Eye tracking device, duplication optics and data glasses

Abstract

An eye tracking device for tracking the position and / or gaze direction of an eye, with at least one LFI sensor, is described, comprising: an infrared laser source for shining an infrared laser signal onto the eye to be tracked, a detector for detecting an interference signal between the infrared laser signal generated by the infrared laser source and a portion of the infrared laser signal reflected from the eye to the LFI sensor, and an eye polarization compensation unit configured to at least partially compensate for a polarization difference, caused by an individual optical property of the eye, between the infrared laser signal initially emitted by the infrared laser source and the portion of the infrared laser signal reflected from the eye to the LFI sensor.wherein the eye polarization compensation unit comprises at least one static optical element with several differently polarization-changing optical functions for different beam ranges of the infrared laser signal and / or for different optical paths of the infrared laser signal, or several static optical elements, each with differently polarization-changing optical functions for different beam ranges of the infrared laser signal and / or for different optical paths of the infrared laser signal, is proposed.

Description

State of the art

[0001] Several eye-tracking systems for smart glasses have already been proposed. These are based, for example, on non-polarization-dependent video oculography, i.e., on the use of camera sensors and infrared LED illumination devices, which makes them large and heavy compared to laser feedback interferometry (LFI) systems. LFI eye-tracking systems that are more easily integrated into the space of smart glasses are also known; however, the polarization dependence of the LFI measurement signals can impair their function in individuals whose eyes exhibit a strong polarization change effect. Disclosure of the invention

[0002] An eye tracking device for tracking the position and / or gaze direction of an eye, for example in an AR headset, is described, comprising at least one laser feedback interferometry (LFI) sensor, comprising: an infrared laser source for illuminating an infrared laser signal onto the eye to be tracked, a detector for detecting an interference signal between the infrared laser signal generated by the infrared laser source and a portion of the infrared laser signal reflected from the eye to the LFI sensor, and an eye polarization compensation unit configured to, in particular, increase the signal strength of the interference signal to compensate for an individual optical property of the eye, in particular an individual birefringence property of the eye.The proposed method is to at least partially compensate for the polarization difference generated between the infrared laser signal initially emitted by the infrared laser source and the portion of the infrared laser signal reflected from the eye to the LFI sensor. The eye polarization compensation unit comprises at least one static optical element with multiple differently polarization-modifying optical functions for different beam regions of the infrared laser signal and / or for different optical paths of the infrared laser signal, or multiple static optical elements, each with different polarization-modifying optical functions for different beam regions of the infrared laser signal and / or for different optical paths of the infrared laser signal. This advantageously enables robust gaze direction tracking / pupil detection that is independent of eye-induced polarization changes and simultaneously compact.Lightweight and energy-efficient, this can be achieved. The use of static optical elements allows for simple, cost-effective, and / or energy-efficient (no control required) polarization compensation. Furthermore, high integration into smart glasses is advantageous, particularly due to the small size and energy requirements, as well as the possibility of reusing / modifying optical elements already present in smart glasses (e.g., segmented lenses for beamlet multiplication / eyebox enlargement). Improved interference signals can be achieved for a large number of different users / different eyes.

[0003] The eye-tracking device is, in particular, part of an augmented reality (AR) system, e.g., an AR headset, or part of a virtual reality (VR) system, e.g., a VR headset. For example, the eye-tracking device can be part of smart glasses. Alternatively, the eye-tracking device can also be used in other systems, such as head-up displays, ophthalmic examination devices, telescopes, microscopes, etc. AR headsets and / or VR headsets are, in particular, head-worn smart devices that project artificially generated image content into a user's field of vision. The LFI sensor can, for example, be designed as a VCSEL, preferably a ViP-VCSEL ("vertical-cavity surface-emitting laser with integrated photodiode"). The LFI sensor is, in particular, integrated into the AR headset and / or the VR headset, preferably the smart glasses, e.g.,The LFI sensor is integrated into the frame, lens, or temple of smart glasses. It can also be part of a laser projector unit that generates the artificial image content of the AR and / or VR headset, for example, integrated together with (RGB) laser diodes. Alternatively, the LFI sensor can be separate from the laser projector unit that generates the artificial image content of the AR and / or VR headset. Furthermore, it is conceivable that the AR and / or VR headset has more than one LFI sensor, e.g., two, three, or more than three. The LFI sensor is based on an interferometric measurement method. Specifically, the LFI sensor emits a laser beam in the infrared spectrum (the infrared laser signal), which then strikes a reflecting surface (e.g., the retina). From this surface, the light of the laser beam is scattered back, 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 either by a photodiode integrated into a back reflector of the laser cavity or by a direct measurement of a voltage of the laser source. The infrared laser source of the LFI sensor is, in particular, an infrared laser diode. The photodetector of the LFI sensor is, in particular, formed by the photodiode. The interference signal measured by the LFI sensor in this way depends on the polarization similarity of the emitted laser beam and the backscattered light. The lower the polarization similarity, the weaker the interference signal. The laser signal of the infrared laser source is, for example,A MEMS micromirror system is used to scan the eye, specifically an area of ​​the smart glasses where the eye is in normal operation. This advantageously allows a spatially resolved reflection signal to be obtained, from which a reflection signal image (of the eye / area) can be generated.

[0004] The terms "intended" and / or "configured" should be understood to mean, in particular, 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.

[0005] The optical property of the eye that generates the polarization difference can be, for example, a birefringence property of the cornea or a part of the retina, or a depolarization property of retinal pigment epithelia. In particular, the optical properties, such as the birefringence, are individually unique to each eye. The phrase "the polarization difference is at least partially compensated" means, in particular, that after passing through the eye polarization compensation unit, the polarization difference between the portion of the infrared laser signal reflected from the eye to the LFI sensor and the infrared laser signal initially emitted by the infrared laser source is significantly smaller, preferably at least 30% smaller, more preferably at least 60% smaller, and most preferably at least 90% smaller.In particular, it is conceivable that, on the path from the LFI sensor to the eye, a portion of the expected polarization difference is precompensated before the polarization-changing effect of the eye even occurs, and that, on the path from the eye to the LFI sensor, a further portion of the polarization difference is postcompensated after it actually occurs. Specifically, the eye polarization compensation unit is configured to influence the polarization of the infrared laser signal twice: between its emission by the LFI sensor and its detection by the LFI sensor. Specifically, the eye polarization compensation unit is configured to precompensate and postcompensate portions of the polarization difference generated by the optical properties of the eye, particularly its birefringence.In particular, the eye polarization compensation unit is designed at least to prevent a mode of the part of the infrared laser signal reflected from the eye to the LFI sensor from being orthogonal to a mode of the infrared laser signal initially emitted by the infrared laser source.

[0006] The eye's gaze direction is preferably determined from the location-dependent strength of the interference signal. If the emitted IR laser beam falls on the retina, this leads to increased backscattering compared to when the IR laser beam falls on the sclera, the iris, or other parts of the eye other than the retina, because the retina's reflectivity in the infrared range is higher than that of other parts of the eye. This effect is also called the red-eye effect or bright pupil effect. This can lead, in particular, to amplitude modulation of the optical power of the LFI sensor's infrared laser source in the area where the IR laser beam is focused through the pupil onto the retina. Furthermore, the amplitude of the light backscattered by the retina is modulated by laser speckling. This effect is caused by the retina's natural optical roughness.The natural roughness of the retina behaves similarly in all people. Part of an incoming wavefront is reflected directly from a surface of the retina, whereby the wavefront of the reflected wave is distorted by signal propagation times through the rough surface of the retina. Another part of the incoming wavefront enters the upper tissue layers of the retina and is reflected from there, which also leads to a distortion of the reflected wavefront. These two effects result in constructive or destructive interference in the LFI sensor, so that so-called bright speckle (constructive interference) and dark speckle (destructive interference) form normally distributed in the reflection area of ​​the retina and thus the pupil in the scanned reflection signal image.This effect can then be used to determine the position of the pupil and thus the current direction of gaze from the currently scanned reflection signal image using an algorithm.

[0007] To isolate the pupil's contribution to the overall signal of the reflection signal image, a sub-region of the histogram is preferably selected from the reflection signal image. Due to the higher IR reflectivity of the retina and the laser speckling effect, the measured amplitude of the optical power of the LFI sensor in the scan area of ​​the pupil in the reflection signal image differs in amplitude (pixel value height) from the rest of the reflection signal image. Thus, the corresponding signal contribution can be separated from the rest of the signal via histogram transformation and thresholding. From the extracted image of the pupil, a three-dimensional pupil position in the spectacle coordinate system and a gaze vector as an angular pair can be determined. In particular, the described setup results in a virtual camera sensor, which scans the eye and allows the pupil to be detected, thereby enabling eye tracking.

[0008] A static optical element is, in particular, an optical element that is fixed, preferably non-rotatable, non-tiltable, and / or non-translatable, positioned relative to the LFI sensor. A static optical element is, in particular, an optical element whose optical function cannot be changed, preferably immutably, by user intervention. Specifically, the static optical element differs from a rotatably mounted optical element, a translatably mounted optical element, a tiltable optical element, an LCD element, and / or a Babinet compensator. The differently polarization-changing optical functions of the static optical element produce, in particular, differently sized polarization changes upon interaction with infrared light.The different beam ranges are, in particular, different scan angle ranges of a projector system scanning the infrared laser signal, especially a MEMS micromirror system. Each set scan angle of the scanning projector system, especially a MEMS micromirror system, preferably generates an optical path of the infrared laser signal that differs from other scan angles. In particular, when the system is configured with a static optical element, the several differently polarization-changing optical functions are combined in a single optical element, for example, at least partially superimposed or at least partially arranged side by side. In particular, when the system is configured with several static optical elements, each of the optical elements has only a single polarization-changing optical function.A combination of the two options is also conceivable, i.e., a plurality of static optical elements, each with more than one integrated optical function. In particular, the static optical element(s) is / are arranged in the data glasses / eye-tracking device such that the infrared laser signal passes through it / them once on its way to the eye and once on its way back from the eye.

[0009] Furthermore, it is proposed that the different polarization-changing optical functions of the static optical element(s) generate different polarization changes for the different beam ranges of the infrared laser signal and / or for the different optical paths of the infrared laser signal. This results in interference signals of varying intensity, depending on the individual optical properties of the eye currently being tracked, preferably approximately simultaneously. This allows for an advantageous improvement in interference signals for a large number of different users / eyes. Advantageously, a universally optimized eye-tracking device based on LFI sensors can be created for all users / eyes.The polarization change can include, in particular, a change in the polarization angle of the infrared laser signal and / or a change in the ellipticity of the infrared laser signal.

[0010] Furthermore, it is proposed that the eye-tracking device include a control unit configured to select a single interference signal, or a subselection of such signals, from the different beam areas and / or optical paths with their respective polarization-modifying optical functions, and to use this selection to determine the eye's position and / or gaze direction. This advantageously optimizes gaze direction tracking. It also advantageously ensures that an optimal signal is used for gaze direction tracking for each individual user. Furthermore, it advantageously achieves high efficiency, particularly computational efficiency.A "control and / or regulation unit" is understood to mean, in particular, a unit with at least one control electronics component. "Control electronics" is understood to mean, in particular, a unit with a processor, a storage medium, and an operating program stored on the storage medium. The control and / or regulation unit may also be provided for additional functions of the smart glasses, e.g., for generating the artificial image content to be displayed to the user. The control and / or regulation unit is preferably integrated into the smart glasses, e.g., into the frame of the smart glasses. Alternatively, the control and / or regulation unit could also be located, at least partially, externally, e.g., in a smartphone, a wearable device such as a smartwatch, or in the cloud. Preferably, unselected interference signals for gaze direction determination are disregarded.

[0011] Furthermore, it is proposed that sections of the static optical element exhibiting the different optical functions, or the multiple static optical elements themselves, are designed as retardation plates with varying degrees of retardation or comparable components that alter polarization to varying degrees, such as meta-optics, polarization holograms, etc. This advantageously provides a simple and / or robust construction. The retardation plates could, for example, be λ / 2 or λ / 4 plates.

[0012] If the static optical element(s) is / are mounted on an optical element of a virtual retinal display, particularly one that is already present, a compact and / or cost-effective design can be advantageously achieved. Furthermore, an already known and / or proven design of a virtual retinal display can be advantageously reused. The virtual retinal display (also called a retinal scan display or light field display) is constructed in a configuration familiar to those skilled in the art. The virtual retinal display is specifically designed to sequentially scan an image by deflecting at least one light beam, particularly a laser beam, from at least one time-modulated light source, such as one or more laser diodes of a laser projector, and to project the image directly onto the retina of the user's eye by means of optical elements.The virtual retinal display preferably comprises an image source for generating the artificial image content. The image source is, in particular, an electronic image source, for example, a graphics output, especially an (integrated) graphics card, of a computer or processor, or the like, especially the control unit. The artificial image content is, in particular, configured as RGB image data. Specifically, the artificial image content can be static or moving images, e.g., videos. The virtual retinal display specifically includes a laser projector unit for generating and outputting the artificial image content. The laser projector unit is preferably designed to output the artificial image content via a visible (RGB) laser beam. In particular, the laser projector unit has RGB laser diodes that generate the visible laser beam.In particular, the laser projector unit also features the LFI sensor. Alternatively, it is also conceivable that the static optical element or elements are integrated into an optical element of the virtual retinal display, especially one that is already present. The optical element of the virtual retinal display is specifically designed as a segmented lens, particularly a multiplication optic, which is preferably intended for multiplying beamlets / exit pupils of the virtual retinal display.

[0013] Furthermore, it is proposed that individual static optical elements of the multiple static optical elements are each assigned to different duplication segments of a duplication optic, in particular a segmented lens of a virtual retinal display. This advantageously allows for a compact and / or cost-effective design. Moreover, an already known and / or proven design of a virtual retinal display can be advantageously reused. In particular, the duplication optic is designed to duplicate the artificial image generated by the virtual retinal display and output it for a plurality of different pupil positions at various locations within an eyebox plane of the virtual retinal display.

[0014] If the respective different duplication segments of the duplication optics are arranged upstream in a beam path of the infrared signal of the duplication optics, in particular leading from the LFI sensor and in particular to the eye / eyebox plane of the virtual retinal display, a simple construction can advantageously be achieved.

[0015] Alternatively, if the static optical elements assigned to the different duplication segments of the duplication optics are arranged downstream in a beam path of the infrared signal of the duplication optics, particularly one originating from the LFI sensor and leading to the eye / eyebox plane of the virtual retinal display, it is advantageous to enable separate generation of the static optical elements with the different optical functions. This can advantageously simplify manufacturing.

[0016] Furthermore, the multiplication optics, in particular the segmented lens, are proposed for use in the eye-tracking device, with one or more static optical elements, exhibiting polarization-modifying optical functions, applied to a source surface or an output surface of the multiplication optics. This advantageously enables a simple design, which in particular does not require any significant modifications to proven and known designs of virtual retinal displays. This allows for high cost-efficiency.

[0017] Furthermore, the smart glasses, especially the AR headset, are proposed to be used with an eye-tracking device. This can advantageously improve interference signals for a large number of different users / different eyes. This, in turn, can optimize the eye-tracking function of the smart glasses.

[0018] The eye-tracking device, the duplicating optics, and the data glasses according to the invention are not to be limited to the application and embodiment described above. In particular, the eye-tracking device, the duplicating optics, and the data glasses according to the invention may, to achieve a functionality described herein, comprise a different number of individual elements, components, and units than the number specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure are also to be considered disclosed and freely usable. drawing

[0019] Further advantages become apparent from the following description of the drawings. The drawings illustrate two exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0020] They show: Fig. 1 A schematic representation of part of a data glasses with a virtual retinal display and with an eye tracking device, Fig. 2 a schematic perspective representation of a duplication optic of the virtual retinal display with a static optical element of the eye tracking device, Fig. 3 a schematic perspective representation of a duplication optic of a virtual retinal display with several static optical elements of an alternative eye tracking device and Fig. 4 A schematic representation of part of a data glasses with the virtual retinal display and with the alternative eye tracking device. Description of the exemplary implementations

[0021] The Fig. Figure 1 schematically shows a part of a pair of smart glasses 50a. The smart glasses 50a form an AR headset 14a. The smart glasses 50a include a virtual retinal display 40a. The virtual retinal display 40a includes a laser projector 52a. The laser projector 52a includes a color laser module (not shown) for outputting an artificial image visible to a user of the smart glasses 50a. The laser projector 52a includes a laser feedback interferometry (LFI) sensor 16a. The LFI sensor 16a is designed to generate an infrared laser signal 20a. The laser projector 52a includes a scanning device 54a for scanning the emitted laser beams. The scanning device 54a is designed as a MEMS micromirror system. Alternative known configurations of scanning devices 54a for laser projectors 52a are also conceivable. The data glasses 50a include a control and / or regulation unit 36a.The control unit 36a is designed to generate the image data for the output artificial images. The data glasses 50a comprise a frame 56a. The laser projector 52a is at least partially integrated into the frame 56a, in particular into a temple of the frame 56a. The control unit 36a is at least partially integrated into the frame 56a, in particular into a temple of the frame 56a. The data glasses 50a comprise a lens 58a.

[0022] The virtual retinal display 40a includes a deflecting element 60a, which is designed to deflect laser beams emitted by the laser projector 52a towards the eye 12a of a user wearing the data glasses 50a. The deflecting element 60a is integrated into the spectacle lens 58a. The deflecting element 60a is formed by a hologram, in particular a holographic optical element (HOE). The virtual retinal display 40a includes an eyebox plane 62a. The deflecting element 60a is designed to focus the visible scanned laser beams containing the artificial image onto the eyebox plane 62a. The deflecting element 60a is designed to collimate the infrared laser signals 20a of the LFI sensor 16a when deflected towards the eye 12a and to project them, in collimated form, onto the eyebox plane 62a.

[0023] The virtual retinal display 40a includes a multiplication optic 46a. The multiplication optic 46a is designed as a segmented lens. The laser beams from the laser projector 52a pass through the multiplication optic 46a before striking the deflecting element 60a. The multiplication optic 46a generates several partial beam bundles, each containing the same information. Each of the partial beam bundles follows a different optical path 30a, 32a on its way from the laser projector 52a to the eye 12a. The partial beam bundles strike the deflecting element 60a at different points, which then directs them to different areas of the eyebox plane 62a. By splitting and deflecting the infrared laser signal 20a, virtual camera nodes 64a, 66a are created on one side of the data glasses 50a / the spectacle lens 58a.

[0024] The data glasses 50a include an eye tracking device 48a. The eye tracking device 48a is designed to track the position and / or gaze direction 10a of the eye 12a. The eye tracking device 48a includes the LFI sensor 16a. The LFI sensor 16a includes an infrared laser source 18a. The infrared laser source 18a is designed to emit the infrared laser signal 20a. The infrared laser source 18a is designed to direct the infrared laser signal 20a onto the eye 12a to be tracked. The eye tracking device 48a includes a detector 22a. The detector 22a is integrated into the LFI sensor 16a. The detector 22a is designed to detect an interference signal between the infrared laser signal 20a generated by the infrared laser source 18a and a part of the infrared laser signal 24a reflected from the eye 12a to the LFI sensor 16a.

[0025] The eye tracking device 48a comprises an eye polarization compensation unit 26a. The eye polarization compensation unit 26a is integrated into the virtual retinal display 40a. The eye polarization compensation unit 26a forms part of the virtual retinal display 40a. The eye polarization compensation unit 26a is configured to at least partially compensate for a polarization difference between the infrared laser signal 20a initially emitted by the infrared laser source 18a and the portion of the infrared laser signal 24a reflected by the eye 12a to the LFI sensor 16a, thereby increasing the signal strength of the interference signal. This compensation difference is caused by an individual optical property of the eye 12a, in particular an individual birefringence property of the eye 12a.

[0026] The eye polarization compensation unit 26a comprises a static optical element 28a (see also Fig. 2) The static optical element 28a is mounted on an existing optical element 38a of a virtual retinal display 40a. The existing optical element 38a is the multiplication optics 46a, specifically the segmented lens. The multiplication optics 46a comprises several multiplication segments 42a, 44a. The static optical element 28a, each assigned to a different multiplication segment 42a, 44a of the multiplication optics 46a, is positioned upstream of the infrared laser signal 20a in a beam path of the multiplication optics 46a. The static optical element 28a has several differently polarization-modifying optical functions for different beam ranges of the infrared laser signal 20a and / or for the different optical paths 30a, 32a of the infrared laser signal 20a.The different polarization-changing optical functions of the static optical element 28a for the different beam ranges of the infrared laser signal 20a and / or for the different optical paths 30a, 32a of the infrared laser signal 20a generate different polarization changes and thus, depending on the individual optical properties of the eye 12a currently being tracked, preferably approximately simultaneously, interference signals of varying strength associated with the different beam ranges of the infrared laser signal 20a or the different optical paths 30a, 32a of the infrared laser signal 20a.The control and / or regulation unit 36a is designed to select a single interference signal or a subselection of interference signals originating from the different beam areas and / or the different optical paths 30a, 32a with the different polarization-changing optical functions and to use it to determine the position and / or viewing direction 10a of the eye 12a.

[0027] The Fig. Figure 2 shows a schematic perspective view of the duplicating optics 46a with the duplicating segments 42a, 44a and the static optical element 28a. The duplicating optics 46a are intended for use in the eye-tracking device 48a. The static optical element 28a is mounted on a single-beam surface of the duplicating optics 46a. The static optical element 28a comprises several separate areas 68a, 70a (shown as dashed lines). Each of the areas 68a, 70a has a different polarization-modifying optical function. Individual optical functions of the static optical element 28a, which has the different optical functions, are each assigned to different duplicating segments 42a, 44a of the duplicating optics 46a.

[0028] In the Fig. 3 and Fig. Figure 4 shows a further embodiment of the invention. The following descriptions and drawings are essentially limited to the differences between the embodiments, whereby, with regard to identically designated components, in particular components with the same reference numerals, reference is also generally made to the drawings and / or the description of the other embodiments, in particular the Fig. 1 and Fig. 2, reference can be made. To distinguish the embodiments, the letter a is the reference numeral of the embodiment in the Fig. 1 and Fig. 2. In the exemplary embodiment of the Fig. 3 and Fig. In 4, the letter a is replaced by the letter b.

[0029] The Fig. Figure 3 shows a schematic perspective view of a duplicating optic 46b with duplicating segments 42b, 44b. The duplicating optic 46b is designed as a segmented lens. The duplicating optic 46b is intended for use in an alternative eye tracking device 48b. The alternative eye tracking device 48b comprises an alternative eye polarization compensation unit 26b. The alternative eye tracking device 48b, in particular the alternative eye polarization compensation unit 26b, comprises several static optical elements 28b, 34b. The several static optical elements 28b, 34b each have different polarization-changing optical functions for different beam ranges of an infrared laser signal 20b and / or for different optical paths 30b, 32b of the infrared laser signal 20b (see Figure 3). Fig. 4) The multiple static optical elements 28b, 34b are applied to a projection surface of the duplicating optics 46b. The duplicating optics 46b is a functional component of a virtual retinal display 40b. The multiple static optical elements 28b, 34b are thus applied to an already existing optical element 38b of the virtual retinal display 40b (cf. Fig. 4) applied. The individual static optical elements 28b, 34b of the multiple static optical elements 28b, 34b are each assigned to different duplication segments 42b, 44b of the duplication optics 46b. Each of the static optical elements 28b, 34b comprises a single area 68b, 70b (shown as a dashed line). Each of the areas 68b, 70b has a different polarization-changing optical function. The multiple static optical elements 28b, 34b are configured as retardation plates with different retardation strengths. Alternatively, the multiple static optical elements 28b, 34b can also be configured as comparable components with different polarization-changing effects, such as meta-optics, polarization holograms, etc.

[0030] The Fig.Figure 4 shows a schematic representation of part of a data glasses 50b with the alternative eye tracking device 48b. The several static optical elements 28b, 34b, each assigned to a different duplication segment 42b, 44b of the duplication optics 46b, are arranged downstream in a beam path of an infrared laser signal 20b, a laser source 18b, an LFI sensor 16b, the alternative eye tracking device 48b, and the duplication optics 46b.

Claims

[1] Eye tracking device (48a-b) for tracking the position and / or gaze direction (10a-b) of an eye (12a-b), for example in an AR headset (14a-b), comprising at least one laser feedback interferometry (LFI) sensor (16a-b), comprising: an infrared laser source (18a-b) to shine an infrared laser signal (20a-b) onto the eye to be tracked (12a-b), a detector (22a-b) for detecting an interference signal between the infrared laser signal (20a-b) generated by the infrared laser source (18a-b) and a part of the infrared laser signal (24a-b) reflected from the eye (12a-b) to the LFI sensor (16a-b), and An eye polarization compensation unit (26a-b) configured to at least partially compensate for a polarization difference generated by an individual optical property of the eye (12a-b), in particular an individual birefringence property of the eye (12a-b), between the infrared laser signal (20ab) initially emitted by the infrared laser source (18a-b) and the part of the infrared laser signal (24a-b) reflected by the eye (12a-b) to the LFI sensor (16a-b), in particular to increase the signal strength of the interference signal, wherein the eye polarization compensation unit (26a-b) comprises at least one static optical element (28a) with several differently polarization-changing optical functions for different beam ranges of the infrared laser signal (20a-b) and / or for different optical paths (30a-b, 32a-b) of the infrared laser signal (20a-b) or several static optical elements (28b, 34b) with each having different polarization-changing optical functions for different beam ranges of the infrared laser signal (20a-b) and / or for different optical paths (30a-b, 32a-b) of the infrared laser signal (20a-b). [2] Eye tracking device (48a-b) according to claim 1, characterized by, that the different polarization-changing optical functions of the static optical element(s) (28a-b, 34b) produce different polarization changes for the different beam ranges of the infrared laser signal (20a-b) and / or for the different optical paths (30a-b, 32a-b) of the infrared laser signal (20a-b) and thus, depending on the individual optical properties of the eye (12a-b) currently being tracked, preferably approximately simultaneously, interference signals of different strengths associated with the different beam ranges of the infrared laser signal (20a-b) or the different optical paths (30a-b, 32a-b) of the infrared laser signal (20a-b). [3] Eye tracking device (48a-b) according to claim 2, characterized bya control and / or regulating unit (36a-b) which is configured to select a single interference signal or a subselection of interference signals originating from the different beam areas and / or the different optical paths (30a-b, 32a-b) with the different polarization-changing optical functions and to use it to determine the position and / or viewing direction (10a-b) of the eye (12ab). [4] Eye tracking device (48a-b) according to any one of the preceding claims, characterized by, that sub-areas of the static optical element (28a) which have the different optical functions, or the several static optical elements (28b, 34b) are designed as retardation plates with different degrees of retardation, or comparable components with different degrees of polarization-changing effect such as meta-optics, polarization holograms, etc. [5] Eye tracking device (48a-b) according to any one of the preceding claims, characterized by , that the static optical element (28a) or the several static optical elements (28b, 34b) is / are applied to an optical element (38a-b) of a virtual retinal display (40a-b), in particular one that is already present. [6] Eye tracking device (48a-b) according to any one of the preceding claims, characterized by, that individual static optical elements (28b, 34b) of the several static optical elements (28b, 34b) or individual optical functions of the static optical element (28a) having the different optical functions are each assigned to different duplication segments (42a-b, 44a-b) of a duplication optic (46a-b), in particular a segment lens of a virtual retinal display (40a-b). [7] Eye tracking device (48a) according to claim 6, characterized by , that the respective different duplication segments (42a, 44a) of the duplication optics (46a) are arranged in front of the duplication optics (46a) in a beam path of the infrared laser signal (20a). [8] Eye tracking device (48b) according to claim 6, characterized by, that the respective different duplication segments (42b, 44b) of the duplication optics (46b) are arranged downstream in a beam path of the infrared laser signal (20b) of the duplication optics (46b). [9] Duplicating optics (46a-b), in particular segmented lens, for use in an eye tracking device (48a-b) according to one of the preceding claims, comprising one or more static optical elements (28a-b, 34b) applied to an input surface of the duplicating optics (46a-b) or to an output surface of the duplicating optics (46a-b) and having polarization-changing optical functions. [10] Data glasses (50a-b), in particular AR headset (14a-b), with an eye tracking device (48a-b) according to any one of claims 1 to 8.

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