A living body recognition depth camera and electronic device

Abstract

A kind of live body recognition depth camera, comprising: light source, for projecting infrared light with first power;Parallel polarizer, located on the light path of the infrared light, to make the infrared light with polarization state irradiate on target object;First multifunctional polarizer, located on the reflection signal light path of the target object, and at least including parallel polarization and vertical polarization two states;First infrared sensor, for receiving the reflection signal passing through the first multifunctional polarizer;Processor, for calculating first AOP according to the reflection signal of the parallel polarization and the vertical polarization, to determine whether the target object is live body.The present application has the characteristics of multi-dimensional information, good noise suppression, high accuracy, good identification effect.

Description

Technical Field

[0001] The present invention relates to the technical field of liveness recognition, and in particular to a liveness recognition depth camera and electronic equipment. Background Art

[0002] In some 2D and 3D payment and recognition applications, the pursuit of high-quality and accurate images is increasing. Polarization technology, due to its unique light field processing capabilities, is increasingly being applied in this area. Through differential imaging, it can effectively suppress some noise and obtain higher-quality images.

[0003] A certain invention provides a liveness verification method and device that performs liveness verification by determining whether the incident light is linearly polarized. The liveness verification method comprises: subjecting the incident light to a set of polarizers, wherein each polarizer in the set does not overlap with another in the direction of light propagation; detecting the intensity of light transmitted through each polarizer in the set to obtain a set of light intensities corresponding to each polarizer; and determining that liveness verification has failed if the set of light intensities meets predetermined conditions. If the incident light is emitted by a liquid crystal display screen, the incident light is linearly polarized, and liveness verification has failed. This invention uses passive light source detection, which is susceptible to interference from external light sources and is unstable. It can only recognize planar prostheses and has poor recognition effect on three-dimensional prostheses such as silicone prostheses, facial molds, and palm molds.

[0004] A certain invention discloses a method for face liveness detection based on polarization imaging, comprising the steps of: real-time acquisition of polarization images of the target to be detected at multiple angles; polarization analysis of the polarization images using a polarization face feature learning and classification network model based on a twin neural network structure to identify the authenticity of the target to be detected. The present invention uses a non-contact real-time detection method that does not require the user's active cooperation. Accurate detection can be achieved even when the user is not cooperating, providing a good user experience. The invention utilizes a twin neural network structure for learning and training, which is time-consuming and cannot effectively identify and distinguish different materials.

[0005] However, the current polarization scheme is still lacking in the ability to distinguish between living organisms and silicone. We need to make some breakthroughs in this technology to make up for this disadvantage.

[0006] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0007] To this end, the present invention sets a parallel polarizer at the transmitting end so that the emitted light is linearly polarized light, and sets a first multifunctional polarizer at the receiving end to obtain reflected signals with different polarization directions, and then calculates the first AOP to determine whether the target object is a living body. It has the characteristics of multi-dimensional information, good noise suppression, high accuracy and good recognition effect.

[0008] In a first aspect, the present invention provides a living body recognition depth camera, characterized by comprising:

[0009] a light source for projecting infrared light at a first power;

[0010] a parallel polarizer, located in the optical path of the infrared light, so that the infrared light is irradiated on the target object in a polarized state;

[0011] A first multifunctional polarizer is located on the reflected signal light path of the target object and has at least two states: parallel polarization and vertical polarization;

[0012] a first infrared sensor, configured to receive a reflected signal from the first multifunctional polarizer;

[0013] The processor is configured to calculate a first AOP based on the parallel polarization and the perpendicular polarization reflection signals, and further determine whether the target object is a living body.

[0014] Optionally, the living body recognition depth camera is characterized by further comprising:

[0015] a second multifunctional polarizer, located in the reflected signal light path of the target object, having the same structure as the first multifunctional polarizer and having a different polarization direction from the first multifunctional polarizer at an aligned position, so as to obtain a different polarization image at the same position of the target object;

[0016] The second infrared sensor is used to receive the reflected signal passing through the second multifunctional polarizer.

[0017] Optionally, the living body recognition depth camera is characterized by further comprising:

[0018] The first driving unit is connected to the first multifunctional polarizer and is used to drive the first multifunctional polarizer to rotate.

[0019] Optionally, the living body recognition depth camera is characterized in that the first multifunctional polarizer includes at least a first polarization zone, a second polarization zone, a third polarization zone and a fourth polarization zone;

[0020] The polarization direction of the first polarization zone is the same as the polarization direction of the parallel polarizer;

[0021] The second polarization region has a first polarization direction;

[0022] The third polarization region has a second polarization direction;

[0023] The polarization direction of the fourth polarization region is perpendicular to the polarization direction of the parallel polarizer;

[0024] The first polarization direction and the second polarization direction are neither the same nor perpendicular to the polarization direction of the parallel polarizer.

[0025] Optionally, the living body recognition depth camera has the following characteristics.

[0026] Optionally, the living body recognition depth camera has the following characteristics.

[0027] Optionally, the living body recognition depth camera has the following characteristics.

[0028] Optionally, the living body recognition depth camera has the following characteristics.

[0029] Optionally, the living body recognition depth camera has the following characteristics.

[0030] In a second aspect, the present application provides an electronic device, which has the following characteristics.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] The present invention projects polarized light and receives at least two different polarization state signals during reception, and can simultaneously obtain the characteristics of the human body surface and human body veins, obtain more information dimensions than the existing technology, and can perform living body recognition more comprehensively.

[0033] The present invention can effectively suppress noise by equipping the transmitting end and the receiving end with polarizers at the same time, so that the obtained signal is clearer and the data is more accurate.

[0034] The present invention uses the first AOP to determine whether the target object is alive, making full use of the information difference between the human body surface and veins. It has a good recognition effect on various types of prostheses such as flat prostheses and silicone prostheses, so the living body recognition effect is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without inventive work. Other features, purposes and advantages of the present invention will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0036] Figure 1 Schematic diagram of the structure of a living body recognition depth camera according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of a first multifunctional polarizer according to an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of another living body recognition depth camera in an embodiment of the present invention;

[0039] Figure 4 This is a schematic structural diagram of a first receiving end according to an embodiment of the present invention;

[0040] Figure 5 is a schematic diagram of another first multifunctional polarizer according to an embodiment of the present invention;

[0041] Figure 6 Schematic diagram of the structure of a switchable light source in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that for those skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made. These are within the scope of the application.

[0043] The terms "first", "second", "third", "fourth" and the like in the description, claims, and drawings of the application, and those above, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the use of the terms so construed can be interchanged, such that, for example, embodiments of the application described herein can operate in other sequences than the one illustrated or other than the one explicitly described herein. Moreover, the terms "comprise", "comprising", "have", "having", "include", "including", and "contains", "containing", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, or contains a list of steps or elements does not include only those steps or elements but can include other not expressly listed steps or elements.

[0044] The embodiment of the application provides a living body recognition depth camera, and aims to solve the problems in the prior art.

[0045] The technical solutions of the application and how the technical solutions of the application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the application will be described below with reference to the drawings.

[0046] The application sets a parallel polarizer at the transmitting end, so that the emitted light is linearly polarized light, sets a first multifunctional polarizer at the receiving end, obtains reflection signals of different polarization directions, calculates the first AOP, and then determines whether the target object is a living body, and has the characteristics of multi-dimensional information, good noise suppression, high accuracy and good identification effect.

[0047] Figure 1 The application provides a structure diagram of a living body recognition depth camera. As shown in the figure, Figure 1 The living body recognition depth camera comprises:

[0048] The light source 1 is used for projecting infrared light at a first power.

[0049] Specifically, the light source can project both structured light spots and flood light. The intensity of the light source must meet safety standards for the human body and the human eye. The first power is a power that enables the first infrared sensor to obtain a clear reflection signal. In some embodiments, the light source is an infrared flood light source, and correspondingly, the infrared sensor is a flood light sensor to obtain more comprehensive target object data. In this embodiment, the light source is the transmitting end. In some embodiments, components such as a collimator and a projection lens are also included to achieve a better projection effect.

[0050] The parallel polarizer 2 is located on the optical path of the infrared light so that the infrared light is irradiated on the target object in a polarized state.

[0051] Specifically, the parallel polarizer converts the light emitted by the light source 1 into linearly polarized light. Due to the characteristics of polarized light, the light intensity is strongest in the polarization direction. The light source 1 and the parallel polarizer 2 constitute the emission end of this embodiment.

[0052] The first multifunctional polarizer 3 is located on the reflected signal light path of the target object and has at least two states: parallel polarization and vertical polarization.

[0053] Specifically, the first multifunctional polarizer and the first infrared sensor constitute the first receiving end of this embodiment. The first multifunctional polarizer is located at the front end of the first infrared sensor and is used to receive reflected light. Figure 2 As shown, the first multifunctional polarizer includes at least two polarization states, so that the reflected light has at least two polarization information. For parallel polarization, since it is in the same polarization direction as the parallel polarizer, its signal is the strongest. For vertical polarization, since it is perpendicular to the polarization direction of the parallel polarizer, its signal is the weakest. For the human body, when linearly polarized light is incident on the skin, the skin surface will reflect the polarized light while the polarization state remains unchanged. The internal tissue of the skin will scatter and reflect, and the polarization direction will change when it is emitted. Parallel polarization can obtain surface information and can be used to extract skin surface textures for matching, meeting the surface information extraction function of conventional cameras; vertical polarization can obtain internal information and can be used to extract subcutaneous tissue information including vein information, which can be used for partial living body and medical imaging applications. The first multifunctional polarizer can be of any shape, such as circular, square, elliptical, etc. Preferably, the shape of the first multifunctional polarizer is the same as that of the first infrared sensor.

[0054] The first infrared sensor 4 is used to receive the reflection signal passing through the first multifunctional polarizer.

[0055] Specifically, the distance between the first multifunctional polarizer and the first infrared sensor is no more than 6 mm. The closer the distance between the first multifunctional polarizer and the first infrared sensor, the better. It can be any value among 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, though other values ​​are also possible. The closer the distance between the first multifunctional polarizer and the first infrared sensor, the more uniform the light sensed by the first infrared sensor, resulting in better imaging quality. As the distance between the first multifunctional polarizer and the first infrared sensor increases, the likelihood of interference between reflected light from different regions increases. In this embodiment, the less signal interference, the higher the accuracy of the polarization information obtained, and the more accurate the recognition results for living organisms.

[0056] The processor 5 is configured to calculate a first AOP based on the parallel polarization and the perpendicular polarization reflection signals, and further determine whether the target object is a living body.

[0057] Specifically, the polarization direction AOP (Angle of Polarization) is used to calculate the ratio of parallel polarization to vertical polarization, thereby obtaining the angle θ of the polarized light. For the case of only parallel polarization and vertical polarization, in the calculation of the first AOP, S2 is the intensity of the vertically polarized light, and S1 is the intensity of the parallel polarized light.

[0058] Figure 3 FIG. 1 is a structural diagram of another living body recognition depth camera according to an embodiment of the present invention. Figure 3 As shown, compared with the above embodiment, another living body recognition depth camera in the embodiment of the present invention further includes:

[0059] The second multifunctional polarizer 6 is located in the reflected signal light path of the target object and has the same structure as the first multifunctional polarizer. Its polarization direction is different from that of the first multifunctional polarizer at the aligned position to obtain different polarization images at the same position of the target object.

[0060] Specifically, the second multifunctional polarizer and the first multifunctional polarizer are identical in terms of the number of polarization states, the size of the polarization zones, and the polarization distribution, except for the difference in polarization direction. If the first multifunctional polarizer only includes parallel and perpendicular polarization states, the second multifunctional polarizer also includes parallel and perpendicular polarization states. If the first multifunctional polarizer includes parallel polarization, perpendicular polarization, +45-degree polarization, and -45-degree polarization, the second multifunctional polarizer also includes parallel polarization, perpendicular polarization, +45-degree polarization, and -45-degree polarization. If the first multifunctional polarizer includes four polarization zones, the second multifunctional polarizer also includes four polarization zones. If the first multifunctional polarizer includes 40 polarization zones, the second multifunctional polarizer also includes 40 polarization zones. The difference between the first and second multifunctional polarizers lies in the different polarization directions within each individual polarization zone. For example, the first multifunctional polarizer is divided into four polarization zones, and the polarization directions are parallel polarization, vertical polarization, +45 degree polarization, and -45 degree polarization. The second multifunctional polarizer is also divided into four polarization zones, and the polarization directions can be +15 degree polarization, -75 degree polarization, +75 degree polarization, and -30 degree polarization; or they can be +45 degree polarization, -45 degree polarization, parallel polarization, and vertical polarization.

[0061] The second infrared sensor 7 is used to receive the reflected signal passing through the second multifunctional polarizer.

[0062] Specifically, the second infrared sensor 7 is identical to the first infrared sensor 4. The second multifunctional polarizer and the second infrared sensor form a second receiving end. Aside from the different polarization directions of the first and second multifunctional polarizers, the second receiving end is identical to the first receiving end in all other respects, including but not limited to the distance between the infrared sensor and the multifunctional polarizer, the orientations of the first and second receiving ends, and the distances between the first and second receiving ends and the transmitting end.

[0063] In this embodiment, a second receiving end is added, which can synchronously generate target objects with different polarization characteristics. By comparing the image of the first infrared sensor with the image of the second infrared sensor, different first AOPs are calculated, and information of different dimensions is added. This can more comprehensively evaluate the characteristics of the target object, have better resistance to prosthesis attacks, and more accurate liveness recognition results.

[0064] Figure 4 FIG. 1 is a schematic diagram of the structure of a first receiving end in an embodiment of the present invention. Figure 4 As shown, in an embodiment of the present invention, a first receiving end further includes:

[0065] The first driving unit 8 is connected to the first multifunctional polarizer 3 and is used to drive the first multifunctional polarizer 3 to rotate.

[0066] Specifically, the first driving part can rotate the first multifunctional polarizer, so that the polarization state of the reflected signal is changed, and the first infrared sensor receives signals of different polarization directions. The first driving part is located at the periphery or lower part of the first multifunctional polarizer and drives the rotation of the first multifunctional polarizer through friction. The first driving part does not affect the transmission of light. Preferably, the first driving part, the first multifunctional polarizer, and the first infrared sensor are circular.

[0067] In some embodiments, the first driving part rotates at a constant speed under the control of the processor, so that the polarization state received by the first infrared sensor is periodically changed. This causes the polarization state on the generated image to be different at adjacent time points, so that images of the target object in multiple different polarization states can be obtained within a period of time. By analyzing and comparing multiple images within a period of time, a more accurate living body judgment result can be obtained.

[0068] In some embodiments, the second receiving end further comprises a second driving part 9 connected with the second multifunctional polarizer 6 for driving the second multifunctional polarizer 6 to rotate. The function of the second driving part is the same as that of the first driving part. Details are not repeated here.

[0069] Figure 5 Another schematic diagram of the first multifunctional polarizer in an embodiment of the present application is shown in FIG. 3. As shown in FIG. 3, the first multifunctional polarizer in the embodiment of the present application at least comprises a first polarization region 31, a second polarization region 32, a third polarization region 33, and a fourth polarization region 34. Figure 5

[0070] The polarization direction of the first polarization region is the same as that of the parallel polarizer;

[0071] The second polarization region has a first polarization direction;

[0072] The third polarization region has a second polarization direction;

[0073] The polarization direction of the fourth polarization region is perpendicular to that of the parallel polarizer;

[0074] The first polarization direction and the second polarization direction are neither the same nor perpendicular to the polarization direction of the parallel polarizer.

[0075] ​Specifically, the first polarization zone, the second polarization zone, the third polarization zone, and the fourth polarization zone are processed on the first multifunctional polarizer through an etching process. The first polarization zone is parallel polarization, and the fourth polarization zone is vertical polarization. The polarization directions of the second polarization zone and the third polarization zone are neither parallel nor vertical. The polarization directions of the second polarization zone and the third polarization zone are also different. The angle between the first polarization direction and the polarization direction of the parallel polarizer does not exceed 45 degrees; the angle between the second polarization direction and the polarization direction of the parallel polarizer is not less than 45 degrees. There are multiple first polarization zones, second polarization zones, third polarization zones, and fourth polarization zones, and the array is distributed on the first multifunctional polarizer. Any four adjacent zones contain the first polarization zone, the second polarization zone, the third polarization zone, and the fourth polarization zone to obtain the polarization characteristics of each zone.

[0076] This embodiment uses Stokes's proposal to use four parameters to describe the intensity and polarization state of light waves. They are: S0, S1, S2 and S3. S0 represents the total incident light intensity, S1 represents the intensity difference between the x component and the y component, S2 represents the intensity difference between the +45° and -45° polarization components, and S3 represents the intensity difference between the left-handed and right-handed circularly polarized components. In calculations, S0, S1, S2 and S3 are generally normalized, with the value of S0 being between 0 and 1, and the values ​​of S1, S2 and S3 being between -1 and +1. For natural non-polarized light, I x =I y , I +45 =I -45 , I l =I r If S1, S2 or S3 is not 0, it means there is polarized light.

[0077] S1=I x -I y ;

[0078] S2=I +45 -I -45 ;

[0079] The polarization direction AOP (Angle of Polarization) is the angle θ between the main axis of the ellipse in elliptically polarized light and the x-axis of the traditional coordinate system:

[0080]

[0081] According to the polarization information of the second polarization zone and the third polarization zone, the Stokes parameter S2 is composed; the polarization information of the first polarization zone and the fourth polarization zone constitutes the Stokes parameter S1; according to S1 and S2, the first AOP can be calculated to obtain the polarization characteristics of the target object; when the polarization characteristics are within the preset range, it is determined to be a living body, otherwise it is a prosthesis.

[0082] When the first polarization direction is 45 degrees and the second polarization direction is -45 degrees, θ can be directly calculated using the above formula. If the first polarization direction and the second polarization direction are not in the above formula, it is necessary to calculate the first polarization direction and the second polarization direction to obtain the light intensity at 45 degrees and -45 degrees, and then use the above formula to calculate.

[0083] When the first, second, third, and fourth polarization zones are arranged in an array on the first multifunctional polarizer, and any four adjacent zones contain the four different polarization zones, four different polarization characteristics can be obtained for each zone. Using the above formula, the AOP for each polarization zone can be calculated. By sequentially calculating the AOP for the entire image, the AOP for all zones can be determined, resulting in an accurate AOP image, which represents the polarization characteristics of the entire image.

[0084] In some embodiments, the first, second, third, and fourth polarization zones are separated by the same distance d, and the distance d is proportional to the distance t between the first multifunctional polarizer and the first infrared sensor. Furthermore, due to manufacturing processes, the edges of the first, second, third, and fourth polarization zones may exhibit irregularities, complex diffraction, and scattering, resulting in reduced effectiveness of signals received by the first infrared sensor at the edges of the first, second, third, and fourth polarization zones. Consequently, signals within a distance s from the edges of the first, second, third, and fourth polarization zones on the first infrared sensor are discarded. The distance s is proportional to the distance t.

[0085] In some embodiments, the light source intensity is adjusted to a second power to obtain a second AOP for liveness detection. Due to individual differences and varying surface and vein characteristics in different parts of the human body, infrared light emitted at a given power can capture different signals from the human body. Therefore, it is necessary to adjust the light source intensity and perform the functions or steps of the aforementioned embodiments to obtain a second AOP for liveness detection and obtain a liveness detection result.

[0086] In some embodiments, the light source can project both structured light and flood light, and has different powers; when adjusting the intensity of the light source, the projection type of the light source is changed. Figure 6 As shown in FIG. 11, the light source includes a light emitting unit 11 and an electrically controlled glass 12. When the light emitting unit 11 works, the light emitting unit projects a structured light beam. The electrically controlled glass can be switched between a first state and a second state by controlling voltage. When the electrically controlled glass is in the first state, the electrically controlled glass is in a transparent state, and the light beam is emitted in the form of structured light. When the electrically controlled glass is in the second state, the electrically controlled glass is in an opaque state, and the light beam is emitted in the form of flood light after being diffused. Since there is a large loss in the diffusion of light, the light power in the second state is less than the light power in the first state. Therefore, by changing the projection type of the light source, the light intensity can also be changed.

[0087] In some embodiments, when the living body recognition results of the first AOP and the second AOP are different, the intensity of the light source is adjusted to a third power, and the third AOP is calculated to obtain a living body recognition result; the third power is the average of the first power and the second power. When the first AOP and the second AOP are consistent, the living body recognition result is taken as the final result. When the living body recognition results of the first AOP and the second AOP are different, there is a part of data abnormality in one case, such as surface roughness, multi-layer material, etc. The third power is additionally taken for data acquisition and calculation to obtain the final living body recognition result.

[0088] The embodiment of the present application also provides an electronic device, which includes the living body recognition depth camera provided by any of the above embodiments, and the electronic device can be a mobile phone, a tablet computer, a payment terminal, a digital camera, etc. The electronic device with living body recognition provided by the present application uses the polarization characteristics for living body recognition, has specific and accurate living body recognition capability, and effectively resists various prosthesis attacks.

[0089] The embodiments in the present specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other. The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications of the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0090] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A living body recognition depth camera, characterized in that: include: a light source for projecting infrared light at a first power; a parallel polarizer, located in the optical path of the infrared light, so that the infrared light is irradiated on the target object in a polarized state; A first multifunctional polarizer is located on the reflected signal light path of the target object and has at least two states: parallel polarization and vertical polarization; a first infrared sensor, configured to receive a reflected signal from the first multifunctional polarizer; a processor, configured to calculate a first AOP based on the parallel polarization and the perpendicular polarization reflection signals, and thereby determine whether the target object is a living body; The first multifunctional polarizer includes at least a first polarization zone, a second polarization zone, a third polarization zone and a fourth polarization zone; The polarization direction of the first polarization zone is the same as the polarization direction of the parallel polarizer; The second polarization zone has a first polarization direction; The third polarization zone has a second polarization direction; The polarization direction of the fourth polarization zone is perpendicular to the polarization direction of the parallel polarizer; The first polarization direction and the second polarization direction are neither the same as nor perpendicular to the polarization direction of the parallel polarizer; According to the polarization information of the second polarization zone and the third polarization zone, the Stokes parameter S2 is composed; the polarization information of the first polarization zone and the fourth polarization zone constitutes the Stokes parameter S1; according to S1 and S2, the first AOP can be calculated to obtain the polarization characteristics of the target object; when the polarization characteristics are within the preset range, it is determined to be a living body, otherwise it is a prosthesis.

2. The living body recognition depth camera according to claim 1, characterized in that: Also includes: a second multifunctional polarizer, located in the reflected signal light path of the target object, having the same structure as the first multifunctional polarizer and having a different polarization direction from the first multifunctional polarizer at an aligned position, so as to obtain a different polarization image at the same position of the target object; The second infrared sensor is used to receive the reflected signal passing through the second multifunctional polarizer.

3. The living body recognition depth camera according to claim 1, characterized in that: Also includes: The first driving unit is connected to the first multifunctional polarizer and is used to drive the first multifunctional polarizer to rotate.

4. The living body recognition depth camera according to claim 1, characterized in that: There are a plurality of the first polarization zones, the second polarization zones, the third polarization zones, and the fourth polarization zones, and the zones are distributed in an array on the first multifunctional polarizer.

5. The living body recognition depth camera according to claim 4, characterized in that: Any four adjacent areas include the first polarization area, the second polarization area, the third polarization area, and the fourth polarization area, so as to obtain polarization characteristics of each area.

6. A living body recognition depth camera, characterized in that: include: a light source for projecting infrared light at a first power; a parallel polarizer, located in the optical path of the infrared light, so that the infrared light is irradiated on the target object in a polarized state; A first multifunctional polarizer is located on the reflected signal light path of the target object and has at least two states: parallel polarization and vertical polarization; a first infrared sensor, configured to receive a reflected signal from the first multifunctional polarizer; a processor, configured to calculate a first AOP based on the parallel polarization and the perpendicular polarization reflection signals, and thereby determine whether the target object is a living body; adjusting the intensity of the light source to a second power to obtain a second AOP for living body recognition; When the liveness recognition results of the first AOP and the second AOP are different, the intensity of the light source is adjusted to a third power, and the third AOP is calculated to obtain the liveness recognition result; the third power is the average of the first power and the second power.

7. An electronic device, characterized in that: A living body recognition depth camera comprising any one of claims 1-6.

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