Lighting device with an optical element having a fluid passage
A lighting device ( 1 ) comprises at least one light source ( 3 ) and at least one optical element ( 5 ). The optical element ( 5 ) may be arranged to transmit light emitted by the light source ( 3 ). The optical element ( 5 ) comprises a light transmissive material ( 7 ) and at least one passage ( 9 ) extending through the light transmissive material ( 7 ) for allowing a flow of fluid through said optical element ( 5 ). The passage ( 9 ) is arranged such that a major portion of the light ( 16 ) emitted by said light source ( 3 ) entering the passage ( 9 ) further propagates through the light transmissive material ( 7 ). The optical element ( 5 ) comprises a plurality of layers ( 18 ) of the light transmissive material ( 7 ) spaced apart from each other, each layer comprising at least one through-hole ( 11 ).
1. A lighting device comprising:
at least one light source; and
at least one optical element arranged to transmit light emitted by the light source, said optical element comprising a light transmissive material and at least one passage extending through the light transmissive material,
wherein the passage is arranged such that a major portion of the light emitted by said light source entering the passage further propagates through the light transmissive material,
wherein the at least one optical element comprises at least two layers spaced apart from each other and made of the light transmissive material, each of the at least two layers comprises a plurality of through holes that constitutes at least a portion of said at least one passage, for allowing a flow of fluid through the at least two layers of said optical element, and
wherein the through holes of one of the at least two layers are misaligned with the through, holes of another one of the at least two layers so as to reduce glare from the light source.
2. The lighting device according to claim 1 , wherein any line of sight extending from the light source and through the passage crosses the light transmissive material.
3. The lighting device according to claim 1 , wherein the passage has a shape adapted such that an imaginary straight line between a first opening and a second opening of the passage crosses the light transmissive material.
4. The lighting device according to claim 1 , wherein the optical element is provided with a plurality of passages.
5. The lighting device according to claim 1 , wherein the optical element comprises a porous material comprising pores extending through the light transmissive material.
6. The lighting device according to claim 5 , wherein the volume of the pores makes up at least 30% of the total volume of the optical element.
7. The lighting device according to claim 6 , wherein the at least one optical element is any one of a wavelength converting element, a diffuser element, and a combination of a diffuser and a wavelength converting element.
8. The lighting device according to claim 6 , wherein the light transmissive material comprises particles for scattering and/or converting a wavelength of light emitted by the light source.
9. The lighting device according to claim 6 , wherein the optical element is positioned at a distance from the at least one light source being larger than 2 cm, such as larger than 3 cm, 1 cm or 0.5 cm.
10. The lighting device according to claim 6 , wherein at least one optical element is positioned at a distance from the at least one light source being closer than 3 mm, such as closer than 2 mm, 1 mm or 0.5 mm.
11. The lighting device according to claim 1 , wherein a ratio of the thickness of the light transmissive material to the average diameter of the passage, is at least 2, such as a least 4 or 6.
12. The lighting device according to claim 6 , further comprising a fan arranged to produce a flow of fluid through the at least one passage.
13. A lamp, luminaire or light engine comprising the lighting device according to claim 1 .