WO2025026913A1

WO2025026913A1 - Lighting device with movable diffuser

Info

Publication number: WO2025026913A1
Application number: PCT/EP2024/071288
Authority: WO
Inventors: Ties Van Bommel; Robert Jacob PET
Original assignee: Signify Holding BV
Current assignee: Signify Holding BV
Priority date: 2023-08-01
Filing date: 2024-07-26
Publication date: 2025-02-06
Anticipated expiration: 2026-02-01

Abstract

A lighting device (100) arranged to emit device light is provided. The lighting device comprises a solid-state light source (110) arranged to emit light source light (115), a light-reflective collimator (120) having a principal optical axis, A, and a light exit opening (140), the light-reflective collimator being arranged in a light-receiving configuration with the solid-state light source and arranged to collimate at least part of the light source light into collimated light, a light-absorbing collimator (150) arranged circumferentially around the principal optical axis, A, and arranged at the light exit opening of the light-reflective collimator, and a diffuser element (170) arranged circumferentially around the principal optical axis, A, and movable along a first direction, B, parallel to the principal optical axis, A, with respect to the light-absorbing collimator, whereby a coverage of the light-absorbing collimator by the diffuser element a screening of the light source light is adjustable.

Description

LIGHTING DEVICE WITH MOVABLE DIFFUSER

FIELD OF THE INVENTION

The present invention generally relates to a lighting device. More specifically, the present invention is related to a lighting device, e.g. in the form of a spotlight, arranged to provide an emission of light which is effective concerning performance and/or functionality, whilst being decorative.

BACKGROUND OF THE INVENTION

Spotlights are ubiquitously used in many lighting applications and/or environments, for example in stores, the hotel and retail sector (HORECA), museums, homes, etc.

In its most basic form(s), the prior art spotlights have a static construction, i.e. that the spotlights are not adjustable for any change or adjustment of their light emission. In contrast, the spotlights that are adjustable with respect to the light emission may have one or more movable (rotatable) elements in order to influence the light-emitting properties of the spotlights.

However, it should be noted that many adjustable spotlights in the prior art suffer from deficiencies. Firstly, the spotlights may be difficult, complex or cumbersome to operate in order to try to achieve the desired light output. Secondly, even if adjustments are made, the spotlights might (still) not be able to achieve the sought lighting effects. Thirdly, prior art spotlights may not be able to provide an aesthetically pleasing light emission.

Hence, it is an object of the present invention to try to overcome at least some of the drawbacks of present spotlights, and to provide lighting arrangements or devices which improve the (spotlighting) performance and/or functionality whilst achieving a decorative lighting.

CN104595811 discloses a zoom projection lamp. The zoom projection lamp comprises a reflection cover, a light source, a fixed lens and a movable lens. According to the zoom projection lamp, the relative position between the movable lens and the fixed lens of the zoom projection lamp can be adjusted by moving the movable lens, so that the zoom projection lamp can be used for outputting a broad beam, a collimating beam or a progressive beam between the broad beam and the collimating beam according to the requirements of users.

In US2005036333 a lamp assembly with a peripheral auxiliary function is described for use with automobile lamps. A moveable shield and a fixed shield are positioned about a light source inside a housing. A first reflective surface and a second reflective surface are formed on the inside of the housing. Thus, the moveable shield may be moved to switch between the main beam and the peripheral beam, creating the ability to alter the functionality of the lamp assembly.

SUMMARY OF THE INVENTION

Hence, it is of interest to overcome at least some of the deficiencies of spotlights according to present technologies, and to provide a lighting device which achieves an improved performance and/or functionality whilst being attractive and/or which may achieve a decorative lighting.

This and other objects are achieved by providing a lighting device having the features in the independent claim. Preferred embodiments are defined in the dependent claims.

According to a first aspect of the present invention, there is provided a lighting device arranged to emit device light. The lighting device comprises a solid-state light source arranged to emit light source light. The lighting device further comprises a light-reflective collimator having a principal optical axis, A, and a light exit opening, the light-reflective collimator being arranged in a light-receiving configuration with the solid-state light source and arranged to collimate at least part of the light source light into collimated light. The lighting device further comprises a light-absorbing collimator arranged circumferentially around the principal optical axis, A, and arranged at the light exit opening of the light- reflective collimator. The lighting device further comprises a diffuser element arranged circumferentially around the principal optical axis, A, and being movably arranged along a first direction, B, parallel to the principal optical axis, A, with respect to the light-absorbing collimator, whereby a coverage of the light-absorbing collimator by the diffuser element for at least partial screening of the light source light is adjustable.

Thus, the present invention is based on the idea of providing a lighting device, e.g. in the form of a spotlight, which is able to provide an adjustment of a coverage of the light-absorbing collimator by the diffuser element, leading to an improved emission of light from the lighting device concerning lighting efficiency, attractiveness of the lighting device, as well as lighting decorativeness.

The present invention is advantageous in that the diffuser element is easily and conveniently movable in the lighting device, thereby achieving an easy and convenient operation of the lighting device, either manually (by an operator (user)) or automatically, for changing or adjusting the property(ies) of the light emission from the lighting device.

The present invention is further advantageous in that the lighting device may provide a decorative light-diffusing ring appearing at the inner side or rim of the lighting device, which is predominantly observable at relatively narrow viewing angles of a user (observer).

The present invention is further advantageous in that the lighting device, dependently on a position of the diffuser element, may provide the mentioned decorative light-diffusing ring appearing at the inner side or rim, as well as on the outer side or rim, of the lighting device, which is predominantly observable at relatively wide viewing angles.

According to a first aspect of the present invention, there is provided a lighting device arranged to emit device light. By “lighting device”, it is here meant substantially any lighting device, unit, lamp, or the like. For example, the lighting device may be a spotlight. The lighting device comprises a solid-state light source arranged to emit light source light. The solid-state light source may comprise, for example, one or more light-emitting diodes, LEDs. The lighting device further comprises a light-reflective collimator having a principal optical axis, A. By “light-reflective collimator”, it is here meant an element which is arranged or configured to reflect light to a relatively large extent. The lighting device further comprises a light-exit opening. By “light exit opening”, it is here meant a hole, a window, or the like, of the lighting device out of (through) which the device light is emitted. The light- reflective collimator is arranged in a light-receiving configuration with the solid-state light source and arranged to collimate at least part of the light source light into collimated light. By the wording “light-receiving configuration”, it is here meant that the light-reflective collimator partially encloses the light source, and is arranged or configured to receive the light source light (i.e. that the light source light is arranged to impinge on the light-reflective collimator during operation of the lighting device). By “collimated light”, it is in this context meant light having a lower full width at half maximum, FWHM, than the FWHM of the light source light, wherein the FWHM represents the width of a spectrum curve measured between those points on the y-axis which are half the maximum amplitude. The lighting device further comprises a light-absorbing collimator arranged circumferentially around the principal optical axis, A, and arranged at the light exit opening of the light-reflective collimator. By “light-absorbing collimator”, it is here meant a collimator which is arranged or configured to absorb light to a relatively large extent. The lighting device further comprises a diffuser element arranged circumferentially around the principal optical axis, A. By “diffuser element”, it is here meant an element, such as a louver, or the like, which is arranged or configured to at least partially diffuse the light source light. The diffuser element is movably arranged along a first direction, B, parallel to the principal optical axis, A, with respect to the light-absorbing collimator. Hence, the diffuser element may be moved (e.g. by a sliding movement) with respect to the light-absorbing collimator. Due to the moveability of the diffuser element vis-a-vis the light-absorbing collimator, a coverage of the light-absorbing collimator by the diffuser element is adjustable for at least partial screening of the light source light during operation of the lighting device.

According to an embodiment of the present invention, the diffuser element may be positionable in (i) a retracted position, wherein the light-absorbing collimator is not covered by the diffuser element, and (ii) a first extended position, wherein the light-absorbing collimator is at least partially covered by the diffuser element. Hence, the diffuser element may be positioned in a retracted position, whereby the light-absorbing collimator is not covered, obstructed or shieled by the diffuser element, and may furthermore be positioned in a first extended position, upon a repositioning of the diffuser element from the retracted position along the first direction, B. The present embodiment is advantageous in that the light source light at high angles may be absorbed by the light-absorbing collimator in the retracted position, thereby leading to an aesthetically appealing light distribution, i.e. a hard cut-off. The present embodiment is further advantageous that an attractive light-diffusing ring appears in the first extended position of the diffuser element, at least partially covering the light-absorbing collimator.

According to an embodiment of the present invention, in the retracted position (i), the lighting device is configured to operate in a first operational mode, wherein the device light has a first full width at half maximum, FWHM1, and in the first extended position (ii), the lighting device is configured to operate in a second operational mode, wherein the device light has a second full width at half maximum, FWHM2, wherein FWHM2 > FWHM1. For example, the difference may be at least 3 degrees or at least at least 5 degrees. By “operational mode”, it is here meant a setting, or the like, of the lighting device. Hence, according to the embodiment, the width of the spectrum curve of the device light is narrower in the retracted position of the diffuser element compared to the first extended position, leading to an even more improved performance, functionality and/or attractiveness of the lighting device.

According to an embodiment of the present invention, the diffuser element may be positionable in (iii) a second extended position, wherein the light-absorbing collimator is (fully) covered by the diffuser element, and wherein the diffuser element projects beyond the light-absorbing collimator in a downstream direction. The present embodiment is advantageous in that a light-diffusing ring may appear, and that the lightdiffusing ring may be observable at wide viewing angles. For example, in case the lighting device comprises a housing, the light-diffusing ring appears at the inner and outer side of the housing.

According to an embodiment of the present invention, in the second extended position (iii), the lighting device is configured to operate in a third operational mode, wherein the device light has a third full width at half maximum, FWHM3, wherein FWHM3 > FWHM2. For example, the difference may be at least 3 degrees or at least at least 5 degrees. Hence, according to this embodiment, the width of the spectrum curve of the device light is narrower in the first extended position of the diffuser element compared to the second extended position, leading to an even more improved performance, functionality and/or attractiveness of the lighting device.

According to an embodiment of the present invention, the light-absorbing collimator and the diffuser element may be tubular-shaped e.g. concentrically arranged, wherein an outer diameter of the diffuser element is smaller than an inner diameter of the light-absorbing collimator. For example, the light-absorbing collimator and the diffuser element may be tubular-shaped and concentrically arranged. Hence, the diffuser element may be (tightly) arranged within the light-absorbing collimator, leading to a space-efficient lighting device.

According to an embodiment of the present invention, the diffuser element may be transflective for the light source light. By the term “transflective”, it is here meant both reflective and transmissive, i.e. that the diffuser element is configured to reflect and transmit the light source light. The present embodiment is advantageous in that the diffuser element, in its second extended position, wherein the diffuser element projects beyond the light-absorbing collimator, may both reflect and transmit the light source light. According to an embodiment of the present invention, the reflectivity, RDE, of the diffuser element may be in a range of 30 - 70%. For example, the diffuser element may be in a range of 40 - 60%.

According to an example of the present invention, the absorbance, ACE, of the light-absorbing collimator may fulfill ACE > 80%, preferably ACE > 85%, and even more preferred ACE > 90%.

According to an embodiment of the present invention, the diffuser element may comprise a gradient in its transreflectiveness. For example, the transmissivity of the diffuser element may increase in the direction, B, i.e. facing away from the light exit window. By the term “transflectiveness”, it is here meant a level, amount or degree of transflectiveness, i.e. reflectivity and transmissivity. Hence, the diffuser element may comprise a (continuous) increase or decrease in its transflectiveness. The present embodiment is advantageous in that an even more customized performance, functionality and/or attractiveness of the lighting device may be provided.

According to an embodiment of the present invention, the diffuser element may be opaque and a reflectivity, RDE, of the diffuser element is at least 80 % or at least 85%.

According to an embodiment of the present invention, the diffuser element may be slidably arranged along a first direction, B, parallel to the principal axis, A, with respect to the light-absorbing collimator. By “slidably arranged”, it is meant that the diffuser element may be slidable arranged (e.g. via rotation) upon a (manual or automatic) pulling or pushing of the diffuser element. The present embodiment is advantageous in that the slidable feature of the diffuser element provides a particularly easy and convenient movement of the diffuser element between any of the retracted position, first extended position and second extended position of the diffuser element.

According to an embodiment of the present invention, the collimated light may have a full width at half maximum, FWHM, in a range of 5 - 40° or 8 - 25°, and/or wherein the length, L, of the light-absorbing collimator, parallel to the principal optical axis, A, may be in a range of 0.2 - 10 cm or 0.5 - 3 cm.

According to an embodiment of the present invention, the lighting device may further comprise a grip element attached to the diffuser element, wherein the grip element is operable to vary a position of the diffuser element for adjusting the coverage of the lightabsorbing collimator by the diffuser element. The present embodiment is advantageous in that the grip element provides a particularly easy and convenient movement of the diffuser element by a user (operator) between any of the retracted position, first extended position and second extended position of the diffuser element.

According to an embodiment of the present invention, the lighting device may further comprise a locking element attached to the diffuser element to lock a position of the diffuser element. The present embodiment is advantageous in that the diffuser element may be conveniently and easily locked and/or fastened in its retracted position, first extended position and/or second extended position.

According to an example of the present invention, the light source may comprise at least one light-emitting diode, LED.

In embodiments, in the retracted position of the diffuser element, the light source light which (is not collimated but) impinges directly on the light-absorbing collimator may be in a range of 3% to 30% of the (total amount) light source light.

In embodiments, the device light may be white light e.g. having a correlated color temperature in a range from 2000K to 6500K and optionally a color rendering index of at least 80 or at least 85.

According to an example of the present invention, the lighting device may further comprise a heat sink thermally coupled to the light source, wherein the heat sink is arranged to dissipate heat from the light source during operation.

According to an embodiment of the present invention, there is provided a luminaire. The luminaire may comprise the lighting device according to any one of the preceding embodiments, and a housing at least partially enclosing the lighting device. The luminaire may further comprise a fastening element attached to the housing, wherein the fastening element is attachable to a wall for a mounting of the lighting device.

Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

Fig. 1 schematically shows spotlights according to the prior art, Figs. 2a-2c schematically show cross-sections of a lighting device according to exemplifying embodiments of the present invention, and

Fig. 3 schematically shows a luminaire comprising a lighting device according to an exemplifying embodiment of the present invention.

DETAILED DESCRIPTION

Fig. 1 schematically shows spotlights 10 according to the prior art. It will be appreciated that spotlights 10 of this kind are ubiquitously used in many lighting applications and environments, such as for example in stores, the hotel and retail sector (HORECA), museums, homes, etc. The prior art spotlights 10 may have a static construction, i.e. that the spotlights 10 are not adjustable for any change or adjustment of their light emission, or that the spotlights 10 do not have the ability to be adjusted (e.g. via one or more movable (rotatable) elements) in order to influence the light-emitting properties of the spotlights 10. It should be noted that these spotlights 10 in the prior art suffer from deficiencies. Firstly, the spotlights 10 may be difficult, complex or cumbersome to operate in order to try to achieve the desired light output. Secondly, even if adjustments are made, the spotlights 10 might (still) not be able to achieve sought lighting effects. Thirdly, prior art spotlights 10 may often be non-attractive, and may furthermore be unable to provide an aesthetically pleasing light emission.

Figs. 2a-2c schematically show cross-sections of a lighting device 100 according to exemplifying embodiments of the present invention. It should be noted that features of the lighting device 100, which are indicated in Fig. 2a, are omitted in Fig. 2b and 2c for an increased visibility.

With reference to Fig. 2a, the lighting device 100 may be substantially any lighting device, unit, lamp, or the like. For example, the lighting device 100 may be a spotlight. The lighting device 100, which is arranged to emit device light, comprises a solid- state light source 110 arranged to emit light source light 115. The solid-state light source 110 may, for example, be or comprise one or more LEDs. The lighting device 100 further comprises a light-reflective collimator 120 having a principal optical axis, A. In this example, the light-reflective collimator 120 is funnel-shaped, with a relatively small diameter in the vicinity of the solid-state light source 110, wherein the diameter increases along the principal optical axis, A. The lighting device 100 further comprises a light exit opening 140, out of which the light source light 115 is emitted during operation. The light-reflective collimator 120 is arranged in a light-receiving configuration with the solid-state light source 110 and is arranged to collimate at least part of the light source light 115 into collimated light, which is shown by the dashed arrows in Fig. 2a. The collimated light may have a full width at half maximum, FWHM, in a range of 8 - 25°.

The lighting device 100 in Fig. 2a further comprises a light-absorbing collimator 150 arranged circumferentially around the principal optical axis, A, and arranged at the light exit opening 140 of the light-reflective collimator 120. In this exemplifying embodiment, the light-absorbing collimator 150 is cylinder-shaped or tube-shaped. Furthermore, the length, L, of the light-absorbing collimator 150, parallel to the principal optical axis, A, may be in a range of 0.5 - 3 cm. Furthermore, the absorbance, ACE, of the light-absorbing collimator 150 may fulfill ACE > 80%, preferably ACE > 85%, and even more preferred ACE > 90%. The characteristics of the light absorbance of the light-absorbing collimator 150 is schematically indicated by the crossed-out reflectivity of impingent light on the light-absorbing collimator 150.

The lighting device 100 further comprises a diffuser element 170 arranged circumferentially around the principal optical axis, A. The diffuser element 170 is movably arranged along a first direction, B, parallel to the principal optical axis, A, with respect to the light-absorbing collimator 150. For example, the diffuser element 170 may be slidably arranged along the first direction, B, with respect to the light-absorbing collimator 150 (e.g. via rotation of the diffuser element 170 in the direction, D, around the principal optical axis, A. Due to the diffuser element 170 being movable along the first direction, B, a coverage of the light-absorbing collimator 150 is adjustable by the diffuser element 170 for at least partial screening of the light source light 115. According to this example of the lighting device 100, the light-absorbing collimator 150 and the diffuser element 170 are tubular-shaped, wherein an outer diameter of the diffuser element 170 is smaller than an inner diameter of the lightabsorbing collimator 150.

The diffuser element 170 may have many different characteristics and/or features. For example, the diffuser element 170 may be transflective (i.e. transmissive and reflective) for the light source light 115. Furthermore, the reflectivity, RDE, of the diffuser element 170 may be in a range of 30 - 70%. Furthermore, the diffuser element 170 may comprise a gradient (i.e. a gradual change) in its transreflectiveness in the length direction, parallel to the principal optical axis, A, and/or in the direction, D, around the principal optical axis, A. According to yet another exemplifying embodiment, the diffuser element 170 may be opaque and a reflectivity, RDE, of the diffuser element 170 may be at least 80 %. Furthermore, the diffuser element 170 may have one or more perforations or holes. Fig. 2a, which is also indicated by index (i), shows the lighting device 100 wherein the diffuser element 170 is positioned in a retracted position. In this (retracted) position in the lighting device 100, the light-absorbing collimator 150 is not covered by the diffuser element 170. Consequently, light source light 115, impingent on the light-absorbing collimator 150, is not reflected, or reflected to a very small degree.

Fig. 2b, which is also indicated by index (ii), shows the lighting device 100 wherein the diffuser element 170 is positioned in a first extended position. In this (partially) extended position, the light-absorbing collimator 150 is at least partially covered by the diffuser element 170. The difference in the characteristics of the emission of device light during operation of the lighting device 100 in the retracted position (i) of the diffuser element 170 compared to the first extended position (ii) of the diffuser element 170 is schematically indicated by the dashed arrows of the light source light 115 in Figs. 2a and 2b. The lightabsorbing collimator 150 is not covered by the diffuser element 170 in the retracted position (i) in Fig. 2a, and provides no (or limited) reflection. In contrast, the light source light 115 as schematically indicated by the dashed arrows in Fig. 2b is reflected via the diffuser element 170 in the first extended position (ii), and the effect is a light-diffusing ring appearing at the inner side or rim of the lighting device 100.

Figs. 2a and 2b further present a difference in the full width at half maximum, FWHM, between the retracted position (i) and the first extended position (ii) of the diffuser element 170. In the retracted position (i), the lighting device 100 is configured to operate in a first operational mode, wherein the device light has a first full width at half maximum, FWHM1. In the first extended position (ii), the lighting device 100 is configured to operate in a second operational mode, wherein the device light has a second full width at half maximum, FWHM2, and wherein FWHM2 > FWHM1.

Fig. 2c, which is also indicated by index (iii), shows the lighting device 100 wherein the diffuser element 170 is positioned in a second extended position. In this second extended position, the light-absorbing collimator 150 is (e.g. completely) covered by the diffuser element 170, and the diffuser element 170 projects beyond the light-absorbing collimator 150 in a downstream direction, i.e. in a direction parallel to the principal optical axis, A. In this second extended position (iii) of the diffuser element 170, the lighting device 100 may be configured to operate in a third operational mode, wherein the device light has a third full width at half maximum, FWHM3, wherein FWHM3 > FWHM2.

The difference in the characteristics of the emission of device light during operation of the lighting device 100 in the first extended position (ii) of the diffuser element 170 compared to the second extended position (iii) of the diffuser element 170 is schematically indicated by the dashed arrows of the light source light 115 in Figs. 2b and 2c. The light source light is (only) reflected via the diffuser element 170 in the first extended position (ii), and the effect is a light-diffusing ring appearing at the inner side or rim 160 of the lighting device 100. In contrast, in the second extended position (iii) of the diffuser element 170, the light source light is reflected and transmitted due to the transflectivity of the diffuser element 170, and the effect of this position of the diffuser element 170 is a lightdiffusing ring appearing at the inner side or rim 160 as well as on the outer side or rim 160, of the lighting device 100.

As exemplified in Fig. 2a, the lighting device 100 may further comprise a heat sink 200 thermally coupled to the light source 110, wherein the heat sink 200 is arranged to dissipate heat from the light source 110 during operation of the lighting device 100. The lighting device 100 may further comprise a grip element 300 attached to the diffuser element 170, wherein the grip element 300 is only schematically indicated by a rectangle. The grip element 300 is operable to vary a position of the diffuser element 170 for adjusting the coverage of the light-absorbing collimator 150 by the diffuser element 170. Hence, a user may vary the position of the diffuser element 170 between the retracted position (i), the first extended position (ii) and the second extended position (iii), via the grip element 300. The lighting device 100 may further comprise a locking element 310 attached to the diffuser element 170, wherein the locking element 310 is only schematically indicated by a rectangle. The locking element 310 may lock a position (i.e. the retracted position (i), the first extended position (ii) or the second extended position (iii)) of the diffuser element 170.

Fig. 3 schematically shows a luminaire 500 comprising a lighting device 100 according to an exemplifying embodiment of the present invention. The luminaire 500 further comprises a housing 510 at least partially enclosing the lighting device 100. The luminaire 500 further comprises a fastening element 520 attached to the housing 510, wherein the fastening element 520 is attachable to a wall (e.g. a vertical wall or a horizontal ceiling) for a mounting of the lighting device 100. The housing 510 may have an opening, e.g. in the form of a slit (not shown) such that the diffuser element 170 can be changed in its position with respect to the housing.

The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, one or more of the light-reflective collimator 120, the light-absorbing collimator 150, the diffuser element 170, etc., may have different shapes, dimensions and/or sizes than those depicted/described.

Claims

CLAIMS:

1. A lighting device (100) arranged to emit device light, comprising: a solid-state light source (110) arranged to emit light source light (115), a light-reflective collimator (120) having a principal optical axis, A, and a light exit opening (140), the light-reflective collimator being arranged in a light-receiving configuration with the solid-state light source and arranged to collimate at least part of the light source light into collimated light, a light-absorbing collimator (150) arranged circumferentially around the principal optical axis, A, and arranged at the light exit opening of the light-reflective collimator, a diffuser element (170) arranged circumferentially around the principal optical axis, A, and being movably arranged along a first direction, B, parallel to the principal optical axis, A, with respect to the light-absorbing collimator, whereby a coverage of the light-absorbing collimator by the diffuser element for at least partial screening of the light source light is adjustable, wherein the diffuser element is positionable in

(i) a retracted position, wherein the light-absorbing collimator is not covered by the diffuser element,

(ii) a first extended position, wherein the light-absorbing collimator is at least partially covered by the diffuser element, and

(iii) a second extended position, wherein the light-absorbing collimator is fully covered by the diffuser element, and wherein the diffuser element projects beyond the lightabsorbing collimator in a downstream direction.

2. The lighting device according to claim 1, wherein in the retracted position (i), the lighting device is configured to operate in a first operational mode, wherein the device light has a first full width at half maximum, FWHM1, and in the first extended position (ii), the lighting device is configured to operate in a second operational mode, wherein the device light has a second full width at half maximum, FWHM2, wherein FWHM2 > FWHM1. in the second extended position (iii), the lighting device is configured to operate in a third operational mode, wherein the device light has a third full width at half maximum, FWHM3, wherein FWHM3 > FWHM2.

3. The lighting device according to any one of the preceding claims, wherein the light-absorbing collimator and the diffuser element are tubular-shaped, wherein an outer diameter of the diffuser element is smaller than an inner diameter of the light-absorbing collimator.

4. The lighting device according to any one of the preceding claims, wherein the diffuser element is transflective for the light source light.

5. The lighting device according to claim 4, wherein the reflectivity, RDE, of the diffuser element is in a range of 30 - 70%.

6. The lighting device according to any one of the preceding claims, wherein the diffuser element comprises a gradient in its transreflectiveness.

7. The lighting device according to any one of the claims 1-3, wherein the diffuser element is opaque and a reflectivity, RDE, of the diffuser element is at least 80 %.

8. The lighting device according to any one of the preceding claims, wherein the diffuser element is slidably arranged along a first direction, B, parallel to the principal axis, A, with respect to the light-absorbing collimator (150).

9. The lighting device according to any one of the preceding claims, wherein the collimated light has a full width at half maximum, FWHM, in a range of 8 - 25°, and wherein the length, L, of the light-absorbing collimator, parallel to the principal optical axis, A, is in a range of 0.5 - 3 cm.

10. The lighting device according to any one of the preceding claims, further comprising a grip element (300) attached to the diffuser element, wherein the grip element is operable to vary a position of the diffuser element for adjusting the coverage of the light- absorbing collimator by the diffuser element.

11. The lighting device according to any one of the preceding claims, further comprising a locking element (310) attached to the diffuser element to lock a position of the diffuser element.

12. A luminaire (500), comprising: the lighting device according to any one of the preceding claims, a housing (510) at least partially enclosing the lighting device, a fastening element (520) attached to the housing, wherein the fastening element is attachable to a wall for a mounting of the lighting device.