Laser reflection unit

Abstract

The present invention provides a laser reflection unit for a laser phosphor projector. The unit includes a housing and a wheel rotatably and drivably received in the housing. The wheel has a top side provided with a phosphor layer for converting an incident laser beam into a reflected light beam. In addition, the wheel has a bottom side opposite to the top side, and the bottom side is provided with cooling fins for inducing an airflow flowing in a radially outward direction at an annular portion radially outward from the central axis of the wheel. The laser reflection unit also includes a heat exchanger received in the housing, the heat exchanger being used to cool the airflow flowing out of the wheel, the heat exchanger extending along a substantially circumferential profile coaxial with the central axis of the wheel. The housing is provided with an inner surface, which guides the airflow from the wheel to the heat exchanger and flows along the heat exchanger.

Description

Technical Field

[0001] The present disclosure relates to a laser reflection unit for a laser phosphor projector. Background Art

[0002] A laser phosphor projector includes a laser reflection unit that converts high-intensity blue laser light into white light for use in the illumination optical element of the laser phosphor projector. When converting light, some energy is lost and converted into heat, which is absorbed in the phosphor layer directly applied to the wheel in the laser reflection unit. The heat is transferred to the wheel and the temperature rises. To keep the temperature inside the wheel at a safe level, it is necessary to dissipate the heat to the cooler surrounding environment at a lower intensity.

[0003] In traditional solutions, cold air is blown directly onto the phosphor wheel itself through a fan inside the unit, circulated towards the heated phosphor wheel, and pushed against the cooled surfaces inside the unit. The hot air needs to be guided to be cooled inside the unit through heat exchange made by heat pipe technology or guided to a large air-cooled area in contact with the cooler surrounding area. Traditional solutions are usually large, bulky, and complex.

[0004] Therefore, there is a need for improvement in the prior art. Summary of the Invention

[0005] To overcome the problems of the prior art, there is thus provided a laser reflection unit for a laser phosphor projector, the unit including a housing and a wheel rotatably and drivably received in the housing, the wheel having a top side provided with a phosphor layer for converting an incident laser beam into a reflected beam, the wheel further having a bottom side opposite to the top side, the bottom side being provided with cooling fins at a radially outer annular portion from the central axis of the wheel, the cooling fins inducing an air flow flowing in a radially outward direction, the laser phosphor unit further including a heat exchanger received in the housing for cooling the air flow flowing out from the cooling wheel, the heat exchanger extending along a substantially circular contour coaxial with the central axis of the wheel, wherein the housing is provided with an inner surface for guiding the air flow from the wheel to the heat exchanger and along the heat exchanger.

[0006] By applying the inner surface of the housing arranged to guide the air flow from the cooling wheel to the heat exchanger and along the heat exchanger, the application of a fan is redundant, thus providing an energy-saving, compact, lightweight, and compact solution.

[0007] Advantageously, the inner surface of the housing defines a combined chamber structure having a radially central portion for receiving the central part of the wheel and a radially outer annular portion for receiving the heat exchanger, the radially outer annular portion of the chamber preferably having a substantially spiral tube shape, thus providing a substantially circular air path in a cross-sectional view, wherein the air is alternately cooled by the heat exchanger and heated by the wheel.

[0008] Specifically, by providing an inner surface of the housing in a radially outer annular portion of the chamber that defines curved edge segments between the ceiling and the radially outer wall and between the floor and the radially outer wall, preferably formed as a smooth wall profile, the air flow is directed from the wheel towards the heat exchanger and along the heat exchanger and then back to the wheel, such that the air flow resistance can be balanced to the pressure on the cooling fins of the wheel without an additional fan.

[0009] Advantageously, the inner surface of the housing can extend from the floor of the radially outer annular chamber portion via the curved edge segments towards the radially central chamber portion, thereby directing the air flow from the heat exchanger towards the wheel to close the circulating air flow, thus providing a closed air flow profile in a cross-sectional view of the spiral tube for alternately cooling air via the heat exchanger and heating air via the wheel.

[0010] Advantageously, the geometry of the inner surface of the housing reduces the air flow resistance to an extent that allows for no additional fan.

[0011] Advantageously, the laser reflection unit can include only a single fan for initiating the air flow, the single fan being formed by a wheel rotatably and drivably received in the housing, thereby taking advantage of the fact that any additional fan is redundant.

[0012] Advantageously, the laser reflection unit can include only a single active unit formed by a wheel rotatably and drivably received in the housing, thereby taking advantage of the fact that any additional fan is redundant. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] These and other features, aspects, and advantages of the devices, systems, and methods of the present disclosure will be better understood from the following description, the appended claims, and the drawings, in which:

[0014] Figure 1 A schematic cross-sectional side view of a laser reflection unit according to the present invention is shown.

[0015] Figure 2 Shown is Figure 1 A schematic exploded view of the shown laser reflection unit.

[0016] Figure 3 Shown is Figure 1 A schematic perspective bottom view of the top of the housing of the shown laser reflection unit and the wheel. DETAILED DESCRIPTION

[0017] The terms used to describe particular embodiments are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly dictates otherwise. The term "and / or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and / or "comprising" specify the presence of the stated features, but do not preclude the presence or addition of one or more other features. It will also be understood that when a particular step of a method is said to follow another step, it may follow immediately after said other step, or one or more intermediate steps may be performed before the execution of the particular step, unless otherwise specified. Similarly, it will be understood that when describing a connection between structures or components, unless otherwise specified, such connection may be established directly or through intermediate structures or components.

[0018] The present invention will be described with reference to specific embodiments and with reference to certain drawings, but the present invention is not limited thereto and is only defined by the claims. The described drawings are merely illustrative and not restrictive. In the drawings, for illustrative purposes, the dimensions of some of the elements may be exaggerated and not drawn to scale. When the term "comprises" is used in this specification and the claims, this term does not exclude other elements or steps.

[0019] Furthermore, the terms first, second, third, etc. in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe an order or a temporal sequence. It should be understood that the terms so used are interchangeable under appropriate circumstances, and the embodiments of the present invention described herein are capable of operating in a different order from that described or illustrated herein.

[0020] The terms "about" or "approximate", etc. are synonyms and are used to indicate that the value modified by the term has an associated range of understanding, where the range can be +20%, +15%, +10%, +5% or +1%. The term "substantially" is used to indicate that the result (e.g., a measured value) is close to the target value, where close can mean, for example, that the result is within 80% of the value, within 90% of the value, within 95% of the value, or within 99% of the value.

[0021] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the present invention are shown. In the drawings, for clarity, the absolute and relative dimensions of systems, components, layers and regions may be exaggerated. Embodiments may be described with reference to schematic and / or cross-sectional illustrations of possible idealized embodiments and intermediate structures of the present invention. Throughout the specification and the drawings, like reference numerals refer to like elements. Related terms and their derivatives should be construed to refer to the orientation shown in the drawings at the time of description or discussion. These related terms are for convenience of description and do not require the system to be constructed or operated in a particular orientation unless otherwise stated.

[0022] Figure 1 Fig. 1 shows a schematic cross-sectional side view of a laser reflection unit 1 according to the present invention. The laser reflection unit 1 can be applied in a laser phosphor projector for converting high-intensity blue laser light into white light.

[0023] Figure 2 shows Figure 1 a schematic exploded view of the laser reflection unit 1 shown in Fig. 1.

[0024] The laser reflection unit 1 has a housing 2 and a wheel 3, and the wheel 3 is rotatably and drivably received in the housing 2. In the illustrated embodiment, the housing 2 includes a top portion 2a and a bottom portion 2b that can be removed from each other (for example, for inspection and / or repairability purposes), and the two portions 2a, 2b are shown separated from each other in Fig. 2. In another embodiment, the housing 2 may include other numbers of portions, such as three or more portions. In the assembled state, as shown in Fig. 3, the housing portions 2a, 2b are connected to each other using screws 4a-c or other connecting elements such as clamping elements. Then, the housing encloses an internal compartment or chamber, which can be dust-sealed, for example, for receiving the wheel 3 and the heat exchanger described below therein to be driven to rotate in the housing. Figure 2 The wheel 3 is rotatably and drivably received in the housing 2, which means that the wheel 3 is received in the housing 2 so as to be driven to rotate in the housing 2 (for example, by an actuator such as a motor). Figure 1 As shown in Fig. 4, the laser reflection unit 1 shown includes a floating bearing motor 5, which is connected to the wheel 3 to drive the wheel 3 to rotate or spin in the housing 2. In the illustrated embodiment, the motor 5 is mounted on the central portion of the bottom of the housing 2b using screws 7a-d or other connecting elements (such as clamping elements), and the central portion preferably has a machined plane 6. The unit 1 includes a power cable 8 for supplying power to the wheel motor 5. The wheel 3 is substantially disc-shaped and has a substantially circular outer contour 9 and a symmetry axis A in the illustrated embodiment. The wheel 3 has a top side 10 and a bottom side 11 opposite to the top side 10. The top side 10 is provided with means for converting the incident laser beam L

[0025] into a reflected beam L

[0026] Figure 1 As shown in Fig. 5, the laser reflection unit 1 includes a floating bearing motor 5, which is connected to the wheel 3 to drive the wheel 3 to rotate or spin in the housing 2. In the illustrated embodiment, the motor 5 is mounted on the central portion of the bottom of the housing 2b using screws 7a-d or other connecting elements (such as clamping elements), and the central portion preferably has a machined plane 6. The unit 1 includes a power cable 8 for supplying power to the wheel motor 5. The wheel 3 is substantially disc-shaped and has a substantially circular outer contour 9 and a symmetry axis A in the illustrated embodiment. The wheel 3 has a top side 10 and a bottom side 11 opposite to the top side 10. The top side 10 is provided with means for converting the incident laser beam L i into a reflected beam L rPhosphor layer 12. The wheel 3 in the illustrated embodiment includes a plurality of concentric portions, namely a radially central portion 13, a radially intermediate annular portion 14, and a radially outer annular portion 15. Here, the radially outer annular portion 15 is adjacent to the outer peripheral contour 9 of the wheel 3, and the radially intermediate annular portion 14 is located between the radially central portion 13 and the radially outer annular portion 15 when viewed from the axis of symmetry A. In the illustrated embodiment, the phosphor layer 12 is provided on the top side 10 of the radially outer annular portion 15. The radially intermediate annular portion 14 is provided with a series of through holes 16 that are substantially evenly distributed along the circumferential direction C around the axis of symmetry A. In addition, the radially central portion 13 of the wheel 3 is mounted on the drive component of the motor 5 on its bottom side 11. Note that in principle, other configurations of the wheel can be applied, for example, by including more radial annular portions or by mounting the top side 10 of the wheel 3 to a motor that rotatably drives the wheel 3. The bottom side 11 of the wheel 3 is provided with cooling fins 17 at the radially outer annular portion 15, which are shaped to generate a local overpressure to cause an air flow F w in the radially outward direction D rad to flow through the radially fan fins, which will be explained in more detail below. The wheel 3 functions as both a fan and a radiator.

[0027] The laser reflection unit 1 further includes a heat exchanger 18 received in the housing 2 for cooling the air flow F flowing out from the cooling fins 17 of the wheel 3 w . The heat exchanger 18 extends along a substantially circular contour Cc coaxial with the axis of symmetry A (also referred to as the central axis A of the wheel 3) of the wheel 3. The substantially circular contour Cc is preferably located slightly below the substantially circular outer peripheral contour 9 of the wheel 3. The heat exchanger 18 includes cooling tubes 19, and the cooling tubes 19 are provided with a fluid input port 20 that can be connected to a fluid input tube 21 and a fluid output port 22 that can be connected to a fluid output tube 23. The fluid input tube 21 and the fluid output tube 23 are located outside the laser reflection unit 1 and can be connected to a common complete cooling circuit in the projector for dissipating heat from the internal or external radiator of the coolant 24 flowing in the cooling tubes 19 and optionally other cooling tubes in the laser phosphor projector. In addition, the heat exchanger 18 includes heat absorption fins 25, and the heat absorption fins 25 are attached to the cooling tubes 19 and extend in a direction substantially transverse to the local tube axis, following the substantially circular contour Cc.

[0028] In the illustrated embodiment, the housing 2a, 2b of the laser reflection unit 1 houses the wheel 3, the motor 5 that rotatably drives the wheel 3 in the housing 2, and the heat exchanger 18. Preferably, the housing 2 is substantially coaxial with the wheel 3 and preferably also coaxial with the heat exchanger 18.

[0029] The top 2a of the housing is provided with an opening 99 and a fitting 100 surrounding the opening 99, and receives a first lens 101 mounted to the fitting 100 by a first clamping element 102. In addition, the fitting 100 receives, on top of the first lens 101, a second lens 103 mounted to the fitting 100 by a second clamping element 104.

[0030] During operation of the laser reflection unit 1, the wheel 3 rotates and reflects the incident laser beam L that enters via the second lens 103, the first lens 101, and the opening 99 i onto the phosphor layer 12 on the wheel 3. Then, the incident beam L i is reflected via the phosphor layer 12 as a reflected beam L r , and this reflected beam L r propagates back outwards via the opening 99, the first lens 101, and the second lens 103. Typically, the incident beam L i can be a blue laser, and the reflected beam L r can be white light. However, other beam characteristics are also applicable, such as having other spectral characteristics. In addition, another lens configuration can be applied, for example including other mounting elements and / or fewer or more than two lenses. Preferably, the lenses 101, 103 are sealed to form a dust-proof sealed compartment or chamber within the housing 2.

[0031] When converting the incident laser beam L i into the reflected beam L r , some of the light energy is lost and converted into heat that is preferably absorbed in the phosphor layer 12 directly applied to the top side 10 of the wheel 3. The heat is directly transferred into the wheel material and then dissipated via the bottom side 11 of the wheel 3. The air at the bottom side 11 of the wheel moves in a spiral from the axis of symmetry A towards and through the cooling fins 17 on the bottom side 11 of the wheel 3 (opposite the phosphor layer 12), towards the peripheral profile 9 of the wheel 3, and then further towards the inner surface of the housing 2. The heat from the wheel 3 is dissipated into the air by convection between the cooling fins 17. The housing 2 can be made of any suitable material, preferably a heat-conductive material such as a metal, for example magnesium. The top 2a of the housing is provided with fins 106 at its outer surface 105 for transferring heat to the surrounding area. Similarly, the outer surface 107 of the bottom 2b of the housing is also provided with fins 108 for cooling the bottom 2b of the housing. The rotating wheel 3, as well as the cooling tubes 19 and the heat-absorbing fins 25 of the heat exchanger 18, can also be made of any suitable material, preferably a heat-conductive material such as a metal, for example aluminum.

[0032] Figure 3 Shows a schematic perspective bottom view of the top of the housing (also referred to as top 2a) and Figure 1 the wheel 3 of the laser reflection unit 1 as shown.

[0033] According to one aspect, the housing 2 is provided with an inner surface 26 that guides the air flow F w from the cooling fins 17 of the wheel 3 to the heat exchanger 18 and flows along the heat exchanger 18. In the illustrated embodiment, the inner surface 26 has a curved section that guides the air flow F w from the cooling fins 17 of the wheel 3 to flow in the radially outward direction D, and then flows downward F d towards the bottom 2b of the housing, towards and along the heat absorbing fins 25 of the heat exchanger 18, and then flows radially inward F in towards the axis of symmetry A, and then upward F up towards the wheel 3, thereby forming a circulating flow F w 、F d 、F in 、F up 。See for example Figure 1 。

[0034] The shape of the inner surface 26 of the housing guides the heated air from the wheel cooling fins 17 in the same radial direction caused by the wheel 3 (i.e., in the radially outward direction D rad ) and causes the air flow to enter axially downward and pass through the heat absorbing fins 25 of the heat exchanger.

[0035] In a cross-sectional view of the laser reflection unit 1 passing through the axis of symmetry A, the inner surface 26 of the housing that guides the air flow F w from the cooling fins 17 of the wheel 3 to and along the heat absorbing fins 25 of the heat exchanger 18 includes: curved corner segments 26a, 26a' at the radial top peripheral contours 27a, 27a' of the housing top 2a that smoothly guide the air flow downward, and curved corner segments 26b, 26b' at the radial bottom peripheral contours 27b, 27b' of the housing bottom 2b for subsequently smoothly guiding the air flow radially inward towards the axis of symmetry A.

[0036] In the illustrated embodiment, the inner surface 26 of the housing, also referred to as the inner housing profile, defines a combined chamber structure that has a radially central portion 28 and a radially outer annular portion 29. The radially central portion 28 receives the radially central portion 13 of the wheel 3 at the upper part of the radially central portion 28, and the radially outer annular portion 29 receives the heat exchanger 18. The motor 5 that drives the wheel 3 is also accommodated in the radially central portion 28 of the combined chamber structure. The radially outer annular portion 15 of the wheel 3 extends to the radially outer annular portion 29.

[0037] The radially outer annular portion 29 of the chamber has a substantially toroidal shape that extends around the axis of symmetry A.

[0038] In addition, the inner surface 26 of the housing defines a ceiling 30, a radially outer sidewall 31, and a floor 32 of a radially outer annular chamber portion 29. Here, the inner surface 26 of the housing defines curved edge segments 26, 26' between the ceiling 30 and the radially outer sidewall 31 and curved edge segments 26b, 26b' between the floor 32 and the radially outer sidewall 31. In Figure 1 In a cross-sectional view, the curved edge segment 26 has also been referred to above as a curved corner segment. Note that the ceiling 30, the radially outer sidewall 31, and the floor 32 of the radially outer annular chamber portion 29 may be flat, substantially flat, or may have another shape (e.g., slightly curved), such that the ceiling 30, the radially outer sidewall 31, the floor 32, and the intermediate curved edge segments form an overall curved segment, the curvature of which is substantially constant or varies only within a small range, thereby forming a substantially circular segment.

[0039] By forming the inner surface 26 of the housing with a smooth wall profile in the radially outer portion of the housing 2 (i.e., at and near the radially outer sidewall 31), the air flow is smoothly guided (i.e., with minimal resistance) towards the floor 32 of the radially outer annular chamber portion 29.

[0040] In the illustrated embodiment, the inner surface 26 of the housing has a central inwardly recessed portion 35 that defines a raised floor surface 6 of the radially central chamber portion 28. The raised floor is also referred to as the machined plane 6. In the illustrated embodiment, the motor 5 is mounted on the surface 6. In addition, in the illustrated embodiment, the inner surface 26 of the housing extends from the floor 32 of the radially outer annular chamber portion via a curved edge segment 33 towards the radially central chamber portion 28 or the raised floor surface 6 for guiding the air flow from the heat exchanger 18 and the floor 32 upward towards the wheel 3, thereby closing the annular air flow as described above.

[0041] The wheel 3 pumps air through the heat exchange fins 25 of the heat exchanger in a continuous cycle. The air continuously flows in a substantially spiral tube shape and is alternately cooled by the exchanger 18 and heated by the wheel 3.

[0042] Thus, the air flow resistance is balanced to the pressure on the cooling fins 17 of the wheel 3, thereby forming a radial fan without the need for an additional boost fan used in conventional solutions.

[0043] The inner surface 26 of the housing of the wheel 3 and the cooling fins 17 are arranged in combination to produce in Figure 1The air flow circulating in the cross-sectional view of the radially outer annular chamber portion shown. In the illustrated embodiment, the air flow circulates along a substantially spiral tube shape of the radially outer annular chamber portion 29, along a more or less natural flow path in a substantially spiral tube-shaped bending plane. When the wheel 3 rotates during the operation of the laser reflection unit 1, the air flow also has a component in the circumferential direction C, along a substantially circumferential profile Cc coaxial with the axis of symmetry A, thereby generating a combined spiral air flow that has the above-mentioned circular component along the spiral tube surface and a circumferential component along the substantially circumferential profile Cc.

[0044] By applying the spiral tube-shaped radially outer annular chamber portion 29, the wheel 3 generates a circulating air flow path along the heat exchanger fins 25 and the cooling tubes 19, thereby providing a relatively large interface between the air to be cooled and the heat exchanger 18, and thus achieving high cooling performance in the laser reflection unit 1 of relatively compact size.

[0045] The heat absorbed by the thermoluminescent layer 12 on the wheel 3 is transferred through the thermally conductive material in the wheel 3 from the phosphorescent layer 12. The wheel 3 is formed as a combined fan and radiator and transfers the heat towards a larger area for exchange with air at the fin surface 17 on the bottom side 11 of the wheel 3. The hot air flowing at high speed within the housing 2 exchanges heat to the heat exchanger fins 25 and the cooling tubes 19 by convection. The cooling tubes 19 are connected to the entire cooling system inside or outside the projector. In applications using the laser reflection unit 1, depending on the available circuitry, the liquid cooling distribution problem can be solved in many different ways.

[0046] The wheel 3 in the laser reflection unit 1 is preferably made to have the function of optically reflecting the incident laser beam L i 、distributing the generated heat and initiating a radially outward-directed air flow F w in a single piece. By including the optical, heat transfer, and air flow initiation functions, the wheel 3 acts as a laser beam reflector, radiator, and fan. Due to the combined arrangement of the inner surface 26 of the housing of the wheel 3 and the cooling fins 17, no additional fan is applied to initiate the air flow. According to one aspect, the wheel 3 can be the only air flow initiation element of the laser reflection unit 1. Other components in the laser reflection unit 1 can be passive, without moving parts, such that the required air flow is initiated and the heat is transferred to the liquid in the cooling tubes of the heat exchanger, and the liquid flows outwards to the fluid output tube outside the laser reflection unit 1.

[0047] In the interpretation of the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different items or by the structures or functions implemented; any one of the disclosed devices or parts thereof may be combined or separated into further parts unless otherwise specifically stated. When a claim refers to another claim, this may indicate the synergistic advantages achieved by combining their respective features. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used advantageously. Accordingly, the present embodiment may include all feasible combinations of the claims, where each claim may, in principle, refer to any preceding claim, unless the context clearly excludes it.

[0048] Although the present invention has been described above with reference to specific embodiments, this is done for purposes of illustration and not limitation.

[0049] Those skilled in the art will understand that various modifications and different combinations of the disclosed features can be made without departing from the scope of the present invention.

Claims

1. A laser reflection unit for a laser phosphor projector, comprising: a housing and a wheel received in the housing and drivable to rotate, the wheel having a top side and a bottom side opposite the top side, the top side being provided with a phosphor layer for converting an incident laser beam into a reflected beam, the wheel further having cooling fins located directly below the phosphor layer, the cooling fins being radially provided at an outer annular portion of the bottom side from a central axis of the wheel, the cooling fins being shaped to generate a local overpressure to initiate an air flow in a radially outward direction, the laser reflection unit further comprising a heat exchanger received in the housing for cooling the air flow initiated by the wheel, the heat exchanger extending along a circumferential profile coaxial with the central axis of the wheel, the heat exchanger including heat absorption fins, wherein an inner surface of the housing is shaped to guide heated air from the cooling fins in the radially outward direction axially downward into and through the heat absorption fins.

2. The laser reflection unit according to claim 1, wherein, the inner surface of the housing defines a combined chamber structure having a radially central portion receiving a central portion of the wheel and a radially outer annular portion receiving the heat exchanger.

3. The laser reflection unit according to claim 2, wherein, the radially outer annular portion of the combined chamber structure is an annular circle.

4. The laser reflection unit according to claim 2, wherein, the inner surface of the housing defines a ceiling, a radially outer side wall and a floor of the radially outer annular portion.

5. The laser reflection unit according to claim 4, wherein, the inner surface of the housing defines curved edge segments between the ceiling and the radially outer side wall and between the floor and the radially outer side wall.

6. The laser reflection unit according to claim 2, wherein, the inner surface of the housing defines a smooth wall profile at the radially outer annular portion of the housing.

7. The laser reflection unit according to claim 2, wherein, the inner surface of the housing has a central inwardly recessed portion, the central inwardly recessed portion defining a raised floor of the radially central portion.

8. The laser reflection unit according to claim 2, wherein, the inner surface of the housing extends from the floor of the radially outer annular portion via the curved edge segments to the radially central portion, guiding air from the heat exchanger to the wheel.

9. The laser reflection unit according to claim 2, wherein, the wheel is located above the radially central portion such that the cooling fins extend into the radially outer annular portion.

10. The laser reflection unit according to claim 2, wherein, the inner surface of the housing and the cooling fins of the wheel are configured to generate an air flow circulating in a cross-sectional view of the radially outer annular portion.

11. The laser reflection unit according to claim 1 or 2, wherein, The wheel is the only airflow inducing element.

12. The laser reflection unit according to claim 1 or 2, characterized in that the heat exchanger includes a pipe provided with a fluid input port and a fluid output port, and the heat absorbing fins are attached to the pipe and extend laterally to a local pipe axis.

13. The laser reflection unit according to claim 1 or 2, characterized in that the housing is coaxial with the wheel.

14. The laser reflection unit according to claim 1 or 2, characterized in that the unit includes only a single fan for inducing airflow, and the single fan is formed by the wheel mounted in the housing.

15. The laser reflection unit according to claim 1 or 2, characterized in that the laser reflection unit further includes a single movable unit, and the single movable unit is formed only by the wheel received in the housing.

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