Polarized light navigation sensor and electronic equipment

Abstract

The invention provides a polarized light navigation sensor and electronic equipment, and relates to the technical field of sensors. The polarized light navigation sensor comprises a double-layer metasurface which comprises a plurality of polarized light detection units arranged in an array mode, and each polarized light detection unit comprises a medium metasurface arranged on the upper surface of a substrate and a metal metasurface arranged on the lower surface of the substrate. The medium metasurface is used for correcting inclined incident light into incident light in the vertical direction and gathering the incident light into one point, and the metal metasurface is used for filtering the incident light which is focused into one point and is in the vertical direction, so that linearly polarized light of various preset types can penetrate through the medium metasurface; phases of all the polarized light detection units are different; the photoelectric sensor is used for converting the linearly polarized light of the target preset type into an electric signal of the target preset type; the signal processing unit is used for outputting the degree of the sky polarization angle based on all the target preset types of electric signals. The utilization rate of the polarized light navigation sensor on the sky polarization information can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a polarized light navigation sensor and electronic equipment. Background Art

[0002] With the development of drones and autonomous driving, navigation technology is playing an increasingly important role in human production and life, as well as in military applications. In nature, insects such as sand ants and bees have evolved the ability to use their compound eyes to sense the polarization patterns of the sky for navigation, providing scientific insights into the development of new polarization navigation sensors.

[0003] Polarized navigation sensors mimic the polarization sensitivity of insect compound eyes to sky light. By detecting the polarization of sky light, they calculate their heading and are used for autonomous navigation in robots and drones. This navigation method offers the advantages of high autonomy and immunity to external electromagnetic interference, making it a key component in the study of biomimetic autonomous navigation. With advances in micro- and nanofabrication technologies, polarized navigation sensors are trending towards miniaturization and integration.

[0004] However, most current polarization navigation sensors use a combination of traditional optical lenses and polarization devices. These sensors are bulky, can only measure polarization information at the zenith, have low utilization of sky polarization information, are susceptible to interference, and have poor robustness, making them inadequate for drones and autonomous driving. Summary of the Invention

[0005] The embodiments of the present invention provide a polarized light navigation sensor and an electronic device to solve the problems of low utilization of sky polarization information and large size of current polarized light navigation sensors.

[0006] In a first aspect, an embodiment of the present invention provides a polarized light navigation sensor, comprising a double-layer metasurface, a photoelectric sensor, and a signal processing unit;

[0007] The double-layer metasurface includes multiple arrayed polarization detection units. Each polarization detection unit includes a dielectric metasurface disposed on the upper surface of the substrate and a metal metasurface disposed on the lower surface of the substrate. The dielectric metasurface is used to correct the inclined incident light to vertical incident light and focus it into a point. The metal metasurface is used to perform polarization filtering on the vertical incident light focused into a point to transmit multiple preset types of linearly polarized light. The phases of all polarization detection units are different.

[0008] The photoelectric sensor is used to convert linearly polarized light of a target preset type into an electrical signal of a target preset type; wherein the target preset type is any one of a plurality of preset types;

[0009] The signal processing unit is used to process the electrical signals of all target preset types and output the target preset polarization angles corresponding to the electrical signals of all target preset types;

[0010] The polarization navigation sensor is used to calculate the navigation angle based on all the preset polarization angles of the target.

[0011] In one possible implementation, the phase of the polarized light detection unit is determined based on a dielectric metasurface phase equation, which is constructed based on the sum of a quadratic phase equation and a light vector correction phase equation;

[0012] The light vector corrected phase equation is constructed by analyzing the vector propagation properties of light based on the vector triangle and converting the optical path into phase.

[0013] In one possible implementation, the polarized light detection unit includes multiple sub-dielectric metasurfaces with different phases, each of which is composed of multiple sub-wavelength-sized metaatoms, and the phase of the metaatom at each position is determined based on the dielectric metasurface phase equation.

[0014] In one possible implementation, the size of the superatom at each position is determined based on the phase of the superatom at that position and a pre-built size phase matrix library.

[0015] In a possible implementation, the pre-built size phase matrix library is constructed based on the size of each meta-atom and the phase modulation amount of a specific polarized light corresponding to the meta-atom of the size.

[0016] In a possible implementation, the shape of the superatom at each position is an elliptical cylinder or a cube.

[0017] In a possible implementation, the polarized light detection unit includes four areas, each area being configured to transmit a preset type of linearly polarized light.

[0018] In a possible implementation, the four regions are used to transmit horizontal linear polarized light, vertical linear polarized light, 45° linear polarized light, and 135° linear polarized light, respectively.

[0019] In one possible implementation, the signal processing unit is used to determine the linear polarization parameters of the Stokes vector based on all target preset types of electrical signals, and determine the target preset polarization angle corresponding to the target preset type of electrical signal based on the linear polarization parameters of the Stokes vector.

[0020] In a second aspect, the present invention further provides an electronic device, comprising the polarized light navigation sensor according to any one of the first aspects.

[0021] An embodiment of the present invention provides a polarization navigation sensor. By utilizing a double-layer metasurface composed of a dielectric metasurface and a metallic metasurface, this sensor can meet the multi-directional polarization measurement requirements while ensuring the accuracy of polarization angle measurement. Furthermore, by ensuring that all polarization detection units have different phases, different polarization detection units can act on incident light at different angles, enabling the double-layer metasurface to perform polarization identification and focusing on multi-directional light. Thus, the double-layer metasurface not only miniaturizes the polarization navigation sensor but also improves its utilization of sky polarization information. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a schematic diagram of the structure of a sky polarization distribution model provided by an embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of a cross-sectional view of a polarized light navigation sensor provided by an embodiment of the present invention;

[0024] Figure 3 is a top view of a double-layer metasurface provided by an embodiment of the present invention;

[0025] Figure 4 1 is a front view of a double-layer metasurface provided by an embodiment of the present invention;

[0026] Figure 5 is a schematic diagram of a vector triangle analysis of incident light provided by an embodiment of the present invention;

[0027] Figure 6 This is a three-dimensional view of the polarized light navigation sensor provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0029] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0030] The following is a detailed description of the implementation of the present invention with reference to the accompanying drawings:

[0031] After the polarized light in the sky is scattered by the atmosphere, it will form a stable polarization pattern. Taking the observer as the origin, the sky is simplified into a hemispherical model to establish a horizontal coordinate system. The sky polarization distribution model is as follows: Figure 1 As shown in the figure, the Z axis is the zenith direction, and point S is the point of direct sunlight. The sky polarization distribution model is a concentric circle centered at point S. The semicircle passing through point S and the zenith is called the meridian, and the sky polarization distribution is symmetrical about the meridian. Figure 1 The thickness of the dotted line indicates the degree of polarization. The linear polarization direction of any observation point P is perpendicular to the plane SOP. Figure 1 It can be seen that the polarization distribution of the sky changes dynamically with the position of the sun, and the degree of polarization at the zenith is not the highest. Generally, the higher the degree of polarization at the zenith, the higher the sensor's polarization angle measurement accuracy. When the degree of polarization at the zenith is low, the sensor's polarization angle measurement accuracy also decreases. Therefore, for polarization sensors that only measure the zenith, the accuracy of the sensor will vary with the position of the sun. In addition, if the zenith is obstructed by clouds or other factors, the sensor's measurement data will be erroneous. Therefore, polarization sensors that only measure the zenith have the disadvantages of low utilization of sky polarization information and susceptibility to external interference.

[0032] Because polarization navigation sensors simultaneously measure the polarization angle at a point in the sky and obtain the corresponding degree of polarization information, multi-directional polarization navigation sensors can choose between corresponding polarization angles based on the measured degree of polarization information, retaining the more accurate polarization angle as the navigation angle, thereby improving sensor accuracy. Furthermore, if there is cloud cover or obstruction in a particular direction, the polarization angle information in that direction can be discarded, and the polarization angle information in other directions can be used as the navigation angle, thereby improving sensor robustness.

[0033] Furthermore, current polarization navigation sensors use a traditional combination of optical lenses and polarization devices. This drawback is their bulkiness. Therefore, there is an urgent need for a smaller sensor that can efficiently utilize sky polarization information.

[0034] Optical metasurfaces are two-dimensional materials composed of a specific arrangement of subwavelength-scale artificial structural units. They can precisely control the amplitude, phase, and polarization of light waves. While typically thinner than a wavelength, their capabilities far exceed those of traditional optical components. Using optical metasurfaces to design a novel biomimetic polarization navigation sensor has become a pressing challenge.

[0035] Figure 2-4 This is a schematic diagram of the structure of a polarized light navigation sensor provided by an embodiment of the present invention. Figure 1 The polarized light navigation sensor includes a double-layer metasurface 110, a photoelectric sensor 120 and a signal processing unit 130.

[0036] The double-layer metasurface 110 includes a plurality of polarized light detection units 1110 arranged in an array. Each polarized light detection unit 1110 includes a dielectric metasurface 1112 disposed on the upper surface of a substrate 1111 and a metal metasurface 1113 disposed on the lower surface of the substrate 1111. The dielectric metasurface 1112 is used to correct the inclined incident light to vertical incident light and focus it to a point. The metal metasurface 1113 is used to polarize and filter the vertical incident light focused to a point to transmit a plurality of preset types of linearly polarized light. The phases of all polarized light detection units 1110 are different.

[0037] The photoelectric sensor 120 is used to convert linearly polarized light of a target preset type into an electrical signal of a target preset type, wherein the target preset type is any one of a plurality of preset types.

[0038] The signal processing unit 130 is configured to process all target preset types of electrical signals and output target preset polarization angles corresponding to all target preset types of electrical signals.

[0039] The polarization navigation sensor is used to calculate the navigation angle based on all the preset polarization angles of the target.

[0040] The substrate 1111 of all polarized light detection units 1110 is the same substrate. That is, the dielectric metasurface 1112 and metallic metasurface 1113 of all polarized light detection units 1110 are arranged on the same substrate 1111. The dual-layer metasurface is manufactured using micro-nanofabrication techniques, rather than assembled from multiple lenses, eliminating assembly errors. Since the dielectric metasurface and metallic metasurface are manufactured on the same substrate, assembly and alignment are unnecessary, eliminating alignment difficulties.

[0041] By making the phases of all polarized light detection units 1110 different, different polarized light detection units can act on incident light at different angles, so that the metasurface can perform polarization recognition and focusing on multi-directional light. Figure 4 The incident light of the double-layer metasurface 110 shown in FIG is natural light, and the outgoing light is polarized light.

[0042] In order to enable the double-layer metasurface 110 to adapt to incident light from multiple directions and to maximize the use of sky polarization information, it is necessary to assign a light vector correction phase to each polarized light detection unit 1110.

[0043] In some embodiments, the phase of the polarized light detection unit 1110 is determined based on a dielectric metasurface phase equation, which is constructed based on the sum of a quadratic phase equation and a light vector correction phase equation. The light vector correction phase equation is used to correct oblique incident light to vertical incident light, and the quadratic phase equation is used to focus the vertical incident light.

[0044] The polarized light detection unit 1110 includes multiple sub-dielectric metasurfaces with different phases. Each sub-dielectric metasurface is composed of multiple sub-wavelength-sized metaatoms, and the phase of the metaatom at each position is determined based on the dielectric metasurface phase equation.

[0045] In this embodiment, the light vector correction phase equation is constructed by analyzing the vector propagation properties of light based on the vector triangle and converting the optical path into a phase.

[0046] The principle diagram of light vector correction phase equation is as follows Figure 5 As shown in the figure, when the oblique light is irradiated on the metasurface ab, the light vector of the incident light before correction is r, and the light vector of the incident light after correction is r'. A perpendicular line bd is drawn from one end b of the metasurface to the oblique incident light, and a vector triangle can be obtained at point c on the metasurface unit. The corrected phase of the light vector required at point c is:

[0047]

[0048] Here, π represents the circumference of a circle, λ represents the wavelength of light, and α represents the tilt angle of light.

[0049] The corrected phase equation for the light vector at any position is:

[0050]

[0051] Where x and y are the coordinates of the center point of the sub-medium metasurface at each position.

[0052] In this embodiment, the quadratic phase equation is:

[0053]

[0054] Among them, π represents pi, λ represents the wavelength of light, R represents the radius of the metasurface, and L represents the depth of focus.

[0055] The phase equation of the dielectric metasurface is:

[0056]

[0057] Through the above dielectric metasurface phase equation, the phase of the sub-dielectric metasurface at each position can be calculated.

[0058] In some embodiments, after the phase of the metaatom at each position is determined based on the dielectric metasurface phase equation, the metaatom placed at that position needs to be selected.

[0059] In this embodiment, the size of the superatom at each position can be determined based on the phase of the superatom at that position and a pre-built size phase matrix library.

[0060] The pre-built size phase matrix library is constructed based on the size of each meta-atom and the phase modulation amount of a specific polarized light corresponding to the meta-atom of that size.

[0061] For example, the shape of the superatom at each position is an elliptical cylinder or a cube. It should be noted that, to facilitate subsequent preparation, the dimensions for the cube refer to the length and width, while for the elliptical cylinder, the dimensions refer to the radius. For ease of preparation, all superatoms have the same height.

[0062] The double-layer metasurface in the present invention is manufactured in an integrated manner using micro-nano processing technology, and there is no assembly error.

[0063] The phase of the polarization detection unit in the present invention first corrects the inclined incident light to vertical incident light through the light vector correction phase equation, and then focuses the vertical incident light through the quadratic phase equation, so as to maximize the use of sky polarization information.

[0064] The quadratic phase equation in the present invention is different from the hyperbolic phase equation. The quadratic phase has two advantages over the hyperbolic phase:

[0065] First, a metasurface designed with a hyperbolic phase focuses light on a point on the optical axis, and its focal plane is a fixed plane. When the incident light is tilted, the focal length of the incident light will change to a certain extent, making it difficult for all polarization detection units on the entire metasurface to accurately focus incident light from different directions on the same focal plane. A metasurface designed with a quadratic phase, on the other hand, focuses light on a line segment along the optical axis, so its focal plane can float within a certain range. When the angle of the incident light changes, even if the focal length of the metasurface changes to a certain extent, all polarization detection units in the metasurface can still be focused on the same plane.

[0066] Second, when the incident light angle changes, the focusing efficiency of the hyperbolic phase-designed metasurface decreases significantly, while the focusing efficiency of the quadratic phase-designed metasurface decreases slowly. Therefore, the quadratic phase-designed metasurface is more adaptable to oblique incident light and has better focusing performance.

[0067] In some embodiments, the metal metasurface typically utilizes a metallic strip lattice structure. Simulation software is used to simulate or numerically calculate the polarization filtering performance of the metal lattice's geometric parameters, such as the strip lattice's height, width, and duty cycle, against incident light. Parameters with high polarization extinction are selected as design parameters for the metal metasurface. Because linearly polarized light exhibits rotational symmetry, rotating the metasurface by a certain angle allows it to be adapted for linearly polarized light at different angles.

[0068] In some embodiments, as Figure 3As shown, the polarized light detection unit includes four areas, each area is used to transmit a preset type of linearly polarized light.

[0069] In this embodiment, the four regions are used to transmit horizontally polarized light, vertically polarized light, 45° linearly polarized light, and 135° linearly polarized light, respectively. Of course, other polarized light can also be transmitted according to the application scenario, as long as four different types of polarized light are used.

[0070] Finally, the four polarized lights are focused onto the photosensor.

[0071] In some embodiments, the signal processing unit 130 is configured to determine linear polarization parameters of the Stokes vector based on all target preset types of electrical signals, and determine the degree of the sky polarization angle based on the linear polarization parameters of the Stokes vector.

[0072] In this embodiment, the signal processing unit 130 includes a chip, a reset switch, a data transmission interface, and other electronic components. The chip is responsible for processing the electrical signal input by the photoelectric sensor and calculating the polarization angle, which is the heading angle used for navigation.

[0073] The calculation process of the polarization angle is:

[0074] First, the polarization detection unit 1110 identifies the linear polarization information in the incident light. The metasurface focuses the four different linear polarizations onto the photosensor 120. The photosensor converts the four linear polarization signals into electrical signals and transmits them to the computing chip. The program in the chip calculates the polarization signals into polarization angle signals and outputs them through the data transmission interface on the circuit board.

[0075] The calculation formula of polarization angle is: First, use the four polarization light signals to calculate the Stokes vector [s0s1s2s3] T s1, s2,

[0076] The calculation formula for the sky polarization angle (AOP) is:

[0077]

[0078] In some embodiments, as Figure 6 As shown, the polarized light navigation sensor also includes a housing for protecting the internal components (metasurface and photoelectric sensor), while having the function of limiting the angle of incident light and preventing ambient light from interfering with the sensor.

[0079] The polarized light navigation sensor provided by the present invention utilizes a double-layer metasurface composed of a dielectric metasurface and a metallic metasurface, which not only meets the requirements for multi-directional polarization measurement of the polarized light navigation sensor but also ensures the accuracy of polarization angle measurement. Furthermore, by making all polarized light detection units have different phases, different polarized light detection units can act on incident light at different angles, allowing the double-layer metasurface to perform polarization identification and focusing on multi-directional light. Thus, the double-layer metasurface not only miniaturizes the polarized light navigation sensor but also improves its utilization of sky polarization information.

[0080] In a second aspect, the present invention further provides an electronic device, which includes the polarized light navigation sensor described above.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A polarized light navigation sensor, characterized in that: It includes a double-layer metasurface, a photoelectric sensor, and a signal processing unit; The double-layer metasurface includes a plurality of polarized light detection units arranged in an array, each polarized light detection unit including a dielectric metasurface disposed on the upper surface of a substrate and a metal metasurface disposed on the lower surface of the substrate. The dielectric metasurface is used to correct inclined incident light to vertical incident light and focus it into a point, and the metal metasurface is used to perform polarization filtering on the vertical incident light focused into a point to transmit a plurality of preset types of linearly polarized light; all of the polarized light detection units have different phases; The photoelectric sensor is used to convert linearly polarized light of a target preset type into an electrical signal of a target preset type; wherein the target preset type is any one of the multiple preset types; The signal processing unit is used to process all the electrical signals of the target preset type and output the target preset polarization angles corresponding to all the electrical signals of the target preset type; The polarized light navigation sensor is used to calculate a navigation angle based on all the preset polarization angles of the targets.

2. The polarized light navigation sensor according to claim 1, wherein: The phase of the polarized light detection unit is determined based on a dielectric metasurface phase equation, which is constructed based on the sum of a quadratic phase equation and a light vector correction phase equation; The light vector correction phase equation is constructed by analyzing the vector propagation properties of light based on the vector triangle and converting the optical path into a phase.

3. The polarized light navigation sensor according to claim 2, wherein: The polarized light detection unit includes a plurality of sub-dielectric metasurfaces with different phases, each of which is composed of a plurality of sub-wavelength-sized metaatoms, and the phase of the metaatom at each position is determined based on the phase equation of the dielectric metasurface.

4. The polarized light navigation sensor according to claim 3, wherein: The size of the superatom at each position is determined based on the phase of the superatom at the position and a pre-built size phase matrix library.

5. The polarized light navigation sensor according to claim 4, wherein: The pre-constructed size phase matrix library is constructed based on the size of each superatom and the phase modulation amount of a specific polarized light corresponding to the superatom of the size.

6. The polarized light navigation sensor according to any one of claims 3 to 5, wherein: The shape of the superatom at each position is an elliptical cylinder or a cube.

7. The polarized light navigation sensor according to claim 1, wherein: The polarized light detection unit includes four areas, each area is used to transmit a preset type of linearly polarized light.

8. The polarized light navigation sensor according to claim 7, wherein: The four regions are used to transmit horizontal linear polarized light, vertical linear polarized light, 45° linear polarized light and 135° linear polarized light respectively.

9. The polarized light navigation sensor according to claim 1, wherein: The signal processing unit is used to determine the linear polarization parameters of the Stokes vector based on all the electrical signals of the target preset type, and determine the target preset polarization angle corresponding to the electrical signal of the target preset type based on the linear polarization parameters of the Stokes vector.

10. An electronic device, characterized in that: The electronic device includes the polarized light navigation sensor according to any one of claims 1 to 9.

Images