Method for assigning measurement signals, method for determining the direction of gaze in smartglasses, LFI multipoint sensor system, and smartglasses

Abstract

The invention relates to a method for assigning measurement signals to local measurement regions and / or measurement points within a measurement region pattern and / or measurement point pattern generated by irradiating an object by means of an LFI multipoint sensor system. At least the following method steps are proposed: radiating at least two LFI measurement beams into each of a plurality of local measurement regions and / or measurement points of the measurement region pattern and / or measurement point pattern by means of the LFI multipoint sensor system, wherein the at least two LFI measurement beams of at least these local measurement regions and / or measurement points each have a known definable and / or fixed mutual intensity ratio which is different at least from intensity ratios of adjacent LFI measurement beam pairs in the measurement region pattern and / or measurement point pattern, capturing measurement signals from the local measurement regions and / or measurement points of the measurement region pattern and / or measurement point pattern by means of the LFI multipoint sensor system, ascertaining intensity ratios from intensities of the captured measurement signals, and assigning captured measurement signal pairs to local measurement regions and / or measurement points of the measurement region pattern and / or measurement point pattern on the basis of a similarity or identity of a captured intensity ratio with respect to one of the known definable and / or fixed intensity ratios of two LFI measurement beams radiated in.

Description

[0001] R.416902

[0002] - 1 -

[0003] Description

[0004] Methods for assigning measurement signals, methods for determining gaze direction in smart glasses, LFI multipoint sensor technology and smart glasses

[0005] State of the art

[0006] Laser feedback interferometry (LFI) multipoint sensors are already known. These are formed by 2D arrays of individual LFI sensors. Since all measurement signals then originate from different individual LFI sensors, the method for assigning the measurement signals is straightforward in this case. However, such 2D arrays of individual LFI sensors are space-consuming, heavy, power-consuming, complex, and expensive. One way to reduce the number of individual LFI sensors is to integrate multiple laser cavities onto a VIP (VCSEL with integrated photodiode) or to generate multiple virtual laser cavities using upstream optics. The challenge with such a design is then to unambiguously assign the signal measured by the VIP, which contains all the beat frequencies of the individual measurement points, back to the individual measurement points.

[0007] Disclosure of the invention

[0008] The invention relates to a method for assigning measurement signals, preferably back-reflection and / or backscatter signals, to local measurement areas and / or measurement points within a system created by radiating light onto an object, for example an eye, in particular the eye of a user of a system. R.416902

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[0010] Data glasses with LFI multipoint sensor technology, generating measurement range patterns and / or measurement point patterns using laser feedback interferometry (LFI) multipoint sensor technology.

[0011] It is proposed that the method comprises at least the following steps: a) radiating at least two LFI measurement beams into several, in particular all, local measurement areas and / or measurement points of the measurement area pattern and / or measurement point pattern using LFI multipoint sensors, wherein the at least two LFI measurement beams of at least these local measurement areas and / or measurement points each have a known, definable and / or fixed mutual intensity ratio, which is different from at least the intensity ratios of neighboring LFI measurement beam pairs in the measurement area pattern and / or measurement point pattern; b) acquiring measurement signals from the local measurement areas and / or measurement points of the measurement area pattern and / or measurement point pattern using LFI multipoint sensors.c) Determining intensity ratios from the intensities of the acquired measurement signals and d) assigning acquired measurement signal pairs to local measurement areas and / or measurement points of the measurement area pattern and / or measurement point pattern based on a similarity or identity of an acquired intensity ratio with one of the known definable and / or fixed intensity ratios of two incident LFI measurement beams. This advantageously allows the use of a laser feedback interferometry (LFI) multipoint sensor system of the type described above with a reduced number of individual LFI sensors, which in particular improves upon the aforementioned problems regarding space, cost, complexity, weight, and energy consumption, preferably without the difficulties associated with assigning measurement signals to measurement points. Advantageously, this enables, for example, smaller, lighter, and more energy-efficient systems.More affordable and / or structurally simpler LFI multipoint sensors can be obtained, which are suitable, for example, for eye tracking / gaze direction determination in smart glasses. The proposed method is advantageously independent of the reflectivity value in the respective measurement areas / points (provided that the reflectivities of the two LFI measurement beams of the local measurement areas and / or points are similar or identical). R.416902

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[0013] The measurement range pattern and / or the measurement point pattern is generated, in particular, by a plurality of LFI measurement beams produced / emitted by the LFI multipoint sensor system. The measurement range pattern preferably comprises a plurality of measurement ranges. The measurement ranges of the measurement range pattern are preferably arranged spatially (in a plane) adjacent to one another. A measurement range is, in particular, a spatial region in which two LFI measurement beams have similar reflectivities and / or in which the measurement signals for distance and velocity of the two LFI measurement beams are similar to each other. The measurement point pattern preferably comprises a plurality of measurement points. The measurement points of the measurement point pattern are preferably arranged spatially (in a plane) adjacent to one another. The measurement points and / or measurement ranges can be arranged uniformly (e.g., in a matrix pattern) or non-uniformly distributed spatially (in the plane).Several of the measurement points and / or measurement areas are preferably generated / irradiated by LFI measurement beams from the same VIP (VCSEL with integrated photodiode) of the LFI multipoint sensor system. In particular, the method assigns each of the measurement signals of the LFI multipoint sensor system to one of the LFI measurement beams of the LFI multipoint sensor system and thus, in particular, to one real or virtual laser cavity of a VIP.

[0014] The LFI multipoint sensor system comprises, in particular, several LFI sensors / VIPs. For example, it is conceivable that the LFI multipoint sensor system forms an LFI sensor array with two, three, or more than three LFI sensors. In particular, each LFI sensor / VIP of the LFI multipoint sensor system generates a plurality of measurement points, in particular two, three, or more than three measurement points, and / or a plurality of measurement areas, in particular two, three, or more than three measurement areas, each of which is irradiated with at least two LFI measurement beams. The LFI measurement beams are preferably laser beams, in particular infrared laser beams. The LFI measurement beams preferably each have defined intensities. The intensities of the LFI measurement beams can be determined, for example, by optical elements, e.g.Diffractive optical elements (DOE), holographic optical elements (HOE), meta-optical elements (MOE), or other optical elements capable of providing suitable optical functions are defined in the beam path of the LFI measurement beams or by the respective laser cavities themselves. Preferably, adjacent LFI-R.416902.

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[0016] Measuring beams of the same wavelength in LFI multipoint sensors always have different intensities.

[0017] The LFI sensor(s) of the LFI multipoint sensor system can, for example, be configured as a VIP (vertical-cavity surface-emitting laser with integrated photodiode). The LFI sensor(s) of the LFI multipoint sensor system can be integrated into smart glasses, e.g., into a frame, lens, or temple. The LFI sensor(s) of the LFI multipoint sensor system can also be part of a laser projector unit that generates the artificial image content of the smart glasses, i.e., integrated together with (RGB) laser diodes. Preferably, however, the LFI sensor(s) of the LFI multipoint sensor system is / are configured separately from a laser projector unit that generates the artificial image content of the smart glasses. Preferably, the LFI sensor(s) of the LFI multipoint sensor system are static and illuminate the eye independently of a scanner.The LFI sensor is based on an interferometric measurement method, also known as laser self-mixing. 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 from the laser beam is backscattered, re-entering a laser cavity within the LFI sensor. Inside the laser cavity, the backscattered light interferes with a locally oscillating field. This modulation of the laser source's power can be detected either by a photodiode integrated into a back reflector of the laser cavity or by directly measuring the voltage of the laser source. The infrared laser source of the LFI sensor is typically an infrared laser diode.

[0018] In particular, the distance, velocity, and / or signal intensity of the object can be determined from the measurement signals, especially the back-reflection and / or backscatter signals. Specifically, the distance and / or velocity of the object is determined using a combination of laser feedback interferometry and frequency-modulated continuous wave (FMCW) known to those skilled in the art. In this process, a laser cavity of the VIP emits a signal with an optical output power of R.416902.

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[0020] A coherent laser beam is emitted towards the object. This laser beam then strikes the object, particularly at an angle of incidence, is attenuated by volume scattering effects and absorption, which can be described by reflectivity, and subsequently coupled back into the laser cavity. The laser beam requires time to travel the distance to the object and back to the laser cavity. The returning light interferes with the oscillating electric field in the laser cavity, resulting in a modulation of the optical power. By controlling the emission wavelength, the change in distance between the laser cavity and the object can be determined by reading the photodiode. This change in distance also leads to a measurable shift in wavelength (Doppler effect), which allows the conclusion that the object's velocity component is parallel to a line connecting the object and the laser cavity.

[0021] Furthermore, it is proposed that each intensity ratio of any combination of two LFI measurement beams in the LFI multipoint sensor system is unique. This advantageously simplifies the unambiguous assignment of measurement signals to their corresponding LFI measurement beams. A particularly high insensitivity of the method to large changes in the object's distance, especially with non-parallel LFI measurement beams, can be achieved.

[0022] If individual intensities of the LFI measurement beams of the LFI multipoint sensor system can be determined, or are determined, by means of one or more optical elements of an optical unit of the LFI multipoint sensor system arranged in the respective beam paths of the LFI measurement beams, a well-defined LFI multipoint sensor system can advantageously be created, which allows for reliable assignment of the measurement signals. An optical element, e.g., a diffractive optical element, can be assigned to exactly one beam path of an LFI measurement beam or to several beam paths of multiple LFI measurement beams. In particular, the assignment of optical elements to LFI measurement beams is known and constant, so that these can be taken into account when evaluating the acquired measurement signals, e.g., by a specially designed processing unit.The terms "intended" and / or "equipped" should be understood to mean specifically programmed, designed and / or fitted out. R.416902.

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[0024] The fact that an object is intended and / or set up for a specific function shall be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0025] Furthermore, it is proposed that the beam directions of the individual LFI measurement beams onto the object, generated by interactions with the optical unit, are such that they do not intersect within the overall axial extent of a intended measurement range of a device equipped with LFI multipoint sensors, such as smart glasses. This advantageously simplifies the assignment. Ambiguities can be avoided. Fewer different intensities are required for the LFI measurement beams, which in turn allows for a simpler design of the optical unit. Advantageously, only the intensity ratios of directly adjacent LFI measurement beams need to be clearly distinguishable. Alternatively, however, LFI multipoint sensors with intersecting LFI measurement beams within the measurement range are also conceivable.

[0026] Furthermore, it is proposed that the entirety of possible known definable and / or fixed intensity ratios of the LFI measurement beams be based on a set of prime numbers. This advantageously prevents duplicate assignments of intensity ratios in a simple manner. The set of prime numbers preferably comprises a large number of prime numbers, e.g.

[0027] 2, 3, 5, 7, 11, 13, 17, 19 and 23 or fewer of these prime numbers, or these prime numbers and other prime numbers.

[0028] In this context, it is proposed that the set of prime numbers has a length of (2*n)-1, where the parameter n specifies the number of LFI measuring beams of the LFI multipoint sensor. This advantageously allows a minimum number of required optical functions of the optical unit to be determined and / or ensures that no accidental ambiguities occur. The set of prime numbers preferably contains all prime numbers from 2 to the (2*n)-1th prime number in ascending order. Alternatively, prime numbers could be skipped as long as the total number of prime numbers still has a length of (2*n)-1. R.416902

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[0030] If each of the individual intensity ratios of the entire set of possible known definable and / or fixed intensity ratios is formed as follows: a) dividing the set of prime numbers into two subsets of prime numbers, each with a length of (n+1) / 2, into which the prime numbers of the set are divided alternately, starting with the smallest prime number in the set, with the exception of the middle prime number, which is assigned to both subsets; b) normalizing the two subsets so that the sum of each subset equals 1; and c) dividing one of the entries of one subset by one of the entries of another subset, it can advantageously be ensured that no duplicate intensity ratios occur. If, for example, the LF I-Mu Itipoint sensor has five LFI measuring beams, the set of prime numbers must have a length of 9.It could therefore consist of the prime numbers 2, 3, 5, 7, 11, 13, 17, 19, and 23 mentioned above as examples. From this set of prime numbers, the two subsets containing the prime numbers 2, 5, 11, 17, and 23, and 3, 7, 11, 13, and 19, would then be formed according to the characteristics mentioned above. A normalization of these subsets according to the above description would lead to the following normalized subsets: (0.034482759, 0.086206897, 0.189655172, 0.293103448, 0.396551724), (0.056603774, 0.132075472, 0.20754717, 0.245283019, 0.358490566). The entries in these subsets yield the following possible intensity ratios, each occurring only once and clearly distinguishable from one another: 0.096189, 0.14058, 0.166144, 0.240472, 0.261084, 0.351459, 0.41536, 0.529038, 0.609195, 0.652709, 0.77321, 0.8176, 0.913793, 1.106171, 1.19496, 2.219212, 3.00246, 3.350575, 5.178161 and 7.005747.

[0031] If the individual intensities of the LFI measuring beams of the LFI multipoint sensor are then set by the optical unit according to exactly one of the values ​​of the standardized subsets, it can advantageously be achieved that all possible combinations of LFI measuring beams within a measuring range can be clearly separated and assigned. This advantageously allows for a significant independence of the functionality of the LFI multipoint sensor from object distances and / or the parallelism of the LFI measuring beams. R.416902

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[0033] Furthermore, it is proposed that the at least two LFI measurement beams directed into the local measurement areas and / or measurement points of the measurement area pattern and / or measurement point pattern are or will be coordinated such that they are reflected by the object with a similar or identical reflectivity. This advantageously allows for a high degree of reliability in the assignment. In particular, the intensity ratios of the intensities of the acquired measurement signals are independent of the reflectivity value of the object, as long as the corresponding LFI measurement beams are reflected with the same reflectivity.

[0034] If the at least two LFI measurement beams directed into the local measurement areas and / or measurement points of the measurement area pattern and / or measurement point pattern are directed at the object at different angles of incidence to adjust the reflectivity, and if these LFI measurement beams also have different polarizations that are adjusted and / or set so that these LFI measurement beams are nevertheless reflected from the object with similar or identical reflectivities, then a great deal of flexibility in the positioning of VIPs of the LFI multipoint sensor system can be advantageously achieved. In particular, the VIPs do not necessarily have to be positioned very close to each other, which can also offer advantages with regard to design and / or manufacturing effort / costs.

[0035] Alternatively, if the at least two LFI measuring beams directed into the local measuring areas and / or measuring points of the measuring area pattern and / or measuring point pattern are directed onto the object with a similar or identical angle of incidence and with a similar or identical polarization to match the reflectivity, it is advantageous to dispense with polarization adjustment of the LFI measuring beams relative to each other, or at least to simplify it considerably. Advantageously, the optical unit can be designed to be particularly simple. "Similar" values, e.g., for the angle of incidence or for the polarization angle, are understood to mean values ​​that differ from each other by less than 10%, preferably by less than 5%, and preferably by less than 2.5%. R.416902

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[0037] To advantageously achieve similar or identical angles of incidence and polarizations, it is proposed that the at least two LFI measurement beams directed into the local measurement areas and / or measurement points of the measurement area pattern and / or measurement point pattern be emitted by two closely positioned ViPs (VCSELs with integrated photodiodes) or two (closely positioned) mesas of a single VIP and be provided with different, definable and / or fixed intensities by a tilted optical grating or a blaze grating. In particular, the use of the tilted optical grating allows the grating constant experienced by the respective VIP or mesa to be differentiated.Since mass production of a precisely tilted optical element can be challenging, a photoactive layer of the corresponding optical element of the optical unit (into which the DOE is written) could be sandwiched between two triangular glass plates. Due to its flat front surfaces, such an optical element would be easier and / or more precise to mass-produce. Using a blaze grating, each mesa / VIP could emit a slightly different wavelength, resulting in separate intensity splitting of the respective laser beams from the mesas / VIPs. The tilted optical grating preferably generates different deflections for each LFI measurement beam. The closer the VIPs are positioned to each other, the more similar the angles of incidence of the LFI measurement beams on the measurement points / areas.This has the particular consequence that the LFI measurement beams then exhibit similar reflectivity at the measurement point / in the measurement area. How close the VIPs must be positioned to each other for the described method to work depends, in particular, on the scattering behavior of the respective object. Specifically, "positioned close to each other" in this case means at a distance of less than ten, preferably less than five, preferably less than three maximum dimensions of an emission region of one of the two VIPs / mesas.

[0038] Furthermore, laser feedback interferometry (LFI) multipoint sensing is proposed at least for the generation of LFI measurement beams and the acquisition of measurement signals generated by scattering at an object and designed as back-reflection and / or backscatter signals of the LFI measurement beams, R.416902

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[0040] The system comprises an optical unit for defining individual intensities of the LFI measurement beams, and a processing unit for assigning the measurement signals to local measurement areas and / or measurement points within a measurement area pattern and / or measurement point pattern generated by illuminating the object using the aforementioned method. This advantageously allows for, for example, smaller, lighter, more energy-efficient, more cost-effective, and / or structurally simpler LFI multipoint sensors, which are suitable, for example, for eye tracking / gaze direction determination in smart glasses. A "processing unit" is understood to be, in particular, a unit with an information input, information processing, and information output.Advantageously, the computing unit comprises at least a processor, memory, input and output devices, other electrical components, an operating program, control routines, and / or calculation routines. The components of the computing unit can be arranged on a common circuit board and / or in a common housing. However, the computing unit can also be at least partially implemented by an external computer system, such as a mobile device, or a cloud computing system, which might be connected to smart glasses that apply the process.

[0041] Furthermore, the proposed smart glasses feature a scanning area for positioning the object, particularly the eye, and incorporate LFI multipoint sensors. This could result in, for example, smaller, lighter, more energy-efficient, more affordable, and / or simpler smart glasses with effective gaze tracking. Smart glasses, such as AR headsets or VR headsets, are also frequently referred to as smart glasses. Alternatively, gaze tracking 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 specifically head-worn smart devices that project artificially generated images into the user's field of vision.

[0042] Furthermore, a method for determining the direction of gaze in the data glasses using laser feedback interferometry (LFI) multipoint sensors is presented, R.416902.

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[0044] The process involves assigning measurement signals from the LFI multipoint sensor to local measurement areas and / or measurement points within a measurement area pattern and / or measurement point pattern generated by shining the sensor onto an eye, using the method described above. From distance and / or velocity information derived from these localized measurement signals, the eye's instantaneous gaze direction is determined. This approach can advantageously lead to, for example, smaller, lighter, more energy-efficient, more affordable, and / or structurally simpler smart glasses with effective gaze tracking.

[0045] The methods, LFI multipoint sensors, and data glasses according to the invention are not limited to the application and embodiment described above. In particular, the methods, LFI multipoint sensors, and data glasses according to the invention may, to achieve a functionality described herein, comprise a different number of individual elements, components, units, and process steps than those specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure are also considered disclosed and freely usable.

[0046] drawing

[0047] Further advantages will become apparent from the following description of the drawing. The drawing illustrates an embodiment of the invention. The drawing, 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.

[0048] They show:

[0049] Fig. 1 shows a schematic representation of data glasses with laser feedback interferometry (LFI) multipoint sensors, R.416902

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[0051] Fig. 2a shows a schematic representation of the LFI multipoint sensor system illuminating an object, with one optical unit and an exemplary beam path.

[0052] Fig. 2b shows a schematic representation of the LFI multipoint sensor system illuminating the object, including the optical unit and another exemplary beam path.

[0053] Fig. 2c shows a schematic representation of the LFI multipoint sensor system illuminating the object, including the optical unit and a second exemplary beam path.

[0054] Fig. 3 shows a schematic representation of a possible alternative LFI multipoint sensor system illuminating the object, with a possible alternative optical unit.

[0055] Fig. 4 shows an optical element of the alternative optical unit,

[0056] Fig. 5 shows a schematic flowchart of a method for assigning measurement signals within a measurement range of the data glasses and

[0057] Fig. 6 shows a schematic flowchart of a method for determining the direction of gaze in the data glasses using LFI multipoint sensors.

[0058] Description of the exemplary embodiment

[0059] Figure 1 schematically shows a head-mounted smart glasses device 52. The smart glasses device 52 includes a recording area 64 for positioning an object 22, which in this case is designed as the eye of the wearer of the smart glasses device 52. The recording area 64 is, in this case, an eye recording area of ​​the smart glasses device 52. The smart glasses device 52 includes a laser feedback interferometry (LFI) multipoint sensor 24. The LFI multipoint sensor 24 is integrated into the smart glasses device 52, in particular into a spectacle frame of the smart glasses device 52. The LFI multipoint sensor 24 forms a measuring area 50 of the smart glasses device 52, within which the gaze directions of the wearer's eye can be determined. The measuring area 50 has a total axial extent of 48.R.416902

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[0061] Figures 2a and 2b show two schematic representations of the LFI multipoint sensor system 24 and its exemplary beam paths. The LFI multipoint sensor system 24 comprises, by way of example, several VIPs (VCSELs with integrated photodiodes) 56, 58. The two VIPs 56, 58 are positioned close to each other. The VIPs 56, 58 shown as examples are each intended to generate LFI measurement beams 38, 40. Alternatively, the two LFI measurement beams 38, 40 could also originate from a single VIP 56 with two mesas (see also Fig. 3). The LFI measurement beams 38, 40 are emitted by the VIPs 56, 58 in the direction of the object 22. The LFI measurement beams 38, 40 are directed onto the object 22 by the VIPs 56, 58. The LFI measuring beams 38, 40 form a measuring area pattern 26 on the object 22. Two LFI measuring beams 38, 40 of the VIPs 56, 58 are each directed into one of several local measuring areas 14, 16 of the measuring area pattern 26. In the example of Fig.In Figure 2a, the two LFI measuring beams 38, 40 of a measuring range 14, 16 strike the object 22 at a common measuring point 18. In the example of Figure 2b, the two LFI measuring beams 38, 40 of a measuring range 14, 16 strike the object 22 at different measuring points 18, 20. The LFI measuring beams 38, 40 strike the object 22 at an angle of incidence 54. The measuring points 18, 20 each form a measuring point pattern 28. For the described method, it is not absolutely necessary that the LFI measuring beams 38, 40 always strike the object 22 at exactly the same measuring point 18, 20. It is only important that they strike a common measuring range 14, 16 in which they experience at least a similar reflectivity and preferably have similar measured values ​​(distance and velocity).

[0062] The LFI measuring beams 38, 40 incident on object 22 are scattered by object 22. This generates back-reflection and / or backscatter signals, which are at least partially reflected back to the emitting VIP 56, 58. The LFI multipoint sensor 24, in particular the respective VIPs 56, 58, are designed to detect measurement signals 10, 12 generated by the scattering at object 22 and which are the back-reflection and / or backscatter signals of the LFI measuring beams 38, 40. Each VIP 56, 58 has a photodetector 66 for this purpose. The LFI multipoint sensor 24 includes an optical unit 46. The optical unit 46 comprises, by way of example, two optical elements 42, 44. However, the optical unit 46 could also have more or fewer optical elements 42, 44 to fulfill its tasks. R.416902

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[0064] The optical unit 46 is arranged in the beam paths of the laser beams emitted by the VIPs 56 and 58. The optical elements 42 and 44 are each arranged in a beam path of one of the two VIPs 56 and 58. The optical elements 42 and 44 are each diffractive optical elements (DOEs). The optical elements 42 and 44 of the optical unit 46 are each designed to define individual intensities of the LFI measurement beams 38 and 40. The optical elements 42 and 44 influence the laser beams of the VIPs 56 and 58 such that each LFI measurement beam 38 or 40 leaving the optical unit 46 has a different intensity. The optical elements 42, 44 influence the laser beams of the VIPs 56, 58 in such a way that each LFI measuring beam pair leaving the optical unit 46 has a different intensity ratio than all neighboring LFI measuring beam pairs or even than all other LFI measuring beam pairs of the LFI multipoint sensor system 24.Thus, all measurement signal pairs detected by the photodetector 66 also exhibit different intensity ratios. Comparisons of the intensity ratios of the LFI measurement beam pairs and the measurement signal pairs allow the measurement signals 10, 12 to be assigned to local measurement areas 14, 16 of the measurement area pattern 26 and / or to measurement points 18, 20 of the measurement point pattern 28. Since the configurations of the VIPs 56, 58 and the optical unit 46 are known, a point in space, in particular relative to a component of the LFI multipoint sensor system 24, can be determined.

[0065] The LFI multipoint sensor 24 has a processing unit 62. The processing unit 62 is integrated into the data glasses 52 as an example, but could alternatively be arranged separately and connected to the LFI multipoint sensor 24 via a wireless data connection. The processing unit 62 is configured to perform a procedure for assigning the measurement signals 10, 12 to local measurement areas 14, 16 and / or measurement points 18, 20 within a measurement area pattern 26 and / or measurement point pattern 28 generated by illuminating the object 22. The processing unit 62 is configured to determine the position of the object 22, in particular the eye or a pupil of the eye, in space by performing the procedure. The processing unit 62 is configured to determine the gaze direction of the eye within the data glasses 52 by performing the procedure. R.416902

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[0067] To explain the necessity of the procedure, the underlying situation is described below with reference to Figures 2a to 2c. An intensity l_R returning from a measuring point 18, 20 and / or a measuring area 14, 16 in the direction of an emitting laser cavity of one of the VIPs 56, 58 depends on an initial intensity l_IN of the respective LFI measuring beam 38, 40 and a reflectivity R of the object 22 directed towards the laser cavity (J_R = R*I_IN). The initial intensity l_IN of each LFI measuring beam 38, 40 has been individually set for each measuring point 18, 20 and / or each measuring area 14, 16, e.g., using a DOE of the optical unit 46, as already described.The reflectivity of object 22 at measuring point 18, 20 and / or in measuring area 14, 16 depends on several factors according to Fresnel's formulas: a) the angle of incidence 54 at which the LFI measuring beam 38, 40 strikes object 22, b) the polarization orientation of the LFI measuring beam 38, 40 (s- or p-polarized light), and c) the difference in refractive index of the media involved. The angle of incidence 54, in particular, can vary considerably depending on the object 22 and the application of the LFI multipoint sensor 24. This can complicate the subsequent assignment of the measurement signals 10, 12 to one of the LFI measuring beams 38, 40, especially if the measures mentioned herein are not taken. If measurement signals 10, 12 of a measurement point 18, 20 are measured by two separate VIPs 56, 58 (see Fig. 2a), a statement can be made about the assignment of the measurement point 18, 20 to the beat frequency of the photodetector 66 of the VIP 56, 58 via their intensity ratio.The intensity ratio is independent of the reflectivity of the surface of object 22 under consideration, provided that the LFI measurement beams 38, 40, which strike the same measurement point 18, 20, experience the same reflectivity R. Assuming that the measurement point 18, 20 is illuminated with an intensity IJN-VIP1 by one of the two VIPs 56, 58 and with an intensity IJN-VIP2 by the other VIP 56, 58, the following equations result for the measurement signals 10, 12 in the direction of the two VIPs 56, 58: l_R1 = R*I_IN-VIP1 and l_R2 = R*I_IN-VIP2. The intensity ratio of the measurement signals 10, 12 is then given by (assuming that R is the same for both LFI measurement beams 38, 40):

[0068]

[0069] R.416902

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[0071] With an intensity distribution of the LFI measuring beams 38, 40 set via the optical unit 46 of \_IN-VIP1 = 2*I_IN-VIP2, the resulting intensity ratio of the measuring signal 10, 12 is independent of the reflectivity:

[0072] IR1 _ 2 ' IlN-VIP2 _ 2

[0073] ?2 IlN-VIP2 1

[0074] This approach could potentially become problematic if the object 22 can shift significantly within the measurement range 50. This could cause LFI measurement beams 38, 40 to generate further intensity ratios in the measurement signals 10, 12 at other points in space (see Fig. 2c, which shows the object 22 at two different distances). However, the structure of the intensity ratios using sets of prime numbers, as described in connection with the method, can prevent such ambiguities from arising, even with large overall axial dimensions 48 of measurement ranges 50.Alternatively or additionally, such ambiguities can be prevented by designing / selecting the beam directions of the individual LFI measuring beams 38, 40 onto the object 22 generated by the interactions with the optical unit 46 in such a way that they do not cross within the total axial extent 48 of the intended measuring range 50 of the data glasses 52 having the LFI multipoint sensor system 24.

[0075] To ensure that the LFI measuring beams 38, 40 are reflected from the object 22 with similar or identical reflectivity in the local measuring areas 14, 16 of the measuring area pattern 26 and / or the measuring points 18, 20 of the measuring point pattern 28, they are aligned. For this purpose, the at least two LFI measuring beams 38, 40 directed into the local measuring areas 14, 16 and / or measuring points 18, 20 of the measuring area pattern 26 and / or measuring point pattern 28 are specifically adjusted to each other with respect to their angles of incidence 54 and their polarizations. If the two LFI measuring beams 38, 40 are directed at the object 22 from different angles of incidence 54, they are provided with correspondingly different, specifically adjusted polarizations so that the LFI measuring beams 38, 40 are nevertheless reflected from the object 22 with similar or identical reflectivities.Alternatively, care could be taken to ensure that the various local measurement areas 14, 16 and / or measurement points 18, 20R.416902 are included.

[0076] - 17 -

[0077] The LFI measuring beams 38, 40 of the measuring range pattern 26 and / or measuring point pattern 28 are always directed onto the object 22 with a similar or identical angle of incidence 54 and always with a similar or identical polarization to match the reflectivities to each other.

[0078] Figure 3 shows an example of an LFI multipoint sensor 24 in which a single VIP 58 is equipped with two mesas, each emitting laser light separately. In this case, an alternative optical unit 46' can be used, which can be designed to be particularly compact. In this case, the optical unit 46' comprises an optical element 42', which is configured as a tilted optical grating 60. The tilted optical grating 60 imparts different, definable and / or fixed intensities to the LFI measurement beams 38, 40. In another (not shown) alternative, the optical unit 46, 46' could also have a blaze grating for the same purpose. Figure 4 shows an exemplary implementation of a corresponding optical element 42' with a tilted optical grating 60.Here, a DOE or HOE, which determines the different intensities, is incorporated into a photoactive layer 68, which is arranged between two transparent wedge-shaped elements 70. Together, the package consisting of the two wedge-shaped elements 70 and the photoactive layer 68 forms a cuboid optical element 42'.

[0079] Figure 5 shows a schematic flowchart of a method for assigning the measurement signals 10, 12 to the local measurement areas 14, 16 and / or measurement points 18, 20 within the measurement area pattern 26 and / or measurement point pattern 28 generated by the LFI multipoint sensor system 24 shining onto the object 22, preferably within the measurement area 50 of the data glasses 52. In at least one method step 30, at least two LFI measurement beams 38, 40 are shining onto the object 22 in several local measurement areas 14, 16 and / or measurement points 18, 20 of the measurement area pattern 26 and / or measurement point pattern 28 by means of the LFI multipoint sensor system 24. The at least two LFI measuring beams 38, 40 of each of these local measuring areas 14, 16 and / or measuring points 18, 20 each have a known fixed mutual intensity ratio. This intensity ratio differs from the intensity ratios of adjacent LFI measuring beam pairs of the LFI-R.416902.

[0080] - 18 -

[0081] Multipoint sensor technology 24 in the measurement range pattern 26 and / or the measurement point pattern 28. Each intensity ratio of any combination of two LFI measurement beams 38, 40 of the LFI multipoint sensor technology 24 is unique.

[0082] The individual intensities of the LFI measuring beams 38, 40 of the LFI multipoint sensor 24 are each determined by means of the optical elements 42, 42', 44 of the optical unit 46, 46' of the LFI multipoint sensor 24 arranged in the respective beam paths of the LFI measuring beams 38, 40. A set of all possible known fixed intensity ratios of the LFI measuring beams 38, 40 is based on a set of prime numbers with a length of (2*n)-1. The parameter n specifies the number of LFI measuring beams 38, 40 of the LFI multipoint sensor 24. The individual intensity ratios of the set of possible known fixed intensity ratios are formed as follows: a) Dividing the set of prime numbers into two subsets of prime numbers with respective lengths of (n+1) / 2,a) into which the prime numbers of the set of prime numbers are divided alternately, starting with the smallest prime number of the set of prime numbers, with the exception of the middle prime number of the set of prime numbers, which is assigned to both subsets; b) normalizing the two subsets so that the sum of each of the subsets equals 1; c) dividing one of the entries of one of the subsets by one of the entries of another of the subsets; and d) adjusting the individual intensities of the individual LFI measuring beams 38, 40 of the LFI multipoint sensor 24 each corresponding exactly to one of the values ​​of the normalized subsets by means of the selection and / or design of the optical unit 46, 46', in particular the optical functions of the optical unit 46, 46' / the optical elements 42, 42', 44 of the optical unit 46, 46'.

[0083] In at least one further process step 72, the LFI measuring beams 38, 40 are reflected by the object 22. This generates the measurement signals 10, 12, which are at least partially backscattered to the VIPs 56, 58. In at least one further process step 32, the measurement signals 10, 12 are acquired from the local measurement areas 14, 16 of the measurement area pattern 26 and / or the measurement points 18, 20 of the measurement point pattern 28 by means of the photodetector 66 of the LFI multipoint sensor system 24. In at least one further process step 34, intensity ratios of the acquired measurement signals 10, 12 are calculated from the intensities of the acquired measurement signals 10, 12, e.g., with the aid of the processing unit 62.

[0084] - 19 -

[0085] In at least one further process step 36, the recorded pairs of measurement signals are assigned to local measurement areas 14, 16 of the measurement area pattern 26 and / or to measurement points 18, 20 of the measurement point pattern 28 based on a similarity or identity of their recorded intensity ratios with one of the known fixed intensity ratios of two incident LFI measurement beams 38, 40. This also assigns the measurement signals 10, 12 to a spatial location within the measurement area 50 of the data glasses 52.

[0086] Figure 6 shows a schematic flowchart of a method for determining the direction of gaze in the data glasses 52 using the LFI multipoint sensor 24. In a process step 74, the measurement signals 10, 12 of the LFI multipoint sensor 24 are assigned to local measurement areas 14, 16 and / or measurement points 18, 20 within the measurement area pattern 26 and / or measurement point pattern 28 generated by shining the light onto an eye, using the method described inter alia in connection with Figure 5. In at least one further process step 76, distance information and / or velocity information are determined from the measurement signals 10, 12 located in this way. In at least one further process step 78, the instantaneous direction of gaze of the object 22, i.e., the eye of the wearer of the data glasses 52, is determined from this distance information and / or velocity information of the measurement signals 10, 12 located in this way.

Claims

R.416902 - 20 - Claims 1. Method for assigning measurement signals (10, 12), preferably back-reflection and / or backscatter signals, to local measurement areas (14, 16) and / or measurement points (18, 20) within a measurement area pattern (26) and / or measurement point pattern (28) generated by illuminating an object (22), for example an eye, using a laser feedback interferometry (LFI) multipoint sensor (24), characterized by at least the method steps (30, 32, 34, 36): - Projecting at least two LFI measurement beams (38, 40) into several, in particular all, local measurement areas (14, 16) and / or measurement points (18, 20) of the measurement area pattern (26) and / or measurement point pattern (28) using the LFI multipoint sensor (24), wherein the at least two LFI measurement beams (38, 40) of at least these local measurement areas (14, 16) and / or measurement points (18, 20) each have a known definable and / or fixed mutual intensity ratio, which is different from at least the intensity ratios of neighboring LFI measurement beam pairs in the measurement area pattern (26) and / or measurement point pattern (28), - Acquiring measurement signals (10, 12) from the local measurement areas (14, 16) and / or measurement points (18, 20) of the measurement area pattern (26) and / or measurement point pattern (28) using the LFI multipoint sensor technology (24), - determining intensity ratios from intensities of the recorded measurement signals (10, 12) and - Assigning detected measurement signal pairs to local measurement ranges (14, 16) and / or measurement points (18, 20) of the measurement range pattern (26) and / or measurement point pattern (28) based on a similarity or identity of a detected intensity ratio with one of the known definable and / or fixed intensity ratios of two irradiated LFI measurement beams (38, 40).

2. Method according to claim 1, characterized in that each intensity ratio of any combination of two LFI measuring beams (38,R.416902 - 21 - 40) the LFI multipoint sensor technology (24) is unique.

3. Method according to claim 1 or 2, characterized in that individual intensities of the LFI measuring beams (38, 40) of the LFI multipoint sensor (24) can be determined or are determined by means of one or more optical elements (42, 44) of an optical unit (46) of the LFI multipoint sensor (24) arranged in the respective beam paths of the LFI measuring beams (38, 40).

4. Method according to claim 3, characterized in that the directions of incidence of the individual LFI measuring beams (38, 40) on the object (22) generated by interactions with the optical unit (46) are such that they do not intersect within an overall axial extent (48) of a provided measuring area (50) of a device having the LFI multipoint sensor technology (24), such as data glasses (52).

5. Method according to one of the preceding claims, characterized in that a totality of the possible known definable and / or fixed intensity ratios of the LFI measuring beams (38, 40) is based on a set of prime numbers.

6. Method according to claim 5, characterized in that the set of prime numbers has a length of (2*n)-1, wherein the parameter n specifies a number of LFI measuring beams (38, 40) of the LFI multipoint sensor (24).

7. Method according to claim 6, characterized in that each of the individual intensity ratios of the totality of possible known definable and / or fixed intensity ratios is formed as follows: - Dividing the set of prime numbers into two subsets of prime numbers with respective lengths of (n+1) / 2, into which the prime numbers of the set of prime numbers are divided alternately starting from the smallest prime number of the set of prime numbers, with the exception of the middle prime number of the set of prime numbers, which is assigned to both subsets, - Normalizing the two subsets so that the sum of each of the subsets equals 1, and R.416902 - 22 - - Dividing one of the entries of one of the subsets by one of the entries of another of the subsets.

8. Method according to claims 3 and 7, characterized in that the individual intensities of the individual LEI measuring beams (38, 40) of the LFI multipoint sensor (24) are set by the optical unit (46) according to exactly one of the values ​​of the normalized subsets.

9. Method according to one of the preceding claims, characterized in that the at least two LFI measuring beams (38, 40) emitted into the local measuring areas (14, 16) and / or measuring points (18, 20) of the measuring area pattern (26) and / or measuring point pattern (28) are or are coordinated such that they are reflected by the object (22) with a similar or identical reflectivity.

10. Method according to claim 9, characterized in that the at least two LFI measuring beams (38, 40) emitted into the local measuring areas (14, 16) and / or measuring points (18, 20) of the measuring area pattern (26) and / or measuring point pattern (28) are emitted onto the object (22) at different angles of incidence (54) to adjust the reflectivity, wherein these LFI measuring beams (38, 40) also have different polarizations which are adapted and / or adjusted such that these LFI measuring beams (38, 40) are nevertheless reflected by the object (22) with similar or identical reflectivities.

11. Method according to claim 9, characterized in that the at least two LFI measuring beams (38, 40) emitted into the local measuring areas (14, 16) and / or measuring points (18, 20) of the measuring area pattern (26) and / or measuring point pattern (28) are emitted to match the reflectivity with a similar or identical angle of incidence (54) and with a similar or identical polarization onto the object (22).

12. Method according to claim 11, characterized in that the at least two are located in the local measuring areas (14, 16) and / or measuring points (18, R.416902). - 23 - 20) of the measurement range pattern (26) and / or measurement point pattern (28) LFI measurement beams (38, 40) are emitted by two closely positioned VIPs (VCSEL with integrated photodiode) (56, 58) or two mesas of a single VIP (56) and are provided by a tilted optical grating (60) or a blaze grating with different definable and / or fixed intensities.

13. Laser feedback interferometry (LFI) multipoint sensor (24) for generating LFI measurement beams (38, 40) and detecting measurement signals (10, 12) generated by scattering at an object (22) and forming back reflection and / or backscatter signals of the LFI measurement beams (38, 40), with an optical unit (46) for determining individual intensities of the LFI measurement beams (38, 40), characterized by a computing unit (62) which is configured to assign the measurement signals (10, 12) to local measurement areas (14, 16) and / or measurement points (18, 20) within a measurement area pattern (26) and / or measurement point pattern (28) generated by irradiating the object (22) by means of a method according to one of the preceding claims.

14. Data glasses (52) with a recording area (64) for positioning the object (22), in particular the eye, and with an LFI multipoint sensor system (24) according to claim 13.

15. Method for determining gaze direction in data glasses (52) with laser feedback interferometry (LFI) multipoint sensor technology (24), wherein measurement signals (10, 12) of the LFI multipoint sensor technology (24) are assigned to local measurement areas (14, 16) and / or measurement points (18, 20) within a measurement area pattern (26) and / or measurement point pattern (28) generated by illuminating an eye using a method according to one of claims 1 to 12, and wherein an instantaneous gaze direction of the eye is determined from distance information and / or velocity information of the measurement signals (10, 12) located in this way.

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