HOLOGRAPHIC PROJECTION DEVICE

Description

[0001] The present invention relates to a holographic projection device for generating an image with the features of the preamble of claim 1.

[0002] Such holographic projection devices are increasingly used in the automotive sector, for example, to provide the driver with a head-up display, where the image is guided and / or deflected across the windshield. A volume hologram, which can be attached to or embedded in the windshield, can be used for this deflection.

[0003] In such a holographic projection device, for example, sunlight (or a certain wavelength range thereof) falling on the windshield at a certain angle can be undesirably deflected by the volume hologram in such a way that it is perceived by the viewer as disturbing light.

[0004] From JP 2013 127489 A and US 2018 / 067321 A1, a holographic projection device for generating an image with the features of the preamble of claim 1 is known. DE 10 2017 213 114 A1 describes a field-of-view display device for a vehicle comprising a holographic optical element, and WO 2020 / 205101 A1 describes electronic displays with holographic filters.

[0005] Based on this, the object of the invention is therefore to provide a holographic projection device with which the described disadvantage can be overcome as completely as possible.

[0006] The invention is defined in independent claim 1. Advantageous embodiments are specified in the dependent claims.

[0007] By incorporating the holographic filter, light not originating from the primary light source, which strikes the first volume hologram at a predetermined solid angle and would otherwise be deflected into unwanted stray light, can be deflected by the holographic filter in such a way that it is no longer perceptible to the observer. Thus, unwanted stray light is avoided. Furthermore, light originating from the primary light source, which would strike the first volume hologram at a predetermined solid angle, can also be deflected by the holographic filter before it reaches the first volume hologram, so that it is not perceptible as unwanted stray light.

[0008] The holographic projection device can be designed to deflect an incoming image using the first volume hologram, so that a viewer can perceive it when they position their eye within a predetermined viewing area and look at the projection surface from a predetermined viewing angle. In this case, the first volume hologram can thus function, for example, as an optical component (such as a lens, mirror, and / or grating).

[0009] Furthermore, the holographic projection device according to the invention can include a reconstruction setup. This means, in particular, that the first volume hologram is designed such that (at least) one image is exposed within it. If this hologram is then illuminated by light in a predetermined manner, a reconstruction of the recorded image takes place in a known manner, so that a viewer can perceive it. Thus, the image to be generated (in particular as a three-dimensional image) can be exposed within the first volume hologram, which is then reconstructed by light from a useful light source (for example, a laser or an LED). The first volume hologram can therefore be designed such that an image (e.g., three-dimensional) or a dynamic image sequence (depending on the viewing angle) is exposed within it. The first volume hologram can be formed in or on a transparent substrate.In this case, the light from the useful light source can also be coupled into the carrier via an input point spaced away from the first volume hologram and guided within the carrier (directly or, for example, by internal total internal reflections or other reflections) to the first volume hologram, so that the desired reconstruction of the recorded image is then generated.

[0010] The first volume hologram of the projection device can also be designed as a diffusing disk.

[0011] Furthermore, the holographic projection device can generate the image as a real image (e.g., outside the plane of the first volume hologram or in that plane) or as a virtual image (e.g., outside the plane of the first volume hologram).

[0012] The unwanted light to be avoided can, for example, be light that a viewer of the generated image can perceive, even though this is to be avoided. Alternatively or additionally, it is also possible that one or more solid angle regions are defined with respect to the holographic projection device and, in particular, with respect to the first volume hologram and / or the holographic filter, in which unwanted light is to be avoided. When using the holographic projection device according to the invention in the vehicle sector, this can, for example, be an area that would disturb pedestrians or other road users.

[0013] The first volume hologram of the holographic projection device is designed, in particular, such that the intended deflection is configured for one or more predetermined wavelength ranges (preferably with a bandwidth of ±50 nm, ±40 nm, ±30 nm, ±20 nm, ±10 nm, ±5 nm). Light not originating from the useful light source that strikes or would strike the first volume hologram within the predetermined solid angle range, potentially causing unwanted stray light, preferably has a wavelength range that does not coincide with the wavelength ranges for which the first volume hologram is designed.

[0014] For example, the first volume hologram might be designed for a wavelength of 500 nm ± 10 nm and an incidence angle of 30° to achieve the desired deflection for image generation. In this case, the first volume hologram might have a high efficiency at, for example, 640 nm for incidence angles of -5° and -67°, which is undesirable.

[0015] Therefore, in this case, the holographic filter can be designed or configured to deflect the stray light of 640 nm + / - 10 nm and the angle of incidence of -5° and -67° in such a way that the stray light is avoided.

[0016] The holographic filter itself can be configured as a second volume hologram, and in particular as a transmissive volume hologram. Of course, it is also possible for it to be configured as a reflective volume hologram.

[0017] The first volume hologram and the holographic filter are located on or within a transparent body. This transparent body can be, for example, a vehicle window (especially the windshield) or any other transparent object. It can be designed as a plane-parallel plate. It is also possible for the transparent body to have at least one curved interface. For example, the transparent body could be designed as a spectacle lens.

[0018] The vehicle can be a land vehicle, a watercraft, or an aircraft. Furthermore, the vehicle can be a motorized vehicle or a human-powered vehicle. In particular, the vehicle can be a passenger car or a truck.

[0019] The vehicle window can have an inner side facing the vehicle interior, with the first volume hologram and the holographic filter being formed on the inner side.

[0020] Furthermore, the vehicle window can have an outer surface facing away from the inner surface, with the holographic filter designed for light not originating from the primary light source that enters the vehicle window via the outer surface. This effectively prevents or reduces interference from ambient light, which typically enters vehicles from the outside.

[0021] The first volume hologram and the holographic filter can be arranged one above the other. In particular, they can be configured as a stack of layers. Furthermore, they can be congruent. The first volume hologram and the holographic filter can also be arranged directly on top of each other or with an interposed connecting layer.

[0022] The holographic filter can be deflected such that the deflected light is guided through at least one reflection within the transparent body. This reflection can be total internal reflection. Alternatively, the transparent body can incorporate a beam trap for the light, which it reaches by being guided through the transparent body. The holographic filter can also be deflected such that the deflected light propagates directly to the beam trap without any reflection within the transparent body.

[0023] Furthermore, the transparent body can have a coupling point that is spaced away from the first volume hologram. For example, the image to be projected can be coupled into the transparent body via the coupling point and guided within it (for example, without reflection or by at least one reflection, such as total internal reflection) until it reaches the first volume hologram.

[0024] The projection device according to the invention can be designed such that the holographic filter deflects the light that does not originate from the primary light source and that strikes or would strike the first volume hologram at the predetermined solid angle, depending on its polarization. Preferably, the larger polarization component can be deflected. The larger polarization component of the light that does not originate from the primary light source and that strikes or would strike the first volume hologram at the predetermined solid angle can, for example, be determined by or result from the coupling of the light into the transparent body. In the case of sunlight entering a transparent body, this can be, in particular, the s-polarization component, so that this s-polarization component is deflected by the holographic filter. This achieves effective filtering.

[0025] The deflection using the first volume hologram can occur in a first plane, and the deflection using the holographic filter can occur in a second plane that is neither parallel to nor coincident with the first plane. In particular, the first and second planes can be perpendicular to each other. However, it is also possible for the two planes to be parallel.

[0026] The holographic filter can be positioned in front of or behind the first volume hologram (e.g., in the direction of view from the exit pupil to the holographic projection device or to the volume hologram).

[0027] The holographic projection device can further include the useful light source. The useful light source can be designed as an image module that generates the image to be projected. The image module can include an image transmitter for generating the image to be projected and, optionally, imaging optics (e.g., lenses, mirrors, etc.) downstream of the image transmitter. In particular, the imaging optics can be located between the image transmitter and the transparent body. The first volume hologram, which redirects the image to be projected, can be designed, in particular, as a transmissive volume hologram. However, it is also possible for it to be designed as a reflective volume hologram.

[0028] Furthermore, the image to be generated can be exposed into the first volume hologram, and the useful light source can be designed in such a way that its light causes the reconstruction of the image to be generated.

[0029] Furthermore, the first volume hologram can have several subgrids, each designed for a predetermined wavelength with a certain bandwidth (e.g., ± 10 nm). These could be wavelengths for red, green, and blue light, for example. This allows a multicolored image to be generated. Preferably, the image generation is adapted accordingly, and corresponding color sub-images are produced. These can be generated simultaneously or so rapidly in succession that a user can only perceive them as a multicolored image when superimposed.

[0030] The holographic projection device can also be designed as a head-mounted device. A holding device, such as a pair of glasses or a helmet, can be provided for this purpose.

[0031] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without leaving the scope of the present invention.

[0032] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings, which also disclose essential features of the invention. These exemplary embodiments serve only for illustration and are not to be interpreted as limiting. For example, a description of an exemplary embodiment with a plurality of elements or components is not to be interpreted as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components from different exemplary embodiments may be combined with one another unless otherwise specified. Modifications and variations described for one of the exemplary embodiments may also be applicable to other exemplary embodiments.To avoid repetition, identical or corresponding elements in different figures are designated with the same reference symbols and are not explained multiple times. The figures show: . Fig. 1 a schematic view of a first embodiment of the holographic projection device 1 according to the invention; Fig. 2 a further schematic view of the holographic projection device 1 according to the invention. Fig. 1 to explain the possible occurrence of stray light; Fig. 3 a further schematic view of the holographic projection device 1 according to the invention. Fig. 1 Fig. 4 illustrates the mode of operation of the holographic filter 12; Fig. 4 shows a schematic representation of the deflection efficiency of the grating for light with 500 nm in the polymer layer 11 as a function of the angle of incidence; Fig. 5 shows a schematic representation to illustrate the occurrence of stray light; Fig. 6 shows a schematic representation to illustrate the mode of operation of the holographic filter 12 for avoiding stray light according to Fig. 5 Fig. 7 is a schematic representation to illustrate the possible occurrence of stray light; Fig. 8 is a representation to illustrate the function of the filter 12 for preventing stray light according to Fig. 7 Fig. 9 a schematic enlarged side view of another embodiment of the holographic projection device 1; Fig. 10 a schematic representation to explain the reference plane for the polarization directions in Fig. 9 Fig. 11 shows a front view of the embodiment of Fig. 9 ; Fig. 12 a representation to illustrate the reference plane of the polarization directions for the diffraction that took place at the holographic filter 12; Fig. 13 a top view of the embodiment of Fig. 9 Fig. 14 a schematic view of a further embodiment of the holographic projection device 1 according to the invention; Fig. 15 a schematic view of a further embodiment of the holographic projection device 1 according to the invention; Fig. 16 a further embodiment of the holographic projection device 1 according to the invention; and Fig. 17 a partial sectional view of the projection surface 1 of Fig. 16 .

[0033] At the in Fig. 1 In the embodiment shown, the holographic projection device 1 according to the invention comprises, as a useful light source, an image module 2 for generating an image (preferably a multicolored image) and a projection unit 3, which here comprises a holographic beam splitter 5 integrated into a windshield 4 of a vehicle, at which the multicolored image (the beam path of a light beam 2 is shown as a representative example) is deflected in the direction of an exit pupil 6 of the projection unit 3 in such a way that a user who positions his eye A in the exit pupil 6 can perceive the multicolored image as a virtual image when he looks at the projection unit 3 (or here at the holographic beam splitter 5) along a predetermined viewing direction 7.

[0034] The image module 2 can comprise an image sensor 8 and a control unit 9 with a processor 10, wherein the control unit 9 controls the image sensor 8 to generate the multi-colored image. The image sensor 8 can be an LCD module, an OLED module, an LCoS module, or a tilting mirror matrix. Furthermore, the image sensor can include a ground glass screen, which is not shown here.

[0035] The multicolored image is generated by the image sensor 8 by producing, for example, three color sub-images with different wavelengths. These could be, for instance, a blue color sub-image with a wavelength of 460 nm, a green color sub-image with a wavelength of 500 nm, and a red color sub-image with a wavelength of 640 nm. The color sub-images can be generated simultaneously or alternately in such rapid succession that only the superposition of the two images is perceptible to the user as a multicolored image.

[0036] The holographic beam splitter 5 has a photopolymer layer 11 in which a volume holographic grating is inscribed for each of the three wavelengths. The three gratings thus overlap in the same volume (namely in the photopolymer layer 11), resulting in a so-called multiplexing (or first volume hologram). Each of the three volume holographic gratings is designed to be reflective for one of the three wavelengths (for example, with a bandwidth of ± 10 nm) and to transmit the remaining wavelengths. The reflectivity of the individual volume holographic gratings is adjusted, for example, to achieve a reflectivity of approximately 45%.This is primarily because, for the described application, reflectivities of 100% are not permissible in the vehicle's windshield 4 for safety reasons, as the driver must be able to see through the windshield 4 even in the area of ​​the holographic beam splitter 5. For other applications where such safety aspects are not relevant, the volume holographic gratings can indeed be designed to have a reflectivity greater than 45%.

[0037] A holographic filter 12 is arranged between the photopolymer layer 11 and the windshield 4, the function of which, in conjunction with the Fig. 2 and 3 is described.

[0038] If the holographic filter were not present, light, e.g., with a wavelength of 640 nm, which falls on the windshield 4 from the front at a predetermined angle (e.g., -5° or -67°), is transmitted through it and falls on the photopolymer layer 11, would be undesirably deflected as stray light towards the exit pupil 6, as shown in Fig. 3 is shown. The corresponding angle of incidence ranges are in Fig. 2 as indicated by the radiation S1 and S2. To prevent stray light from entering the exit pupil 6 (which can also be referred to as eyebox 6) in this manner, the holographic filter 12 is provided, which deflects (here reflects) the incident radiation S1, S2 with a wavelength of 640 nm at this angle so that the radiation S1, S2 does not strike the photopolymer layer 11, but is guided in the windshield 4, for example by total internal reflection, to a beam trap 13 located, for example, at the upper edge, where it is absorbed, as shown in Fig. 3 shown.

[0039] This described undesirable property of the lattices in the photopolymer layer 11 is associated with Fig. 4 The grating for the wavelength 500 nm is explained.

[0040] In Fig. 4 The wavelength in nm is plotted along the x-axis and the angle of incidence in ° along the y-axis, with the deflection efficiency increasing with the brightness of the image.

[0041] As can be seen from the illustration, the deflection efficiency for the wavelength of 500 nm is in the range of 30° (range B1).

[0042] In addition, the grating exhibits an undesirable and unavoidable high deflection efficiency for the angles of incidence of -5° (area B2) and -67° (area B3) at a wavelength in the range of 640 nm.

[0043] Therefore, the holographic filter 12 is designed to deflect the light for this wavelength and these angles of incidence such that the stray light no longer reaches the exit pupil. Preferably, the filter deflects the light for this wavelength (640 nm) and these angles of incidence (-5° and -67°) such that the radiation is deflected in the disk 4 until it reaches the beam trap 13. This reliably prevents the unwanted stray light from reaching the exit pupil.

[0044] The occurrence of stray light and its prevention will be discussed below in connection with Figuren 5 bis 8 will be described in more detail.

[0045] In the schematic sectional view in Fig. 5 It has been shown that the radiation S1 would pass through the windshield 4 and onto the photopolymer layer 11, where a reflection would take place towards the front of the windshield 4, where in turn a reflection would take place towards the eye A of the observer.

[0046] To prevent this, as in Fig. 6 The holographic filter 12 is shown, which deflects the light (radiation S1) reflected by the photopolymer layer 11 in such a way that the deflected light then passes through the windshield 4 by total internal reflection to the edge of the windshield and there, for example, to the beam trap 13 ( Fig. 3 ) is guided. Thus, the stray light no longer reaches eye A of the viewer.

[0047] In Fig. 7 The case shown is where the light S1 passes through the windshield 4 and is deflected at the photopolymer layer in such a way that it would hit the eye A of the viewer.

[0048] In Fig. 8 It has been shown that, due to the holographic filter 12, the radiation S1 is deflected towards the windshield 4 before it strikes the photopolymer layer 11. The deflection towards the windshield 4 occurs in such a way that the radiation is guided within the windshield 4. This can preferably extend to the beam trap 13 ( Fig. 3 ) are present.

[0049] In this way, it is effectively possible to prevent unwanted stray light from entering the exit pupil 6. The radiation S1, S2 can be ambient light (e.g., sunlight) or light from a light source other than the image sensor 8.

[0050] In connection with Fig. 1 bis 3 In the described embodiment, the unwanted light S1, S2 is deflected in the yz-plane in the same way as the light L from the image sensor 8. In the case of a car windshield, this is the plane perpendicular to the road surface.

[0051] However, the holographic filter 12 can also be designed such that the unwanted light S1, S2 or the unwanted radiation S1, S2 is deflected in a plane parallel to the roadway, and thus in a plane perpendicular to the y-axis and parallel to the z-axis. As a result, the diffraction of the light L from the image sensor 8 generated by the photopolymer layer 11 lies in a different plane than the diffraction of the holographic filter 12 (in particular, the two planes are perpendicular to each other), so that the diffractions are decoupled.

[0052] In connection with Fig. 1 bis 3 In the described embodiment, the holographic filter 12 is located behind the polymer layer 11 with respect to the viewing direction 7. However, it is also possible to reverse the order of the holographic filter 12 and the photopolymer layer 11. In this case, the unwanted light S1, S2, which is diffracted at the photopolymer layer 11, is deflected by the holographic filter 13 so that it does not reach the exit pupil 6. The unwanted light S1, S2 is thus diffracted in a direction that is not critical.

[0053] If the unwanted light S1, S2 is unpolarized (as is the case with sunlight), the diffraction efficiency of the holographic filter 12 can be optimized for the polarization that has a higher proportion after entering the windshield 4. In the schematically enlarged side view according to... Fig. 9 A sunlight beam 14 is shown, exhibiting p-polarization components 15 and s-polarization components 16. Upon entering the windshield 4, a portion of the beam 14 is reflected as beam 17, and a remaining portion 18 enters the windshield 4. This effect is polarization-dependent and results in the reflected beam 17 having a larger s-polarization component than the coupled-in beam 18. This is indicated by the two dots 16 for beam 17 and the single dot 16 for beam 18. Accordingly, the reflected beam 17 has a smaller p-polarization component (only one double arrow 15) than the coupled-in beam 17 (two double arrows 15).

[0054] The s-polarization is the polarization perpendicular to the reference plane spanned by the incident ray 14 and the reflected ray 17 ( Fig. 10 Accordingly, p-polarization is the polarization parallel to this reference plane.

[0055] The holographic filter 12 is now designed such that it reflects the p-polarization component of the coupled beam 18, as shown by the circle 19 with inscribed x in Fig. 9 This is indicated. However, the reflection occurs in the x-direction and thus into the drawing plane. This is better illustrated in the front view according to... Fig. 11 It is evident in which the reflected ray 19 runs along the x-direction.

[0056] The s-polarized portion of beam 18 is largely transmitted by the holographic filter 12 (beam 20). However, this portion is significantly smaller than the p-polarization portion, so the unwanted stray light 20 is almost completely suppressed. Fig. 12 The reference plane for the polarization for diffraction at the holographic filter 12 is shown. This plane is spanned by the incident beam 18 and the diffracted beam 19.

[0057] In Fig. 13 The top view is shown, from which it can be seen that the curved part 19 in the windshield 4 is guided by total internal reflection, as in connection with Fig. 3 has already been described.

[0058] Of course, it is possible that the projection device 1 according to the invention includes further optical elements, for example for minimizing aberrations. Mirrors and lenses can be used. As in Fig. 14 As shown schematically, for example an optic 21 can be arranged between the image sensor 8 and the holographic beam splitter 5, which is shown schematically here as a lens.

[0059] Furthermore, in Fig. 15 A modification is shown in which the light from the image sensor 8 is coupled into the windshield 4 via a coupling element 22 (for example, a deflecting mirror) and is guided through this by at least one reflection to the photopolymer layer 11, where the described extraction is carried out.

[0060] Instead of the windshield 4, any other transparent body can also be used for the projection device 1 according to the invention. This transparent body can be designed as a plane-parallel plate. However, it is also possible that at least one interface (for example, the front and / or back) is curved.

[0061] The photopolymer layer 11 and / or holographic filter 12 can be integrated into the transparent body, as with the windshield 4 in Fig. 15 shown, be embedded. However, it is also possible that the photopolymer layer 11 and / or the holographic filter 12 is formed on the front or back of the transparent body, as e.g. in Fig. 1-3 , 13 and 14 as shown. Furthermore, a cover layer can be provided on the photopolymer layer 11 and / or the holographic filter 12.

[0062] The projection device 1 according to the invention can also be designed to be placed on the user's head and for this purpose has a holding device 32 that can be placed on the user's head, which can be designed, for example, in the manner of a conventional eyeglass frame ( Fig. 16 In this case, the projection device 1 can have a first and a second lens 33, 34, which are attached to the holding device 32. The holding device 32 with the lenses 33, 34 can be designed, for example, as sports glasses, sunglasses and / or glasses for correcting a visual impairment, whereby the virtual image can be projected into the user's field of vision via the first lens 33.

[0063] The image module 2 can be arranged in the area of ​​the right temple of the spectacle holder 32, as shown in Fig. 16 is shown schematically.

[0064] How best to understand the enlarged, schematic partial section view in Fig. 17As can be seen, the first spectacle lens 33 has a back surface 37 and a front surface 38. The back surface 37 and the front surface 38 are curved. However, it is also possible that they are flat. The curvature can be spherical or aspherical.

[0065] If the virtual image is to be visible in superimposed form with the surroundings, an effective redirection efficiency of, for example, 50% is possible. If the surroundings are not to be visible, the redirection efficiency can be chosen to be higher.

Claims

1. A holographic projection device for generating an image that a viewer can perceive when their eye (A) is positioned in a predetermined viewing region and they look at the projection device (1) at a predetermined viewing angle, wherein the projection device (1) comprises a first volume hologram which, when exposed to light from a used light source, deflects this light for generating the image, wherein the first volume hologram further has the property that it would deflect light that does not originate from the used light source and is incident on the first volume hologram at a predetermined solid angle such that it is perceptible as unwanted interfering light, characterized in that the projection device (1) comprises a holographic filter (12), which is arranged on or in a transparent body (4) wherein the first volume hologram is arranged on or in a transparent body (4), and wherein the holographic filter (12) - deflects the light that does not originate from the used light source and would be incident on the first volume hologram at the predetermined solid angle before being incident on the first volume hologram, in such a way that it is not perceptible as unwanted interfering light, and / or - deflects the light that does not originate from the used light source and is incident on the first volume hologram at the predetermined solid angle after the deflection by means of the first volume hologram, in such a way that it is not perceptible as unwanted interfering light.

2. The holographic projection device as claimed in claim 1, wherein the holographic filter (12) deflects the light that does not originate from the used light source and is or would be incident on the first volume hologram at the predetermined solid angle such that it is guided in the transparent body (4) as deflected light by way of at least one reflection.

3. The holographic projection device as claimed in claim 2, wherein the deflected light in the transparent body (4) is guided by way of the at least one reflection to a beam trap (13).

4. The holographic projection device as claimed in any of the preceding claims, wherein the body (4) comprises a coupling point (22) via which the light from the used light source is suppliable and after which a guidance in the body (4) to the first volume hologram, which is spaced apart from the coupling point, takes place.

5. The holographic projection device as claimed in any of the preceding claims, wherein the transparent body (4) is formed as a window of a vehicle and in particular as a windshield of a vehicle.

6. The holographic projection device as claimed in claim 5, wherein the window or windshield comprises an inner side facing the interior of the vehicle, wherein the first volume hologram and the holographic filter (12) are formed on the inner side, wherein preferably the window or windshield comprises an outer side facing away from the inner side, and the holographic filter (12) is designed for light that does not originate from the used light source and enters the window or the windshield via the outer side.

7. The holographic projection device as claimed in any of the preceding claims, wherein the first volume hologram and the holographic filter (12) are arranged one above the other.

8. The holographic projection device as claimed in any of the preceding claims, wherein the first volume hologram causes for at least one first wavelength range the deflection for generating the image and the light that does not originate from the used light source and is or would be incident on the first volume hologram at the predetermined solid angle originates from a second wavelength range, which differs from the at least one first wavelength range.

9. The holographic projection device as claimed in any of the preceding claims, wherein the holographic filter (12) comprises a second volume hologram, and / or wherein the holographic filter (12) reflects the light that does not originate from the used light source and would be incident on the first volume hologram at the predetermined solid angle.

10. The holographic projection device as claimed in any of the preceding claims, wherein the holographic filter (12) deflects of the light that does not originate from the used light source and is or would be incident on the first volume hologram at the predetermined solid angle the polarization component which is the greater.

11. The holographic projection device as claimed in claims 1 and 10, wherein the greater polarization component is determined by coupling the light that does not originate from the used light source and is or would be incident on the first volume hologram at the predetermined solid angle into the transparent body (4).

12. The holographic projection device as claimed in any of the preceding claims, wherein the deflection by means of the first volume hologram is effected in a first plane, and the deflection by means of the holographic filter (12) is effected in a second plane, which is neither parallel to nor coincides with the first plane, wherein preferably the second plane is perpendicular to the first plane.

13. The holographic projection device as claimed in any of the preceding claims, comprising A used light source (2).

14. The holographic projection device as claimed in claim 13, wherein the used light source is formed as an image module (2), which generates an image which is deflected by means of the volume hologram for generating the image, wherein preferably the image module (2) comprises an image generator (8) for generating the image to be projected and an imaging optical unit (21) arranged downstream of the image generator (8).

15. The holographic projection device as claimed in any of claims 1 to 13, wherein the image to be generated is exposed into the first volume hologram and the used light source is designed such that its light causes the reconstruction of the image to be generated.