Laser-based optical system

Abstract

An optical system (1) configured to guide laser light and comprising a plurality of optical fibers, each optical fiber (3-11) of the plurality of optical fibers comprising a longitudinal axis (L), a first end (12) forming a light incident plane, a second end (15), a first section (13) extending from the first end (12) to the second section (14) in a direction parallel to the longitudinal axis (L), and a second section (14) extending from the second end (15) to the first section (13) in a direction parallel to the longitudinal axis (L). And a second section (14) extending in a direction parallel to the longitudinal axis (L) from the first section (13) to the second end (15), the first section (13) comprising a first cross-section comprising a first cross-sectional area that is constant in the direction parallel to the longitudinal axis (L), at least one of the second end (15) and at least a portion (17) of the outer surface (141) of the second section (14) forming a light exit surface, the second section (14) comprising a second cross-sectional area that is constant in the direction parallel to the longitudinal axis (L), and the second section (14) comprising a second cross-sectional area that is constant in the direction parallel to the longitudinal axis (L). And the second section (14) comprises a second cross-section comprising a second cross-sectional area decreasing from the first section (13) towards the second end (15) in a direction parallel to the longitudinal axis (L), the plurality of optical fibers (3-11) being arranged in an array (2) of optical fibers, the array (2) comprising n * m optical fibers, n and m being integers, and at least one of n and m being 2 or greater.

Description

Technical Field

[0001] The present invention relates to a lamp or a luminaire comprising an optical system based on a laser or an optical system configured to guide a laser, the optical system comprising a plurality of optical fibers, each of the plurality of optical fibers comprising a longitudinal axis, a first end forming a light entrance surface, a second end, a first section and a second section. Background Art

[0002] In laser-based lighting, it is well known that light can be transmitted and delivered through optical fibers. At the end of the optical fiber, lenses or reflectors are required for beam shaping and color mixing. These components greatly increase the size of the lighting system.

[0003] Commercially available fiber combiners are known in the prior art, in which a fixed number of input fibers are fused together into one. The number of fibers is fixed, for example three or four, and cannot be changed. If it is desired to combine more or fewer fibers, a new combiner needs to be installed.

[0004] WO 97 / 34175A1 discloses a fiber optic probe assembly for weak light spectroscopy, which improves the response to subtle light-matter interactions with high analytical importance and reduces sensitivity to other major effects. This fiber optic probe assembly includes a central fiber with a flat end face at its distal end and multiple optical fibers surrounding the central fiber and having a shaped end face at its distal end. Multiple optical fibers are parallel to the central fiber at their distal ends, and the shaped end face provides an internal reflection surface for guiding the field of view associated with the multiple optical fibers to the central fiber. The optical fiber also combines filters, crosstalk inhibitors and other features to provide a high-performance probe in a sturdy package. Design changes provide side views, observations through a common aperture, observations along a common axis and other features.

[0005] JP-A-S56119108 discloses printing using a laser light source and an optical fiber bundle to increase the printing speed.

[0006] Kosterin, Andrey, ea, "Tapered fiber bundles for combining high-power diode lasers", Applied Optics, Vol. 43, No. 19, July 2004, discloses the use of tapered fiber bundles to combine the output power of several semiconductor lasers into one optical fiber to increase brightness.

[0007] US-B1-9063289 discloses a tapered coupler comprising a plurality of optical fibers in order to increase brightness. The tapering is the result of the fusion of the optical fibers in the fusion and tapering region.

[0008] US-A1-2021 / 0263217 discloses an optical coupler array for coupling multiple optical fibers to an optical device for remote communication in order to improve optical coupling between a group of isolated optical fibers.

[0009] CN-B_109621098 discloses a system for measuring spatial optical radiation using a fiber optic transmission bundle.

[0010] It is desirable to provide a laser-based optical system that is more compact and includes a reduced number of optical components. Summary of the invention

[0011] It is an object of the present invention to overcome this problem and to provide a lamp or luminaire comprising a laser based optical system which is more compact and comprises a smaller number of optical components.

[0012] According to a first aspect of the present invention, this object and other objects are achieved by a lamp or a lamp fixture, which includes an optical system configured to guide laser light, the optical system including multiple optical fibers, each of the multiple optical fibers including a longitudinal axis, a first end forming a light incident surface, a second end, a first segment and a second segment, the first segment extending from the first end to the second segment in a direction (substantially) parallel to the longitudinal axis, and the second segment extending from the first segment to the second end in a direction (substantially) parallel to the longitudinal axis, the first segment including a first cross-section including a first cross-sectional area that is (substantially) constant in a direction parallel to the longitudinal axis, at least one of the second end and at least a portion of the outer surface of the second segment forms a light exit surface, and the second segment includes a second cross-section including a second cross-sectional area that decreases in a direction parallel to the longitudinal extension from the first segment to the second end, wherein the multiple optical fibers are arranged in an array of optical fibers, the array including n*m optical fibers, n and m are integers, and at least one of n and m is 2 or greater.

[0013] Thus, the second section of each optical fiber is tapered or conical in nature. When using optical fibers of the above type, in particular when such optical fibers are arranged in an array of optical fibers, the array comprising n*m optical fibers, wherein n and m are integers and wherein at least one of n and m is 2 or greater, the obtained optical fiber bundle does not need to be fused, since the second end has a reduced size that already fits into a small area.

[0014] Thus, a defective fiber can be easily replaced with another one, and a fiber can be easily added or removed from a fiber bundle, both of which are not possible in conventional fused combiners. It is also possible to combine emissions from different fibers at different angles, such as to compensate for angular chromatic aberration, or for aesthetics.

[0015] In other words, these optics offer greater customization possibilities to luminaire manufacturers. In addition, they are easier to disassemble and separate for recycling purposes and are therefore better suited to the circular economy.

[0016] Furthermore, using optical fibers of the type described above and arranging them in an array provides an optical system configured to guide laser light, with which separate optical elements such as lenses or reflectors required for beam shaping and color mixing are no longer required. As a result, such optical systems are more compact and require a smaller number of optical elements, since no optical elements are required other than the tapered optical fibers.

[0017] In one embodiment, at least one of n and m is at least three, at least six, or at least nine.

[0018] In principle, the integers n and m can be chosen to be any desired integers. Thus, a laser-based optical system can be obtained with any desired number of optical fibers in the array of optical fibers. Therefore, the design and construction of the laser-based optical system has a large degree of freedom.

[0019] In one embodiment, at least a portion of an outer surface of the second section adjacent to the second end forms at least a portion of the light exit surface.

[0020] Thus, not only improved color mixing is achieved, but also improved exit beam broadening.

[0021] In one embodiment, the second segment includes a taper angle β defined as an angle between a longitudinal center axis of the second segment and an outer surface of the second segment, wherein the taper angle β is less than 2 degrees.

[0022] In one embodiment, the second section extends between 65% and 90% of the total longitudinal extension of the at least one optical fiber.

[0023] In one embodiment, the cross-sectional area of ​​the second end is less than 10% of the cross-sectional area at the first end.

[0024] Thus, a tapered optical fiber with a pointed or sharp second end is obtained. Such optical fibers provide an optical system configured to guide laser light, with which a high degree of broadening of the exiting light beam and / or a complex far-field light pattern or intensity pattern can be obtained.

[0025] In one embodiment, the second segment includes a taper angle β defined as an angle between a longitudinal center axis of the second segment and an outer surface of the second segment, wherein the taper angle β is between 2 degrees and 6 degrees.

[0026] In one embodiment, the second section extends between 35% and 65% of the total longitudinal extension of the at least one optical fiber.

[0027] In one embodiment, the cross-sectional area of ​​the second end is less than 25% of the cross-sectional area at the first end.

[0028] Thus, a tapered optical fiber with a second end having a small surface area is obtained. Such optical fibers provide an optical system configured to guide laser light, with which an exiting light beam with a high degree of broadening is obtained while the far-field light pattern or intensity pattern obtained is not too complex.

[0029] In one embodiment, the second segment includes a taper angle β defined as the angle between a longitudinal center axis of the second segment and a circumference of a circle circumscribing an outer surface of the second segment, wherein the taper angle β is between 6 and 15 degrees.

[0030] In one embodiment, the second section extends between 1% and 35% of the total longitudinal extension of the at least one optical fiber.

[0031] In one embodiment, the cross-sectional area of ​​the second end is less than 50% of the cross-sectional area at the first end.

[0032] Thus, a tapered optical fiber with a second end of small surface area is obtained. Such optical fibers provide an optical system configured to guide laser light, with which the exiting light beam is only broadened to a relatively limited extent, while the obtained far-field light pattern or intensity pattern is uniform and well defined.

[0033] Therefore, by adjusting the geometrical parameters of the optical fiber, in particular the taper angle β, it is generally possible to obtain a far-field light pattern or intensity pattern suitable for a particular purpose.

[0034] In one embodiment, the second end is any one of blunt and pointed or point-like.

[0035] In one embodiment, the second section is any one of a tapered shape, a conical shape, and a frustoconical shape.

[0036] The blunt second end or frusto-conical second section enables a uniform and well-defined far-field light pattern or intensity pattern to be obtained.

[0037] A pointed or point-shaped second end or a tapered or conical second section enables a more complex structure of the far-field light pattern or intensity pattern and an additional broadening of the light beam to be achieved.

[0038] In one embodiment, the first segment is configured to mix light propagating therethrough.

[0039] Thus, improved color mixing can be obtained without any additional optical elements.

[0040] In one embodiment, the second segment is configured to widen the angular spread of light propagating therethrough.The second segment is also configured to outcouple light propagating therethrough.

[0041] Thus, an improved exit beam broadening is obtained without requiring any additional optical elements.

[0042] In one embodiment, the optical fibers of the array of optical fibers all comprise cross-sections of the same shape.

[0043] In one embodiment, at least one optical fiber of the array of optical fibers comprises a cross-section having a first shape and the remaining optical fibers of the array of optical fibers comprise cross-sections having a second shape different from the first shape.

[0044] Hence, a further parameter suitable for adjusting the geometrical parameters of the optical fiber, in particular the taper angle β, is provided to obtain a far-field light pattern or intensity pattern suitable for a specific purpose.

[0045] In one embodiment, the cross-sectional shape of each optical fiber of the array perpendicular to the longitudinally extending optical fibers is any one of square, rectangular, octagonal, circular and hexagonal.

[0046] An advantage of optical fibers with a square, rectangular, octagonal or hexagonal cross-sectional shape is that the tapered ends can be stacked very densely without any gaps. This in turn provides for more compact laser-based optical devices.

[0047] Optical fibers with a circular cross-sectional shape have the advantage of being particularly simple to manufacture, while also providing compact laser-based optical devices.

[0048] In an embodiment, at least one optical fiber of the array of optical fibers further comprises a mirror or a rotatable mirror arranged at the light exit face.

[0049] In one embodiment, the array of optical fibers further comprises a monolithic mirror element arranged at the light exit faces of the optical fibers of the array of optical fibers.

[0050] Providing a mirror, a rotatable mirror or a monolithic mirror element provides the advantage of being able to redirect light exiting one or more optical fibers.

[0051] In one embodiment, the laser-based optical system further comprises a plurality of laser light sources, each of which is configured to emit a laser beam during operation, and at least two of the plurality of laser light sources are arranged to emit a respective laser beam in a direction toward a first end of a same optical fiber of the plurality of optical fibers.

[0052] Thereby, the overall light output of the laser-based optical system is increased and / or the mixing of laser light of different wavelengths is improved.

[0053] The lamp or luminaire further comprises at least one laser light source configured to emit a laser beam in operation, the at least one laser light source being arranged to emit the laser beam in a direction towards the first end of at least one of the plurality of optical fibers.

[0054] The term "laser light source" refers in particular to a laser. Such a laser may in particular be configured to generate laser light having one or more ultraviolet, visible or infrared wavelengths, in particular having a wavelength selected from a spectral wavelength range of 200 nm-2000 nm, such as 300 nm-1500 nm. The term "laser" refers in particular to a device that emits light by an optical amplification process based on stimulated emission of electromagnetic radiation.

[0055] In particular, in embodiments, the term "laser" may refer to a solid-state laser. In certain embodiments, the term "laser" or "laser light source" or similar terms refers to a laser diode (or diode laser).

[0056] In an embodiment, the term "laser light source" or "solid state laser" may refer to one or more of the following: cerium-doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), chromium-doped chrysoberyl (Alexandrite) laser, chromium ZnSe (Cr:ZnSe) laser, divalent samarium-doped calcium fluoride (Sm:CaF2) laser, Er:YAG laser, erbium-doped and erbium-ytterbium co-doped glass laser, F-centered laser, holmium YAG (Ho:YAG) laser, Nd:YAG laser, NdCrYAG laser, neodymium-doped calcium gadolinium yttrium borate Nd:YCa4O(BO3)3 or Nd:YCOB, neodymium-doped Yttrium vanadate (Nd:YVO4) laser, neodymium glass (Nd: glass) laser, neodymium YLF (Nd:YLF) solid laser, promethium 147 doped phosphate glass (147Pm3+: glass) solid laser, ruby ​​laser (Al2O3:Ti3+), thulium YAG (Tm:YAG) laser, titanium sapphire (Ti: sapphire; Al2O3:Ti3+) laser, trivalent uranium doped calcium fluoride (U:CaF2) solid laser, ytterbium doped glass laser (rod, plate / sheet, optical fiber), ytterbium YAG (Yb:YAG) laser, Yb2O3 (glass or ceramic) laser, etc.

[0057] In an embodiment, the term "laser light source" or "solid-state laser" may refer to one or more semiconductor laser diodes, such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP, lead salt, vertical cavity surface emitting laser (VCSEL), quantum cascade laser, hybrid silicon laser, etc.

[0058] In one embodiment, the optical system further comprises an optical fiber arranged to direct the laser beam from the at least one laser light source to the first end of at least one optical fiber of the plurality of optical fibers.

[0059] Thus, the amount of light loss between the at least one laser light source and the optical fiber is minimized or completely eliminated.

[0060] The lamp or luminaire further comprises a controller configured to control or individually control one or more of the at least one laser light source.

[0061] In one embodiment, the lamp or luminaire comprises a plurality of laser light sources (19), each of which is configured to emit a laser beam during operation, at least two of the plurality of laser light sources being arranged to emit a respective laser beam in a direction towards a first end of a same optical fiber of the plurality of optical fibers.

[0062] In one embodiment, the controller is configured to individually control each of the plurality of laser light sources.

[0063] It is noted that the invention relates to all possible combinations of features recited in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0065] Figure 1 A perspective view of an optical system configured to guide laser light according to a first embodiment of the present invention is shown.

[0066] Figure 2 Shown according to Figure 1 Cross-sectional side view of the optical system.

[0067] Figure 3 A perspective view of an optical system according to a second embodiment of the present invention is shown, each optical fiber having a blunt second end.

[0068] Figure 4 Shows something like Figure 3 A cross-sectional side view of an optical system of FIG. 1 , but wherein each optical fiber has a sharp or pointed second end.

[0069] Figure 5 A perspective view of an optical system according to a third embodiment of the present invention is shown, each optical fiber having a blunt second end.

[0070] Figure 6 Shows something like Figure 5 A cross-sectional side view of an optical system of FIG. 1 , but wherein each optical fiber has a sharp or pointed second end.

[0071] Figure 7 A cross-sectional side view of an optical system according to a fourth embodiment of the present invention is shown.

[0072] Figure 8 A perspective view of three optical fibres, which may form part of an optical system according to the invention, are shown, the three optical fibres having mutually different cross-sectional shapes.

[0073] Fig. 9 Shown according to Figure 8 Cross-sectional side view of three optical fibers.

[0074] Fig.10 A cross-sectional side view of an exemplary optical fiber of an optical system according to the present invention is shown, illustrating various geometrical properties of such optical fibers.

[0075] Fig.11A total of 15 simulation results are shown, in each simulation result, 9 laser beams, three red, three green and three blue, are transmitted via standard optical fibers (not shown) and then coupled into an optical system according to the present invention, which includes an array of 3*3 optical fibers with a square cross-sectional shape. For each simulation result, the light pattern at 50 mm from the second end (left) and the far-field intensity distribution (right) are shown. The top row shows the light pattern according to the second end. Figure 1 The middle row shows the simulation results for a 3*3 fiber array. Figure 2 The bottom row shows the simulation results for an array of 3*3 fibers. Figure 3 Simulation results of a 3*3 optical fiber array.

[0076] Fig.12 Another set of 15 simulation results in total is shown, in which 9 laser beams, three red, three green and three blue, are transmitted via standard optical fibers (not shown) and subsequently coupled into a laser-based optical system according to the present invention, which includes an array of 3*3 optical fibers. For each simulation result, the light pattern (left) at 50 mm from the second end and the far-field intensity distribution (right) are shown. The top row shows the simulation results of an array of 3*3 optical fibers with a circular cross-sectional shape. The middle row shows the simulation results of an array of 3*3 optical fibers with a hexagonal cross-sectional shape. The bottom row shows the simulation results of an array of 3*3 optical fibers with a square cross-sectional shape.

[0077] Figure 13A-13C Yet another simulation result is shown. Fig.13A An embodiment of an optical system according to the invention is illustrated on which simulation results were obtained. Fig. 13B The effect of the first and second sections of each optical fiber is shown. Fig. 13C A graph of the simulated far-field intensity distribution is shown.

[0078] Fig.14 Embodiments of luminaires and lamps are schematically depicted.

[0079] As shown in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, therefore, are provided to illustrate the general structure of embodiments of the present invention. Like reference numerals refer to like elements throughout. DETAILED DESCRIPTION

[0080] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided to be thorough and complete and to fully convey the scope of the present invention to the skilled person.

[0081] Figure 1 A perspective view of an optical system 1 configured to guide laser light according to a first embodiment of the present invention, also referred to as laser-based optical system 1 in the following, is shown. Figure 2 Shown according to Figure 1 A cross-sectional side view of a laser-based optical system 1.

[0082] In general, regardless of the embodiment, the laser-based optical system 1 includes a plurality of optical fibers 3-11. The plurality of optical fibers 3-11 are arranged in an array 2 of optical fibers. The array 2 generally includes n*m optical fibers, n and m are integers, and at least one of n and m is 2 or more. Figure 1 In the embodiment shown, the array 2 is a 3*3 array with a total of nine optical fibers 3, 4, 5, 6, 7, 8, 9, 10, 11. However, the integers n and m may be selected to have any values ​​suitable for providing an array of the desired size. For example, one or both of n and m may be at least three, at least six, or at least nine.

[0083] refer to Figure 2 In general, and regardless of the embodiment, each optical fiber 3-11 of the array of optical fibers 2 comprises a longitudinal axis L, a first end 12, a second end 15, a first section 13 and a second section 14. Figure 1 and Figure 2 As shown, with reference to the intervening coordinate system, the longitudinal axis L extends in the Z direction.

[0084] The first end 12 forms a light incident surface for coupling laser light 20a, 20b, 20c from a laser light source 19 into each optical fiber 3-11. For simplicity, the laser light source 19 and the laser light 20a, 20b, 20c are not shown in FIG. Figure 1 and Figure 2 See also Figure 7 .

[0085] The first section 13 extends from the first end 12 or the light incident face to the second section 14 in a direction parallel to the longitudinal axis L. The first section 13 is configured to mix the laser light coupled into the optical fiber and propagating through the first section 13. The first section 13 includes a first cross section. Figure 1 and Figure 2 As shown, with reference to the inserted coordinate system, the first section extends in the XY plane and is therefore perpendicular to the longitudinal direction l. The first section comprises a first diameter D1 (see Fig.10 ) and a first cross-sectional area. The first cross-sectional area is constant in a direction parallel to the longitudinal axis L.

[0086] The second section 14 extends from the first section 12 to the second end 15 in a direction parallel to the longitudinal axis L. The first section 13 and the second section 14 extend from each other. The second section 14 is configured to widen the angular spread of mixed light, which is light that has propagated through the first section 13 and propagated through the second section 14. The second section 14 is also configured to couple out light propagated through the second section 14, in particular light propagated at or through the second end 15. The second section 14 includes a second cross section. Figure 1 and Figure 2 As shown, with reference to the inserted coordinate system, the second section extends in the XY plane and is therefore perpendicular to the longitudinal direction l. The second section includes a second cross-sectional area and a second diameter D2 (see Fig.10 ). The second cross-sectional area of ​​the second cross section decreases from the first section 13 toward the second end 15 in a direction parallel to the longitudinal axis L. Therefore, the second cross-sectional area of ​​the second cross section is the largest at the first section 13 and the smallest at the second end 15. Figure 1 and Figure 2 In the embodiment shown, the second end 15 is pointed or even point-shaped. The second section 14 is tapered, conical or frustoconical.

[0087] The second end 15 and at least a portion 17 of the outer surface of the second segment 14 ( Figure 8 ) forms a light exit surface, through which the light that has propagated through the optical fiber is coupled out of the optical fiber. Figure 1 and Figure 2 In the embodiment shown, mainly a portion 17 of the outer surface of the second section 14 adjacent to the second end 15 forms a light exit surface through which light that has propagated through the optical fiber is coupled out of the optical fiber.

[0088] By way of example, the geometric structure of each optical fiber 3-11 can also be described as follows. Each of the optical fibers 3-11 has a first end 12 or an incident surface. For example, the size of the first end 12 is 1×1 mm. The first end 12 is arranged at a position Z=0 mm. The first section 13 with a straight non-tapered cross section extends from Z=0 mm to a position Z=Z_cone mm, which corresponds to the transition section 16 between the first section 13 and the second section 14 in the figure. The first section 13 is used as a mixing section to homogenize the laser injected at Z=0 mm. Then, at Z=Z_cone, the tapered second section 14 begins to extend until position Z=Z_end. The second end 15 is arranged at position Z_end. The total length of the optical fiber can be, for example, 20 mm, so that Z_end is 20 mm. At position Z_end, the cross section of each optical fiber has a size (X_end, Y_end).

[0089] For example, when the total length of the optical fiber is 20 mm, that is, Z_end = 20 mm, and Z_cone = 2 mm, the second section 14 of the optical fiber is long and sharp, and the second end 15 is a pointed end. Figure 1 and Figure 2 The situation of the embodiment shown.

[0090] On the contrary, if Z_cone=18 mm, the second section 14 of the optical fiber is shorter and the second end 15 can also be a blunt end (see Figure 5 and Figure 7 The laser-based optical systems 101 and 102 of the third and fourth embodiments shown in FIG. Figure 6 A modified third embodiment of the laser-based optical system 101a) is shown.

[0091] Finally, if Z_cone=10 mm, the second section 14 of the optical fiber has a medium length and the second end 15 can be blunt (see Figure 3 The laser-based optical system 100 according to the second embodiment shown) or a sharp end (see Figure 4 A laser-based optical system 100a) according to a modified second embodiment is shown.

[0092] In general, the length of the second section 14 and whether the second end 15 is blunt or sharp may be selected to suit the desired use or purpose of the resulting laser-based optical system 1 , 100 , 101 , 102 .

[0093] refer to Figure 7 , shows a laser-based optical system 102 according to a fourth embodiment of the present invention. In this embodiment, the laser-based optical system 102 further comprises a mirror 18 or a rotatable mirror, which is arranged at the light exit surface or the second end 15 of at least one optical fiber 5 of the array of optical fibers. Figure 5 It is also feasible that all optical fibers 3-11 of the laser-based optical system 101 are provided with a mirror 18 or a rotatable mirror. In this case, the mirror or rotatable mirror can be provided as a monolithic mirror element 24, which is arranged at the light exit face or second end 15 of the optical fiber 3-11 of the array of optical fibers 2. The provision of a mirror 18, a rotatable mirror or a monolithic mirror element is able to redirect the light leaving the optical fiber 3 or the array of optical fibers to a desired direction.

[0094] The laser-based optical system may also include at least one laser light source 19 (see Figure 5 and Figure 7 ), the laser light source is configured to emit at least one laser beam 20a, 20b, 20c in operation. At least one laser light source 19 is arranged to emit laser light into at least one optical fiber 3-11 through the light incident surface or the first end 12. Figure 5 As shown, an array of laser light sources 19 may be provided. The laser light sources 19 may be configured to emit light of different colors, such as red, green, and blue, respectively, or to emit light of the same color.

[0095] Figure 8 Three examples of different cross-sectional shapes of each optical fiber 3-11 of an array of optical fibers of a laser-based optical system according to the present invention are shown. Non-limiting examples of possible cross-sectional shapes are square ( Figure 8 A) Round ( Figure 8 B) Hexagon ( Figure 8 C), rectangular and octagonal. The cross-sectional shape of each optical fiber 3-11 is the same along the entire length of the optical fiber. That is, the first section 13 and the second section 14 include the same cross-sectional shape. The optical fibers 3-11 of the array of optical fibers may all include the same cross-sectional shape. Alternatively, at least one optical fiber 3-11 in the array of optical fibers may include a cross-sectional shape that is different from the cross-sectional shapes of the remaining optical fibers.

[0096] Now turn to Fig.10 , shows a schematic cross-sectional side view of an optical fiber 3 of an array of optical fibers of a laser-based optical system according to the present invention. Fig.10 , other parameters of each optical fiber of the array of optical fibers of the laser-based optical system according to the present invention will be described.

[0097] The second segment 14 includes a taper angle β. The taper angle β is defined as the angle between the longitudinal center axis L of the second segment 14 and the circumference of the outer surface 141 of the second segment 14. Figure 3 The optical fiber 3 shown comprises a circular cross section, the outer surface 141 of the second section 14 coinciding with the circumference of a circle circumscribing the outer surface 141 of the second section 14 in this case. The taper angle β may be, for example, less than 2 degrees, between 2 degrees and 6 degrees, or between 6 degrees and 15 degrees. The relationship between the taper angle β and the length 22 of the second section 14 may be selected to determine whether the second end 15 is sharp or blunt, or to what extent the second end 15 is sharp or blunt.

[0098] The first segment 13 comprises a length 21. The second segment 13 comprises a length 22. The optical fiber 3 comprises a total length 23, which is the sum of the length 21 of the first segment 13 and the length 22 of the second segment 14. The second segment 14 may extend, for example, between 1% and 35% of the total length 23 of the optical fiber 3, between 35% and 65% of the total length 23 of one optical fiber 3, or between 65% and 90% of the total length 23 of the optical fiber 3. Furthermore, the cross-sectional area of ​​the optical fiber 3 at the second end 15 may be less than 50%, 25%, or 10% of the cross-sectional area of ​​the optical fiber 3 at the first end 12.

[0099] Laser-based optical systems according to the present invention may be used in lighting applications such as, but not limited to, laser-based lighting in retail locations, downlights, decorative lighting, and pixelated lighting.

[0100] Now go to Fig.11 , Fig.12 and Figure 13, several examples are shown and will be described below.

[0101] Example 1

[0102] Fig.11 A total of fifteen simulation results are shown. The top row shows the simulation results according to the present invention and including Figure 1 The middle row shows the simulation results of a laser-based optical system according to the present invention and including an array of 3*3 optical fibers. Figure 2 The bottom row shows the simulation results of a laser-based optical system according to the present invention and including an array of 3*3 optical fibers. Figure 3 The simulation results of the laser-based optical system of the array of 3*3 optical fibers are shown in Figure 1. These columns show the simulation results of optical fibers with the sizes of the second end 15 being 0.4mm×0.4mm, 0.3mm×0.3mm, 0.2mm×0.2mm, 0.1mm×0.1mm and 0.01mm×0.01mm, respectively, from left to right.

[0103] In each simulation, nine laser beams, three red, three green and three blue or 3x (RGB), are transmitted via standard optical fibers (not shown) and subsequently coupled into a laser-based optical system according to the present invention, which includes an array of 3*3 optical fibers having a square cross-sectional shape. For each simulation result, the light pattern at 50 mm from the second end (left) and the far-field intensity distribution (right) are shown.

[0104] The white light is composed of the nine laser beams. Each laser provides a circular beam with a beam angle of ±18°. By selecting the geometry of the optical fiber, especially the tapering angle β, the generated output white light beam can be widened or squared. For example, a widening to about ±25°, ±35° or ±55° can be obtained, such as Fig.11 shown.

[0105] Example 2

[0106] Fig.12Another set of fifteen simulation results is shown. The top row shows simulation results for a laser-based optical system according to the present invention and comprising an array of 3*3 optical fibers having a circular cross-sectional shape. The middle row shows simulation results for a laser-based optical system according to the present invention and comprising an array of 3*3 optical fibers having a hexagonal cross-sectional shape. The bottom row shows simulation results for a laser-based optical system according to the present invention and comprising an array of 3*3 optical fibers having a square cross-sectional shape. Thus, Fig.12 The effect of using different fiber cross sections is illustrated. The columns show, from left to right, simulation results for fibers with second end 15 sizes of 0.4 mm x 0.4 mm, 0.3 mm x 0.3 mm, 0.2 mm x 0.2 mm, 0.1 mm x 0.1 mm, and 0.01 mm x 0.01 mm, respectively.

[0107] In each simulation, nine laser beams, three red, three green and three blue or 3x (RGB), are transmitted via standard optical fibers (not shown) and subsequently coupled into a laser-based optical system according to the present invention, which includes an array of 3*3 optical fibers. For each simulation result, the light pattern at 50 mm from the second end (left) and the far-field intensity distribution (right) are shown.

[0108] It can be seen that the optical fiber with a circular cross-sectional shape ( Fig.12 In addition, as the taper angle β becomes smaller, the size corresponding to the second end 15 becomes smaller and thus becomes increasingly sharp (in Fig.12 (viewed from left to right in the figure), resulting in a circular far-field distribution.

[0109] Optical fiber with a hexagonal cross-sectional shape ( Fig.12 The middle row in FIG. 1 creates a hexagonal far-field pattern that becomes more pronounced as the taper angle β decreases, corresponding to the second end 15 becoming smaller and thus becoming increasingly sharp (in FIG. Fig.12 (read from left to right in the figure).

[0110] Optical fiber with a square cross-sectional shape ( Fig.12 The bottom row in FIG. 1 first widens the beam in a circular manner and forms a four-fold symmetry as the taper angle β decreases, corresponding to the second end 15 becoming smaller in size and thus increasingly sharper (at Fig.12 (read from left to right in the figure).

[0111] Example 3

[0112] Figure 13A-13C Another simulation result is shown. The simulation result is obtained on a laser-based optical system 103 according to the present invention, which includes an array of 1*3 optical fibers - see Fig.13A The three optical fibers are closely placed together to transmit red (R), green (G) and blue (B) lasers respectively. The three optical fibers include a square cross-sectional shape.

[0113] The light entrance face or first end 12 of each optical fiber has a size of 1 mm x 1 mm. The second end 15 or exit face of each optical fiber has a size of 0.6 mm x 0.6 mm. The three optical fibers are placed at a center-to-center distance of 1.1 mm. The beam angle of the incident laser beam is ±18°. The mixing sections corresponding to the respective first sections 13 of the respective optical fibers ensure light uniformity over the respective optical fiber cross section - see Fig. 13B The mixing section of each optical fiber comprises a length of 10 mm. The tapered section corresponding to the respective second section 14 of the respective optical fiber widens the light beam to a desired beam diameter value. The tapered section of each optical fiber comprises a length of 10 mm.

[0114] In this example, the laser-based optical system used also comprises a turning mirror 18 for redirecting the light. Each optical fiber is provided with a turning mirror 18 arranged adjacent to the second end 15. Alternatively, the turning mirrors 18 may be combined into one monolithic mirror element 24.

[0115] Because the size of the second end 15 or the light exit surface of each optical fiber is small as described above, and the optical fibers are also placed closely as described above, the color mixing obtained in the far field is very good, such as Fig. 13C shown.

[0116] Table 1 below shows three different sizes of the second end 15 or exit face of each optical fiber for a laser-based optical system according to the present invention, expressed as full width at half maximum (FWHM) and full width at 10% of maximum (FW10M), respectively, and includes such Fig.13A An array of 1*3 optical fibers is shown.

[0117] Table 1

[0118] The size of the second end 15 FWHM FW10M 0.6×0.6mm 58° 69° 0.8×0.8mm 44° 51° 1.0×1.0mm 35° 40°

[0119] Fig.14 An embodiment of a luminaire 2 comprising an optical system as described above is schematically depicted. Reference numeral 301 indicates a user interface which may be functionally coupled to a controller 300 comprised by the luminaire 2 or functionally coupled to the luminaire 2. The controller 300 may be configured to control one or more laser light sources of the luminaire 2. Fig.14An embodiment of a lamp 10 comprising an optical system is also schematically depicted. The controller 300 may be configured to control one or more laser light sources of the lamp 10. Reference numeral 3 indicates a projector device or a projector system, which may be used to project an image, such as on a wall, and which may also include the optical system 1. Thus, Fig.14 Schematically depicted are embodiments of a lamp 10, a luminaire 2, a projector device 3, and an optical wireless communication device 5, comprising an optical system 1 as described herein. Light escaping from the luminaire 2, the lamp 10, and the optical wireless communication device 5 is indicated with reference numeral 1201. Reference numeral 1300 refers to a space, such as a room. Reference numeral 1305 refers to a floor, reference numeral 1310 refers to a ceiling; reference numeral 1307 refers to a wall.

[0120] Those skilled in the art realize that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0121] Those skilled in the art will understand the terms "substantially" or "essentially" and similar terms herein. The terms "substantially" or "essentially" may also include embodiments with "entirely", "completely", "all", etc. Therefore, in an embodiment, the adjective substantially or substantially may also be removed. Where applicable, the term "substantially" or the term "essentially" may also relate to 90% or more, such as 95% or more, particularly 99% or more, even more particularly 99.5% or more, including 100%. In addition, the terms "about" and "approximately" may also relate to 90% or more, such as 95% or more, particularly 99% or more, even more particularly 99.5% or more, including 100%. With respect to numerical values, it should be understood that the terms "substantially", "essentially", "about" and "approximately" may also refer to a range of 90%-110%, such as 95%-105%, and in particular 99%-101%, of the referenced value(s).

[0122] Moreover, variations to the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention, by studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. 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.

Claims

1. A lamp (10) or a lamp fixture (2), comprising an optical system (1), at least one laser light source (19) and a controller (300), wherein The optical system (1) is configured to guide laser light, the optical system comprising a plurality of optical fibers, each optical fiber (3-11) of the plurality of optical fibers comprising a longitudinal axis (L), a first end (12) forming a light incident surface, a second end (15), a first section (13) and a second section (14), The first section (13) extends from the first end to the second section in a direction substantially parallel to the longitudinal axis, and the second section (14) extends from the first section to the second end in a direction substantially parallel to the longitudinal axis, The first section (13) comprises a first cross-section comprising a first cross-sectional area that is substantially constant in a direction parallel to the longitudinal axis, At least one of the second end (15) and at least a portion (17) of the outer surface (141) of the second section forms a light exit surface, and The second section (14) comprises a second cross section, the second cross section comprises a second cross-sectional area, the second cross-sectional area of ​​the second cross section decreases from the first section towards the second end in a direction parallel to the longitudinal extension, The plurality of optical fibers (3-11) are arranged in an array (2) of optical fibers, the array comprising n*m optical fibers, wherein n and m are integers, and wherein at least one of n and m is 2 or greater, The at least one laser light source (19) is configured to emit a laser beam (20a, 20b, 20c) in operation, the at least one laser light source being arranged to emit the laser beam in a direction towards the first end of at least one of the plurality of optical fibers, The controller (300) is configured to control or individually control one or more laser light sources among the at least one laser light source (19).

2. The lamp or luminaire of claim 1, wherein at least one of n and m is at least three, at least six or at least nine.

3. The lamp or the luminaire according to any one of the preceding claims, wherein at least a portion (17) of the outer surface (141) of the second section adjacent to the second end forms at least a portion of the light exit surface.

4. The lamp or luminaire according to any one of the preceding claims, wherein the second segment (14) comprises a taper angle β, the taper angle β being defined as the angle between the longitudinal center axis (L) of the second segment and the circumference of a circle circumscribing the outer surface of the second segment, wherein the taper angle β is less than 2 degrees, or wherein the taper angle β is between 2 degrees and 6 degrees, or The taper angle β is between 6 degrees and 15 degrees.

5. A lamp or a lighting fixture according to any one of the preceding claims, wherein The second section (14) extends between 1% and 35% of the total longitudinal extension of the at least one optical fiber, or wherein The second section (14) extends between 35% and 65% of the total longitudinal extension of the at least one optical fiber, or wherein The second section (14) extends between 65% and 90% of the total longitudinal extension of the at least one optical fiber.

6. A lamp or a luminaire according to any one of the preceding claims, wherein the cross-sectional area at the second end (15) is less than 50%, 25% or 10% of the cross-sectional area at the first end.

7. A lamp or a luminaire according to any one of the preceding claims, wherein one or both of the following apply: The second end (15) is either blunt or pointed, and The second section (14) is any one of a tapered shape, a conical shape and a frustoconical shape.

8. The lamp or the luminaire according to any one of the preceding claims, wherein the first section (13) is configured to mix light propagating therethrough.

9. The lamp or the luminaire according to any one of the preceding claims, wherein the second section (14) is configured to widen the angular spread of light propagating therethrough.

10. The lamp or the luminaire according to any one of the preceding claims, wherein the optical fibers (3-11) of the array (2) of optical fibers all comprise a cross section of the same shape, or At least one optical fiber of the array (2) of optical fibers comprises a cross-section having a first shape, and the remaining optical fibers of the array of optical fibers comprise cross-sections having a second shape different from the first shape.

11. A lamp or a lamp fixture according to any one of the preceding claims, wherein the cross-sectional shape of each optical fiber (3-11) of the array (2) of optical fibers perpendicular to the longitudinal axis is any one of square, rectangular, octagonal, circular and hexagonal.

12. A lamp or luminaire according to any one of the preceding claims, wherein at least one optical fiber (5) of the array of optical fibers further comprises a mirror (18) or a rotatable mirror arranged at the light exit face.

13. The lamp or the lamp fixture according to any one of the above claims 1-10, wherein the array (2) of optical fibers further comprises a monolithic mirror element (24), which is arranged at the light exit surface of the optical fiber of the array of optical fibers.

14. The lamp or the lamp fixture according to any of the above claims further comprises a plurality of laser light sources (19), each of which is configured to emit a laser beam during operation, and at least two of the plurality of laser light sources are arranged to emit the corresponding laser beam in a direction toward the first end of the same optical fiber among the plurality of optical fibers.

15. The lamp or the luminaire according to claim 14, wherein the controller (300) is configured to control each of the plurality of laser light sources (19) individually.

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