Optical system for a virtual retinal scan display

Abstract

The invention relates to an optical system (1) for a virtual retinal scan display which has an illumination device (13), said illumination device (13) having at least one first light source for emitting a first light beam (14). Furthermore, the optical system (1) comprises a first controllable deflection unit (12) as a first optical component for the first light beam (14) for the scanning projection of the image content, and the optical system (1) has a holographic optical element (6) which is designed to deflect the scanning first light beam (3a, 3b) onto a retina (4) of a user of the optical system (1). The holographic optical element (6) has regions with different diffraction efficiencies for the first light beam (3a, 3b) according to the angle of incidence (22a, 22b) of the first light beam (3a, 3b) on the holographic optical element (6). The optical system (1) additionally has at least one first intensity filter (16a, 16b, 16c, 16d) which is designed to adapt a first intensity of the first light beam (3a, 3b) in such a way that, when the intensity of the first emitted light beam (14) is constant, the light beam deflected by the holographic optical element (6) onto the retina (4) is also incident on the user's retina (4) with a constant intensity at points in time over a first scanning region (20a).

Description

[0001] Description

[0002] Optical system for a virtual retinal display

[0003] The invention relates to an optical system for a virtual retinal display (retinal scan display).

[0004] State of the art

[0005] Data glasses (smartglasses) with retinal scan displays and holographic optical elements for redirecting light rays to the eye are already known.

[0006] It is an object of the present invention to optimize the quality of the image projected onto the user's retina.

[0007] Disclosure of the invention

[0008] To achieve this object, an optical system according to claim 1 is proposed. The optical system for a virtual retinal display (retinal scan display) has at least one illumination device, in particular a projector unit. The illumination device has at least one first light source for emitting a first light beam. The first light source is in particular designed as a laser diode. Furthermore, the optical system has a controllable deflection unit as the first optical component for the first light beam for the scanning projection of the image content. The controllable deflection unit in particular has at least one rotatably mounted micromirror. Furthermore, the optical system has a holographic optical element which is designed to deflect the scanning first light beam onto a retina of a user of the optical system.The holographic optical element has regions with different diffraction efficiencies for the first light beam depending on a first angle of incidence of the first light beam on the holographic optical element. In particular, the holographic optical element is designed as a reflection hologram.Furthermore, the optical system has at least one first intensity filter which is designed to adapt a first intensity of the first, in particular scanning, light beam in such a way that the light beam deflected by the holographic optical element to the retina, at times over a first scanning range, also strikes the retina of the user with, in particular substantially, the same intensity as the first emitted light beam. In other words, the first intensity filter ensures that the predetermined profile of the image intensity is not changed by the different diffraction at the holographic optical element. In principle, intensity can be lost on the path from the illumination device to the user's eye. However, the basic intensity profile of the image remains.

[0009] The optical system preferably further comprises a second optical component. The second optical component is designed to deflect the first, in particular scanning, light beam in the direction of the holographic optical element of the optical system in the first scanning range at first deflection angles and in a second scanning range at second deflection angles that are different from the first. In this context, the first intensity filter is designed to adapt the first intensity of the first light beam deflected at the first deflection angles such that the first light beam deflected by the holographic optical element to the retina also strikes the user's retina with the same intensity as the first emitted light beam at times across the first scanning range.Furthermore, the optical system additionally has a second intensity filter which is designed to adapt a second intensity of the first light beam deflected at the second deflection angles in such a way that the first light beam deflected by the holographic optical element to the retina also strikes the user's retina with the same intensity as the first emitted light beam at times across the second scanning area. The principle can therefore also be applied to a system with multiple beamlets. In this case, each scanning area is assigned an intensity filter which ensures that the predetermined intensity profile of the projected image is maintained. The second optical component is preferably designed as an optical segment lens. In this case, the first and / or second intensity filter is arranged on a surface, in particular an outer surface, of the optical segment lens.The first and / or second intensity filter is arranged, in particular, on a surface of the segment lens oriented in the direction of the holographic optical element. Alternatively, the first and / or second intensity filter is arranged on a surface of the segment lens oriented in the direction of the controllable deflection unit. Alternatively, the second optical component is designed as a tilting mirror, in particular one-dimensionally rotatably mounted. The first and / or second intensity filter is arranged on a surface, in particular an outer surface, of the tilting mirror.

[0010] Preferably, the first and / or second intensity filter is arranged on a further third, in particular optical, component of the optical system. The third component is preferably designed as an optical exit window for the first light beam from the temple of the optical system.

[0011] The optical system is preferably designed as a pair of data glasses. The illumination device, the first optical component, the second optical component, and / or the third component are arranged in a temple of the data glasses. In this context, the holographic optical element is arranged in a lens of the data glasses.

[0012] Preferably, the first and / or second intensity filter is formed from a material for absorbing a wavelength of the first light beam. The material is preferably formed as a dark-colored polymer or glass whose transmission is reduced by dyes (e.g., based on metal complexes).

[0013] Preferably, the first and / or second intensity filter is formed as a vapor-deposited layer. In particular, the vapor-deposited layer is an interference layer, preferably consisting of several layers of different dielectric materials.

[0014] Preferably, the holographic optical element has a first region, in particular an edge region, with a first diffraction efficiency value depending on the angle of incidence of the first light beam on the holographic optical element. Furthermore, the holographic optical element has a second region, in particular a central region, with a second diffraction efficiency value depending on the angle of incidence of the first light beam on the holographic optical element. The first diffraction efficiency value is smaller, in particular significantly smaller, than the second diffraction efficiency value. Consequently, less light is diffracted toward the user's eye at the edge of the user's field of view than in the center of the field of view.In this context, the first or alternatively the second intensity filter preferably allows more light, in particular more first light rays, to pass through a first sub-region of the first or second scanning region assigned to the first region of the holographic optical element, than in a second sub-region of the first or second scanning region assigned to the second region of the holographic optical element. This ensures a consistent intensity distribution of the projected image. Preferably, the first and second sub-regions together form the first or second scanning region. This ensures a consistent intensity distribution of the projected image within the entire scanning region.

[0015] Description of the drawings

[0016] Figure 1 shows an optical system for a virtual retinal display (retinal scan display).

[0017] Figure 2a shows areas of the holographic optical element with different diffraction efficiency values.

[0018] Figure 2b shows the distribution of diffraction efficiency.

[0019] Figure 2c shows a corresponding transmission profile of a first intensity filter.

[0020] Figure 2d shows the resulting intensity profile of the image projected onto the retina.

[0021] Description of the Embodiments Figure 1 schematically shows an optical system for a virtual retinal display (retinal scan display) 1 in the form of data glasses. The optical system 1 has an illumination device 13, in particular a projector unit. The illumination device 13 has at least one first light source (not shown here), in particular a laser diode, for emitting a first light beam 14. Furthermore, the optical system 1 has a controllable deflection unit 12 as the first optical component for the first light beam 14 for the scanning projection of the image content. The controllable deflection unit 12 has at least one micromirror (not shown here), in particular a rotatably mounted micromirror.Furthermore, the optical system 1 has a holographic optical element 6, which is designed to redirect the scanning first light beam 14 onto a retina 4 of a user's eye 19 of the optical system 1. The holographic optical element 6 has regions with different diffraction efficiencies for the first light beam 3a and 3b, depending on an angle of incidence 22a and 22b of the first light beam 3a and 3b on the holographic optical element 6.Furthermore, the optical system 1 has at least one first intensity filter 16a to 16d, which is designed to adapt a first intensity of the first, in particular scanning, light beam 3a such that the light beam deflected by the holographic optical element 6 to the retina 4, at times present over a first scanning area 20a, also strikes the retina 4 of the user with, in particular substantially, the same intensity as the first emitted light beam 14s.

[0022] Optionally, the optical system 1 further comprises a second optical component 15, which is designed to deflect the first, in particular scanning, light beam 3a in the direction of the holographic optical element 6 of the optical system 1 in the first scanning area 20a with first deflection angles 21a and in a second scanning area 20b with second deflection angles 21b that are different from the first. In this context, the first intensity filter 16a to 16d is designed to adapt the first intensity of the first light beam 3a deflected at the first deflection angles 21a such that the first light beam 3a deflected by the holographic optical element 6 to the retina 4 also strikes the user's retina 4 with the same intensity as the first emitted light beam 14 at points in time across the first scanning area 20a.Furthermore, the optical system 1 additionally has a second intensity filter 17a to 17d, which is designed to adapt a second intensity of the first light beam 3b deflected with the second deflection angles 21b in such a way that the first light beam 3b deflected by the holographic optical element 6 to the retina 4 also strikes the retina 4 of the user with the same intensity as the first emitted light beam 14 at times present over the second scanning area 20b.

[0023] In this exemplary embodiment, the second optical component 15 is designed as an optical segment lens, in which the first intensity filter 16c and 16d and the second intensity filter 17c and 17d are arranged on a surface, in particular an outer surface, of the optical segment lens. In a further alternative, not shown here for the sake of simplicity, the second optical component 15 is designed as a tilting mirror, in particular one-dimensionally rotatably mounted, in which the first intensity filter 16a to 16d and / or second intensity filter 17a to 17d are arranged on a surface, in particular an outer surface, of the tilting mirror.

[0024] Furthermore, in the optical system 1, the first intensity filters 16a and 16b and the second intensity filters 17a and 17b are arranged on a further third, in particular optical, component 10 of the optical system 1. In this embodiment of the optical system 1, the third component 10 is designed as an optical exit window of the first light beam 14 from a spectacle temple 8 of the optical system 1.

[0025] The illumination device 13, the first optical component 12, the second optical component 15, and the third component 10 are arranged in or on the temple 8 of the data glasses. The holographic optical element 6 is arranged in a lens 7 of the data glasses.

[0026] The first intensity filter 16a to 16d and / or second intensity filter 17a to 17d is / are formed, in particular, from a material for absorbing a wavelength of the first light beam 14. Furthermore, the first intensity filter 16a to 16d and / or second intensity filter 17a to 17d is / are formed as a vapor-deposited layer, in particular an interference layer.

[0027] Figure 2a shows regions of the holographic optical element with different diffraction efficiency values, which result from the different angles of incidence of the first light beam. Depending on the angle of incidence of the first light beam on the holographic optical element, the holographic optical element has first regions 103 with a first diffraction efficiency value. This is, in particular, an edge region of the associated field of view of the user of the optical system. Furthermore, depending on the angle of incidence of the first light beam on the holographic optical element, the holographic optical element has a second region 102 with a second diffraction efficiency value. This is, in particular, a central or centric region of the associated field of view of the user of the optical system.Reference numeral 91 denotes a horizontal direction of the holographic optical element, and reference numeral 90 denotes a vertical direction of the holographic optical element. Figure 2b shows the distribution of the diffraction efficiency along a horizontal direction 93 of the holographic optical element. The diffraction efficiency values ​​are plotted on the Y-axis 92. As can be seen there, the first diffraction efficiency values ​​104 are smaller, in particular significantly smaller, than the second diffraction efficiency values ​​105. Figure 2c shows the associated transmission profile of a first or second assigned transmission profile of an intensity filter. A horizontal direction of the intensity filter is plotted on the X-axis 95. The transmission of the first light beam through the first or second intensity filter is plotted on the Y-axis 94.As can be seen here, the first or second intensity filter allows more light, in particular first light rays, to pass through in the first partial regions 106 of the first or second scanning region assigned to the first region 103 of the holographic optical element, than in a second partial region 107 of the first or second scanning region assigned to the second region 102 of the holographic optical element. Figure 2d shows the resulting intensity profile of the image projected onto the retina. A horizontal direction of the holographic optical element is again plotted on the X-axis 96. An intensity of the projected image is plotted on the Y-axis 97. As can be seen here, in this case the intensity of the projected image 108 is constant. This intensity 108 corresponds in its profile to the intensity of the emitted first light beam.

Claims

Claims 1. Optical system (1) for a virtual retinal display (retinal scan display), comprising at least one illumination device (13), in particular a projector unit, of the optical system (1), wherein the illumination device (13) has at least one first light source, in particular a laser diode, for emitting a first light beam 14, and a controllable deflection unit (12) as a first optical component, in particular having at least one micromirror, for the first light beam (14) for scanning projection of the image content, and a holographic optical element (6) which is designed to deflect the scanning first light beam (3a, 3b) onto a retina (4) of a user of the optical system (1), wherein the holographic optical element (6) is dependent on an angle of incidence (22a, 22b) of the first light beam (3a,3b) on the holographic optical element (6) has regions with a different diffraction efficiency for the first light beam (3a, 3b), characterized in that the optical system (1) further comprises at least one first intensity filter (16a, 16b, 16c, 16d) which is designed to adapt a first intensity of the first, in particular scanning, light beam (3a, 3b) such that the first light beam deflected by the holographic optical element (6) to the retina (4) also strikes the retina (4) of the user with, in particular substantially, the same intensity at times present over a first scanning region (20a).

2. Optical system (1) according to claim 1, characterized in that the optical system (1) further comprises a second optical component (15), wherein the second optical component (15) is designed to deflect the first, in particular scanning, light beam (3a, 3b) in the direction of the holographic optical element (6) of the optical system (1) in the first scanning area (20a) with first deflection angles (21a) and in a second scanning area (20b) with two different angles to the first deflection angles (21b), wherein the first intensity filter (16a, 16b, 16c, 16d) is designed to adapt the first intensity of the first light beam (3a) deflected at the first deflection angles (21a) in such a way that the first light beam deflected by the holographic optical element (6) to the retina (4) also strikes the retina (4) of the user with the same intensity as the first emitted light beam (14) at times present over the first scanning area (20a), wherein the optical system (1) additionally has a second intensity filter (17a, 17b, 17c, 17d), wherein the second intensity filter (17a, 17b, 17c, 17d) is designed to adapt a second intensity of the first light beam (3b) deflected at the second deflection angles (20b) to adapt in such a waythat the first light beam deflected by the holographic optical element (6) to the retina (4) also strikes the retina (4) of the user with the same intensity as the first emitted light beam (14) at times over the second scanning area (20b).

3. Optical system (1) according to claim 2, characterized in that the second optical component (15) is designed as an optical segment lens, and the first (16a, 16b, 16c, 16d) and / or second intensity filter (17a, 17b, 17c, 17d) is arranged on a, in particular outer, surface of the optical segment lens.

4. Optical system (1) according to claim 2, characterized in that the second optical component (15) is designed as a tilting mirror, in particular one-dimensionally rotatably mounted, wherein the first (16a, 16b, 16c, 16d) and / or second intensity filter (17a, 17b, 17c, 17d) is arranged on a, in particular outer, surface of the tilting mirror.

5. Optical system (1) according to one of claims 1 or 2, characterized in that the first (16a, 16b, 16c, 16d) and / or second intensity filter (17a, 17b, 17c, 17d) is arranged on a further third, in particular optical, component (10) of the optical system (1).

6. Optical system (1) according to claim 5, characterized in that the third component (10) is designed as an optical exit window of the first light beam (3a, 3b) from a temple (8) of the optical system (1) 7. Optical system (1) according to one of claims 1 to 6, characterized in that the optical system (1) is designed as data glasses, wherein the lighting device (13), the first optical component (12) and / or the second optical component (15) and / or the third component (10) are arranged in the temple (8) of the data glasses, wherein the holographic optical element (6) is arranged in a spectacle lens (7) of the data glasses.

8. Optical system (1) according to one of claims 1 to 7, characterized in that the first (16a, 16b, 16c, 16d) and / or second intensity filter (17a, 17b, 17c, 17d) is formed from a material for absorbing a wavelength of the first light beam (3a, 3b) 9. Optical system (1) according to one of claims 1 to 8, characterized in that the first (16a, 16b, 16c, 16d) and / or second intensity filter (17a, 17b, 17c, 17d) is formed as a vapor-deposited layer, in particular an interference layer 10. Optical system (1) according to one of claims 1 to 9, characterized in that the holographic optical element (6) has a first region (103), in particular an edge region, with a first diffraction efficiency value depending on the angle of incidence (22a, 22b) of the first light beam (3a, 3b) on the holographic optical element (6b) (104), wherein the holographic optical element (6) has a second region (102), in particular a central region, with a second diffraction efficiency value (105), depending on the angle of incidence (22a, 22b) of the first light beam (3a, 3b) on the holographic optical element (6), wherein the first diffraction efficiency value (104) is smaller, in particular significantly smaller, than the second diffraction efficiency value (105) is.

11. Optical system (1) according to claim 10, characterized in that the first (16a, 16b, 16c, 16d) or second intensity filter (17a, 17b, 17c, 17d) allows more light, in particular first light rays, to pass through in a first partial region (106) of the first (20a) or second scanning region (20b) assigned to the first region (103) of the holographic optical element (6) than in a second partial region (107) of the first (20a) or second scanning region (20b) assigned to the second region (102) of the holographic optical element (6).

12. Optical system (1) according to claim 11, characterized in that the first (106) and second partial area (107) together form the first (20a) or second scanning area (20b).

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