Optical device, and method for coupling a light beam into an optical element, and smart glasses comprising the optical device

Abstract

The invention relates to an optical device (100) and to a method for coupling a light beam (2) into an optical element (4), for example a waveguide, the optical device comprising: a first deflection device (102), for example a tilting mirror, which is designed to deflect the light beam (2) in a first spatial dimension; a second deflection device (104), for example a tilting mirror, which is designed to deflect the light beam (2) deflected by the first deflection device (102) in a second spatial dimension; a coupling-in structure (106) which is designed to couple the light beam (2) deflected by the second deflection device (104) into the optical element (4); wherein the optical device (100) is designed to image the first or the second deflection device (102, 104) onto the coupling-in structure (106) such that a variation of a field angle in a field angle range (108) of the deflection device (102) not imaged onto the coupling-in structure (106) brings about a linear variation (110) of the light beam (2) on the coupling-in structure (106). The invention also relates to smart glasses comprising the optical device (100).

Description

[0001] R.413522

[0002] - 1 -

[0003] Description

[0004] title

[0005] Optical device and method for coupling a light beam into an optical element, as well as data glasses comprising the optical device

[0006] State of the art

[0007] The present invention relates to an optical device and a method for coupling a light beam into an optical element, as well as to data glasses comprising the optical device.

[0008] Augmented Reality (AR) glasses allow a user to see both a real environment and virtually superimposed image content simultaneously. This is achieved, for example, using a combiner, an optical element that transmits ambient light to the user's eye and overlays or combines it with the light that generates the virtual image content.

[0009] The virtual image content can be generated, for example, by a combination of a laser light source and a tilting mirror, or a tilting mirror arrangement. By tilting the mirror, the laser beam from the laser light source can be deflected in different directions to create the virtual image content.

[0010] The combiner can, for example, be designed as a waveguide. The deflected laser beams are coupled into the waveguide by means of a coupler. The coupler should be designed with a spatial extent such that all field angles generated by the tilting mirror in two spatial dimensions can be coupled into the waveguide. Depending on the distance between the tilting mirror and the coupler, the spatial distribution of the field angles changes; this distribution must be taken into account with the coupler R.413522.

[0011] - 2 - to cover so that the virtual image content can be displayed correctly. With increasing size of the coupler, the risk of parasitic coupling from laser beams already coupled into the waveguide increases, for example, if they encounter the coupler during a consecutive step in the waveguide. These couplings cause, for example, efficiency losses, inhomogeneities, and ghost images.

[0012] A tilting mirror can be a mirror that can be tilted in two spatial dimensions. These types of tilting mirrors are complex in their construction and slow and energy-inefficient in forming an image.

[0013] Therefore, it is desirable to be able to provide a projection device that enables fast and energy-efficient image generation and requires a small coupler to increase the quality of the virtual image to be displayed by a combiner.

[0014] Disclosure of the invention

[0015] This is achieved through an optical device and a method for coupling a light beam into an optical element, as well as data glasses encompassing the optical device.

[0016] The optical device for coupling a light beam into an optical element, for example a waveguide, comprises: a first deflection device configured to deflect the light beam in a first spatial dimension, for example a tilting mirror; a second deflection device configured to deflect the light beam deflected by the first deflection device in a second spatial dimension, for example a tilting mirror; a coupling structure configured to couple the light beam deflected by the second deflection device into the optical element; wherein the optical device is configured to map the first or the second deflection device onto the coupling structure, such that a variation of a field angle in a field angle range of the deflection device not mapped onto the coupling structure causes a line-shaped variation of the light beam on the coupling structure.In the present context, the light beam includes not only rays of a type R.413522 that is suitable for a human.

[0017] - 3 - visible spectrum, but any type of electromagnetic radiation. The light beam can be, for example, a laser beam from an RGB laser light source to create a virtual image to be displayed, or an infrared laser beam used for a sensor application. The first and second spatial dimensions are, for example, two perpendicular spatial directions, so that a two-dimensional plane can be illuminated point by point using the light beam. An orientation of the deflected light beam can thus be described, for example, by two field angles or beam angles set by the first and second deflection device. The field angle range describes a range of field angles that the first or second deflection device can image, for example, by tilting a mirror.The use of the first and second deflection devices enables fast and energy-efficient image acquisition, as both can be implemented using simple one-dimensional joints or kinematics. Furthermore, mapping the first or second deflection device onto the coupling structure allows for a narrow coupling structure, which positively impacts the image quality of the optical element.

[0018] The coupling structure can be designed to have a rectangular, or in particular linear, spatial extent. This reduces the size of the coupling structure and improves the image quality of the optical element, as parasitic outcoupling of coupled light rays from the optical element is reduced.

[0019] It can be provided that the second deflection device has a predetermined spatial distance, in particular a minimized spatial distance, from the coupling structure, such that any spreading of a field angle range caused by the second deflection device relative to the coupling structure is minimized, and, for example, the second deflection device is mapped onto the coupling structure, in particular approximately as a point. Due to the small spatial distance, an approximately point-like mapping results, since the spreading of the field angle range or the divergence of the deflected light rays is small. The spreading is not compensated, but merely reduced. This results in an effect described in R.413522.

[0020] - 4 - which approximately corresponds to a point-like image of the deflection device. The minimized spatial distance describes a distance between the second deflection device and the coupling structure that cannot be chosen to be smaller, for example, due to design or functional constraints. The smaller the assigned distance, the smaller the dispersion pattern and the more optimal, or point-like, the image of the second deflection device onto the coupling structure becomes. The more point-like the image, the narrower the coupling structure can be. The minimized spatial distance is based, for example, on the swivel range of a mirror of the deflection device. The minimized spatial distance corresponds to a distance within which the mirror can still move without restriction.The minimized spatial distance is, for example, at least half of the extent of an optically effective surface of the mirror that is oriented orthogonally to the pivot axis.

[0021] The optical arrangement may include an imaging optic, in particular a relay optic, configured to image the first or second deflection device onto the coupling structure, especially with a focused image. The imaging optic enables optimal imaging of one of the deflection devices onto the coupling structure, allowing the latter to be designed to be narrower and therefore smaller.

[0022] It can be provided that the propagation direction of coupled light rays from the optical element is oriented perpendicular to the linear variation of the light ray. The propagation direction describes an imaginary direction in which the coupled light rays are directed within the optical element, for example, by means of discontinuities in the sense of total internal reflection. This direction is oriented, for example, such that the light rays are directed to an output coupling structure of the optical element. The linear variation of the light ray preferably runs along a longitudinal axis of the input coupling structure so that all deflected light rays can be coupled in by the narrow input coupling structure.This orientation of the coupling structure reduces the probability that coupled light rays will hit the coupling structure, thus improving the quality of the optical element, as fewer to no parasitic outcouplings occur and all light rays only interact once with the R.413522.

[0023] - 5 -

[0024] The coupling structure interacts during coupling. The coupling structure can be narrower than the step length of the light beam during total internal reflection within the optical element.

[0025] The coupling structure can be designed as a diffractive optical element, in particular as a holographic optical element, and / or an expander structure. These structures enable efficient coupling of the light beams into the optical element and cost-effective integration of the coupling structure into the optical element.

[0026] The method for coupling a light beam into an optical element, for example a waveguide, comprises: deflecting the light beam in a first spatial dimension by means of a first deflection device; deflecting the light beam deflected by the first deflection device in a second spatial dimension by means of a second deflection device; coupling the light beam deflected by the second deflection device into the optical element by means of a coupling structure; wherein the first or the second deflection device is mapped onto the coupling structure, such that a variation of a field angle in a field angle range of the deflection device not mapped onto the coupling structure causes a line-shaped variation of the light beam on the coupling structure.

[0027] It may be provided that an optical device is operated by means of the method described above.

[0028] The data glasses include an optical device as described above.

[0029] It may be provided that the optical element is integrated into a lens of the smart glasses and / or that the first and second deflection devices are arranged in or on a temple or frame of the smart glasses.

[0030] Further embodiments are shown in the drawing and the following description. The drawing shows:

[0031] Figure 1 is a schematic representation of an optical device; R.413522

[0032] - 6 -

[0033] Figure 2 shows a schematic representation of the optical setup and an imaging optic in a perspective view;

[0034] Figure 3 shows a flowchart of a process;

[0035] Figure 4 shows a schematic representation of data glasses.

[0036] Figure 1 shows a schematic representation of an optical device 100. The optical device 100 is configured to couple a light beam 2 into an optical element 4, for example, a waveguide. The optical device 100 comprises a first deflection device 102, configured to deflect the light beam 2 in a first spatial dimension, a second deflection device 104, configured to deflect the light beam 2 deflected by the first deflection device 102 in a second spatial dimension, and a coupling structure 106, configured to couple the light beam 2 deflected by the second deflection device 104 into the optical element 4.The optical device 100 is configured to map the first or the second deflection device 102, 104 onto the coupling structure 106, such that a variation of a field angle within a field angle range 108 of the deflection device 102 not mapped onto the coupling structure 106 causes a line variation 110 of the light beam 2 on the coupling structure 106. In the illustrated example, the second deflection device 104 is mapped onto the coupling structure, whereas a movement of the first deflection device 102 varies the light beam 2 along the line variation 110. A movement of the second deflection device 104, due to its mapping onto the coupling structure 106, does not cause any variation of the light beam 2 on the coupling structure 106 in the illustrated example.

[0037] The first and / or second deflection device 102, 104 can, for example, be configured as a tilting mirror, in particular as a micro-electro-mechanical system (MEMS) mirror. Alternatively, the first and / or second deflection device 102, 104 can be configured as prisms or lens arrangements designed to deflect or redirect a light beam in one direction. R.413522

[0038] - 7 -

[0039] The coupling structure 106 can, for example, be configured as a prism or an oblique mirror, or be formed by diffractive optical elements such as gratings or holograms. It is possible for the coupling structure 106 to be integrated into, or in particular embedded in, the optical element 4.

[0040] The optical element 4 is, for example, a combiner in the form of a waveguide. It can be configured as a flat or curved plate with a high-refractive-index core. The light rays 2 coupled into the optical element 4 are guided as total internal reflection modes (TIR modes) within this core. Within the core, various k-vectors (ray directions or angles) can be guided, each propagating with its own lateral jump length between a first side and a side opposite the first side.

[0041] The coupling structure 106 can be designed to have a rectangular, or in particular linear, spatial extent. Such a design of the coupling structure 106 is possible by mapping one of the two deflection devices 102, 104 onto the coupling structure. By mapping, the light beam 2 varies only in the spatial dimension of the deflection device not being mapped. In this context, the term "rectangular" also includes shapes with rounded edges or corners that have a length-to-width ratio of a rectangle. For reliable coupling, the coupling structure 106 should have a width that corresponds to a diameter or extent of the mapping of the mapped deflection device onto the coupling structure 106.The length of the coupling structure 106 should cover at least a corresponding fanned-out field angle range of the deflection device not mapped onto the coupling structure 106, so that the light beam 2 is coupled into the optical element 4 for all field angles that can be mapped by the deflection devices 102, 104.

[0042] It may be provided that the optical device 100 comprises an imaging optic 112, in particular a relay optic configured to direct the first or the second deflection device 102, 104 onto the coupling structure R.413522

[0043] - 8 -

[0044] 106, in particular in focus, to image the corresponding first or second deflection device 102, 104 as a point onto the coupling structure. Using the imaging optics 112, for example, the image of the corresponding deflection device 102, 104 can be reduced to a minimum in its extent, which also allows the coupling structure 106 to be reduced to a minimum in its spatial extent, particularly in its width. The imaging optics 112 can, for example, be designed as a lens arrangement or a mirror arrangement.

[0045] By imaging one of the two deflection devices 102, 104 onto the coupling structure 106 with the imaging optics 112, all field angles of this deflection device are focused onto a point, or approximately a point, on the coupling structure 106. By varying the field angle of the non-imaging deflection device, this point of the light beam 2 moves along the line-shaped variation 110 depending on this field angle.

[0046] It can be provided that the second deflection device 104 has a predetermined spatial distance, in particular a minimized spatial distance, from the coupling structure 106, such that the fanning out of a field angle range 114 caused by the second deflection device 104 relative to the coupling structure 106 is minimized, and, for example, the second deflection device 104 is mapped onto the coupling structure 106, in particular approximately as a point. The deflected light beam 2 diverges from the second deflection device 104. Due to a smaller distance to the coupling structure 106, the fanning out of the field angle range 114 resulting from the diverging is reduced, which also reduces the size of the image of the second deflection device 104. This distance can be reduced until the second deflection device 104 is approximately mapped as a point on the coupling structure 106.In this embodiment, the optical device 100 does not include imaging optics 112.

[0047] Figure 2 shows part of the optical device 100 in a perspective schematic representation. The first deflection device 102 R.413522

[0048] - 9 - and the second deflection device 104 are not shown for illustrative purposes. The imaging optics 112 are shown in a front view with a viewing direction oriented along the path of the light beam 2. The field angle range 108, represented by a dashed line, depicts the field angle range 108 of the first deflection device 102. The first deflection device 102 is designed to deflect the light beam 2 along the field angle range 108. If the first deflection device 102 is designed as a tilting mirror, the depicted field angle range 108 is oriented orthogonally to an axis of rotation of the tilting mirror. The field angle range 108 symbolizes the first spatial dimension.

[0049] The field angle range 114, represented by a dotted line, depicts the field angle range 114 of the second deflection device 104. The second deflection device 102 is configured to deflect the light beam 2 along the field angle range 114. If the second deflection device 104 is configured as a tilting mirror, the depicted field angle range 114 is oriented orthogonally to an axis of rotation of the tilting mirror. The field angle range 114 symbolizes the second spatial dimension. By combining the first deflection device 102 with the field angle range 108 and the second deflection device with the field angle range 114, the light beam 2 can be deflected in a two-dimensional plane, for example, onto an eyepiece-side lens of the imaging optics 112.

[0050] The symbols in Figure 2, in the form of a circle, triangle, and cross, represent points in the path of light rays 2a, 2b, 2c. Each of these light rays 2a, 2b, 2c represents a light ray 2 that has been deflected by the first and second deflection devices 102, 104, with different field angles into the imaging optics 112. The coupling points 2a', 2b', 2c' show points of the corresponding path of the light rays 2a, 2b, 2c on the coupling structure 106. In the example shown in Figure 2, the second deflection device 104, with the field angle range 114, is imaged by the imaging optics 112 onto the coupling structure 106.

[0051] In the example shown, the light beam 2a strikes the imaging optic 112 centrally. This is achieved, for example, by aligning both deflection devices 102 and 104 in a neutral or center position. The light beam 2a R.413522

[0052] - 10 - is centrally imaged onto the coupling point 2a' of the coupling structure 106 by means of the imaging optics 112.

[0053] In the example shown, the light beam 2b is deflected only in the second spatial dimension within the field angle range 114 of the second deflection device 104. Since the second deflection device 104 is imaged onto the coupling structure 106 by the imaging optics 112 in this example, the coupling point 2a' and the coupling point 2b' are located at the same position on the coupling structure 106.

[0054] Compared to light beam 2b, light beam 2c is additionally deflected in the first spatial dimension along the field angle range 108 of the first deflection device 102. Due to the deflection in the second spatial dimension, the coupling point 2c' moves along the linear variation 110 on the coupling structure 106 according to the deflection.

[0055] It can be provided that a propagation direction 6 of coupled light rays 2 of the optical element 4 is oriented perpendicular to the linear variation 110 of the light ray 2. Preferably, the linear variation 110 extends along a longitudinal axis of the coupling structure 106 and the propagation direction 6 is oriented orthogonally to this longitudinal axis.

[0056] It may be provided that the coupling structure 106 is designed as a diffractive optical element, in particular as a holographic optical element and / or expander structure.

[0057] Figure 3 shows a flowchart of a method 200 for coupling a light beam 2 into an optical element 4, for example, a waveguide. The method 200 comprises deflecting 202 the light beam 2 in the first spatial dimension by means of the first deflection device 102 and deflecting 204 the light beam 2 deflected by the first deflection device 102 in the second spatial dimension by means of the second deflection device 104. Furthermore, the method 200 comprises coupling 206 the light beam 2 deflected by the second deflection device 104 into the optical element 4 by means of the coupling structure 106. The first or the second deflection device 102, 104 is mapped onto the coupling structure 106, such that R.413522

[0058] - 11 - a variation of a field angle in a field angle range 108 of the deflection device 102 not mapped onto the coupling structure 106 causes a linear variation 110 of the light beam 2 on the coupling structure 106.

[0059] It may be provided that the optical device 100 is operated by means of the method 200 in accordance with the above descriptions.

[0060] Figure 4 shows a schematic representation of a data glasses 300 comprising the optical device 100. For the sake of clarity, only a part of the optical device 100 is shown.

[0061] The optical element 100 may be integrated into a lens 302 of the smart glasses 300, and / or the first and second deflection devices 102, 104 may be arranged in or on a temple 304 or frame of the smart glasses 300. The optical device 100 may be part of a projection device of the smart glasses 300. The light beam 2 may, for example, be a light beam from a red-green-blue RGB laser light source, which is used to generate a virtual image for a user of the smart glasses 300. The virtual image is constructed using the first deflection device 102 and the second deflection device 104, for example, in a scanning process.

Claims

R.413522 - 12 - Claims 1. Optical device (100) for coupling a light beam (2) into an optical element (4), for example a waveguide, comprising: a first deflection device (102) configured to deflect the light beam (2) in a first spatial dimension, for example a tilting mirror; a second deflection device (104) configured to deflect the light beam (2) deflected by the first deflection device (102) in a second spatial dimension, for example a tilting mirror; a coupling structure (106) configured to couple the light beam (2) deflected by the second deflection device (104) into the optical element (4);wherein the optical device (100) is configured to map the first or the second deflection device (102, 104) onto the coupling structure (106), such that a variation of a field angle in a field angle range (108) of the deflection device (102) not mapped onto the coupling structure (106) causes a line-shaped variation (110) of the light beam (2) on the coupling structure (106).

2. The optical device (100) according to claim 1, wherein the coupling structure (106) is rectangular in its spatial extent, in particular linear.

3. The optical device (100) according to one of the preceding claims, wherein the second deflection device (104) has a predetermined spatial distance, in particular a minimized spatial distance, to the coupling structure (106), such that a fanning out of a field angle range (114) caused by the second deflection device (104) relative to the coupling structure (106) is minimized and, for example, the second deflection device (104) is imaged onto the coupling structure (106), in particular approximately as a point. R.413522 - 13 - 4. The optical device (100) according to one of claims 1 or 2 comprising an imaging optic (112), in particular a relay optic, which is configured to image the first or the second deflection device (102, 104) onto the coupling structure (106), in particular in focus.

5. The optical device (100) according to one of the preceding claims, wherein a propagation direction (6) of coupled light rays (2) of the optical element (4) is oriented perpendicular to the linear variation (110) of the light ray (2).

6. The optical device (100) according to one of the preceding claims, wherein the coupling structure (106) is designed as a diffractive optical element, in particular as a holographic optical element and / or expander structure.

7. Method (200) for coupling a light beam (2) into an optical element (4), for example a waveguide, comprising: - Deflecting (202) the light beam (2) in a first spatial dimension by means of a first deflection device (102); - Deflecting (204) the light beam (2) deflected by the first deflecting device () in a second spatial dimension by means of a second deflecting device (104); Coupling (206) of the light beam (2) deflected by the second deflection device (104) into the optical element (4) by means of a coupling structure (106); wherein the first or the second deflection device (102, 104) is mapped onto the coupling structure (106), such that a variation of a field angle in a field angle range (108) of the deflection device (102) not mapped onto the coupling structure (106) causes a line-shaped variation (110) of the light beam (2) on the coupling structure (106).

8. The method (200) according to claim 7, wherein an optical device (100) according to claims 1 to 6 is operated by means of the method (200).

9. Data glasses (300) comprising an optical device (100) according to claims 1 to 6. R.413522 - 14 - 10. The data glasses (300) according to claim 9, wherein the optical element (100) is integrated into a lens (302) of the data glasses (300) and / or the first and second deflection device (102, 104) are arranged in or on a temple (304) or frame of the data glasses (300).

Images