (and wherein the LED filament 500 may provide filament light 501 having an angular light distribution as depicted in Fig. 5 A). Alternatively, solid state light sources 10 may be configured on the first major surface 551 and the second major surface 552, wherein the elongated carrier 550 may be light transparent or opaque (and wherein the LED filament 500 may provide filament light 501 having an angular light distribution with a roughly equal spectral power provided in the range of 30- 150° and the range of 210-330°). The LED filament 500 may be configured to generate filament light 501. The filament light 501 may comprise light source light 11 generated by the solid state light sources 10. Additionally, the filament light 501 may comprise luminescent material light 201. Hence, the LED filament 500 may comprise an elongated encapsulant 510 comprising a luminescent material 200, configured to convert at least part of the light source light 11 into luminescent material light 201. The device light 101 may comprise, especially consist of, the filament light 501.

[0101] Fig. 6 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000. Reference 301 indicates a user interface which may be functionally coupled with a control system 300 comprised by or functionally coupled to the light generating system 1000. Fig. 6 also schematically depicts an embodiment of a lamp 1 comprising the light generating system 1000. Hence, Fig. 6 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1 and a luminaire 2, comprising the light generating system 1000. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments be system light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor, reference 1310 to a ceiling, and reference 1307 to a wall.

[0102] 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”. 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.

[0103] 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.

[0104] The devices, 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, or systems in operation. 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. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In 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. The invention also provides a control system that may control the device or system, or that may execute a mode of operation of the system. 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, or system, controls one or more controllable elements of such device, or system. The invention further applies to a device, 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 comprising one or more of the characterizing features described in the description and / or shown in the attached drawings.

[0105] 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 an elongated light generating device (100), and an elongated collimator lens (4000) that comprises a light transparent material and that is configured in a light receiving relationship with the elongated light generating device (100), wherein the elongated collimator lens (4000) comprises an axis of elongation (Ai) and an elongated cavity (400) along the axis of elongation (Ai), wherein the elongated light generating device (100) is configured in the elongated cavity (400), wherein the elongated light generating device (100) is configured to generate a first beam (5) of device light (101) with a non-zero light intensity over the entire range of 30- 150° and 210-330° around the axis of elongation (Ai), wherein the light transparent material encloses the axis of elongation (Ai) over an angle (y) of at least 260°, thereby defining the elongated cavity (400), wherein the elongated collimator lens (4000) comprises in a cross-sectional view perpendicular to the axis of elongation (Ai): (i) a light exit face (4010), (ii) a first total internal reflection face (4020), and (iii) a second total internal reflection face (4030), and wherein the elongated collimator lens (4000) is configured such that for device light (101) provided by the elongated light generating device (100) applies that:(i) a reflected part (12) escapes from the elongated collimator lens (4000) via the light exit face (4010) after a single total internal reflection at the first total internal reflection face (4020), and(ii) a double reflected part (13) escapes from the elongated collimator lens (4000) via the light exit face (4010) after a first total internal reflection at the second total internal reflection face (4030) and subsequently a second total internal reflection at the first total internal reflection face (4020).

2. The light generating system (1000) according to claim 1, wherein a directly escaping part (11) of the device light (101) escapes from the elongated collimator lens (4000) via the light exit face (4010) without internal reflection.

3. The light generating system (1000) according to claim 2, wherein one or more of the following applies:(a) the double reflected part (13) comprises 2-30% of a radiant flux of the device light (101) escaping from the elongated collimator lens (4000);(b) the reflected part (12) comprises 15-50% of the radiant flux of the device light (101) escaping from the elongated collimator lens (4000); and(c) the directly escaping part (11) comprise 25-70% of a radiant flux of the device light (101) escaping from the elongated collimator lens (4000).

4. The light generating system (1000) according to any one of the preceding claims, wherein the elongated collimator lens (4000) has a cross-sectional perimeter (4001), wherein the cross-sectional perimeter (4001) is at least defined by the light exit face (4010), the first total internal reflection face (4020), and the second total internal reflection face (4030); wherein the perimeter (4001) has a perimeter length (Lp); wherein: the light exit face (4010) has a first length (Li) along the perimeter (4001), wherein 0.1 *LP< Li < 0.6*Lp; the first total internal reflection face (4020) has a second length (L2) along the perimeter (4001), wherein 0.25*Lp< L2 < 0.8*Lp; and the second total internal reflection face (4030) has a third length (L3) along the perimeter (4001), wherein 0.05*Lp< L3 < 0.2*Lp.

5. The light generating system (1000) according to claim 4, wherein one or more of the following applies: a continuous subsection of the first total internal reflection face (4020) with length > 0.4*L2 is configured at a first mutual angle (an) with a continuous subsection of the second total internal reflection face (4030) with length > 0.4*1 ?; wherein 90° < an < 120°; and a continuous subsection of the light exit face (4010) with length > 0.25 *Li is configured at a second mutual angle (an) with a continuous subsection of the first total internal reflection face (4020) with length > 0.4*L2; wherein 30° < an < 70°.

6. The light generating system (1000) according to any one of the preceding claims 2-5, wherein the elongated collimator lens (4000) comprises a center plane (Pc)parallel to the axis of elongation (Ai) and intersecting at least the light exit face (4010); wherein the elongated cavity (400) comprises a cavity wall (450); wherein on each side of the center plane (Pc) the cavity wall (450) comprises a cavity wall first section (451), a cavity wall second section (452), and a cavity wall third section (453), and wherein: the cavity wall first section (451) is configured over a first angle (ai) with respect to the axis of elongation (Ai); wherein 5° < ai < 90°; wherein the cavity wall first section (451) is configured to receive at least the directly escaping part (11); the cavity wall second section (452) is configured over a second angle (a?) with respect to the axis of elongation (Ai); wherein 50° < 0.2 < 160°; wherein the cavity wall second section (452) is configured to receive at least the reflected part (12); the cavity wall third section (453) is configured over a third angle (0,3) with respect to the axis of elongation (Ai); wherein 10° < 013 < 60°; wherein the cavity wall third section (453) is configured to receive at least the double reflected part (13); and 140° < 011+012+013 < 180°.

7. The light generating system (1000) according to claim 6, wherein in a cross- sectional view perpendicular to the axis of elongation (Ai) one or more of the following applies:(a) at least one of the cavity wall first section (451), the cavity wall second section (452), and the cavity wall third section (453) is planar; and(b) at least one of the cavity wall first section (451), the cavity wall second section (452), and the cavity wall third section (453) is convex.

8. The light generating system (1000) according to any one of the preceding claims 2-7, wherein the elongated collimator lens (4000) has a collimator width (Wc) in a cross-sectional view perpendicular to the axis of elongation (Ai); wherein 5 mm < Wc < 60 mm; wherein the elongated collimator lens (4000) has a collimator height (He) in the cross- sectional view perpendicular to the axis of elongation (Ai); wherein He < 0.6*Wc; and wherein the elongated collimator lens (4000) has a collimator length (Lc) along the axis of elongation (Ai); wherein Lc > 2*Wc.

9. The light generating system (1000) according to any one of the preceding claims, wherein one or more of the following applies:(a) the center plane (Pc) as defined in claim 6 defines a plane of symmetry (Ps) of the elongated collimator lens (4000); and(b) the light transparent material encloses the axis of elongation (Ai) over 360°.

10. The light generating system (1000) according to any one of the preceding claims, wherein the light transparent material encloses the axis of elongation (Ai) over < 360°.

11. The light generating system (1000) according to any one of the preceding claims, wherein one or more of the following applies: the light transparent material comprises one or more of PMMA and PC; the light exit face (4010) comprises a collimator lens element (4015), wherein the collimator lens element (4015) has an amplitude di selected from the range of 1-5 mm; the light exit face (4010) is at least partially diffuse transmissive for visible light; and the elongated collimator lens (4000) comprises one or more prismatic structures (4050) on the light exit face (4010); wherein the one or more prismatic structures (4050) are configured to collimate the device light (101) in a plane parallel to the axis of elongation (Ai) and the collimator height (He) as defined in claim 8.

12. The light generating system (1000) according to any one of the preceding claims, wherein the light generating system (1000) is configured to generate a second beam (6) of system light (1001) having a second beam angle (01,2), defined by a full width half maximum of the second beam (6) in a plane perpendicular to the axis of elongation (Ai); wherein the second beam angle (00,2) is selected from the range of < 100°.

13. The light generating system (1000) according to any one of the preceding claims, wherein one or more applies of the elongated light generating device (100) comprises a LED filament; the elongated light generating device (100) has a first diameter (Di) in a cross- sectional view perpendicular to the axis of elongation (Ai); wherein the elongated collimator lens (4000) has a collimator width (Wc) in a cross-sectional view perpendicular to the axis of elongation (Ai); wherein 5 < Wc / Di < 50; wherein the elongated collimator lens (4000) has a collimator height (He) in the cross-sectional view perpendicular to the axis of elongation(Ai); wherein He < 0.6*Wc; and wherein the elongated collimator lens (4000) has a collimator length (Lc) along the axis of elongation (Ai); wherein Lc > 2*Wc; and the elongated collimator lens (4000) comprises one or more prismatic structures (4050) on the light exit face (4010); wherein the one or more prismatic structures (4050) are configured to collimate the device light (101) in a plane parallel to the axis of elongation (Ai) and the collimator height (He); wherein the second beam (6) of system light (1001) has a third beam angle (a.bs), defined by a full width half maximum of the second beam (6) in a plane parallel to the axis of elongation (Ai) and the collimator height (He); wherein the third beam angle (0.1,3) is selected from the range of < 70°.

14. A lighting device (1200) selected from the group of a lamp (1) and a luminaire(2), comprising the light generating system (1000) according to any one of the preceding claims.

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