WO2025195944A1

WO2025195944A1 - Light source device

Info

Publication number: WO2025195944A1
Application number: PCT/EP2025/057158
Authority: WO
Inventors: Hugo Johan Cornelissen; Yngwie BARON; Olexandr Valentynovych VDOVIN; Christoph Gerard August HOELEN; Marcellus Jacobus Johannes Van Der Lubbe
Original assignee: Signify Holding BV
Current assignee: Signify Holding BV
Priority date: 2024-03-19
Filing date: 2025-03-17
Publication date: 2025-09-25
Anticipated expiration: 2026-09-19

Abstract

A light source device comprises first and second light emitter arrays comprising a respective plurality of first and second solid-state light emitters configured to provide respective first and second light in a respective first and second light direction. A transparent beam combining plate has a first side configured with a plurality of parallel ridges and/or grooves and a second side opposite the first side. The first and second light emitter arrays and the beam combining plate are spatially arranged such that the first light is incident on the first side of the plate, the second light is incident on the second side of the plate, the first and second light are combined by the plate to exit the plate via the first side in an exit direction, and configured such that any one of the first and second light undergoes at least one total internal reflection (TIR) within the plate.

Description

LIGHT SOURCE DEVICE

FIELD OF THE INVENTION

The present invention generally relates to light source devices. More specifically, the present invention is related to a light source device comprising two light emitter arrays and a beam combining plate.

BACKGROUND OF THE INVENTION

Light source devices providing high intensity light beams with small divergence, such as laser-based light emitters, for general lighting are most commonly based on blue laser diodes that excite a ceramic phosphor element. For example, with one Watt of blue radiation power approximately 150-200 lumen of white light can be created. High power blue laser diodes typically generate 5W or more optical output each, meaning that with a single blue laser diode approximately 750-1000 lumen of white light can be generated. To generate more light, the output of several lasers is focused simultaneously onto the phosphor.

To improve mechanical and thermal management, and provide compact high power density laser sources, multiple laser diodes are combined in so-called laser banks or laser arrays, also called multi-chip package (MCP) or multi-die package (MDP). The individual lasers in such arrays cannot be placed arbitrarily close to one another in view of heat generation and space required for collimating optics. Hence an array of light beams is generated with a certain spatial, e.g. X/Y, size necessarily having dark space in between the light beams, also called “dark zones”.

In some applications the power output of a single laser array is not sufficient to meet the required light output, and two or more laser arrays must therefore be combined. However, when combining laser arrays the total beam size, in terms of cross-sectional dimensions and/or in terms of angular extent of the beam, will increase to a typically undesired size, as well as requiring large lenses and other large optical components.

Examples of prior art arrangements that combine beams without increasing the beam size include polarization-, spectral- and geometrical beam combining arrangements. These require the use of a Polarizing Beam Splitter (PBS), a diffraction grating or dichroic mirror, and a stepped- or perforated mirror, respectively. Such prior art arrangements are associated with drawbacks. For example, polarization- or spectral combining is not always desired or possible for complexity and cost reasons. Other drawbacks of such prior art arrangements include the effect of a mixed polarization state or a wider spectrum (or with additional peaks) after combining. This in turn restricts the design flexibility of the optics after combining. A known approach for geometrical combining is most straightforward but requires structured, highly reflective mirrors or, at the cost of additional space, a large set of mutually very well aligned mirrors. Such arrangements typically have a disadvantage of power losses due to limited reflectivity of the mirrors.

SUMMARY OF THE INVENTION

It is of interest to provide a light source device that is capable of overcoming drawbacks of prior art devices.

This and other objects are achieved in a first aspect by providing a light source device having the features of the appended independent claim. Preferred embodiments are defined in the appended dependent claims.

Hence, according to the present invention there is provided a light source device comprising a first light emitter array comprising a plurality of first solid-state light emitters. Each first solid-state light emitter is configured to provide first light in a first light direction, Z. A second light emitter array comprises a plurality of second solid-state light emitters. Each second solid-state light emitter is configured to provide second light in a second light direction, Y.

Examples of such light emitter arrays include laser diode (LD) arrays, superluminescent diode (SLD) emitter arrays and arrays of stacked-multi -junction high brightness light emitting diodes.

A transparent beam combining plate, i.e. plate material itself, has a first side configured with a plurality of parallel ridges and/or grooves and a second side opposite the first side.

Preferably, the first light emitter array, comprising a plurality of first solid- state light emitters, comprises a first laser bank comprising an array of a first plurality of laser diodes. Preferably, the second light emitter array, comprising a plurality of second solid-state light emitters, comprises a second laser bank comprising an array of a second plurality of laser diodes. A laser bank may comprise a light emitting arrangement comprising an (2D) array of a plurality of laser diodes arranged on a thermally conductive carrier and a (lens array having a) plurality of collimator lenses corresponding to the laser diodes such that each laser diode of the plurality of laser diodes comprises a collimator lens for collimating laser light emitted by the laser diode. The arrangement may comprise a package architecture or a canned architecture. In case of the package architecture a laser diode chip array is arranged on the thermally conductive carrier. A plurality of electrodes may be present for electrically connecting the plurality of laser diodes. The 2D array may e.g. comprise at least 8 laser diodes. A laser diode (or diode laser) may be a semiconductor device substantially similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. This is known to a person skilled in the art. Preferably, the first plurality of laser diodes and the second plurality of laser diodes are configured to generate one or more of violet light and blue light. The term “violet light” may especially relate to light having a wavelength in the range of about 380-440 nm. In specific embodiments, the violet light may have a centroid wavelength in the 380-440 nm range. The term “blue light” may especially relate to light having a wavelength in the range of about 440-490 nm (including some violet and cyan hues). In specific embodiments, the blue light may have a centroid wavelength in the 440-490 nm range.

The first light emitter array, the second light emitter array and the beam combining plate are spatially arranged in relation to each other such that: the first light is incident on the first side of the beam combining plate, such that the second light is incident on the second side of the beam combining plate, such that the first light and the second light are combined by the beam combining plate to exit the beam combining plate via the first side in an exit direction, and configured such that any one of the first light and the second light undergoes at least one total internal reflection (TIR) within the beam combining plate.

That is, such a light source device provides geometrical beam combining that does not require thin film reflective or polarizing coatings but relies on highly efficient Total Internal Reflection. The light of the first light emitter array enters the transparent beam combining plate and reflects by TIR from the back side of the beam combining plate and leaves the beam combining plate in the exit direction. The light of the second light emitter array passes the plate without or with only a small plan-parallel displacement. The light of both light emitter arrays is now combined and propagates in the exit direction and thereby provides a high intensity beam of light comprising light emitted from both light emitter arrays.

It is to be noted that the concept of combining is to be interpreted in a wide sense. For example, in the case of laser emitters, individual laser beams are not necessarily combined in the sense of being made completely overlapping both spatially and angularly, but being made to be emitted from the beam combining plate all parallel to each other in one and the same exit direction such that spatially on average they are combined. In fact, in the far field the beams will also actually overlap.

In other words, such a light source device may be used to combine the power of, e.g., two laser banks into a combined beam with increased power density, e.g., for two blue laser banks to almost double the irradiance. Furthermore, such a light source device may be used to not just combine light beams of the same wavelength, but additionally or alternatively to combine light beams of various wavelengths without the need of applying dichroic beam combiners. For example, red light emitter array beams may be combined with blue or green light emitter array beams, or the beams of two RGB mixed light emitter arrays can be combined. The resulting light distribution can be a decent mix of R-G-B light, as for instance useful for entertainment spot lighting. A key advantage is that for all these solutions no dichroic or polarizing coatings are required. Another advantage is that both laser banks can be oriented to emit light in a desired polarization state, such that the ratio between S- and P- polarization components can be freely chosen at the exit, provided TIR still occurs.

Each first solid-state light emitter may be configured to emit the first light such that the first light has a first luminosity profile in a plane transverse the first light direction, Z, at the beam combining plate, i.e. upon incidence at the beam combining plate. Similarly, each second solid-state light emitter may be configured to emit the second light such that the second light has a second luminosity profile in a plane transverse the second light direction, Y, at the beam combining plate. The first light emitter array and the second light emitter array may then be arranged in relation to each other such that the first luminosity profile and the second luminosity profile have little or no overlap at the beam combining plate.

In various embodiments, the first light emitter array, the second light emitter array and the beam combining plate are spatially arranged in relation to each other such that: the first light enters the beam combining plate with a zero angle of incidence with respect to a surface normal direction via a surface of the ridges and/or grooves in the first side. The first light then undergoes TIR at the second side and exits the beam combining plate with a zero angle of refraction with respect to a surface normal direction via a surface of the ridges and/or grooves in the first side in the exit direction. The second light enters the beam combining plate via the second side and exits the beam combining plate via the first side in the exit direction. For example, the beam combining plate may be arranged in relation to the first light emitter array and the second light emitter array such that the beam combining plate lies in a plane that is at a 45 degree angle with the first light direction Z and a 45 degree angle with the second light direction Y. Moreover, the ridges and/or grooves in the first side may be prismatic 90 degree grooves.

For example, in some embodiments the second side of the beam combining plate may be smooth. Then, the second light enters the beam combining plate with a non-zero angle of incidence with respect to a surface normal direction via the second side and exits the beam combining plate with a non-zero angle of refraction with respect to a surface normal direction via the first side in the exit direction.

In some embodiments, the second side of the beam combining plate may comprise a plurality of parallel grooves and/or a plurality of parallel ridges. Then, the second light enters the beam combining plate with a non-zero angle of incidence with respect to a surface normal direction via a surface of the grooves and/or the ridges in the second side and exits the beam combining plate with a non-zero angle of refraction with respect to a surface normal direction via the first side in the exit direction.

In some embodiments, the second side of the beam combining plate may comprise a plurality of parallel grooves and/or a plurality of parallel ridges. Then, the second light enters the beam combining plate with a zero angle of incidence, with respect to a surface normal direction via a surface of the grooves and/or the ridges in the second side and exits the beam combining plate with a zero angle of refraction, with respect to a surface normal direction via the first side in the exit direction (130).

It is to be noted that, as used herein, a direction of light and zero angle of incidence and refraction refers only to the main propagation direction, i.e. optical axis, of the respective propagating light. For example, laser light is well collimated, but still has some divergence/angular spread (typically up to 2 degrees spread).

In some embodiments, each first solid-state light emitter is configured to emit the first light such that the first light has a first elliptic luminosity profile in a plane (160) transverse the first light direction, Z, at the beam combining plate. The first elliptic luminosity profile may then have a first major axis that is parallel to the ridges and/or grooves in the first side of the beam combining plate.

Similarly, in some embodiments, each second solid-state light emitter is configured to emit the second light such that the second light has a second elliptic luminosity profile in a plane transverse the second light direction, Y, at the beam combining plate. The second elliptic luminosity profile may then have a second major axis that is parallel to the grooves and/or the ridges in the second side.

That is, in embodiments where a combination of the first light and the second light takes place using a parallel configuration of luminosity profile major axes and groove/ridge directions, an increased efficiency is obtained in relation to a combination of the first light and the second light using a non-parallel configuration of luminosity profile major axes and groove/ridge directions.

In various embodiments, the second side of the beam combining plate comprises a plurality of parallel grooves and the first side of the beam combining plate may comprise a plurality of mirror surfaces configured to reflect the first light into the exit direction. In such embodiments, the second light enters the beam combining plate with a zero angle of incidence, with respect to a surface normal direction, via a surface of the grooves and/or the ridges in the second side. The second light then undergoes specular reflection via the mirror surfaces on the first side and TIR via the second side and exits the beam combining plate with a zero angle of refraction, with respect to a surface normal direction, via a surface of the grooves in the first side in the exit direction.

In some of these embodiments, the beam combining plate is arranged in relation to the first light emitter array and the second light emitter array such that the beam combining plate lies in a plane that is at a 45 degree angle with the first light direction, Z, and a 45 degree angle with the second light direction Y. The grooves in the first side may be prismatic 90 degree grooves. The grooves in the second side may comprise a respective facet via which the second light enters the beam combining plate with a zero angle of incidence and comprise a respective facet via which the second light undergoes the TIR.

In some embodiments, the mirror surfaces are configured as elongated parallel strips and each first solid-state light emitter is configured to emit the first light such that the first light has a first elliptic luminosity profile in a plane transverse the first light direction, Z, at the beam combining plate. Then, the first elliptic luminosity profile may have a first major axis that is parallel to the mirror surfaces configured as elongated parallel strips.

In some embodiments, each second solid-state light emitter is configured to emit the second light such that the second light has a second elliptic luminosity profile in a plane transverse the second direction, Y, at the beam combining plate. Then, the second elliptic luminosity profile may have a second major axis that is parallel to the grooves in the second side. In various embodiments, the beam combining plate is monolithic and, in various other embodiments, the beam combining plate is modular comprising a plurality of modules.

In a further aspect there is provided a lighting device selected from the group of a lamp, a luminaire, a projector device, visible light communication device, searchlight and a stage lighting/entertainment lighting system, comprising the light source device as summarized above.

Such a lighting device and embodiments thereof provide effects and advantages that correspond to those summarized above.

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 where:

Fig. la schematically illustrates a perspective view of a light source device,

Fig. lb schematically illustrates a side view of the of the light source device in Fig- la,

Fig. 1c schematically illustrates an alternative configuration of the light source device in Fig. la,

Figs. Id and le schematically illustrate a respective luminosity profile,

Figs. 2 to 5 schematically illustrate a respective beam combining plate,

Fig. 6 schematically illustrates modular beam combining plate,

Figs. 7a to 7d are graphs of luminosity simulations,

Fig. 8a schematically illustrates a side view of a light source device,

Fig. 8b schematically illustrates a mirror surface configuration in the light source device in Fig. 8a, and

Fig. 9 schematically illustrates a lighting device.

DETAILED DESCRIPTION

As illustrated in Figures la and lb, a light source device 100 according to the invention comprises a first light emitter array 101 comprising a plurality of first solid-state light emitters 102. Each first solid-state light emitter 102 is configured to provide first light 103 in a first light direction Z. A second light emitter array 111 comprises a plurality of second solid-state light emitters 112. Each second solid-state light emitter 112 is configured to provide second light 113 in a second light direction Y. A transparent beam combining plate 120 has a first side 121 configured with a plurality of parallel ridges and/or grooves 122 and a second side 123 opposite the first side 121.

The first light emitter array 101, the second light emitter array 111 and the beam combining plate 120 are spatially arranged in relation to each other such that the first light 103 is incident on the first side 121 of the beam combining plate 120 and the second light 113 is incident on the second side 123 of the beam combining plate 120. The first light 103 and the second light 113 are combined by the beam combining plate 120 to exit the beam combining plate 120 via the first side 121 in an exit direction 130. Any one of the first light 103 and the second light 113 undergoes at least one total internal reflection (TIR) within the beam combining plate 120.

Figures la and lb illustrates an example of how the light emitter arrays 101, 111 may be arranged in relation to each other, i.e. essentially arranged in perpendicular planes, whereby the first light 103 and second light 113 are emitted perpendicular to each other and arrive at the beam combining plate 120 perpendicular to each other. However, the light emitter arrays 101, 111 may be arranged in other angular relations with respect to each other, for example parallel with each other as Figure 1c illustrates. A reflector 180 may then be arranged such that the first light 103 and second light 113 arrive at the beam combining plate 120 perpendicular to each other.

As exemplified in Figures la and lb, the first light emitter array 101, the second light emitter array 111 and the beam combining plate 120 may be spatially arranged in relation to each other such that the first light 103 enters the beam combining plate 120 with a zero angle of incidence, with respect to a surface normal direction 148, via a surface of the ridges and/or grooves 122 in the first side 121. The first light 103 then undergoes TIR at the second side 123 and exits the beam combining plate 120 with a zero angle of refraction, with respect to a surface normal direction 149, via a surface of the ridges and/or grooves 122 in the first side 121 in the exit direction 130. The second light 113 enters the beam combining plate 120 via the second side 123 and exits the beam combining plate 120 via the first side 121 in the exit direction 130.

When referring to a zero angle of incidence we mean actually that the angle of incidence of the optical axis of the beam with respect to the surface normal is within a°, while the halfangle divergence for a beam propagating in the Z direction, at least in a plane through the Z direction and the Y direction, is within °. Then the maximum angular deviation from the surface normal direction of light propagation in a plane through the Z direction and the Y direction is a° + °. Preferably, a + 0 < 10°, such as < 5°. E.g., a < 3° and 0 < 2°. Similarly, for a beam propagating in the Y direction, the half-angle divergence at least in a plane through the Z direction and the Y direction is within 0°.

As exemplified in Figures la and lb, the beam combining plate 120 may be arranged in relation to the first light emitter array 101 and the second light emitter array 111 such that the beam combining plate 120 lies in a plane 119 that is at a 45 degree angle with the first light direction Z and a 45 degree angle with the second light direction Y. Moreover, the ridges and/or grooves 122 in the first side 121 may be prismatic 90 degree grooves.

As exemplified in Figures la and lb, the second side 123 of the beam combining plate 120 may be smooth. Then, the second light 113 may enter the beam combining plate 120 with a non-zero angle of incidence 150, with respect to a surface normal direction 151, via the second side 123 and exit the beam combining plate 120 with a non-zero angle of refraction 152, with respect to a surface normal direction 153, via the first side 121 in the exit direction 130.

With reference to Figures 2 and 3, and with continued reference to Figures la and lb, the second side 123 of the beam combining plate 120 may comprise a plurality of parallel grooves 124 and/or a plurality of parallel ridges 125. Then, the second light 113 may enter the beam combining plate 120 with a zero angle of incidence, with respect to a surface normal direction 246, via a surface of the grooves 124 and/or the ridges 125 in the second side 123 and exit the beam combining plate 120 with a zero angle of refraction, with respect to a surface normal direction 247, via the first side 121 in the exit direction 130.

With reference to Figures 4 and 5, and with continued reference to Figures la and lb, the second side 123 of the beam combining plate 120 may comprise a plurality of parallel grooves 124 and/or a plurality of parallel ridges 125. Then, the second light 113 may enter the beam combining plate 120 with a non-zero angle of incidence 250, with respect to a surface normal direction 251, via a surface of the grooves 124 and/or the ridges 125 in the second side 123 and exits the beam combining plate 120 with a non-zero angle of refraction 252, with respect to a surface normal direction 253, via the first side 121 in the exit direction 130.

With reference to Figure Id, and with continued reference to Figures la and lb and Figures 2 to 5, each first solid-state light emitter 102 may be configured to emit the first light 103 such that the first light 103 has a first elliptic luminosity profile 104 in a plane 160 transverse the first light direction Z at the beam combining plate 120. The first elliptic luminosity profile 104 then has a first major axis 105 that is parallel to the ridges and/or grooves 122 in the first side 121 of the beam combining plate 120.

With reference to Figure le, and with continued reference to Figures la and lb and Figures 2 to 5, each second solid-state light emitter 112 may be configured to emit the second light 113 such that the second light 113 has a second elliptic luminosity profile 114 in a plane 161 transverse the second light direction Y at the beam combining plate 120. The second elliptic luminosity profile 114 then has a second major axis 115 that is parallel to the grooves 124 and/or the ridges 125 in the second side 123.

As exemplified in Figures 2 to 5, the beam combining plate 120 may be monolithic. However, as illustrated in Figure 6, the beam combining plate 120 may be modular comprising a plurality of modules 131, 132. The modules 131 and 132 may be prismatic strips of glass or fused silica, cut and polished under the correct angle from a large plate or made by extrusion. They may then be glued together with index-matching adhesive to minimize Fresnel reflection losses.

In any embodiment, the beam combiner is preferably made of a glass material, or another substantially transparent inorganic material such as a transparent ceramic or a solgel material, with minimal absorption in the spectral range of the light emitters 102, 112. Lower refractive index glass, such as fused silica, material may be preferred in order to minimize beam displacements and Fresnel losses.

Figures 7a-d present simulation results illustrating that the efficiency of combining the first light 103 and the second light 113 is increased for a configuration where the first elliptic luminosity profile 104 has a first major axis 105 that is parallel to the ridges and/or grooves 122 in the first side 121 of the beam combining plate 120 and the second elliptic luminosity profile 114 has a second major axis 115 that is parallel to the grooves 124 and/or the ridges 125 in the second side 123. Figures 7a and 7b illustrate such a parallel arrangement of the luminosity profile major axes and grooves/ridges, whereas Figures 7c and 7d illustrate a non-parallel configuration where the first elliptic luminosity profile 104 has a first major axis 105 that is transverse to the ridges and/or grooves 122 in the first side 121 of the beam combining plate 120 and the second elliptic luminosity profile 114 has a second major axis 115 that is transverse to the grooves 124 and/or the ridges 125 in the second side 123.

In Figure 7a, reference numeral 701 indicates detected luminosity by a two- dimensional light detector 150 that is arranged to, as schematically illustrated in Figure la, detect the combined first and second light 103, 113 transverse the exit direction 130. Reference numerals 702 and 703 indicate respective graphs of luminosity values along a representative row and a representative column of the detected luminosity 701.

In Figure 7b, reference numeral 704 indicates detected luminosity by a two- dimensional light detector 151 that is arranged to, as schematically illustrated in Figure la, detect light 721 not combined by the beam combining plate 120 but consisting of fractions of first light 103 transmitted through the beam combining plate 120 and fractions of second light 113 reflected by the second side 123 and/or the first side 121 of the beam combining plate 120; that is, light that is not combined into the desired exit direction. Of course there is some combining of residual fraction of light (propagating non-ideally) that leaves the beam combiner plate into the non-desired Z-direction.

As indicated in Figure la, such a two-dimensional light detector 151 is arranged transverse the first direction Z. Reference numerals 705 and 706 indicate respective graphs of luminosity values along a representative row and a representative column of the detected luminosity 704.

In Figures 7c and 7d, detected luminosity 707, 710 and graphs 708, 709, 711, 712 of luminosity values along representative rows and columns of the detected luminosity 707, 710 are illustrated for the non-parallel configuration.

What Figures 7a-d illustrate is a finding that, using the parallel configuration, a combination of the first light 103 and the second light 113 has an efficiency of 96%, whereas a combination of the first light 103 and the second light 113, using the non-parallel configuration, has an efficiency of only 84%, where the rest of the light is not combined into desired propagation direction and leaked through the beam combining plate 120 further along the Z-direction or lost by undesired Fresnel reflections into other directions.

Moreover, continuing with reference to Figures la, lb, Id, le and Figure 7a, each first solid-state light emitter 102 may be configured to emit the first light 103 such that the first light 103 has a first luminosity profile 104 in a plane 160 transverse the first light direction, Z, at the beam combining plate 120 and each second solid-state light emitter 112 may be configured to emit the second light 113 such that the second light 113 has a second luminosity profile 114 in a plane 161 transverse the second light direction, Y at the beam combining plate 120. Then, the first light emitter array 101 and the second light emitter array 111 may be arranged in relation to each other such that the first luminosity profile 104 and the second luminosity profile 114 have little or no overlap at the beam combining plate 120. That is, the luminosity profiles of the first light 103 and the second light 113 that would be exiting the plate in the exit direction have little or no overlap at the beam combining plate 120 in case the beam combining plate 120 would be ideally reflective for the first light 103 and in case the beam combining plate 120 would be ideally transmissive for the second light 113.

To exemplify the concept of overlap, referring to Figures la, lb, 7c and 7d, let the centers of the luminosity profiles of a first light emitting array with 7x4 emitters be located after the beam combiner 120 at coordinates (X, Z)_l = ( 0 +i * 2.3mm, 0 + j * 6mm) with i = 0..6 and j = 0..3. Then the centers of the luminosity profiles of a second light emitting array with 7x4 emitters may be located after the beam combiner 120 at coordinates (X, Z)_2 = ( 1.15 + i *2.3mm, 3 + j * 6mm) with i = 0..6 and j = 0..3.

That is, there are two aspects: first the location of the centers of luminosity of the beams exiting the beam combining plate 120, and second the lateral extents of the individual beams, as incident on the beam combining plate 120, relative to the pitch between rows of luminosity centers of the luminosity profiles.

For clarity it may be of use to define a primary pitch and a secondary pitch. The primary pitch is then the pitch between rows of luminosity centers, the rows of luminosity centers being defined in a direction parallel to the grooves and/or ridges in the beam combining plate 120, and the primary pitch being defined in a direction perpendicular to these rows of luminosity centers (i.e., as the distance between these rows of luminosity centers) in a plane perpendicular to the beam propagation; in the above example, this primary pitch is defined along the Z direction and is 6 mm. The pitch between luminosity centers along a line parallel to the grooves and/or ridges in the beam combining plate may be indicated as the secondary pitch; in the above example this secondary pitch is defined along the X direction and is 2.3 mm. For the efficiency of the beam combiner, the primary pitch is critically important and needs, for both the first and the second light 103,113, to be equal to a projected pitch of the grooves and/or ridges of the beam combining plate 120 on a plane perpendicular to the beam propagation. Therefore, for a beam combining plate mounted under an angle of 45 degrees, as exemplified and illustrated in Figures la and lb, with the first and second light 103 and 113, a pitch (or period) of the grooves and/or ridges in the plane 119 of the beam combining plate 120 would be SQRT(2) times the primary pitch of the lines of luminosity centers in the first and second light 103, 113. The secondary pitch of the first and the second light, however, may differ as this secondary pitch does not impact the efficiency of the beam combining plate 120. It may be advantageous, though, to use a same secondary pitch for the first and the second light 103, 113 as that enables a balanced and most homogeneous filling of the plane perpendicular to the exit direction 130 with luminosity centers. Note that the primary and secondary pitch of the first and second light 103, 113, respectively, do not necessarily need to be equal to the corresponding pitches of light sources 102, 112 in the light source arrays 101 and 111, as ID or 2D beam expanding optics may be used between one or both of the light source arrays 101, 111 and the beam combining plate 120 to adjust these primary and/or secondary pitches between the luminosity centers.

For efficiency optimization, preferably >75% of the light of individual light beams from the first light emitter array 101 is arriving at the beam combining plate 120 within a lateral “spread” along the Y-direction less than or equal to the primary pitch (i.e., 6 mm in this example), and >75% of the light of individual light beams from the second light emitter array I l l is arriving at the beam combining plate 120 within a lateral “spread” along the Z-direction less than or equal to the corresponding pitch (i.e., 6 mm in this example), or higher percentages for improved efficiency of course. In other words, at least 75% of the light of individual light beams should be within the maximum width (or “spread”) in a direction perpendicular to the incident light propagation direction and perpendicular to the direction of the ridges and/or grooves, that results, as intended, in transfer from input plane to output plane of the beam combining plate 120. That maximum width is equal to the primary pitch. It may also be formulated as that this maximum width should be equal to or less than the primary pitch.

Upon arrival at the beam combining plate, the lateral spread of the individual light beams from the first light emitter array 101 in the X direction and the lateral spread of the individual light beams from the second light emitter array 111 in the X direction may or may not be equal and do not need to be related to the secondary pitch of the luminosity centers in the first light 103 and the second light 113. This lateral spread has no substantial impact on the efficiency of the beam combiner plate 120.

In addition, while for the position of the luminosity centers in the Z direction it is important to have the luminosity centers of the second light offset in the Z direction by half the primary pitch relative to the luminosity centers of the first light (to minimize overlap at the plane 119 of the beam combining plate 120), the relative offset of the luminosity centers of the second light 113 in the X direction relative to the luminosity centers of the first light 103 in the X direction is not impacting the efficiency of the beam combining plate 120, but does impact the distribution of luminosity centers in the combined beam (i.e., in a plane perpendicular to the exit direction 130) and therefore the uniformity of the light distribution. Therefore, it may be preferred to also use an offset of half the secondary pitch in the X direction between the luminosity centers of the first light 103 and the second light 113. As illustrated in Figures 8a-c, and with continued reference to Figures la-e, the second side of the beam combining plate 120 may in various embodiments comprise a plurality of parallel grooves 128. In such embodiments, the beam combining plate 120 may comprise a plurality of mirror surfaces 126 arranged on the first side 121. These mirror surfaces 126 are configured to reflect the first light 103 into the exit direction 130. In such embodiments, the second light 113 enters the beam combining plate 120 with a zero angle of incidence, with respect to a surface normal direction 246, via a surface of the grooves 128 and/or the ridges 129 in the second side 123 and undergoes specular reflection via the mirror surfaces 126 on the first side 121 and undergoes TIR via the second side 123 and exits the beam combining plate 120 with a zero angle of refraction, with respect to a surface normal direction 247, via a surface of the grooves 122 in the first side 121 in the exit direction 130.

For example, the beam combining plate 120 may be arranged in relation to the first light emitter array 101 and the second light emitter array 111 such that the beam combining plate 120 lies in a plane 119 that is at a 45 degree angle with the first light direction Z and a 45 degree angle with the second light direction Y. Moreover, the grooves

122 in the first side 121 may be prismatic 90 degree grooves, the grooves 128 in the second side 123 may comprise a respective facet 127 via which the second light 113 enters the beam combining plate 120 with a zero angle of incidence, and the grooves 128 in the second side

123 may comprise a respective facet 141 via which the second light 113 undergoes the TIR.

In some of these embodiments, the mirror surfaces 126 are configured as elongated parallel strips as exemplified in Figure 8b. Each first solid-state light emitter 102 may be configured to emit the first light 103 such that the first light 103 has a first elliptic luminosity profile 104 in a plane 160 transverse the first light direction Z at the beam combining plate 120, and the first elliptic luminosity profile 104 may have a first major axis 105 that is parallel to the mirror surfaces 126 configured as elongated parallel strips. The mirror surfaces 126 may be elongated along an elongation direction 171. As exemplified in Figure 8b, the mirror surfaces 126 may be elongated in a simple elongated rectangle form.

In some of these embodiments, each second solid-state light emitter 112 is configured to emit the second light 113 such that the second light 113 has a second elliptic luminosity profile 114 in a plane 161 transverse the second direction Y at the beam combining plate 120. The second elliptic luminosity profile 114 may then have a second major axis 115 that is parallel to the grooves 128 in the second side 123. Figure 9 illustrates a lighting device 500. The lighting device 500 may be selected from the group of a lamp, a luminaire, a projector device and an entertainment lighting system, comprising the light source device 100 as described herein.

Claims

CLAIMS:

1. A light source device (100) comprising : a first light emitter array (101) comprising a plurality of first solid-state light emitters (102), each first solid-state light emitter (102) being configured to provide first light (103) in a first light direction (Z), a second light emitter array (111) comprising a plurality of second solid-state light emitters (112), each second solid-state light emitter (112) being configured to provide second light (113) in a second light direction (Y), a transparent beam combining plate (120) having a first side (121) configured with a plurality of parallel ridges and/or grooves (122) and a second side (123) opposite the first side (121), wherein: the first light emitter array (101), the second light emitter array (111) and the beam combining plate (120) are spatially arranged in relation to each other such that:

- the first light (103) is incident on the first side (121) of the beam combining plate (120),

- the second light (113) is incident on the second side (123) of the beam combining plate (120),

- the first light (103) and the second light (113) are combined by the beam combining plate (120) to exit the beam combining plate (120) via the first side (121) in an exit direction (130), and such that:

- any one of the first light (103) and the second light (113) undergoes at least one total internal reflection, TIR, within the beam combining plate (120).

2. The light source device (100) according to claim 1, wherein: the first light emitter array (101), the second light emitter array (111) and the beam combining plate (120) are spatially arranged in relation to each other such that: the first light (103) enters the beam combining plate (120) with a zero angle of incidence, with respect to a surface normal direction (148), via a surface of the ridges and/or grooves (122) in the first side (121) and undergoes TIR at the second side (123) and exits the beam combining plate (120) with a zero angle of refraction, with respect to a surface normal direction (149), via a surface of the ridges and/or grooves (122) in the first side (121) in the exit direction (130), and the second light (113) enters the beam combining plate (120) via the second side (123) and exits the beam combining plate (120) via the first side (121) in the exit direction (130).

3. The light source device (100) according to claim 2, wherein the second side (123) of the beam combining plate (120) is smooth and wherein: the second light (113) enters the beam combining plate (120) with a non-zero angle of incidence (150), with respect to a surface normal direction (151), via the second side (123) and exits the beam combining plate (120) with a non-zero angle of refraction (152), with respect to a surface normal direction (153), via the first side (121) in the exit direction (130).

4. The light source device (100) according to claim 2, wherein the second side (123) of the beam combining plate (120) comprises a plurality of parallel grooves (124) and/or a plurality of parallel ridges (125), and wherein: the second light (113) enters the beam combining plate (120) with a non-zero angle of incidence (250), with respect to a surface normal direction (251), via a surface of the grooves (124) and/or the ridges (125) in the second side (123) and exits the beam combining plate (120) with a non-zero angle of refraction (252), with respect to a surface normal direction (253), via the first side (121) in the exit direction (130).

5. The light source device (100) according to claim 2, wherein the second side

(123) of the beam combining plate (120) comprises a plurality of parallel grooves (124) and/or a plurality of parallel ridges (125), and wherein: the second light (113) enters the beam combining plate (120) with a zero angle of incidence, with respect to a surface normal direction (246), via a surface of the grooves

(124) and/or the ridges (125) in the second side (123) and exits the beam combining plate (120) with a zero angle of refraction, with respect to a surface normal direction (247), via the first side (121) in the exit direction (130).

6. The light source device (100) according to any one of claims 2 to 5, wherein: each first solid-state light emitter (102) is configured to emit the first light (103) such that the first light (103) has a first elliptic luminosity profile (104) in a plane (160) transverse the first light direction (Z) at the beam combining plate (120), and the first elliptic luminosity profile (104) has a first major axis (105) that is parallel to the ridges and/or grooves (122) in the first side (121) of the beam combining plate (120).

7. The light source device (100) according to any one of claims 4 to 6, wherein: each second solid-state light emitter (112) is configured to emit the second light (113) such that the second light (113) has a second elliptic luminosity profile (114) in a plane (161) transverse the second light direction (Y) at the beam combining plate (120), and the second elliptic luminosity profile (114) has a second major axis (115) that is parallel to the grooves (124) and/or the ridges (125) in the second side (123).

8. The light source device (100) according to any one of claims 2 to 7, wherein: the beam combining plate (120) is arranged in relation to the first light emitter array (101) and the second light emitter array (111) such that the beam combining plate (120) lies in a plane (119) that is at a 45 degree angle with the first light direction (Z) and a 45 degree angle with the second light direction (Y), and the ridges and/or grooves (122) in the first side (121) are prismatic 90 degree grooves.

9. The light source device (100) according to claim 1, wherein the second side of the beam combining plate (120) comprises a plurality of parallel grooves (128), and wherein: the beam combining plate (120) comprises a plurality of mirror surfaces (126) arranged on the first side (121) and configured to reflect the first light (103) into the exit direction (130), the second light (113) enters the beam combining plate (120) with a zero angle of incidence, with respect to a surface normal direction (246), via a surface of the grooves (128) and/or the ridges (129) in the second side (123) and undergoes specular reflection via the mirror surfaces (126) on the first side (121) and undergoes TIR via the second side (123) and exits the beam combining plate (120) with a zero angle of refraction, with respect to a surface normal direction (247), via a surface of the grooves (122) in the first side (121) in the exit direction (130).

10. The light source device (100) according to claim 9, wherein: the beam combining plate (120) is arranged in relation to the first light emitter array (101) and the second light emitter array (111) such that the beam combining plate (120) lies in a plane (119) that is at a 45 degree angle with the first light direction (Z) and a 45 degree angle with the second light direction (Y), the grooves (122) in the first side (121) are prismatic 90 degree grooves, the grooves (128) in the second side (123) comprise a respective facet (127) via which the second light (113) enters the beam combining plate (120) with a zero angle of incidence, and the grooves (128) in the second side (123) comprise a respective facet (141) via which the second light (113) undergoes the TIR.

11. The light source device (100) according to any one of claims 9 to 10, wherein: the mirror surfaces (126) are configured as elongated parallel strips, each first solid-state light emitter (102) is configured to emit the first light (103) such that the first light (103) has a first elliptic luminosity profile (104) in a plane (160) transverse the first light direction (Z) at the beam combining plate (120), and the first elliptic luminosity profile (104) has a first major axis (105) that is parallel to the mirror surfaces (126) configured as elongated parallel strips.

12. The light source device (100) according to any one of claims 9 to 11, wherein: each second solid-state light emitter (112) is configured to emit the second light (113) such that the second light (113) has a second elliptic luminosity profile (114) in a plane (161) transverse the second direction (Y) at the beam combining plate (120), and the second elliptic luminosity profile (114) has a second major axis (115) that is parallel to the grooves (128) in the second side (123).

13. The light source device (100) according to any one of claims 1 to 12, wherein: each first solid-state light emitter (102) is configured to emit the first light

(103) such that the first light (103) has a first luminosity profile (104) in a plane (160) transverse the first light direction (Z) at the beam combining plate (120), each second solid-state light emitter (112) is configured to emit the second light (113) such that the second light (113) has a second luminosity profile (114) in a plane (161) transverse the second light direction (Y) at the beam combining plate (120), the first light emitter array (101) and the second light emitter array (111) are arranged in relation to each other such that the first luminosity profile (104) and the second luminosity profile (114) have little or no overlap at the beam combining plate (120). 14. The light source device (100) according to any one of claims 1 to 13, wherein: the beam combining plate (120) is monolithic or modular comprising a plurality of modules (131, 132), the first light emitter array comprises a first laser bank comprising an array of a first plurality of laser diodes, - the second light emitter array comprises a second laser bank comprising an array of a second plurality of laser diodes.

15. A lighting device (500) selected from the group of a lamp, a luminaire, a projector device, a spot light, a search light, a signaling light, a stage lighting system, an architectural lighting system and an entertainment lighting system, comprising the light source device (100) according to any one of the preceding claims.