Device and method for capturing at least one stereo image of a pupil of an eye, hologram unit and data spectacles

Abstract

Proposed is a device (52), in particular a data spectacles device, for capturing at least one stereo image (10) of a pupil (12) of an eye (14), in particular of a data spectacles user, said device having: at least one projector unit (18) emitting at least one measurement laser beam (16); at least one hologram unit (20) which is designed to convert each measurement laser beam (16) incident in the hologram unit (20) into at least two output measurement laser beams (26, 28) which exit the hologram unit (20) in the direction of the eye (14) at different angles (22, 24); and at least one optical detector unit (30) at least for capturing reflections of the output measurement laser beams (26, 28) generated by the eye (14), in particular reflections which are perspectively different, wherein the hologram unit (20) comprises a holographic-optical element (HOE 36) which comprises at least two stacked hologram layers (32, 34).

Description

[0001] Description

[0002] Device and method for capturing at least one stereo image of a pupil of an eye, hologram unit and data glasses

[0003] State of the art

[0004] Data glasses have already been proposed in which pupil positions, gaze vectors, etc. are determined using video oculography.

[0005] Disclosure of the invention

[0006] A device, in particular a data glasses device, for capturing at least one stereo image of a pupil of an eye, in particular of a data glasses user, is proposed, comprising at least one projector unit emitting at least one measuring laser beam, at least one hologram unit which is at least configured to convert each measuring laser beam incident on the hologram unit into at least two output measuring laser beams leaving the hologram unit at different angles in the direction of the eye, and at least one optical detector unit for capturing at least reflections of the output measuring laser beams generated by the eye, in particular reflections with different perspectives, wherein the hologram unit comprises a holographic-optical element (HOE) comprising at least two stacked holograms, in particular hologram layers.This advantageously enables a particularly efficient determination of the pupil position and / or gaze vector of the eyes of data glasses users. Advantageously, multiple virtual cameras can be generated from a single scanned laser system. This advantageously enables energy-efficient recording from different perspectives. Advantageously, parallel recording of two or more pupil images during a single scan of the measuring laser beam can be enabled. Advantageously, a detectable measurement volume of a scan area in which pupils are searched for can be enlarged compared to single-perspective methods. Advantageously, power consumption can be kept low, in particular due to the low necessary computational complexity of a stereoscopic method that determines the pupil position from the stereo images.In addition, a high degree of robustness, particularly slippage robustness, can be advantageously achieved for pupil determination. For example, reliable pupil detection can be achieved even if a pupil is partially occluded from one of the perspectives or if there is a weak signal from one of the perspectives.

[0007] In particular, the device enables the implementation of a stereoscopic method and / or a stereoscopic reconstruction for determining the pupil position and / or the gaze vector. The device is designed, in particular, as a data glasses device. A "data glasses device" in particular forms at least part of a pair of data glasses. "Data glasses" should be understood, in particular, to mean a wearable (head-mounted display) by means of which information can be added to a user's field of vision. Data glasses preferably enable augmented reality, virtual reality, and / or mixed reality applications. Data glasses are also commonly referred to as smart glasses, VR glasses, or AR glasses.In particular, in addition to outputting the measuring laser beam, the projector unit is provided for generating and outputting virtual content or video content by means of a further laser beam or RG B laser beam bundle, in particular one different from the measuring laser beam. The projector unit could, for example, be arranged in a side region (e.g., temple area) of the data glasses. The data glasses preferably comprise at least one imaging optics, such as a lens, in particular a pancake lens of a VR headset or a spectacle lens of an AR headset. The hologram unit preferably forms part of this imaging optics. In particular, the projector unit, preferably the device, forms a, in particular integral, component of an eye-tracking system of the data glasses.The eye-tracking system could be designed to detect the eye and / or pupil position of the user's eye based on an evaluation of the stereo images with regard to a so-called "dark pupil effect." Preferably, however, the eye-tracking system is designed to detect the eye and / or pupil position from the stereo images using the so-called "bright pupil effect," which is based in particular on the high infrared reflectivity of the retina of the eye. In particular, the retina produces a so-called speckle pattern upon reflection of a laser beam, in particular a sufficiently coherent laser beam. The speckle pattern (also called laser granulation or light granulation) is in particular a grainy-looking interference phenomenon that can be observed with sufficiently coherent illumination of optically rough object surfaces, such as the retina of the eye (cf. cones and rods of the retina).The speckle pattern thus indicates the position and shape of the pupil in an image, particularly in the individual images forming stereo images. "Intended" and / or "configured" should be understood to mean, in particular, that an object is specifically programmed, designed, and / or equipped. The fact that an object is intended and / or configured for a specific function should be understood to mean, in particular, that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0008] A stereo image comprises an image of the same object, e.g., part of the eye of the data glasses user, from at least two, preferably exactly two different perspectives. In particular, the stereo image thus comprises two individual images of the same object, each from a different perspective. This advantageously allows a spatial image impression to be created. In addition, spatial information about the object, e.g., the eye, can advantageously be read out from the stereo images. The measuring laser beam is particularly designed as an (eye-safe) infrared laser beam. In particular, the measuring laser beam is irradiated onto the eye of the data glasses user via the imaging optics, in particular at least via the hologram unit, reflected by the eye of the data glasses user, and subsequently a portion of the reflections is recorded by a detector unit that generates the stereo images.In particular, the perspectively different reflections originate from the individual measuring laser beams each leaving the hologram unit at different angles, which in particular have irradiated the eye from different angles and therefore generate perspectively different reflection images of the eye in the detector. In particular, the reflection passes through the same hologram unit and will therefore leave the hologram unit again on the return path / reflection path in at least substantially the same directions towards the detector unit. The detector unit is in particular arranged behind the hologram unit on the return path / reflection path. However, it is also conceivable that the detector unit is arranged in front of the hologram unit on the return path / reflection path or that the reflection signal reaching the detector unit does not pass through the hologram unit at all and, for example, reaches the detector unit directly."Stacked holograms" are understood to mean, in particular, holograms that are at least partially overlapping in a planar manner. "Stacked hologram layers" are understood to mean, in particular, layers arranged one above the other or one behind the other in an optical path, each layer containing individual holograms, preferably partial hologram layers. In particular, the hologram layer comprises at least two, preferably exactly two, individual hologram layers stacked in a sandwich-like manner.

[0009] It is further proposed that the hologram layers of the HOE be stacked so as to overlap over their entire surface. This advantageously allows for a simple construction. In particular, the hologram layers are stacked flush with one another, preferably stacked.

[0010] Alternatively, it is proposed that the holograms of the HOE each comprise different holographic-optical deflection functions integrated into a single hologram layer. This advantageously allows for a simple, particularly flat, construction. The holographic-optical deflection functions of the stacked hologram are integrated into the single hologram layer in such a way that the Bragg structure associated with each of the two holograms, which is responsible for the respective holographic-optical deflection functions, is embossed into a common photopolymer layer. This advantageously simplifies the alignment process for calibrating the two holograms.It is proposed that the at least two different / individual holographic optical deflection functions be recorded in the individual photopolymer layer (angle multiplexing), so that only a single holographic film needs to be integrated into the lens. This advantageously minimizes the required thickness of the lens.

[0011] Furthermore, it is proposed that the hologram layers of the HOE each comprise different / individual holographic-optical deflection functions, in particular holographic-optical reflection functions. This advantageously allows a detector signal comprising multiple perspectives, in particular a stereo image, to be generated from a measuring laser beam, in particular a scanned one, in a simple manner. Each of the deflection functions converts a single incident measuring laser beam into a separate output measuring laser beam exiting the hologram unit at an individual angle. The individual output measuring laser beams exit the hologram unit toward the eye and are reflected by the eye.The part of the output measuring laser beams that enters the eye through the pupil and interacts with the retina is interfered with by the roughness of the retina and is reflected back from the eye through the pupil to the detector unit as a laser speckle pattern.

[0012] It is additionally proposed that the optical detector unit comprise a detector element which is configured to at least detect the reflections of both output measuring laser beams generated by the eye. This advantageously allows a simple construction to be achieved. Advantageously, a lightweight and / or compact construction can be achieved, which in particular requires only a single detector element for recording stereo images. In particular, the same detector element detects the reflection signals of both / all output measuring laser beams. In particular, the same detector element detects the reflection signals of both / all perspectives. In particular, the detector element is designed as a photodiode, in particular as an infrared photodiode. In particular, the detector element is integrated into the data glasses, for example into a frame or a temple of the data glasses.

[0013] Furthermore, it is proposed that the projector unit comprise a laser feedback interferometry sensor (LFI sensor), which at least partially forms the detector unit. This advantageously enables a lightweight, compact, and / or energy-efficient design. Furthermore, this advantageously allows for an extension of the pupil position measurement to include a third spatial dimension (distance of the eye from the spectacle lens / from the hologram unit). Advantageously, a highly accurate pupil measurement can be achieved, which is particularly free of parallax or scale errors. In particular, the LFI sensor is provided for emitting the measuring laser beam. The measuring laser beam can, for example, have a wavelength of approximately 850 nm, approximately 940 nm, or above 1000 nm.In particular, both hologram layers of the HOE each have a Bragg structure that deflects, preferably reflects, light with the wavelength emitted by the LFI sensor. Alternatively, a single hologram layer has two different Bragg structures simultaneously. The LFI sensor can be designed, for example, as a VCSEL, preferably a ViP-VCSEL (“vertical cavity surface-emitting laser with integrated photo diode”). The LFI sensor is integrated, in particular, into the data glasses, e.g., into a frame, lens, or temple of the data glasses. The LFI sensor can be integrated into a shared laser module / projector unit with the (RGB) laser diodes of the data glasses that generate the projected image. This advantageously makes the detector elements invisible to the wearer of the data glasses.Advantageously, no camera sensors visible from the outside or to the wearer are required for pupil tracking. Alternatively, the LFI sensor can also be designed separately from the laser projector with the (RGB) laser diodes that generate the projected image. It is also conceivable for the data glasses to have more than one LFI sensor, e.g., two, three, or more than three LFI sensors. The LFI sensor is based on an interferometric measuring method. The LFI sensor can also be capable of detecting a distance to a target (e.g., the eye) as well as a surface speed of the target. In particular, the LFI sensor emits the measuring laser beam in the infrared spectrum, which then strikes a surface with a reflectivity R at the various angles of the output measuring laser beams. The light of the laser beam is then scattered back from this surface, so that it re-enters a laser cavity of the LFI sensor.In the laser cavity of the LFI sensor, the backscattered light interferes with a locally oscillating field of the LFI sensor. This leads, in particular, to a modulation of the laser power of the laser source, which can be detected by the detector element, e.g., by a photodiode integrated into a back reflector of the laser cavity, or by a direct measurement of a voltage of the laser source. In particular, the photodiode of the LFI sensor, which is integrated into the laser module, is intended to detect the backscattered portion of the output measuring laser beams and convert them into an electrical signal. Furthermore, a current of the laser source of the LFI sensor can be modulated with a preferably triangular modulation signal in order to achieve a cyclic shift in the wavelength of the measuring laser beam. If the laser parameters are known, a beat frequency and a Doppler frequency can then be determined.From this, the surface speed of the eye, the distance of the LFI sensor to the eye and other eye parameters can be determined using known equations.

[0014] It is further proposed that the projector unit comprise at least one mirror system, in particular a MEMS micromirror system, which is configured to scan the measuring laser beam over at least a large portion of a surface of the HOE, in particular a holographically active / holographically functionalized region of the HOE, preferably the two stacked hologram planes of the HOE. This advantageously allows the perspectively different images of the eye to be recorded. Advantageously, the output measuring laser beams are each scanned over a substantial portion of the eye. In particular, the mirror system forms part of a microscanner. The microscanner represents, in particular, a micro-opto-electro-mechanical system from the class of micromirror actuators for the dynamic modulation of light.A modulating movement of individual mirrors of the mirror system, in particular of the MEMS micromirror system, can occur in a rotational manner around at least one or two axes, which in particular deflects light beams incident on the individual mirrors, e.g., the measuring laser beam. In particular, the scanned laser beam is scanned line by line. However, scanning the scanned laser beam column by column is also conceivable. Typical dimensions of individual mirrors of a MEMS micromirror system are in the range between one and three millimeters. However, larger mirror apertures (e.g., 10 mm x 3 mm) can also be manufactured. Scanning frequencies of the MEMS micromirror system are in the range of several kilohertz, in particular in the range up to 50 kHz.Furthermore, it is proposed that each of the two holograms, in particular each of the two hologram layers, has a virtual node / construction point, in particular a permanently encoded one, which is arranged and aligned in such a way that any overlap, in particular temporal and / or spatial, of pupil reflection signals in the optical detector unit is excluded. This advantageously enables parallel recording of two pupil signals via two holograms / two hologram layers, in particular using a single LFI sensor, without interference between the pupil signals of the two holograms / hologram layers. This is achieved in particular by ensuring that the pupil signals of two or more output measuring laser beams / two or more perspectives never enter the detector element simultaneously.Advantageously, overlap of the pupil signals of two or more output measuring laser beams / two or more perspectives in the stereo image is prevented. In particular, light with a sufficiently high signal strength, especially one that exceeds background noise, is reflected back into the LFI sensor only from the retina of the eye. In particular, the deflection functions of the two holograms / two hologram layers are designed such that, at any given time during the mirror system scan, only light reflected from the retina from one of the two holograms / one of the two hologram layers is detected by the detector element.In particular, the output measuring laser beams are aligned towards the eye by the individual deflection of the holograms / hologram layers, preferably separated in such a way that during a scan of the measuring laser beam generated by the mirror system, only one of the two output measuring laser beams can enter the pupil of the eye. In particular, the images of the pupil in the signal of the detector element, in particular the stereo image, are spatially separated and preferably easily separable. In particular, the detector unit records only one pupil signal from exactly one perspective for each scan angle of the mirror system. In particular, the arrangement of the virtual nodes / construction points (positioning and orientation) of the holograms eliminates double images or superimpositions of the pupil signals in the infrared image / stereo image generated by a complete scan across the holographically active area of ​​the HOE.In particular, for each beam of the respective output measuring laser beam, a pupil image only appears in a single scan area in the hologram plane of the HOE. In particular, the geometries of the virtual nodes are permanently encoded in the holograms of the hologram unit.

[0015] In particular, virtual single-pixel cameras resulting from the virtual nodes can be calibrated using a stereo calibration algorithm known from the state of the art. This advantageously defines the rotation and translation of the virtual single-pixel cameras relative to one another and in relation to the measurement plane (“extrinsic camera calibration parameters”). In addition, imaging and camera properties are advantageously determined (“intrinsic camera calibration parameters”). If the rotation and translation are known, a pupil position in all three spatial dimensions, a gaze vector and / or a center of an eyeball can be reconstructed three-dimensionally using triangulation or stereo matching (stereo correspondence). This is particularly described in the publication by Meyer et al.: “A Holographic Single-Pixel Stereo Camera Sensor for Calibration-free Eye-Tracking in Retinal Projection Augmented Reality Glasses”, 2022 Symposium on Eye Tracking Research and Applications (ETRA '22), Association for Computing Machinery, New York, NY, USA, Article 20, 1-7 . In contrast to the use of only a virtual single-pixel camera, the use of the stereo images generated by the hologram unit in a stereoscopic process advantageously avoids systematic measurement errors, in particular those which generate parallax errors (pupils located outside the calibration plane appear shifted laterally and vertically) and scale errors (pupils further away from the lens / HOE of the data glasses appear smaller) when the data glasses are shifted relatively out of a calibrated measurement plane, e.g. away from the eye or towards the eye.These calibration parameters can be determined fully automatically during production of the data glasses. The calibration parameters can be determined by presenting suitable calibration objects (e.g., plates or solid bodies with defined structures visible in the IR image) at one or more locations in the measurement volume of the data glasses. In addition, it is proposed that the device comprise an evaluation unit configured to determine a three-dimensional position of the eye, the pupil, and / or a gaze vector of the eye by means of an evaluation, in particular triangulatory and / or stereo correspondence-based, of the reflections of the output measuring laser beams detected by the optical detector unit, in particular reflections with different perspectives. This enables advantageous eye tracking for data glasses, in particular, to be realized.In particular, the calibration parameters are stored in the evaluation unit. In particular, the calibration parameters include the relative rotation and / or translation of the two virtual nodes of the holograms of the hologram unit. In particular, the calibration parameters are used when calculating the pupil properties by means of the evaluation unit based on the stereo images. The evaluation unit can be integrated into the data glasses or at least partially separated from the data glasses, e.g., as part of a cloud or an external device such as a mobile device (smartphone, etc.). An "evaluation unit" is to be understood in particular as a unit with at least one control and / or evaluation electronics unit.The term “control and / or evaluation electronics” is to be understood in particular as a unit with a processor and with a digital data memory as well as with an operating program stored in the digital data memory.

[0016] Furthermore, the hologram unit and data glasses with the hologram unit are proposed, wherein the hologram unit can be integrated into at least one lens of the data glasses. This advantageously allows a particularly lightweight and / or compact design to be achieved. In particular, the lens with the hologram unit is designed to deflect certain light wavelengths toward the eye, while at least a large portion of the remaining light wavelengths can pass through the lens with the hologram unit.

[0017] Furthermore, a method for capturing at least one stereo image of a pupil of an eye is proposed, wherein at least one measuring laser beam is emitted, each incident measuring laser beam being converted by a hologram unit into at least two output measuring laser beams exiting the hologram unit at different angles toward the eye, and wherein at least two reflections of the output measuring laser beams generated by the eye, in particular with different perspectives, are detected by a detector unit, wherein the measuring laser beam is deflected by at least two stacked hologram layers of the hologram unit at the respective different angles. This advantageously enables a particularly efficient determination of the pupil position and / or gaze vector of the eyes of data glasses users.

[0018] The device according to the invention, the hologram unit according to the invention, the data glasses according to the invention, and the method according to the invention are not intended to be limited to the application and embodiment described above. In particular, the device according to the invention, the hologram unit according to the invention, the data glasses according to the invention, and the method according to the invention can have a number of individual elements, components, units, and method steps that differs from the number stated herein in order to fulfill a functionality described herein. Furthermore, in the value ranges specified in this disclosure, values ​​within the stated limits are also to be considered disclosed and can be used arbitrarily.

[0019] drawing

[0020] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0021] They show:

[0022] Fig. 1 shows a schematic representation of exemplary data glasses with a device for capturing stereo images of a pupil of a user's eye, Fig. 2 shows a schematic representation of the formation of laser speckle patterns during reflection on a retina of the eye,

[0023] Fig. 3 is a schematic representation of the device,

[0024] Fig. 4 a schematic and exemplary stereo image,

[0025] Fig. 5 schematically shows (virtual) beam paths during a scan of a measuring laser beam of the device and

[0026] Fig. 6 is a schematic flow diagram of a method for capturing the stereo image.

[0027] Description of the embodiment

[0028] Figure 1 schematically shows an example of a pair of data glasses 54. The data glasses 54 form an AR (Augmented Reality) system. The AR system has, for example, a virtual retinal display 72. The virtual retinal display 72 is provided for projecting an artificially generated image content directly onto a retina 58 of an eye 14 of a data glasses user. The data glasses 54 comprise a device 52. The device 52 forms a data glasses device. The device 52 is provided for capturing stereo images 10 (cf. Fig. 4) of a pupil 12 of the eye 14. The device 52 has a projector unit 18. The projector unit 18 from the exemplary embodiment in Fig. 1 is integrated into a temple piece 60 of the data glasses 54. The projector unit 18 is provided for generating a visible projector light (not shown). The visible projector light contains the artificially generated image content.The projector unit 18 is provided for generating a measuring laser beam 16. The projector unit 18 is provided for emitting the measuring laser beam 16 toward a hologram unit 20. The measuring laser beam 16 is an infrared laser beam. The measuring laser beam 16 has a fixed wavelength. The projector unit 18 includes an LFI sensor 62. The LFI sensor 62 is provided for emitting the measuring laser beam 16.

[0029] The device 52 comprises the hologram unit 20. The hologram unit 20 comprises a holographic optical element (HOE 36). The hologram unit 20 is integrated into a spectacle lens 56 of the data glasses 54. The hologram unit 20 partially forms the spectacle lens 56 of the data glasses 54. The spectacle lens 56 of the data glasses 54 forms a combiner, in particular a free-space combiner, of the virtual retinal display 72. The hologram unit 20 is configured at least to convert each measuring laser beam 16, the wavelength of which is matched to optical deflection functions 38, 40 (cf. Fig. 3) of the hologram unit 20, into at least two output measuring laser beams 26, 28, which exit the hologram unit 20 at different angles 22, 24. The output measuring laser beams 26, 28 impinge on the user's eye 14 at different locations. The output measuring laser beams 26, 28 impinge on the user's eye 14 from different angles.The output measuring laser beams 26, 28 illuminate the user's eye 14 from different perspectives.

[0030] The projector unit 18 comprises a mirror system 44. The mirror system 44 is designed as a MEMS micromirror system. The mirror system 44 forms part of a microscanner of the projector unit 18. The mirror system 44 is configured to scan the measuring laser beam 16 across at least a large portion of a surface of the HOE 36. The mirror system 44 is configured to scan the measuring laser beam 14 across a holographically active region of the HOE 36. By scanning the measuring laser beam 16, an area of ​​the HOE 36 is scanned. By scanning the measuring laser beam 16, the output measuring laser beams 26, 28 leaving the HOE 36 are also automatically scanned. As a result, the eye 14 is scanned two-dimensionally from two different perspectives using the output measuring laser beams 26, 28.A reflection signal is generated at each point of impact of the output measuring laser beams 26, 28 on the eye 14 or outside the eye 14. Reflection images can be generated from the mirror positions of the mirror system 44 and the reflection signals detected by a detector unit 30 of the device 52. When the reflection signals from two separate output measuring laser beams 26, 28 are input simultaneously into the detector unit 30, two superimposed reflection images are thus generated simultaneously by the detector unit 30.

[0031] If a sufficiently coherent infrared laser beam, in particular one of the output measuring laser beams 26, 28, falls on the retina 58, this leads to increased backscattering, since the infrared reflectivity of the retina 58 is stronger than the infrared reflectivity of other parts of the eye 14, such as the iris or the sclera (utilizing the red eye effect / bright pupil effect). This leads to an amplitude modulation of the optical power of the output measuring laser beam 26, 28 for a region of the eye 14 in which the output measuring laser beam 26, 28 is imaged through the pupil 12 onto the retina 58. In addition, the amplitude of the backscattered light of the output measuring laser beam 26, 28 is modulated by laser speckle. The reflection signal of the retina 58 thus forms a laser speckle pattern. This takes advantage of the optical roughness of the retina 58.The roughness of the retina 58 is related to the anatomy of the eye 14 (cones and rods) and behaves similarly for all people. The laser beam, e.g., the output measuring laser beam 26, 28, penetrates a cornea 64 of the eye 14 and is focused by a lens 66 of the eye 14 onto the retina 58 (see Fig. 2). There, the laser beam, e.g., the output measuring laser beam 26, 28, strikes a surface 68 of the retina 58 with its coherent wavefront. Part of an incoming wavefront is directly reflected by the surface 68 of the retina 58, with a wavefront 70 of the reflected wave being distorted by the signal propagation times through the rough surface 68 of the retina 58 (see Fig. 2). A further portion of the laser beam, e.g. the output measuring laser beam 26, 28, enters the upper tissue layers of the retina 58 and is reflected from there, which also leads to a distortion of the reflected wavefront 70 (cf. Fig. 2).These two effects result in constructive or destructive interference, so that light and dark speckles form in a normally distributed manner in the area of ​​the retina 58 and thus the pupil 12 of the eye 14 in the scanned image (stereo image 10) captured by the detector unit 30. These effects, in particular the obtained images, are exploited to determine a particularly efficient algorithm for determining the position of the pupil 12 from the scanned images. In order to isolate a signal contribution from the pupil 12 in the overall signal / image, the sub-area of ​​the histogram containing the pupil 12 must first be selected from the image. For example, a histogram transformation and thresholding can be used to separate a signal contribution corresponding to the pupil 12 from the residual signal.From the image of the pupil 12 thus extracted, a three-dimensional pupil position in the spectacle coordinate system and a gaze gaze vector as an angle pair can then be determined. The device 52 comprises the optical detector unit 30. The projector unit 18 comprises the optical detector unit 30. The optical detector unit 30 is at least partially formed by the LFI sensor 62. The optical detector unit 30 is provided for detecting infrared light. The optical detector unit 30 is provided for detecting reflections of the measuring laser beam 16 generated by the eye 14, in particular the output measuring laser beams 26, 28 generated from the measuring laser beam 16. The reflections of the output measuring laser beams 26, 28 generated by the eye 14 have different perspectives. The stereo image 10 is generated from the detected reflections of the output measuring laser beams 26, 28. The optical detector unit 30 comprises a detector element 42.The detector element 42 is configured to detect the reflections of both, in particular all, output measuring laser beams 26, 28 generated by the eye 14. The detector element 42 is configured as a photodiode integrated into the LFI sensor 62.

[0032] The device 52 comprises an evaluation unit 50. The evaluation unit 50 is configured to determine a three-dimensional position of the eye 14, the pupil 12 and / or the gaze vector of the eye 14 by means of a triangulatory and / or stereo correspondence determination evaluation of the perspectively different reflections of the output measuring laser beams 26, 28 detected by the optical detector unit 30 (see also Fig. 4).

[0033] Figure 3 shows a schematic representation of the device 52. The hologram unit 20 comprises at least one holographic optical element (HOE) 36. The HOE 36 is completely embedded in the spectacle lens 56. The hologram unit 20, in particular the HOE 36, comprises at least two stacked hologram layers 32, 34. The hologram unit 20 could also comprise more than two stacked hologram layers 32, 34. The number of stacked hologram layers 32, 34 corresponds to the number of output measuring laser beams 26, 28 generated by the hologram unit 20 from a single measuring laser beam 16 irradiated onto the hologram unit 20; the hologram layers 32, 34 of the HOE 36 are stacked with an overlap over their entire surface. The hologram layers 32, 34 of the HOE 36 each comprise different holographic-optical deflection functions 38, 40, in particular holographic-optical reflection functions.Alternatively or additionally, one of the hologram layers 32, 34 could also comprise two holographic-optical deflection functions 38, 40 simultaneously. In this case, the HOE 36, in particular the spectacle lens 56, could also comprise only a single hologram layer 32.

[0034] Figure 4 shows a schematic and exemplary stereo image 10 that could be recorded using the device 52 according to the invention. The stereo image 10 comprises a first pupil reflection signal 74. The first pupil reflection signal 74 originates from a reflection of a first output measuring laser beam 26, which left the hologram unit 20 at a first angle 22 and illuminated / scanned the eye 14 from a first perspective. The stereo image 10 comprises a second pupil reflection signal 76. The second pupil reflection signal 76 originates from a reflection of a second measuring laser beam 28, which is different from the first output measuring laser beam 26, which left the hologram unit 20 at a second angle 24 different from the first angle 22 and illuminated / scanned the eye 14 from a second perspective different from the first perspective.Arrows 78, 80 indicate the horizontal and vertical scanning directions in which the measuring laser beam 16 generating the output measuring laser beams 26, 28 is scanned by the mirror system 44. The pupil reflection signals 74, 76 are non-overlapping. The pupil reflection signals 74, 76 are each recorded at completely different scanning angles in the two scanning directions. The holographic-optical deflection functions 38, 40 of the two hologram layers 32, 34 are selected such that the deflection of the output measuring laser beams 26, 28 is so different that the pupil signals resulting from their reflections do not overlap each other in the detector unit 30 / in the stereo image 10.

[0035] Figure 5 schematically shows (virtual) beam paths during a scan of the measuring laser beam 16. Each of the two hologram layers 32, 34, in particular their respective holographic-optical deflection function 38, 40, has a permanently encoded virtual node 46, 48. The virtual nodes 46, 48 are each arranged and aligned in such a way that an overlap, in particular temporal and / or spatial, of pupil reflection signals 74, 76 in the optical detector unit 30 is excluded. The virtual nodes 46, 48 of the hologram layers 32, 34 can be viewed as positions of virtual scanned single-pixel cameras. In the example of Fig. 5 it is shown that for each scanning area 82, 84 of the output measuring laser beams 26, 28 a pupil image only occurs in non-overlapping partial areas 86, 88 of a hologram plane 90 of the hologram unit 20.

[0036] Figure 6 shows a schematic flow diagram of a method for capturing at least one stereo image 10 of a pupil 12 of an eye 14 in the data glasses 54. In at least one method step 92, the measuring laser beam 16 is emitted. In at least one further method step 94, the measuring laser beam 16 enters a hologram unit 20 and is converted into at least two output measuring laser beams 26, 28 leaving the hologram unit 20 at different angles 22, 24 in the direction of the eye 14. In this process, the measuring laser beam 16 is deflected by two stacked hologram layers 32, 34 of the hologram unit 20 into the respective different angles (22, 24). In at least one further method step 96, the output measuring laser beams 26, 28 are irradiated onto the eye 14 from different perspectives. The eye 14 generates perspectively different reflections of the output measuring laser beams 26, 28.In at least one further method step 98, the perspectively different reflections generated by the eye are again passed through the hologram unit 20 and thereby combined into a common light signal. In at least one further method step 100, the two perspectively different reflections of the output measuring laser beams 26, 28 generated by the eye 14 are detected by the detector unit 30. In at least one further method step 102, the detected detector signal is evaluated by the evaluation unit 50 to determine the pupil position of the pupil 12 and / or the gaze vector of the eye 14. In at least one further method step 104, the eye information thus obtained is output to the data glasses 54, in particular to a control unit (not shown) of the data glasses 54.

Claims

Claims 1. Device (52), in particular a data glasses device, for capturing at least one stereo image (10) of a pupil (12) of an eye (14), in particular of a data glasses user, with at least one projector unit (18) emitting at least one measuring laser beam (16), with at least one hologram unit (20) which is at least configured to convert each measuring laser beam (16) incident on the hologram unit (20) into at least two output measuring laser beams (26, 28) leaving the hologram unit (20) at different angles (22, 24) in the direction of the eye (14), and with at least one optical detector unit (30) at least for capturing reflections of the output measuring laser beams (26, 28) generated by the eye (14), in particular reflections which differ in perspective, wherein the hologram unit (20) has at least two stacked holograms, in particular hologram layers (32, 34), comprehensive holographic optical element (HOE 36) comprises 2. Device (52) according to claim 1, characterized in that the hologram layers (32, 34) of the HOE (36) are stacked overlapping over their entire surface.

3. Device (52) according to claim 1 or 2, characterized in that the hologram layers (32, 34) of the HOE (36) each comprise different holographic-optical deflection functions (38, 40), in particular holographic-optical reflection functions.

4. Device (52) according to claim 1 or 2, characterized in that the holograms of the HOE (36) each comprise different holographic-optical deflection functions (38, 40) which are integrated into a single hologram layer (32).

5. Device (52) according to one of the preceding claims, characterized in that the optical detector unit (30) comprises a detector element (42) which is configured at least to detect the reflections of both output measuring laser beams (26, 28) generated by the eye (14).

6. Device (52) according to one of the preceding claims, characterized in that the projector unit (18) comprises a laser feedback interferometry sensor (LFI sensor 62) which at least partially forms the detector unit (30).

7. Device (52) according to one of the preceding claims, characterized in that the projector unit (18) comprises at least one mirror system (44), in particular a MEMS micromirror system, which is designed to scan the measuring laser beam (16) over at least a large part of a surface of the HOE (36), in particular a holographically active region of the HOE (36).

8. Device (52) according to one of the preceding claims, characterized in that each of the two holograms, in particular each of the two hologram layers (32, 34) has a, in particular permanently encoded, virtual node (46, 48), which is arranged and aligned in such a way that a, in particular temporal and / or spatial, superposition of pupil reflection signals (74, 76) in the optical detector unit (30) is excluded.

9. Device (52) according to one of the preceding claims, characterized by an evaluation unit (50) which is set up to determine a three-dimensional position of the eye (14), the pupil (12) and / or a gaze vector of the eye (14) by means of an evaluation, in particular triangulatory and / or via a stereo correspondence determination, of the reflections of the output measuring laser beams (26, 28) detected by the optical detector unit (30), in particular reflections which differ in perspective.

10. Hologram unit (20) for a device (52) according to one of the preceding claims.

11. Data glasses (54) with a hologram unit (20) according to claim 10, in particular with a device (52) according to one of claims 1 to 9, characterized in that the hologram unit (20) is integrated into at least one spectacle lens (56) of the data glasses (54).

12. A method for capturing at least one stereo image (10) of a pupil (12) of an eye (14), in particular in data glasses (54) according to claim 11, wherein at least one measuring laser beam (16) is emitted, wherein each incident measuring laser beam (16) is converted by a hologram unit (20) into at least two output measuring laser beams (26, 28) leaving the hologram unit (20) at different angles (22, 24) in the direction of the eye (14), and wherein at least two reflections of the output measuring laser beams (26, 28) generated by the eye (14), in particular with different perspectives, are detected by a detector unit (30), wherein the measuring laser beam (16) is deflected by at least two stacked hologram layers (32, 34) of the hologram unit (20) into the respective different angles (22, 24). becomes.

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