System of multiple single-mode laser sources

Abstract

The present invention relates to a system of multiple single-mode laser sources, having: - a multi-mode laser source (14) for generating a multi-mode light beam (LBMM) ,- at least one mode filter (175, 175', 175") which filters a single-mode light beam (LBSM, LBSM', LBSM") out of a multi-mode light beam (LBMM, LBMM', LBMM") and allows a remaining light beam (LBR, LBR', LBR") to pass, and - at least one light mixer (176, 176', 176") to which the remaining light beam (LBR, LBR', LBR") is supplied and which generates a mode-mixed multi-mode light beam (LBMM', LBMM").

Description

[0001] 202405062

[0002] 1

[0003] Designation

[0004] System of multiple single-mode laser sources

[0005] The present invention relates to a system of multiple single-mode laser sources. Such single-mode laser sources are used, for example, in projection devices. Often, several projection devices are used together in a single application. Projection devices are used, for example, in a head-up display (HUD) to generate a virtual image behind / above the windshield or to project it onto other windows or surfaces of a motor vehicle. A head-up display, also known as a HUD, is a display system in which the viewer can maintain their line of sight because the displayed content is projected into their field of vision. While such systems were originally used primarily in the aerospace industry due to their complexity and cost, they are now also being mass-produced in the automotive sector.

[0006] Head-up displays generally consist of an image-generating unit (PGU), an optical unit, and a mirror unit. The image-generating unit creates the image, using at least one display element. Modern head-up displays typically use displays or scanning systems for image generation. Displays can be, for example, LCDs (LC: Liquid Crystal), p-LED displays (LED: Light Emitting Diode), LCoS displays (LCoS: Liquid Crystal on Silicon), or DMD systems (DMD: Digital Micromirror Device). A laser scanning system is an example of a scanning system. The optical unit directs the image onto the mirror unit. The mirror unit is a partially reflective, translucent disc.The viewer thus sees the content displayed by the imaging unit as a virtual image and simultaneously the real world behind the glass. In the automotive sector, the windshield often serves as the mirror unit, its curved shape being taken into account in the display, for example by pre-distorting the image displayed by the imaging unit. (By the 202405062.)

[0007] 2

[0008] The interaction of the optical unit and the mirror unit results in a virtual image that is an enlarged and distorted representation of the image produced by the imaging unit.

[0009] Projection devices generally consist of a picture generating unit (PGU) and a projection surface on which a real image is visible. The projection surface can be an opaque surface, such as one mounted on the dashboard of a vehicle, or a transparent window pane of a vehicle with a special diffusion property that ensures the projection is visible while minimizing obstruction of the view through the vehicle. The picture generating unit creates the image, using at least one display element. Modern projection devices typically use displays or scanning systems for image generation.Displays can be, for example, LCDs (LC: Liquid Crystal), p-LED displays (LED: Light Emitting Diode), LCoS displays (LCoS: Liquid Crystal on Silicon), or DMD systems (DMD: Digital Micromirror Device). An example of a scanning system is a laser beam scanner (often abbreviated as LBS). In this system, a laser beam modulated with image information is guided across the projection surface. This can be done, for example, in a line grid. If the projection surface has a diffuser, the image drawn by the laser beam can be seen by a viewer. Since the laser beam has a small angular spread (small aperture angle), the light coming from the diffuser is also generally limited to a specific angular range. This depends on the diffusion properties of the diffuser.If the diffuser scatters light over a wide angle, the amount of light reaching the viewer's eye is less than with a diffuser that has a narrow angle (when the eye is positioned within that angle). For energy-saving reasons, a diffuser that scatters light over a relatively narrow angle is therefore usually used. This benefits the brightness of the image, which can be achieved with the given, usually quite limited, projector power. The smaller the angle, the better.

[0010] The greater the area into which the diffuser scatters the light, the greater the brightness of the image as perceived by the viewer.

[0011] The diffuser can be, for example, a scattering, possibly backscattering, and transparent disc. Partial scattering or partial backscattering is desirable for the projection to be visible. The viewer then sees the content displayed by the imaging unit as a real image and simultaneously the real world behind this disc. In the automotive sector, a side window or the rear window, another transparent or reflective surface, or even an opaque surface, such as the dashboard or headliner, often serves as the projection surface. The curved shape of such a surface is taken into account during the projection, for example, by pre-distorting the image displayed by the imaging unit.

[0012] The viewer can only perceive the virtual image of a head-up display or the real image emanating from a diffuser from the position of the so-called eyebox. The eyebox is defined as an area whose height and width correspond to a theoretical viewing window. The size of the eyebox depends on the angle of incidence of the light coming from the display element or the diffuser. As long as the viewer's eye is within the eyebox, all elements of the virtual or real image are visible. If, however, the eye is outside the eyebox, the virtual or real image is only partially visible or not visible at all. Therefore, the larger the eyebox, the less restricted the viewer is in their choice of seating position.When using a diffuser, the eyebox is not sharply cut off at the edge, as is the case with a typical head-up display. Instead, the image brightness decreases towards the edge of the eyebox, but may still be visible further outside. In this case, the eyebox boundary can be defined, for example, by a relative decrease in image brightness.

[0013] The optical unit of a head-up display typically includes several mirrors to minimize the required installation space. The imaging unit (202405062)

[0014] 4

[0015] Light emitted from a unit is reflected, for example, by a folding mirror onto a curved mirror, which then reflects it towards the windshield. Currently used curved mirrors are essentially flat plates with a high degree of curvature, corresponding to the desired optical function. Such curved mirrors are manufactured, for example, by injection molding or compression molding.

[0016] In laser beam scanner systems, the light from RGB color laser diodes – typically one laser diode per color component R, G, and B – is scanned across the display area by a scanner that, for example, incorporates oscillating MEMS mirrors (MEMS: micro-electro-mechanical system). The image is then generated on the display area by modulating the power of the color laser diodes synchronously with the movement of the mirrors.

[0017] Laser scanning systems are distinguished from LCD-based display solutions by their less complex optics, higher energy efficiency, and different cooling requirements.

[0018] Laser scanning systems typically exhibit greater temperature sensitivity than LCD-based display solutions. The latter can therefore often be passively cooled, while laser-based systems in the automotive sector tend to require active cooling, such as cooling using Peltier elements. As an alternative to RGB color laser diodes, a short-wavelength laser can also be used to scan an RGB wavelength converter in a suitable intermediate image plane.

[0019] With coherent light, such as that emitted by a laser light source, unwanted speckle patterns often appear, which should be reduced or eliminated to achieve a good image quality. Speckle patterns, light granulation, laser granulation, or simply speckle, refer to the granular interference phenomena that can be observed, for example, when optically rough object surfaces (unevenness on the order of the wavelength) are illuminated with sufficiently coherent light. With more ordered structures such as lens arrays, these disruptive interference effects can also significantly impact image quality.

[0020] 5

[0021] exhibit a degree of order. At this point, we broaden the definition of speckle or speckle pattern and also include such effects.

[0022] The term "speck," which refers to both a single spot of light and the entire interference pattern, is derived from the English word "speckle." Depending on the imaging system used, the predominantly English-language literature also distinguishes between "subjective speckle" and "objective speckle": If the speckle is projected directly onto a screen without the aid of a lens or other optical devices, it is called objective speckle. In contrast, subjective speckle refers to the imaging of the interference pattern using a lens or more complex optical systems. This includes the human eye.

[0023] Some applications require mode-pure light. In laser beam scanners, light with only one transverse mode, also known as a single-mode light beam, is needed, for example, for small focal points to achieve a sharp, high-resolution image. If multiple projectors with laser beam scanners are used, for example, in a vehicle, many single-mode laser sources are required. Each of the laser beam scanners is then equipped with a set of single-mode laser sources, such as laser diodes.

[0024] Single-mode laser sources are currently only economically available at low power levels. Each set of single-mode laser sources, for example, consisting of laser diodes for red (R), green (G), and blue (B) light, requires its own cooling system, which incurs additional costs. Furthermore, dissipating the waste heat at the projector's location is not always straightforward, which is another disadvantage.

[0025] The transverse modes of a laser source are defined as the distribution of the phase of the waves perpendicular to the direction of propagation. If a mode forms that does not fill the space perpendicular to the resonator mirrors, but rather runs at a slight angle, the light and resonator path becomes longer, and the 202405062

[0026] 6

[0027] The frequency shifts slightly. This leads, on the one hand, to competition for excited elements of the laser medium between the different frequencies (mode competition), and on the other hand, to the formation of standing waves that exhibit nodal lines within the laser profile. With a cylindrical cross-section, the beam intensity ideally has a Gaussian profile; this mode is called the TEM00 mode. However, other profiles with angular and radial dependencies can also occur. Depending on the number of their nodal lines in the horizontal and vertical directions, they are called the TEMxy mode. Single-mode laser sources typically produce light with pure TEM00 mode.

[0028] The brightness levels achievable with laser beam scanners based on oscillating MEMS mirrors are further limited by the inherent power handling capacity of the MEMS mirrors. The power handling limit of a MEMS mirror is in the watt range. This means, for example, that only small projections can be displayed with sufficient brightness.

[0029] A reduction in the number of single-mode laser sources requiring cooling is desirable.

[0030] According to the invention, the desired TEMOO component is filtered out from the light of a multi-mode laser source, for example, a corresponding laser diode, and fed to a first output. The remaining light is remixed, and its TEMOO component is again fed to the next output. This process is repeated until all outputs are supplied.

[0031] A system of multiple single-mode laser sources according to the invention comprises:

[0032] - a multi-mode laser source for generating a multi-mode light beam,

[0033] - at least one mode filter which filters out a single-mode light beam from a multi-mode light beam, and allows a remaining light beam to pass through, and

[0034] - at least one light mixer to which the remaining light beam is fed and which generates a mode-mixed multi-mode light beam. 202405062

[0035] 7

[0036] This offers several advantages, including the following: A smaller number of laser sources, such as fewer laser diodes, are required, which can be positioned conveniently along with their cooling system. From there, multiple applications requiring single-mode light, such as projectors with laser beam scanners, are supplied with light and / or image information via optical fibers. The invention proposes methods for controlling the distribution to the individual single-mode channels. With the solution according to the invention, the distribution of power to each channel is not a matter of chance. This is a crucial advantage, benefiting reliability, efficiency, and image dynamics.

[0037] One embodiment of the invention provides that the mode filter has an input lens, a mirror and an output lens, wherein the input lens focuses a multi-mode light beam onto the mirror, in the center of which the aperture of a single-mode optical fiber is arranged, and whose mirror surface focuses onto the output lens, which in turn focuses onto the light mixer.

[0038] Another embodiment of the invention provides that the mode filter comprises an input lens and a concave mirror, wherein the input lens focuses a multi-mode light beam onto the concave mirror, in the center of which the aperture of a single-mode optical fiber is arranged, and whose mirror surface focuses onto the light mixer. This embodiment is compatible with

[0039] The light mixer advantageously features a multi-mode fiber. Such multi-mode fibers are inexpensive, compact, and their mixing behavior can be influenced by deformation.

[0040] The multi-mode fiber is advantageously designed as a controllable mixer. This allows the amount of power coupled to each output to be regulated.

[0041] Advantageously, the multi-mode fiber features a movement mechanism. The movement of the multi-mode fiber serves to regulate the light output at the 202405062

[0042] 8 individual outputs. For example, a multimode fiber is laid into a loop (or several turns) and fitted with a permanent or ferromagnet located in the field of a coil. The current in the coil can move / deform the loop. One can then control how much power is coupled into the first output and vary the coil current until the desired power is achieved. A control loop can stabilize the selected setting.

[0043] A projection system according to the invention has:

[0044] - a previously described system of multiple single-mode laser sources, and

[0045] - several mirror units for moving a collimated light beam over a projection surface, wherein each of the mirror units is supplied with a single-mode light beam provided by one of the multi-mode filters.

[0046] To achieve sufficient brightness on larger projection surfaces and to prevent overloading the MEMS mirrors in the laser beam scanners, the light provided by a powerful laser is split using beam splitters, thus limiting the power of each individual beam. The light from each beam is then transmitted, for example via fiber optics, to a separate MEMS mirror. Using these multiple MEMS mirrors, a partial image can be projected simultaneously onto different, potentially adjacent, areas of the surface, thereby creating a larger overall image. The intensity and color of the image content generated by each MEMS mirror are controlled by intermediate switching elements. The invention also allows for the use of multiple MEMS mirrors for projection onto the same projection surface. This enables a brighter image to be displayed.

[0047] According to one embodiment of the invention, each individual color (R / G / B) is projected via a separate MEMS mirror, and the individual projections are superimposed. 202405062

[0048] 9

[0049] One advantage of the projection system according to the invention lies in the greater achievable brightness of large projections using only a single laser light source. Furthermore, the effort required for controlling and temperature regulation of the laser light source is reduced.

[0050] A system according to the invention can also be used effectively in other applications where there is a need for single-mode light of the same wavelength at several locations.

[0051] The brightness increase according to the invention by beam splitting of a central laser light source is generally suitable for laser beam scanner systems, especially for large projections with high brightness requirements.

[0052] In a training course, various projectors displaying different content are used. The modulation is no longer performed globally via the laser diode current, but advantageously on a channel-by-channel basis. In this case, a light modulator is provided for the color channels of each laser scanner. This is implemented, for example, as a Kerr cell, possibly in combination with an interferometer. Implementation in a PIC (Photonic Integrated Circuit) is advantageous. In such a circuit, the mixing is achieved via electric fields and not via mechanical movement, such as the aforementioned moving fiber loops.

[0053] Further aspects and elaborations of the invention are also included in the following figure description. This shows:

[0054] Fig. 1 shows a head-up display.

[0055] Fig. 2 an imaging unit

[0056] Fig. 2 an imaging unit

[0057] Fig. 4 a projection system

[0058] Fig. 5 shows a system of multiple single-mode laser sources.

[0059] Fig. 6 shows an embodiment of a mode filter.

[0060] Fig. 7 a projection system 202405062

[0061] 10

[0062] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. The same reference numerals are used in the figures for identical or equivalently acting elements and are not necessarily described again for each figure. It is understood that the invention is not limited to the embodiments shown and that the described features can also be combined or modified without departing from the scope of protection of the invention as defined in the appended claims.

[0063] Fig. 1 schematically shows a head-up display for a vehicle as an example of an image generation system 1. The head-up display comprises an imaging unit 2, an optical unit 3, and a mirror unit 4. A beam of light SB1 originates from a projection surface 21 and is reflected by a first mirror 31 onto a curved mirror 32, which reflects it towards the mirror unit 4. The mirror unit 4 is represented here as the windshield 41 of the vehicle. From there, the beam of light SB2 travels towards the eye 61 of a viewer.

[0064] The viewer sees a virtual image VB, which is located outside the vehicle, above the hood or even in front of the vehicle. Through the interaction of optical unit 3 and mirror unit 4, the virtual image VB is a magnified representation of the image coming from the projection surface 21. Here, a speed limit, the current vehicle speed, and navigation instructions are symbolically displayed. As long as the eye 61 is within the eyebox 62, indicated by a rectangle, all elements of the virtual image are visible to the eye 61. If the eye 61 is outside the eyebox 62, the virtual image VB is only partially visible or not visible at all. The larger the eyebox 62, the less restricted the viewer is in choosing their seating position.The curvature of the curved mirror 32 is adapted to the curvature of the windscreen 41 and ensures that the image distortion is not exceeded by 202405062.

[0065] 11. The entire eyebox 62 is as stable as possible. The curved mirror 32 is rotatably mounted by means of a bearing 321. The resulting rotation of the curved mirror 32 allows the eyebox 62 to be moved and thus its position to be adjusted to the position of the eye 61. The first mirror 31 ensures that the path traveled by the beam SB1 between the projection surface 21 and the curved mirror 32 is long, while simultaneously keeping the optical unit 3 compact. The optical unit 3 is separated from its surroundings by a transparent cover 33. The optical elements of the optical unit 3 are thus protected, for example, from dust in the interior of the vehicle. A glare shield 34 serves to reliably absorb light reflected across the interface of the cover 33, so that no glare is caused to the viewer.Besides sunlight SL, light from another interfering light source 64 can also reach the projection surface 21.

[0066] Fig. 2 schematically shows an embodiment of an imaging unit 2 with light sources 14R, 14G, 14B that emit coherent light. The figure shows a controllable mirror unit 73 in the imaging unit 2, which acts as a display element 11. The mirror unit 73 consists, for example, of a two-dimensional arrangement of micromirrors, each of which is positioned in one of two positions when controlled. A light beam LB incident on it is thus modulated in a pixel grid to generate the virtual image VB. This is a DMD. According to another embodiment, the controllable mirror unit 73 consists of a mirror adjustable about several axes, which is controlled such that an incident laser beam is reflected according to a two-dimensional grid, thereby generating the virtual image VB.

[0067] The light beam LB, which strikes the micromirrors of mirror unit 73, or the laser beam, which falls on the mirror adjustable about several axes, originates from the light sources 14R, 14G, 14B. The light sources 14R, 14G, 14B are indicated here as schematic boxes. They can be considered conventional 202405062

[0068] 12

[0069] Light sources may be designed, for example, as light-emitting diodes (LEDs) or as laser light sources.

[0070] Fig. 3 shows an imaging unit 2 according to the invention. The light sources 14R, 14G, 14B are designed as laser diodes. The light emitted by them is collimated, indicated here by lenses 151. By means of a mirror 161 or by means of two dichroics 162, 163, the light emitted by the three light sources is combined in a common direction of propagation. It passes through a lens, which here schematically represents an illumination optic 155. It is then deflected by means of the mirror unit 73 as an image transmitter 11 according to an image to be displayed. It then reaches a lens, which here schematically represents a projection optic 156. It then reaches a diffuser 172 arranged in the projection surface 21 of the projection optic 156. After the diffuser 172, the light continues as a beam SB1. This is indicated here schematically by means of a truncated cone.Ideally, the beam SB1 in the plane of the diffuser 172 is not wider than the beam incident on the diffuser 172.

[0071] Fig. 4 schematically shows a projection system comprising a projection device as the imaging unit 2, here a laser beam scanner 22 (LBS), which is installed inside a vehicle 100. The LBS 22 is shown, by way of example, mounted on a rearview mirror of the vehicle 100. The LBS 22 projects an image onto the instrument panel, which serves here as the projection surface 21. The projection image is indicated here as a direction and speed indication. A computing unit 52 executes an algorithm that controls the output of the LBS 22 to generate the desired image at the desired location. Since the instrument panel is not a flat surface but a three-dimensionally curved surface, the projection surface 21 is also curved accordingly; the computing unit takes this curvature into account when controlling the LBS 22. An additional LBS 22' is shown, by way of example, mounted on the rearview mirror of the vehicle.This LBS 22' is aligned with a side window, which forms its projection surface 21'. A circular diffuser 172 is arranged on the side window. This is from the LBS 22' 202405062.

[0072] The incoming laser light is scattered by the diffuser 172 into a limited angular range. Depending on the scattering properties of the diffuser 172, a real image is visible both from inside the vehicle and from outside the vehicle, as long as the viewer's eye is within the corresponding angular range, i.e., within the eyebox.

[0073] Fig. 5 shows a system of several single-mode laser sources. A multi-mode laser source 14 generates a multi-mode light beam LBMM. This is fed to a first mode filter 175. This filters out a single-mode light beam LBSM from the multi-mode light beam LBMM and allows a remaining light beam LBR to pass through. The remaining light beam LBR is fed to a light mixer 176. This generates a mode-mixed multi-mode light beam LBMM' from it. This is shown in the figure in a first stage 1650.

[0074] The mode-mixed multi-mode light beam LBMM' is fed to a second mode filter 175'. This filters out a single-mode light beam LBSM' from the multi-mode light beam LBMM' and allows a remaining light beam LBR' to pass through. The remaining light beam LBR' is fed to a light mixer 176'. This generates another mode-mixed multi-mode light beam LBMM'. This is shown in the figure in a second stage 1650'. Further corresponding stages, not shown here, can be advantageously added.

[0075] The mode filters 175, 175' each have an input lens 1751, 1751', a mirror 1753, 1753', and an output lens 1755, 1755'. The input lens 1751, 1751' focuses a multi-mode light beam LBMM, LBMM' supplied to it onto the respective mirror 1753, 1753'. The aperture 1781, 1781' of a single-mode optical fiber 178, 178' is located in the center of the mirror 1753, 1753'. The mirror surface 1754, 1754' of the mirror 1753, 1753' focuses onto the output lens 1755, 1755'. The output lens 1755, 1755' focuses onto the light mixer 176, 176'. 202405062

[0076] 14

[0077] The light mixer 176,176' is designed as a multi-mode fiber 1761,1761'. A movement mechanism 1763,1763' is arranged on the multi-mode fiber 1761,1761', which is only symbolically indicated here. The movement of the multi-mode fiber 1761,1761' caused by the movement mechanism 1763,1763' serves to regulate the light output at the individual outputs.

[0078] The multi-mode light beam LBMM is thus produced in several stages.

[0079] At 1650, 1650', 1650" each, a single-mode light beam LBSM, LBSM', LBSM" is extracted. The multi-mode light beam LBMM is extracted at each stage.

[0080] The light is focused at 1650, 1650', 1650" onto a mirror 1753, 1753', in the center of which sits the aperture 1781 of a single-mode fiber of a single-mode optical fiber 178. The uncoupled portion of the light, the remaining light beam LBR, is reflected by the mirror 1753 and coupled by a lens 1755 into a multi-mode fiber 1761 for mixing. With the exit from the fiber 1761, stage 1650 is completed, which is then repeated several times.

[0081] Fig. 6 shows an alternative embodiment of a mode filter 175. This filter comprises an input lens 1751 and a concave mirror 1752. The input lens 1751 focuses a multi-mode light beam LBMM onto a concave mirror 1752. The aperture 1781 of a single-mode optical fiber 178 is located in the center of the concave mirror 1752. A single-mode light beam LBSM is coupled into this optical fiber. The mirror surface 1756 of the concave mirror 1752 focuses the remaining light beam LBR onto the light mixer 176. The mirror and lens of the previously described embodiment are thus replaced by a concave mirror.

[0082] Fig. 7 shows a projection system according to the invention with a system of single-mode laser sources according to the invention. A strong light source 14 generates a collimated light beam LBH of high intensity 11. This light beam LBH is divided in several stages 1650, 1650', 1650", which are symbolized here by beam splitters 165, 165', 165", into several partial beams LBT, LBT', LBT". The figure shows a division into three partial beams. A division into two partial beams or into more than three partial beams is also within the scope of 202405062.

[0083] 15

[0084] Invention. Each partial beam LBT, LBT', LBT" is directed to an imaging unit 2, 2', 2". These imaging units 2, 2', 2" have mirror units 73, 73', 73" (not shown) by means of which the partial beams LBT, LBT', LBT" are moved across respective projection surfaces 21, 2T, 21" to generate an image. The respective intensity IT, IT', IT" is below the intensity IB of the load limit of the mirror units 73, 73', 73".

[0085] A projection system according to the invention can be used for projections in the motor vehicle sector, such as projection onto side windows (Side Window Projection), projection onto a rear window (Rear Window Projection), or projections in the area of ​​the dashboard.

Claims

202405062 16 Patent claims 1. System of multiple single-mode laser sources, comprising - a multi-mode laser source (14) for generating a multi-mode light beam (LBMM), and - at least one mode filter (175, 175', 175") which filters out a single-mode light beam (LBSM,LBSM',LBSM") from a multi-mode light beam (LBMM, LBMM', LBMM") and allows a remaining light beam (LBR,LBR',LBR") to pass through, - at least one light mixer (176, 176', 176") to which the remaining light beam (LBR,LBR',LBR") is fed and which produces a mode-mixed multi-mode light beam (LBMM) 1 , LBMM") generated.

2. System according to claim 1, wherein the mode filter (175, 175', 175") comprises an input lens (1751, 1751', 1751"), a mirror (1753, 1753', 1753") and an output lens (1755, 1755', 1755"), wherein the input lens (1751 , 1751 ', 1751 ") a multi-mode light beam (LBMM, LBMM', LBMM") is focused onto the mirror (1753, 1753', 1753"), in the center of which the aperture (1781 , 1781', 1781") of a single-mode optical fiber (178, 178', 178") is arranged, and its mirror surface (1754, 1754', 1754") faces the output lens (1755, 1755', 1755") focuses, which in turn focuses on the light mixer (176, 176', 176").

3. System according to claim 1, wherein the mode filter (175, 175', 175") comprises an input lens (1751, 1751', 1751") and a concave mirror (1752, 1752', 1752"), wherein the input lens (1751, 1751', 1751") focuses a multi-mode light beam (LBMM, LBMM', LBMM") onto the concave mirror (1752, 1752', 1752"), in the center of which the aperture (1781, 1781', 1781") of a single-mode optical fiber (178, 178', 178") is arranged, and whose mirror surface (1756, 1756', 1756") focuses onto the light mixer (176, 176', 176") focused.

4. System according to any of the preceding claims, wherein the light mixer (176, 176', 176") comprises a multi-mode fiber (1761 , 1761 ', 1761 "). 202405062 17 5. System according to claim 4, wherein the multi-mode fiber (1761, 1761', 1761") is configured as a controllable mixer.

6. System according to claim 4 or 5, wherein the multi-mode fiber (1761, 1761', 1761") comprises a movement mechanism (1763, 1763', 1763").

7. Projection system, featuring - a system according to one of the preceding claims, - several mirror units (73, 73', 73") for moving a collimated Light beam via a projection surface (21 ,21 ',21"), wherein each of the mirror units (73, 73', 73") is supplied with a single-mode light beam (LBSM,LBSM',LBSM") provided by one of the multi-mode filters (175, 175', 175").

Images