WO2017050598A1

WO2017050598A1 - Efficient collimating optics by collecting the full hemisphere in tir-fresnel lens designs

Info

Publication number: WO2017050598A1
Application number: PCT/EP2016/071426
Authority: WO
Inventors: Hendrikus Hubertus Petrus Gommans; Arno VREDENBORG
Original assignee: Philips Lighting Holding B.V.
Priority date: 2015-09-21
Filing date: 2016-09-12
Publication date: 2017-03-30

Abstract

The invention provides a lighting device (1) comprising a light source unit (10), the light source unit (10) comprising a light source (100), a lens comprising optical element (200), and a light redirection element (300), wherein: - the lens comprising optical element (200) comprises (i) a first lens part (210) with Fresnel functionality, and (ii) a second lens part (220) having total internal reflection 5 functionality; - the light source (100) is configured to generate light source light (101) having a light exit angle (σ) larger than 45° relative to the optical axis, wherein a first part (101a) of the light source light (101) can reach the lens comprising optical element (200) without a redirection, and a second part (101b) of the light source light (101) cannot reach the lens 10 comprising optical element (200) without a redirection; and - the light redirection element (300) is configured to redirect at least part of the second part (101b) of the light source light (101) to the second lens part (220) having total internal reflection functionality.

Description

Efficient collimating optics by collecting the full hemisphere in TIR-Fresnel lens designs

FIELD OF THE INVENTION

The invention relates to a lighting device, especially a solid state light source based lighting device, as well as to its (specific use). BACKGROUND OF THE INVENTION

Beam shaping is known in the art. US2004/0155565, for instance, describes that an emitter within LED lamp(s) radiates light over of solid angle of approximately 2π steradians or an approximate hemisphere. Conventionally, some of the light emitted is directly transmitted to the object to be illuminated and another portion is indirectly transmitted by means of a reflector, refractive optic or both. The in US2004/0155565 described method is alleged to increase the collection efficiency of the radiated energy from LED lamp(s) by turning the LED or other light source so that all of its transmitted light is directed away from the object of the apparatus and directed into a reflector. The reflector then reflects the light toward the object. This singular handling of all the energy from the emitter results in more precise control of the radiated energy of the source. Optional subsequent controlling elements may be utilized efficiently due to the fact that the rays they will affect are of a single class of rays. In an embodiment of US2004/0155565, the surface of material filling the reflector and embedding the emitter may be contoured or shaped into a lens, in a specific embodiment a Fresnel lens.

SUMMARY OF THE INVENTION

An efficient optical system is especially relevant for high lumen lighting applications such as stadium lighting, where spot-like luminaires are being used that have e.g. 100 kilolumen or more overall light output and requires a narrow light distribution (<15° full width half maximum or high peak luminous intensity >15 cd/lm).

One might use total internal reflection collimators, which have a high light output ratio for a high peak luminous intensity. However, this is a single solid optical piece that requires a considerable amount of material in case of a narrow light distribution (<15° full width half maximum). Thus, the total weight of the optics becomes significant. In an alternative solution, one could use a compound parabolic concentrator (CPC), but this has the disadvantage that the optical component becomes long and needs to be located within an enclosure for moisture protection of the luminaire. The consequence is that the size of the enclosure becomes more expensive on luminaire level.

Hence, it is an aspect of the invention to provide an alternative lighting device, which preferably further at least partly obviates one or more of above-described drawbacks. Especially, the optical design should be compatible with standard mass-manufacturing processes. Further, it is desirable to provide a (cost-effective) optical design that allows for high resolution light control. Yet, it is further desirable that the lighting device has a low form factor (small thickness).

For this purpose, it is amongst others proposed to provide thin micro- structured films for beam shaping. Typically, such a micro-structured film is based on small facets (for example having a hexagonal shape with a 100 μηι size) that can redirect/deflect the light of a low-etendue source (e.g. an individual LED) independently from neighboring facets. This gives the luminaire designer an increased freedom to create a wide variety of beam shapes or luminaire appearances. It appears that especially Fresnel lenses may advantageously be used. Hence, especially it is herein proposed to use a lens having Fresnel properties, especially for those light rays having relatively small angles with the optical axis (< 45°), and having total internal reflection (TIR) properties for those light rays having relatively large angles with the optical axis (> 45°), as TIR elements may be better able to redirect the large exit angle light source rays upstream from the lens into a desired beam downstream from the lens, and Fresnel elements may be better able to redirect the small exit angle light source rays upstream from the lens into a desired beam downstream from the lens. It appears that TIR-Fresnel lens designs may collimate light in an efficient manner.

Further, especially solid state light sources, such as LEDs, are desirable. As

LEDs are Lambertian emitters collecting the full hemisphere by a planar design requires a lens diameter exceeding practical dimension: collecting a cone angle of 65° already requires the diameter of a planar lens to exceed two times the focal distance. For all collimating designs beam control is limited by the collecting angle of the optical element. In order to be able to provide a relatively thin lighting device and/or to reduce material use, it appears desirable that the distance between the optical element and the light source should be relatively small. However, this may lead to a reduction of light output, as not all light is collected by the optical element. As indicated above, the use of internal reflection collimators or compound parabolic concentrator is not desirable. For this reason it is herein suggested using a lens having Fresnel properties and having TIR properties, and to collect the complementary solid angle of the LED, i.e. the part that is not collected by the planar TIR-Fresnel design, by a second optical element that redirects the rays within the beam. It would be most favorable in case this second element collects substantially complementary to the (planar) lens design as in this way it does not substantially increase the form factor of the optical design as a whole but does add to the peak intensity with minimal beam broadening. Here, minimal broadening is especially defined such that beam broadening resulting from the source extensiveness should exceed the broadening due to the TIR elements that now collect two beamlets as opposed only one directly from the source.

Hence, in a first aspect the invention provides a lighting device (herein also indicated as "device") according to claim 1. Hence, the lighting device comprising a light source unit, the light source unit comprising a light source, a lens comprising optical element ("optical element"), and a light redirection element ("redirection element"), wherein (a) the lens comprising optical element comprises (i) a first lens part with Fresnel functionality, and (ii) a second lens part having total internal reflection functionality, wherein the lens comprising optical element may especially be configured at a first distance (dl) selected from the range of 0.1-200 mm; (b) the light source is configured to generate light source light, especially having a light exit angle (σ) (herein also indicated as "exit angle"; sometimes also indicates as "light extraction angle" or "extraction angle") larger than 45° relative to an optical axis (especially, a solid state light source provide a substantially Lambertian distribution of the light source light), wherein especially a first part of the light source light can reach the lens comprising optical element without a redirection, and a second part of the light source light cannot reach the lens comprising optical element without a redirection; and (c) the light redirection element is configured to redirect essentially all of the second part of the light source light (as redirected light source light) to cross a plane (P) through the optical axis upstream of the lens, of which at least a part to the second lens part having total internal reflection functionality, especially wherein the redirection element is configured to redirect especially at least 50%, like at least 60%, such as especially at least 80%>, of said redirected light source light to said second lens part having total internal reflection functionality, the light redirection element does not extend beyond the light source in an upstream direction along the optical axis for precluding redirection of light source light back to the light source.

With such lighting device substantially the full hemisphere of a LED light source, that substantially emits Lambertian, may be collected. The optics with TIR-Fresnel lens designs may efficiently beam shape the light of the light source (collimate the light source light). With this design, the lighting device can be relatively small (thin), as the light of the light source light that does not directly reach the optical element that may be configured close to the leach source, nevertheless may reach the optical element via redirection (reflection, including optionally refraction). With the special design of the optical element a good collimation may be obtained. With this design, the lighting device may also be light. The lens comprising optical element is especially configured to beam shape the light source light, more especially to collimate the light source light. Both the first part and the second part of the lens comprising optical element are configured to beam shape the light source light, more especially to collimate the light source light. The efficiency of the light source unit may be equal to or over 80%, such as at least 85%, even more especially at least 90%.

The redirection of the rays of the light source may in principal include a relatively small redirection, including a redirection to a part of the second lens part (having total internal reflection functionality) closest to the (part of the) redirection element. In such instance, the redirected light stays at the same side of the optical axis. Hence, in embodiments the light redirection element is configured to redirect at least part of the second part of the light source light to (part of) the second lens part (having total internal reflection

functionality) without crossing a plane through the optical axis, but these types of

embodiments do not form part of the invention. However, the redirection element may also direct essentially all of the second part of the light source light to that part of the second lens part (having total internal reflection functionality) across the optical axis. Therefore, in embodiments according to the invention said light redirection element is configured to redirect essentially all of the second part of the light source light to the second lens part (having total internal reflection functionality) with crossing a plane through the optical axis. The former embodiments, not according to the invention, may be easier to align and may have better collimation, whereas the latter embodiments may be smaller sized and more light- weighted and the redirection element may be configured closer to the light source.

Here, the term "collimation" and similar terms especially refer to reshaping the source light into a beam of rays such that light rays are made (more) parallel and hence the beam spread is minimized as much as possible when propagating. The field angle of the light source may be substantially reduced with the optical element and redirection element from well over 45° to well below 45°, such as below 25°. The field angle of a solid state light source is especially in the range of about 90-180°, such as in the range of about 135-180°. The phrase "a light exit angle (σ) larger than 45° relative to the optical axis" especially implies that the light source provides such a light distribution of the light source light that part of the light source light is provided as light rays within an angle of 45° with the optical axis, but also part of the light source light includes light rays having angles larger than 45° with the optical axis. Especially, this may apply e.g. for solid state light sources. Hence, the light source is especially configured to provide light source light having a light distribution with light rays with angles smaller, equal to and larger than 45° relative to the optical axis. Hence, the light source is herein especially defined as configured to generate light source light having a light exit angle (σ) larger than 45° relative to the optical axis.

The lighting device may especially be used as spot light or as stadium light.

Further, especially the lighting device may be used for outdoor lighting, such as stadium lighting but also for e.g. job site lighting, such as construction lighting, etc..

The invention also provides a lighting device comprising a light source unit, the light source unit comprising a light source, a lens comprising optical element, and a light redirection element, wherein the light source unit comprises an optical axis, and wherein: (a) the light source is configured to generate said light source light having a first cross-sectional area perpendicular to the optical axis at a first distance from said light source; (b) the lens comprising optical element is configured at said first distance (dl) and configured to beam shape (especially collimate) the light source light, wherein the lens comprising optical element has a second cross-sectional area perpendicular to the optical axis, wherein said first distance may especially be selected from the range of 0.1-200 mm, and wherein said second cross-sectional area is smaller than said first cross-sectional area, thereby defining said first part of the light source light that can reach the lens comprising optical element without a redirection, and said second part of the light source light that cannot reach the lens comprising optical element without a redirection, wherein the lens comprising element comprises (i) said first lens part with Fresnel functionality configured to receive at least part of said first part of the light source light, and (ii) said second lens part having total internal reflection functionality; and (c) said light redirection element is configured to redirect at least part of the second part of the light source light (as redirected light) to the second lens part (having total internal reflection functionality), especially wherein the redirection element is configured to redirect especially at least 50%, like at least 60%, such as especially at least 80%), of said redirected light source light to said second lens part having total internal reflection functionality. In a specific embodiment, the light source comprises a solid state light source, such as a LED. The term "light source" may also relate to a plurality of light sources, such as 2-512 (solid state) LED light sources. Hence, the term LED may also refer to a plurality of LEDs. In the present invention, however, each unit may especially include a limited number of (solid state) light sources, such as 1 -20 LEDs. Optionally, a light source unit may comprise a plurality of light sources, with each light source comprising a light direction element.

Especially, the light source unit comprises no more than 20 solid state light sources, such as 1-16, like 1-4 solid state light sources, such as a single solid state light source.

Especially, the lighting device is configured to provide white light. Hence, especially the light sources are configured to provide white light. For instance, phosphor converted LEDs may be applied. The term white light herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2700 K and 6500 K, and especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

The light source light generated by the light source may have a Lambertian distribution that is characterized by a cosine dependence and has a beam angle or

equivalently full width half maximum (FWHM) of 120° and thus an exit angle well over 45° relative to the optical axis (the exit angle may approximately be 90° relative to the optical axis, i.e. about an opening angle or apex cone angle of about 180°). In a specific

embodiment, the light source may (already) comprise an optical element, such as a reflector or lens (to be distinguished from the redirection element and lens comprising optical element respectively). In such embodiment, the exit angle, relative to the optical axis, may be smaller than for a solid state light source, but will still be more than 45° relative to an optical axis of the combination of the light source including reflector and/or lens.

Hence, the invention is especially useful for light sources having an exit angle well over 45°, such as at least about 60°, like even about 90° (hemisphere). Likewise, the field angle of the light source light may be well over about 45°, such as at least about 60°, such as at least 75°, such as at least 90°, like over 135°. In general, for a light source the beam angle is smaller than the field angle, which is smaller than 2*σ (twice the exit angle).

At the first distance the lens comprising optical element may be arranged. The term "lens comprising optical element" refers to an optical element that comprises a lens. Hence, the lens comprising optical element especially has a lens function. More especially, the lens comprising optical element has a collimation function. The lens comprising optical element is especially configured as light transmissive window. Hence, light source light generated upstream from the lens comprising optical element is especially transmitted and redirected by the lens comprising optical element to provide a (collimated) beam of light downstream from the lens comprising optical element.

The lens is especially arranged at said first distance is selected from the range of 0.1-200 mm, more especially 0.1-100 mm. Yet even more especially, said first distance is selected from the range of 0.1-25 mm.

At this first distance, the light source light (beam) has a first cross-sectional area perpendicular to the optical axis. In the present invention, the (second) cross-sectional area of the optical element is smaller than of the cross-sectional area of the light source beam at the same first distance defined by the exit angle. The second cross-sectional area of the optical element may especially be in the range of 1 -10,000 mm2, such as especially in the range of 1-400 mm2. The cross-sectional area may be substantially equal to a surface area.

As indicated above, collecting a cone angle of 65° already requires the diameter of a planar lens to exceed two times the focal distance. Further, when the exit angle is larger than 45° relative to the optical axis an optical element having only Fresnel functionality does not have optimal properties. An optical element relatively close to Lambertian light source is desirable in view of device depth (thickness). However, the beam width or exit angle is so large, that the cross-section of the beam at the optical element is substantially larger than the cross-section of the optical element. As said second cross- sectional area is smaller than said first cross-sectional area, thereby automatically a first part of the light source light is defined that can reach the lens comprising optical element without a redirection, and a second part of the light source light that cannot reach the lens comprising optical element without a redirection. The first part will be closer to the optical axis and the latter part will diverge further away from the optical axis. The latter part is herein especially also indicated as complementary exit angle, i.e. that part of the light source light that cannot directly reach the optical element.

The lens comprising element comprises (i) a first lens part with Fresnel functionality configured to receive at least part of said first part of the light source light, and (ii) a second lens part having total internal reflection functionality. Both lens parts are (of course) transmissive for the light source light. As indicated above, TIR elements may be better able to redirect the large exit angle light source rays upstream from the lens into a desired beam downstream from the lens, and Fresnel elements may be better able to redirect the small exit angle light source rays upstream from the lens into a desired beam downstream from the lens (see also below). Hence, in a specific embodiment said second lens part (having total internal reflection functionality) circumferentially surrounds said first lens part. Hence, in specific embodiments the lens comprising element comprises a first lens part especially configured to collect rays within a cone angle relative to the optical axis below about 55°, like below about 50°, such as up to about 45°, and a second lens part is especially configured to collect rays within a cone angle relative to the optical axis larger than about 35°, like larger than about 40°, such as larger than about 45°, such as above about 55°. The latter part will especially receive redirected light, whereas the former part may not substantially receive redirected light in order to maintain collimation. Hence, especially the first lens part is configured within a cone with a cone angle relative to the optical axis and the second lens part is configured at a larger angle than said cone angle, wherein the cone angle is selected from the range of 35-55°, especially 40-50°, even more especially about 45°.

The terms "upstream" and "downstream" relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the first light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is "upstream", and a third position within the beam of light further away from the light generating means is "downstream".

As part of the light source light will not reach the optical element without additional measures, the invention provides a redirection element which redirects the large exit angle light source light in the direction of the optical element. However, in order to optimize the beam shape of the beam of light downstream from the optical element, especially the redirection element predominantly directs this (otherwise lost) light source light to the lens part with the TIR structures.

Therefore, in embodiments the light redirection element is especially configured to redirect at least part of the second part of the light source light within the range of 45-90° (relative to the optical axis). This is because for angles > 45°, TIR can be used to deflect the beamlets parallel to the optical axis. Hence, the light redirection element is especially configured to redirect at least part of the second part of the light source light to the second lens part (having total internal reflection functionality). Especially, the ratio of the light source light directed to the first part relative to the light source light directed to the second part is <1, even more especially < 0.5, such as especially <0.2. Hence, in specific embodiments the light redirection element is configured to redirect at least part of the second part of the light source light as redirected light source light to the second lens part (having total internal reflection functionality), wherein said redirection element is configured to redirect at least 80% of said redirected light source light to said second lens part (having total internal reflection functionality).

The redirection element especially comprises a reflective element. For instance, the reflective element may include a metal mirror. However, also elements making use of refraction (thus also reflection) may be used. For instance, when using (also) TIR structures for at least part of the redirection element, the beam shaping may be further optimized as the second part of the light source light may even better be directed to the

(second part of) the optical element. Hence, in specific embodiments the redirection element comprises a refractive element. Note that the redirection element may have a substantially rotational geometry, circumferentially surrounding the light source and/or the optical axis. Further, the redirection element may especially be configured at a redirection angle (η) with the optical axis (O) selected from the range of 50-85°, especially 55-80° (e.g. providing a cone with opening angle 100-170° or 1 10-160°, respectively). In this way, a substantial part of the light received by the redirection element can be redirected (as redirected light) to the second lens part. Hence, the redirection element is configured to redirect at least 60%, such as especially at least 70%, such as even more especially at least 80%), of said redirected light source light to said second lens part having total internal reflection functionality. By choosing the redirection angle and/or configuration of the refractive element of the redirection element, the redirected light may be redirected to substantially only the second lens part. The redirection element may in embodiments include reflective facets or planes (i.e. reflective elements), configured at different redirection angles. Alternatively or additionally, the redirection element may include a plurality of refractive elements (TIR), which can be configured to redirect the light to substantially only the second lens part.

The lighting device can have a light redirection element which is configured to redirect a part of the second part of the light source light to the second lens part having total internal reflection functionality with crossing the plane P through the optical axis at an angle φ with the optical axis in the range of 50° to 70°. If the angle φ is larger than 50°, it is practically ensured that redirected light impinges on the second lens part and not on the first lens part as said angle is a relatively close low boundary to the typically and generally used shielding angle of 65°. By limiting the angle φ up to 70°, the size of the lens can be limited without the redirected rays to be redirected to areas outside the lens as said angle is a relatively close high boundary to said typically and generally used shielding angle of 65°.

The lighting device can have a light redirection element which has a specular or a TIR reflector surface concavely curved towards the optical axis, such that for each redirected ray an angle φ between a ray as issued and after being redirected differs at the most by 25° from the angle φ of other redirected rays. Then the redirection of all the light beamlets/rays is about constant, i.e. is over about the same angle, which enables a

simplification of the design/shape of the redirection element.

As indicated above, the lens comprising optical element may especially comprise a first part with Fresnel functionality and a second part with total internal reflection functionality. Both parts are configured to beam shape light source light that enters the optical element at an upstream face into a light beam (herein also indicated as "light source unit beam") downstream of the optical element, which leaves the optical element at a downstream face. The beam angle at the downstream face may be below about 45°, such as below about 35°, like even below about 25°, such as equal to or less than 20°. The field angle may be below about 40°, such as below about 30°, like below about 25°, like in the range of 10-25°. Hence, especially the light source unit provides a beam of light downstream from the optical element that is substantially more collimated than the light source light upstream of the optical element. In specific embodiments, the lens comprising optical element is configured to beam shape the light source light into a beam having a beam angle (Θ) of equal to or less than 45°, especially equal to or less than 35°, such as more especially equal to or less than 25°, like yet more especially equal to or less than 20°, such as in the range of 5-20°, like 10-15°. In specific embodiments, the lens comprising optical element is configured to beam shape the light source light into a beam having a field angle below about 40°, such as below about 30°, like below about 25°, such as in the range of 5-30°, like in the range of 10- 25°. For instance by choosing the optical structures comprised by the first lens part and second lens part, the desired collimation may be obtained. For instance, the position and angle of facets of refractive structures or reflective structures may be chosen such that the desired collimation is obtained.

The first part of the optical element and second part of the optical element are especially arranged at different distances from the optical axis (of the light source unit). Assuming the optical element having a longest length (or diameter), relative to the optical axis, the first part may e.g. be configured such that it spans about a distance from 0-80% of this longest length and the second part may especially be configured such that it spans about a distance of 50-100% of the longest length. Especially, the first part and second part do not substantially overlap. For instance, the first part may e.g. be configured such that it spans about a distance from 0-60% of this longest length and the second part may especially be configured such that it spans about a distance of 60-100%) of the longest length. Note however that the first part and second part are not necessarily configured at the same side (or face) of the optical element. Especially, the first part with Fresnel functionality may be configured at the downstream face of the optical element. Further, especially the second part with TIR functionality may configured at the upstream face of the optical element. Such configuration appears to provide the best optical properties, such as light output and (narrow) beam shape. Especially, relative to the optical axis the Fresnel functionality part is within a cone starting from the light source to the optical element having a cone angle of about 2*45°; the remaining part beyond this cone angle may especially have TIR properties. In general, the cone angle defining this transition from the TIR part to the Fresnel part is within the range of 35-45°, such as within the range of 40-50°, such as about 45°.

Each optical element comprises a plurality of optical structures. These optical structures may especially comprise one or more of prismatic structures, lenses, total internal reflection (TIR) structures, refractive structures, facetted structures. Optionally, a subset of structures may be translucent or scattering (see also below). In general, at least a subset or all of the optical structures are transparent. The optical structures may be embedded in the optical element, and may especially be part of an optical element side (or face), such as especially a downstream side or an upstream side, or both the downstream and upstream side. Herein, the optical structures are especially further described in relation to optical structures having a Fresnel or refractive function and optical structures having a total internal reflection function. Each optical structure may comprise one or more facets

The optical structures (including facets) may be arranged at an upstream side or a downstream side or both the upstream side and downstream side of the optical element. Especially, TIR structures are especially available at an upstream side of the optical element, whereas the refractive structures, such as Fresnel lenses, may be arranged at the upstream and/or downstream side of the optical element (see also above).

Refraction is used for beam collimation for incident angles of about 0 to 45°

(relative to the optical axis), where 0° is parallel to the optical axis, and TIR is especially used beyond about 45°.

One or more of the dimensions of the facets (of these structures), especially of the TIR structures, like height, width, length, etc., may in embodiments be equal to or below 5 mm, especially in the range of 0.01-5, such as below 2 mm, like below 1.5 mm, especially in the range of 0.01 -1 mm. However, other dimensions may also be possible. The diameters of the refractive Fresnel/TIR lenses may in embodiments be in the range of 0.02-50 mm, such as 0.5-40 mm, like 1-30 mm, though less than 30 mm may thus (also) be possible, like equal to or smaller than 5 mm, such as 0.1-5 mm. The diameters may also be much larger, such as e.g. up to 50 cm. The height of these facets will also in embodiments be below 5 mm, such as below 2 mm, like below 1.5 mm, especially in the range of 0.01 -1 mm. However, other dimensions may also be possible. Here the term "facet", especially in TIR embodiments, may refer to a (substantially) flat (small) faces, whereas the term "facet", especially in Fresnel embodiments, may refer to curved faces. Thus curvature may especially be in the plane of the optical element, but also perpendicular to the plane of the optical element ("lens"). The Fresnel lenses are not necessarily round, they may also have distorted round shapes or other shapes. By choosing the dimensions, the (redirected) light may be collimated with the desired collimation. Hence, the dimensions may vary over the lens comprising optical element to optimally collimate all light received by the lens comprising optical element.

A lighting device may include one or more of the herein described light source units. Hereby, the lighting device may provide an intense lighting device beam having well defined optical properties. Hence, especially the optical axes of the light source unit are configured substantially parallel when more than one light source unit is comprised by the lighting device. Therefore, in embodiments the lighting device comprises a plurality of said light source units. For instance, a substrate may be provided with a plurality of solid state light sources and a plurality of light redirection elements. Thereon, or at some distance the lens comprising optical elements may be provided. Especially, the lighting device comprises a foil comprising a plurality of said lens comprising optical elements. Each of the optical elements may be optically coupled to a light source. Optionally, a subset of the plurality of light sources share a single lens comprising optical element.

Foils can be very thin and can e.g. easily be stretched between e.g. the walls of a light chamber. The foil may be configured to a window or may be configured as window.

The total thickness of the windows(s) (or foils) may be in the range of 0.2-20 mm, especially 0.2-5 mm, including the optical elements. The window(s) may have cross- sectional areas in the range of 4 mm2 - 50 m2, although even larger may be possible. Also tiles of windows, arranged adjacent to each other, may be applied. The windows are transmissive, i.e. at least part of the light, especially at least part of the visible light illuminating one side of the window, i.e. especially the upstream side, passes through the window, and emanates from the window at the downstream side. This results eventually in the lighting unit light. Especially, the windows comprise, even more especially substantially consist of, a polymeric material, especially one or more materials selected from the group consisting of PE (polyethylene), PP (polypropylene), PEN (polyethylene naphthalate), PC (polycarbonate), polymethylacrylate (PMA), polymethylmethacrylate (PMMA) (Plexiglas or Perspex), cellulose acetate butyrate (CAB), silicone, polyvinylchloride (PVC), polyethylene terephthalate (PET), (PETG) (glycol modified polyethylene terephthalate), PDMS

(polydimethylsiloxane), and COC (cyclo olefin copolymer). However, other (co)polymers may also be possible. Hence, also the window regions of the respective windows are transmissive for at least part of the light of the light source(s).

The optical structures may include optical structures that are configured to couple light out after total internal reflection (TIR) (and then refraction). Alternatively or additionally, optical structures may include optical structures that are configured to (directly) couple light out after refraction; this is especially the case for the optical structures comprised by the part of the optical element having Fresnel functionality. Hence, the beam shaping properties of the beam shaping element may especially be provided by optical structures that impose total internal reflection to the light source light, and provide lighting device light after outcoupling via refraction of the light source light after internal reflection. Additionally, the beam shaping properties of the beam shaping element may especially be provided by optical structures that impose refraction to the light source light without previous reflection within the optical structure, and (thus) provide lighting device light after outcoupling via (only) refraction of the light source light (optical structures used for Fresnel functionality). The former structures are herein also indicated as TIR structures, wherein the latter are herein also indicated as refractive structures. Hence, TIR optical structures may also be indicated as TIR+refraction optical structures. As indicated below, an optical structure may also provide both effects, dependent upon the base angles of the facets of the optical structures.

The optical structures, as indicated above, may have different facets. Hence, a single optical structure may in embodiments also provide via one facet outcoupling via (first) TIR and via another facet outcoupling via (direct) refraction.

The lighting device 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, green house lighting systems, horticulture lighting, etc..

BRIEF DESCRIPTION OF THE DRAWINGS

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:

Figs.l a-lh schematically depict some aspects of the invention;

Figs. 2a-2d schematically depict some further aspects of the invention;

Figs. 3a-3h schematically depicts some aspects and examples of the invention, including some comparative results; and

Fig. 4 schematically depicts the redirection element in more detail.

The schematic drawings are not necessarily on scale. DETAILED DESCRIPTION OF THE EMBODIMENTS

The lens comprising optical elements especially include optical structures that are configured to generate the Fresnel functionality or TIR functionality. Embodiments of these optical structures ("structures"), indicated with reference 230, are further described below.

Figures la and lb show a facet array in 2D and in 3D, respectively. The tops of the optical structures 230 are indicated with reference T; the distance (or pitch) between the tops is indicated with reference TD. References 231 (and Fl and F2) indicate faces or facets. Reference γ indicates the facet or Fresnel lens angle (assuming a Fresnel part of the optical element). Fig. lb schematically depicts facet. However, also ring-like structures (including facets) may be applied. Figure lc shows a TIR structure in 2D. In Figure lc, light enters the left surface by refraction. Then it reflects at the second surface by TIR. To get from this 2D model to a 3D model, in a non-limiting embodiment, we sweep the 2D model around the vertical axis. This gives the rotationally symmetric structure that is also depicted in Figure Id. Here, ring-like structures are schematically depicted, though also other kind of structures may be provided (such as similar to Fig. lb). Reference 6in indicates the angle of incidence of a ray of light (arrow) on the structure and 6m indicates the angle of refraction in the medium and 6out indicates the refraction out of the medium. Reference a indicates the angle of the facet, indicated with reference Fl, with the plane of the optical element, such as a foil comprising the optical element (see also below); and reference β indicates the (other) facet, indicated with reference F2. Hence, the TIR structures may especially be indicated by the angles a and β, which are especially in the order of about at least 30°. The value of γ is especially in the range of at maximum 55°; this is the angle of facet Fl with the plane of the optical element, such as a foil comprising the optical element. The angle of facet F2 with the plane of the optical element, such as a foil comprising the optical element in the case of TIR refractive structures may especially be close to perpendicular, such as > 80°. Note that in case of Fresnel lenses, the facets Fl may be curved, and the indicated angle γ may especially be a maximum angle.

Fig. 1 e schematically depicts a side view of a lighting device 1 and a light source unit 10. The lighting device 1 comprises the light source unit 10. The light source unit 10 comprises a light source 100, a lens comprising optical element 200, and a light redirection element 300. The light source unit 10 comprises an optical axis O. The lens comprising optical element 200 comprises a first lens part 210 with Fresnel functionality, and a second lens part 220 having total internal reflection functionality. The light source 100 is configured to generate light source light 101 having an light exit angle σ larger than 45° relative to the optical axis. The reference TIR refers to the second lens part 220, having TIR properties; the reference RF refers to the first lens part 210, having refractive properties and especially having Fresnel functionality. Note that two TIR regions, i.e. second lens parts (having total internal reflection functionality), indicated with reference 220, are arranged at both sides of the optical axis, indicated with O, with the first lens part, or Fresnel

functionality lens part, indicated with reference 210, in between. Hence, the second lens part 220 may circumferentially surround the first part 210. Reference 300 indicates the light redirection element, such as a mirror. Reference 100 indicates a light source, especially a solid state light source, indicated with reference 120. The functional combination of light source 100, lens comprising optical element 200 and light redirection element 300 is herein also indicated as light source unit, indicated with reference 10. The solid angle of a

Lambertian light source is very large, as the light is substantially entirely distributed over a hemisphere. The exit angle or light exit angle, i.e. the angle within the light source light 101 is distribution along the optical axis is indicated with reference σ, which may be close to 90° (here depicted as 90°). The field angle, not depicted, and the beam angle, also not depicted, of the light source of the light source light (upstream of the Note that the reflector 300 blocks those rays at a very large solid angel. Or, the light rays escaping from the light source 100 at very large exit angles σ are blocked by the reflector. The reflector 300 provides an angle, or mean angle over the length of the reflector length LI, herein indicated as reflector angle or redirection angle η. Note that this reflector angle or redirection angle with the optical axis O is essentially always between 45-90° (relative to the optical axis), such as in the range of 45- 80°, like 55-80°. With reflector part of the light that would otherwise be lost is now redirected to the optical element 200. The reflector or redirection element has a (reflector) length LI, which may e.g. be in the range of 1-100 mm, such as 1-10 mm, like 1-5 mm.

Especially, the length LI may be such that the redirection element substantially extend to the lens element 200. By way of example, here the light source comprises a solid state light source including a dome. By choosing the optical structures comprised by the first lens part and second lens part (examples of these optical structures can be found in Figs, la- Id), the desired collimation downstream from the lens comprising optical element 200 may be obtained. For instance, the position and angle of facets of refractive structures or reflective structures (see also Figs, la- Id) may be chosen such that the desired collimation is obtained.

The collecting angle of the lens comprising optical element is especially defined by the length/width or diameter of the lens comprising element. A virtual cone starting from the light source to the optical element with a cone angle smaller than about 45° may especially define at the lens comprising optical element the first lens part 210, and the part with a larger cone angle than about 45° may especially define at the lens comprising optical element the second lens part 220. The TIR part of first part 210 may especially be found with a cone angle of 45° (opening angle 2*45°). The remaining part, the second part 220 may be addressed by light source light that is first redirected by the redirection element 300, which is further explained in more detail.

In the schematically depicted embodiment of Fig. le, and assuming the lens comprising optical element 200 and the redirection element to be essentially rotational symmetric with respect to the optical axis O, the reflector angle η is also cone angle; and in Fig. le the exit angle σ is also a cone angle. Hence, the lens comprising optical element and redirection elements schematically depicted herein may especially be configured rotationally symmetric relative to the optical axis.

Fig. 1 f schematically depicts a top view of an embodiment of the lens comprising element 100. The reference "T" refers to a top of an optical structure.

Figs, lg-lh further provide some aspects and variants of the optical element.

Reference dl indicates the distance between the light source 100 and the first window 200. The distance dl may especially be in the range of 0.1-25 mm, such as 1-8 mm; though larger distances may also be possible, such as e.g. up to 20 cm. Fig. lg schematically depicts some options to vary the optical structures 230, here very schematically depicted as prismatic structures, for instance with slightly changes facets 231 , like including convex (or concave) facets at some of the facets of the prismatic structures. Reference γ indicates the top angle of the optical structures, reference h indicates the height and reference w indicates the width. Additionally or alternatively, one or more of these parameters may vary over the lens comprising optical element 200 to provide the desired optical properties. Hence, the shape of the optical structures 230 may vary over the lens comprising optical element 200 in one or more of (i) the mutual angle (γ), a (ii) height-width ratio, and (iii) a shape of a facet. In this graph, especially the shape of the facets are varied from flat to curved. Reference 107 indicates e.g. an LED die.

By way of example, only three optical structures 230 have been indicated in this drawing, at each side of the optical axis O of the light source 100. Reference d2 indicates the distance along the transmissive window, calculated from the optical axis. The value of d2 at the edge is d2max, which may e.g. be in the range of 0.2-50 mm, especially 0.5-10 mm. Hence, reference d2max indicates the edge of the lens comprising optical element 200.

The optical structures 230 may include different facets, which are by way of example indicated as first facet Fl and second facet F2. In fig. l g, the first facets Fl may (re)direct the rays, indicated with reference(s) lr, via (direct) refraction, whereas the second facets may (re)direct the rays after total internal reflection (TIR) and refraction. Up to a value of about d2/dl=l, the first facets Fl may be configured to redirect the light source light via direct refraction, i.e. a single refraction. At a value larger than about d2/dl=l, i.e. at angles of the rays lr with the lens comprising optical element 200 smaller than about 45°, the first facets or refractive facets, may refract in the direction of the second facets F2, and after TIR (and refraction) the rays are redirected. Reference d2 indicates the distance along the lens comprising optical element 200 calculated from the optical axis 0. Hence, d2=0 right above the light source 100 in this schematic embodiment. Especially, refractive facets may be arranged at one or more of the upstream face 1210 and the downstream face 1220, whereas TIR faces may only be arranged on the upstream face of the lens comprising optical element 200.

Fig. lh schematically depicts a further embodiment of the lens comprising optical element 200, here with by way of example the optical structures 230 arranged at the upstream face 1210 instead of the downstream face 1220. The position and angle of facets of the optical structures 230, especially refractive structures and reflective structures, may be chosen such that the desired collimation is obtained (see also Figs. 3a-3h). Figs, lg and li are only examples of possible embodiments. Alternative embodiments, such as shown below, or combinations thereof, etc., may also be possible to obtain the desired mixing.

Fig. 2a schematically depicts an embodiment of a lighting device 1 comprising a light source unit 10. Here, a first part 101a of the light source light 101 can reach the lens comprising optical element 200 without a redirection, and a second part 101b of the light source light 101 cannot reach the lens comprising optical element 200 without a redirection. Note that in this schematic drawing the exit angle σ is chosen about 80°. The light source unit 10 comprises a light source 100 configured to generate light source light 101 having an optical axis O and an exit angle σ defining a first cross-sectional area Al perpendicular to the optical axis O at a first distance dl from said light source 100. Hence, the thus obtained cone of light source light provides at distance dl a cross-section Al . The light source unit 10 further comprises a lens comprising optical element 200 configured at said first distance dl and configured to beam shape the light source light 101, wherein the lens comprising optical element 200 has a second cross-sectional area A2 perpendicular to the optical axis O.

Especially, the first distance dl is selected from the range of 0.1-200 mm. further, as depicted the second cross-sectional area A2 is smaller than said first cross-sectional area Al . Thereby, a first part 101a of the light source light 101 that can reach the lens comprising optical element 200 without a redirection is defined, and also a second part 101b of the light source light 101 that cannot reach the lens comprising optical element 200 without a redirection is defined. Further, the lens comprising element 200 comprises a first lens part 210 with Fresnel functionality configured to receive at least part of said first part 101a of the light source light 101, and a second lens part 220 having total internal reflection functionality. Further, the light source unit 10 comprises a light redirection element 300 configured to redirect at least part of the second part 101b of the light source light 101 to the second lens part 220 having total internal reflection functionality. Further, A2 is especially larger than dl *(V2). Fig. 2b schematically depicts the embodiment of Fig. 2a in perspective. The redirection element 300 may include a reflective element 305 and/or a refractive element 306 (see Figs 34-3i). Angle η indicates the angle the reflective element or redirection element 300 makes with the optical axis O. This angle is especially larger than about 45°. In fig. 2b, the rotational symmetry about the optical axis O is depicted in some more detail. The cone angle defined by the cone including the first lens part 210 may especially be about 45°, such as in the range of 55-35°, especially 40-50°. By way of reference, this cone angle is indicated with reference ηΐ . The reflector angle or redirection angle is indicated with reference η. Hence, the first lens part 210 is configured within a cone with a cone angle nl relative to the optical axis O and the second lens part is configured at a larger angle than said cone angle ηΐ, wherein the cone angle nl is selected from the range of 35-55°, especially 40-50°, even more especially about 45°.

Fig. 2c schematically depicts an embodiment wherein the lighting device 1 comprises a plurality of said light source units 10. In such embodiment, the lighting device may comprise a foil 1200 comprising a plurality of said lens comprising optical elements 200. The lighting device 1 is especially configured to provide lighting device light 2, as depicted in Fig. 2d, based on one or more light source units 10 (see other Figures).

The design of the invention may thus include a reflector with a shape and orientation such that the ray set of the complementary solid angle is redirected towards the TIR part of the TIR Fresnel lens. As a result ray deflection via the TIR-Fresnel lens yields an increase in beam intensity, such that the beam broadening is small compared to deflection via refractive facets. There two reasons why the TIR facets yield a higher degree of collimation with respect to refractive facets: (a) TIR facets in a TIR-Fresnel lens design preserve etendue more than refractive facets as both the collecting and the extracting facet have an orientation nearly perpendicular to the beamlet direction. This is in contrast with refractive facets that in a typical collimating Fresnel design are oriented under grazing incidence. Grazing incidence for collecting and extracting facets broaden narrow beamlets; (b) the distance between TIR facets and the lens' focal point is larger than that for refractive facets and the focal point. As a result they are more tolerant for deltas on the exact source position. Thus beamlets originating from the reflecting element are deflected in a direction very similar as beamlets originating directly from the light source. This is clearly visualized in the figures.

In a first comparative example a single specular reflecting surface for small angular deflection is used, with a polished metal or ESR (3M) surface. The source size was lxl mm2; the source-lens distance was 5 mm, and the lens radius was 10 mm. The flux used is 100 1m.

Fig. 3a-3b show the geometry and luminous intensity without reflecting element. The rays indicated with reference 101b are in the solid angle that cannot be captured by the planar lens element. The following data are obtained:

coll. flux: 80 lm

lum. intensity: 1809 cd

beam angle: 10.9°

field angle: 21°

The term beam angle may especially refer to the angle between the two directions opposed to each other over the beam axis (optical axis) for which the luminous intensity is half that of the maximum luminous intensity. The luminous intensities are measured in a plane normal to the nominal beam centerline. If the beam is not rotationally symmetric, then the beam angle is usually given in two planes at 90° of each other, possibly the maximum and minimum angles. The field angle is the angle between the two directions opposed to each other over the beam axis for which the luminous intensity is 10% that of the maximum luminous intensity. The efficiency of the light source unit is about 80% (100 lm in; 80 lm out).

Fig. 3c-3d shows the geometry and lum. intensity with the reflecting element. Rays indicated with reference 101b make a 5° angle with respect to the optical axis O. The following data are obtained:

coll. flux: 94 lm

lum. intensity: 1813 cd

beam angle: 13°

field angle: 21°

The beam performance is closely related to the geometric layout: i.e. source lens distance and the source size. These are kept constant in the comparison. Of course one may obtain more narrow beams by decreasing the source size or increasing the source-lens distance.

For the sake of visualization a small part of the rays is not deflected towards the TIR structure. One part of these rays are deflected to the refractive structure (first optical element part 210). It is apparent that degree of collimation is not preserved in the refractive part. In the example and embodiment as schematically depicted in Fig. 3 c, it is also shown that the light redirection element 300 is configured to redirect at least part of the second part 101b of the light source light 101 as redirected light source light 101b' to the second lens part 220, such as e.g. wherein said redirection element 300 is configured to redirect at least 80%) of said redirected light source light 101b' to said second lens part 220. Fig. 3c also schematically shows that when the second part 101b of the light source light is not substantially redirected to the second lens part 220 of the optical element 200, i.e. to the TIR structures, but to the refractive part with Fresnel properties, i.e. the first lens part 210, the deflection becomes less controlled/desired.

In an inventive embodiment the rays are deflected by a specular reflecting surface such that the deflected rays are extracted by the TIR facets across the optical axis, i.e. light rays or beamlets are redirected by the redirection element arranged on one side of a plane P in which the optical axis o lies to a lens part which is located on another side of said plane P. The optical performance is shown below.

Fig. 3e-3f shows the geometry and lum. intensity with specular reflecting element. Rays indicated with reference 101b make a 10° angle with respect to the optical axis O. The following data are obtained:

coll. flux: 89 lm

lum. intensity: 1809

cd beam angle: 10.9°

field angle: 22°

An additional 9 lumens is collected by the receiver with respect to the design without specular reflector, but less than in the example where the light is redirected without crossing the optical axis (plane). The rays extracted via the TIR facets make an angle of about 10° with the optical axis and hence marginally increase the field angle.

In this geometry the location of the virtual source, i.e. the source position where the blue rays appear to originate from the lens point of view, is on the right side of the real source at a distance about twice the spacing between the real source and the reflecting mirror.

This is in contrast with the first proposed embodiment where the virtual source appears to be located on the optical axis somewhat behind the real source.

This difference in virtual source location makes that the light exit angle at the

TIR facets (with respect to the optical axis) is 5° in the first example and 10° in the second example.

The length of the reflector in the second embodiment is significant smaller than the first embodiment and can be even further reduced when positioned closer to the source. It depends on the applied mass manufacturing technology to determine the minimal size.

In a further embodiment one may use a TIR reflector as reflective element 300 with subsequently collecting and extracting facets. Compared to the first embodiment this has the benefit of increased beamlet control as besides the reflecting surface two additional refractive interfaces are at one's disposal. This embodiment is schematically depicted in Figs.

3g-3h. The following data are obtained:

coll. flux: 88 lm

lum. intensity: 1200 cd

beam angle: 15° field angle: 22°

efficiency: 88%

With devices of the invention efficiency of the light source units of at least 85% may be obtained.

Fig. 4 schematically depicts an enlarged cross section of the lighting device 1 showing the redirection element in more detail. In the figure two types of redirection elements are shown, both the light redirection elements do not extend beyond the light source in an upstream direction 440 along the optical axis for precluding redirection of light source light back to the light source (the downstream direction is indicated by reference number 430). In Fig. 4 on the left a reflective redirection element 300' is shown which redirects beamlets/rays 101b without said redirected rays crossing a plane P comprising the optical axis O. It is clear from the figure that redirection element 300' must be relatively large, i.e. needs to extend from the light source 100 to the lens 200 to obviate glare because of light rays escaping beyond exit angle σ, through a gap 470 between the lens and the redirection element. Because of the size of the redirection element 300', the light source together with the light direction element cannot simply be mounted in an unobtrusive way, and generally will remain visible together with the lens. As a random example, in Fig. 4 the exit angle σ is 40° but typically light exit angle σ is 65° or less to avoid glare.

In Fig. 4 on the right a reflective redirection element 300 is shown which redirects beamlets/rays with said redirected rays crossing, upstream of the lens 200, the plane P comprising the optical axis O. It is clear from the figure that the redirection element 300 can be relatively small, i.e. needs only to extend from the light source 100 over a relatively small section of the distance from light source to the lens 200, to obviate glare. All light rays 101b issued from the light source at a respective angle δ larger than light exit angle σ are redirected over a respective redirection angle φ by redirection element 300 and cross a redirected rays 101b' the plane P/optical axis at a respective angle cp. As shown in Fig. 4 the angle φ is about constant enabling a relatively simple curvature 460 of reflective portion 450 of the redirection element. The desired local tangent 420 to the curvature, which makes an angle ε with a line O' parallel to the optical axis O, can simply be calculated, for a reflective redirection element, with the formulae: ε = (δ - cp) / 2 This means the ε can also become negative. Because of the size and typical curvature of the redirection element 300, the light source together with the light direction element can be mounted in an unobtrusive way, for example mounted inside a relatively small opening in a surface, for example a ceiling, with only the lens being visible and yet render the lighting device to be relatively efficient.

The term "substantially" herein, such as in "substantially all light" or in "substantially consists", will be understood by the person skilled in the art. The term

"substantially" may also include embodiments with "entirely", "completely", "all", etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term "substantially" 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" includes also embodiments wherein the term "comprises" means "consists of. The term "and/or" especially relates to one or more of the items mentioned before and after "and/or". For instance, a phrase "item 1 and/or item 2" and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices herein are amongst others 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 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. 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. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. 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 lighting device (1) comprising a light source unit (10), the light source unit (10) comprising a light source (100), a lens comprising optical element (200), and a light redirection element (300), wherein the light source unit (10) comprises an optical axis (O), wherein:

- the lens comprising optical element (200) comprises (i) a first lens part (210) with Fresnel functionality, and (ii) a second lens part (220) having total internal reflection functionality;

the light source (100) is configured to generate light source light (101) having a light exit angle (σ) larger than 45° relative to the optical axis, wherein a first part (101a) of the light source light (101) can reach the lens comprising optical element (200) without a redirection, and a second part (101b) of the light source light (101) cannot reach the lens comprising optical element (200) without a redirection; and

the light redirection element (300) is configured to redirect essentially all of the second part (101b) of the light source light (101) to cross upstream of the lens a plane (P) through the optical axis (O) , of which at least a part as redirected light source light (101b') to the second lens part (220) having total internal reflection functionality, wherein said redirection element (300) is configured to redirect at least 50% of said redirected light source light (101b') to said second lens part (220) having total internal reflection functionality, the light redirection element does not extend beyond the light source in an upstream direction (440) along the optical axis for precluding redirection of light source light back to the light source.

2. The lighting device (1) according to claim 1, wherein:

the light source (100) is configured to generate said light source light (101) having a first cross-sectional area (Al) perpendicular to the optical axis (O) at a first distance (dl) from said light source (100);

the lens comprising optical element (200) is configured at said first distance (dl), wherein the lens comprising optical element (200) has a second cross-sectional area (A2) perpendicular to the optical axis (O), wherein said first distance (dl) is selected from the range of 0.1 -200 mm and wherein said second cross-sectional area (A2) is smaller than said first cross-sectional area (Al), thereby defining said first part (101a) of the light source light (101) that can reach the lens comprising optical element (200) without a redirection, and said second part (101b) of the light source light (101) that cannot reach the lens comprising optical element (200) without a redirection.

3. The lighting device (1) according to claim 2, wherein said first distance (dl) is selected from the range of 0.1-25 mm, and wherein said light source light (101) comprises a solid state light source (120).

4. The lighting device (1) according to any one of the preceding claims, wherein the redirection element (300) is configured at a redirection angle (η) selected from the range of 55-80° with the optical axis (O), comprises a reflective element (305) and wherein the redirection element (300) is configured to redirect at least 60% of said redirected light source light (101b') to said second lens part (220) having total internal reflection functionality.

5. The lighting device (1) according to any one of the preceding claims, wherein the redirection element (300) comprises one or more of a refractive element (306) and a reflective element (305).

6. The lighting device (1) according to any one of the preceding claims, wherein first lens part (210) is configured within a cone with cone angle (nl) relative to the optical axis (O) and wherein the second lens part (220) is configured at a larger angle than said cone angle (nl), wherein the cone angle (nl) is selected from the range of 40-50°, wherein the first lens part (210) with Fresnel functionality and the second lens part (220) having total internal reflection functionality of said lens comprising optical element (200) is are configured to beam shape the light source light (101) into a beam (1 1 1) having a beam angle (Θ) of equal to or less than 20°.

7. The lighting device (1) according to any one of the preceding claims, wherein said light redirection element (300) is configured to redirect at least part of the second part (101b) of the light source light (101) having an exit angle (σ) selected from the range of 150- 180°, and wherein the redirection element (300) is configured at a redirection angle (η) with the optical axis (O) selected from the range of 55-80°.

8. The lighting device (1) according to any one of the preceding claims, wherein said light redirection element (300) is configured to redirect at least part of the second part (101b) of the light source light (101) as redirected light source light (101b') to the second lens part (220) having total internal reflection functionality, wherein said redirection element (300) is configured to redirect at least 80% of said redirected light source light (101b') to said second lens part (220) having total internal reflection functionality.

9. The lighting device (1) according to any one of the preceding claims, wherein said second lens part (220) having total internal reflection functionality circumferentially surrounds said first lens part (210).

10. The lighting device (1) according to any one of the preceding claims, wherein said light redirection element (300) is configured to redirect a part of the second part (101b) of the light source light (101) to the second lens part (220) having total internal reflection functionality with crossing the plane (P) through the optical axis at an angle φ with the optical axis in the range of 50° to 70°.

1 1. The lighting device (1) according to any one of the preceding claims, wherein said light redirection element (300) has a specular or TIR reflector surface concavely curved towards the optical axis, such that for each redirected ray an angle φ between a ray (101b) as issued and after being redirected as redirected ray (101b') differs at the most by 25° from the angle φ of other redirected rays.

12. The lighting device (1) according to any one of the preceding claims, comprising a plurality of said light source units (10).

13. The lighting device (1) according to claim 12, wherein the lighting device comprises a foil (1200) comprising a plurality of said lens comprising optical elements (200).

14. Use of the lighting device (1) according to any one of the preceding claims as spot light or as stadium light.

15. Use of the lighting device (1) according to any one of the preceding claims 1-

13 for outdoor lighting.