A linear polarization angle measurement device and method for enhancing the polarization degree of skylight reception

Abstract

The present disclosure relates to the technical field of skylight polarization parameter measurement, and provides a device and a method for enhancing the measurement of skylight polarization degree, including two skylight detection units and a differential amplifier. The output end of each skylight detection unit is respectively connected to the differential amplifier, and the differential amplifier outputs the light intensity component of a preset polarization angle. The preset polarization angles of the two skylight detection units differ by 90 degrees. The photosensitive voltage generated by one skylight detection unit is amplified and used as the control voltage of the liquid crystal layer of the other skylight detection unit. The two skylight detection units cooperate with each other to filter out the common-mode components in the skylight and enhance the total polarization degree of the transmitted light. During the measurement process of the device of the present disclosure, detection is achieved through the mutual control of the two skylight detection units, which can increase the measurement difference between the two skylight detection units, realize the enhancement of the polarization degree of the perspective light, and thus measure a more accurate linear polarization angle.

Description

Technical Field

[0001] The present disclosure relates to the technical field related to the measurement of sky light polarization parameters. Specifically, it relates to a linear polarization angle measurement device and method for enhancing the polarization degree of received sky light. Background Art

[0002] The statements in this part merely provide background technical information related to the present disclosure and do not necessarily constitute prior art.

[0003] Light is an electromagnetic wave and a transverse wave. Usually, the light waves emitted by a light source have the vibration of the light wave vector randomly oriented perpendicular to the propagation direction of the light. According to statistical results, in all possible directions in space, the distribution of the light wave vectors can be regarded as uniform, and their sum is symmetric with the propagation direction of the light, that is, the light wave vector has the characteristics of axial symmetry, uniform distribution, and the same amplitude of vibration in all directions. This kind of light is called natural light. The plane formed by the vibration direction and the propagation direction of the light wave is called the vibration plane. The light whose vibration plane is limited to a certain fixed direction is called plane polarized light or linearly polarized light. The light emitted by a general light source has a vibration plane that is not limited to a single fixed direction but is uniformly distributed in direction. This kind of light is called natural light. Among them, transverse waves have polarization. The asymmetry of the vibration direction with respect to the propagation direction is called polarization. The phenomenon that the spatial distribution of the vibration of the light wave electric vector loses symmetry with respect to the propagation direction of the light is called the polarization of light. The light that loses this symmetry of vibration is called polarized light.

[0004] In scientific fields related to the propagation of transverse waves, such as optics (polarization), electromagnetics (polarization), etc., polarization is an important parameter. Although the names of polarization are different in different disciplines, the parameters described are the same; polarization in optics and polarization in electromagnetics are essentially the same. In an optical system, lights with a linear polarization angle difference of 90 degrees are orthogonal. Using the polarization characteristics of light, a 3D vision system can be developed, and an orthogonal light modulation or transmission system can be developed; similarly, horizontally polarized and vertically polarized electromagnetic waves in electromagnetics also have orthogonal characteristics. Insects or marine animals use the distribution characteristics of the polarization components in sky light for navigation, and people also develop underwater bionic polarization compasses using the navigation principle of marine animals.

[0005] The inventors found that in current polarization measurement methods, since the actually measured polarization degree of sky light is often very small, especially the sky light detected in deep water areas or rainy days, the polarization degree is sometimes less than 0.001. For common polarization angle test methods, it is very difficult to ensure the measurement accuracy of the linear polarization angle of sky light. Summary of the Invention

[0006] To solve the above problems, the present disclosure proposes a linear polarization angle measurement device and method for enhancing the polarization degree of received skylight. During the measurement process, detection is achieved through mutual control of two skylight detection units, which can increase the difference value between the two skylight detection units, enhance the polarization degree of the received transmitted light, and thus measure a more accurate linear polarization angle. Two sets of polarization angle detection units that are perpendicular to each other, namely the skylight detection units, mutually filter out the common-mode components of the two units through negative feedback to improve the polarization degree of the received skylight, and then use a classic differential amplifier to obtain the polarization components. The use of dual measurement units greatly improves the test accuracy of the polarization component distribution characteristics.

[0007] To achieve the above object, the present disclosure adopts the following technical solutions:

[0008] One or more embodiments provide a linear polarization angle measurement device for enhancing the polarization degree of received skylight, including two skylight detection units and a differential amplifier. The output end of each skylight detection unit is respectively connected to the differential amplifier, and the differential amplifier outputs the light intensity component of a preset polarization angle.

[0009] The photosensitive voltage generated by one skylight detection unit is amplified and used as the control voltage of the liquid crystal layer of the other skylight detection unit. The two skylight detection units cooperate with each other to filter out the common-mode components in the skylight and enhance the total polarization degree of the received transmitted light.

[0010] One or more embodiments provide a method for measuring the polarization angle of skylight, which measures the polarization angle of skylight by measuring the light intensity component of a preset polarization angle, including the following steps:

[0011] Receive the irradiation of skylight. The antireflection layer reduces the reflection of light and increases the intensity of transmitted light, and the enhanced light enters the polarization layer.

[0012] After the light enters the polarization layer, it is divided into two kinds of polarized light with different directions by the polarizer in the polarization layer. The polarized light passes through the liquid crystal layer and enters the photosensitive layer.

[0013] When the light enters the photosensitive layer, the photosensitive layer outputs a photosensitive voltage according to the brightness of the light. Two sets of skylight detection units mutually activate the liquid crystal layer, and the liquid crystal layer adjusts the light transmittance according to the received photosensitive voltage.

[0014] Two photosensitive layers output different photosensitive voltages to the differential amplifier according to the received light brightness. The differential amplifier amplifies the voltage difference at the input end and outputs a measurement voltage, and the measurement voltage corresponds to the light intensity component of the incident light, that is, the skylight, at a preset polarization angle.

[0015] Compared with the prior art, the beneficial effects of the present disclosure are:

[0016] In the present disclosure, the structure of the skylight polarization degree enhancement device is simple and easy to implement. Detection is achieved through the mutual control of two skylight detection units, which can reduce the common-mode components of the two skylight detection units, enhance the polarization degree of perspective light, and thus measure a more accurate linear polarization angle.

[0017] The advantages of the present disclosure and the advantages of additional aspects will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings forming a part of this disclosure are used to provide a further understanding of the disclosure. The illustrative embodiments of the disclosure and their descriptions are used to explain the disclosure and do not constitute a limitation to the disclosure.

[0019] Figure 1 is a schematic structural diagram of the measuring device according to Embodiment 1 of the present disclosure.

[0020] Figure 2 is the state where the liquid crystal layer in Embodiment 1 of the present disclosure is not activated;

[0021] Figure 3 is the state where the liquid crystal layer in Embodiment 1 of the present disclosure has the maximum voltage. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present disclosure will be further described below in conjunction with the drawings and embodiments.

[0023] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present disclosure belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features in the present disclosure can be combined with each other. The embodiments will be described in detail below in conjunction with the drawings.

[0025] Embodiment 1

[0026] In the technical solutions disclosed in one or more embodiments, as Figures 1 - 3As shown in the figure, a device for enhancing the measurement of the polarization degree of skylight is a linear polarization angle measurement device that can enhance the polarization degree of received skylight. It includes two skylight detection units and a differential amplifier. The output terminals of each skylight detection unit are respectively connected to the differential amplifier, and the differential amplifier outputs the light intensity component corresponding to the preset polarization angle.

[0027] The preset polarization angles of the two skylight detection units differ by 90 degrees. The photosensitive voltage generated by one skylight detection unit is amplified and used as the control voltage for the liquid crystal layer of the other skylight detection unit. The two skylight detection units cooperate with each other to filter out the unpolarized components in the skylight and enhance the total polarization degree of the transmitted light.

[0028] In this embodiment, the structure of the device for enhancing the measurement of the polarization degree of skylight is simple and easy to implement. Detection is achieved through the mutual control of the two skylight detection units, which can increase the polarization degree of the received skylight, thereby making the measurement of the preset linear polarization angle component more accurate. Since the polarization degree of skylight in nature is very small, it makes the measurement of the linear polarization angle difficult and the measurement accuracy low. The device provided in this embodiment increases the polarization degree of the actually received skylight and can be used in devices such as navigation and positioning based on the polarization angle of skylight, making the measurement easier and the data more accurate.

[0029] Optionally, in this embodiment, the preset polarization angles of the two skylight detection units differ by 90 degrees, that is, the polarization directions of the polarization layers in the two skylight detection units are perpendicular to each other, which can enable the two skylight detection units to cooperate with each other to filter out the unpolarized components in the skylight and enhance the total polarization degree of the transmitted light.

[0030] In some embodiments, each skylight detection unit includes an antireflection layer, a polarization layer, a liquid crystal layer, and a photosensitive layer connected in sequence, which reduces reflection, filters, and then adjusts the light transmittance of the liquid crystal layer for skylight, and finally transmits it to the differential amplifier through the photosensitive layer to enhance the polarization degree of skylight.

[0031] Antireflection layer: In addition to antireflection, this layer also serves as the control electrode for the liquid crystal layer. It is used to reduce the reflection of skylight, increase the intensity of the transmitted light, and improve the light transmission performance of the device. The light enhanced by the antireflection layer enters the polarization layer.

[0032] Polarization layer: It is used to filter skylight and filter out the light that is inconsistent with the preset polarization direction of the polarization layer; the polarization angle set in the polarization layer polarizes the skylight to obtain polarized light with a preset polarization direction.

[0033] Liquid crystal layer: It is used to control the light transmission ratio. The light passing through the polarization layer will pass through the liquid crystal layer to reach the photosensitive layer; the higher the voltage of the liquid crystal layer, the lower the light transmittance.

[0034] Photosensitive layer: It is used to generate a photosensitive voltage according to the received light intensity; at the same time, this layer also serves as the control electrode for the liquid crystal layer. When the light irradiating the photosensitive layer is bright, the voltage output by the photosensitive layer is high; when the light irradiating the photosensitive layer is dim, the voltage output by the photosensitive layer is low.

[0035] In this embodiment, two skylight detection units are provided. The photosensitive layer of one skylight detection unit is connected to the antireflection layer and the photosensitive layer of the other skylight detection unit. The light transmittance of the liquid crystal layer of the other skylight detection unit is controlled by the photosensitive voltage, so that the difference in the photosensitive voltages output by the two photosensitive layers increases.

[0036] Optionally, the antireflection layer can use a titanium dioxide antireflection film. The titanium dioxide antireflection film has excellent refractive index, good electrical conductivity, and certain waterproof and moisture-proof effects.

[0037] Optionally, the polarization layer can adopt a polyvinyl alcohol sheet. The production method of the polarizer is: using polyvinyl alcohol as the sheet base, immersing it in iodine solution, stabilizing it by reduction with boric acid aqueous solution, and then unidirectionally stretching to make the polarizer.

[0038] Optionally, the specific structure of the liquid crystal layer is: a liquid crystal material polymerized with epoxy resin, and the mass fraction of epoxy resin is less than 10%. Negative liquid crystal molecules and epoxy resin polymerize to form a polymer network structure. In the normal state, the liquid crystal molecules are arranged perpendicular to the photosensitive layer, and the liquid crystal layer is in a transparent state. Under the action of an electric field, the liquid crystal molecules deflect along the direction perpendicular to the electric field, but the elastic force of the epoxy resin in the polymer network will hinder the deflection of the liquid crystal molecules, so that the liquid crystal molecules become disordered as a whole, and the transparency of the liquid crystal layer decreases.

[0039] Optionally, the photosensitive layer can adopt an amorphous silicon thin film, which generates electric energy under the irradiation of light.

[0040] Furthermore, a voltage amplifier is also included. Each output terminal of the photosensitive layer is connected to a voltage amplifier, and the voltage amplifiers are respectively connected to a differential amplifier and the antireflection layer and the photosensitive layer of the other skylight detection unit, which can control the liquid crystal molecules of the liquid crystal layer of the other skylight detection unit, and output the light intensity component for measuring the linear polarization angle through the differential amplifier.

[0041] In this embodiment, the photosensitive voltage generated by one skylight detection unit is amplified and used as the control voltage for the liquid crystal layer of the other skylight detection unit. Specifically, the stronger the light intensity received by the photosensitive layer, the higher the photosensitive voltage, and the lower the light transmittance of the liquid crystal layer of the other skylight detection unit; the weaker the light intensity received by the photosensitive layer, the lower the photosensitive voltage, and the higher the light transmittance of the liquid crystal layer of the other skylight detection unit. After the liquid crystal layer is activated, the final brightness irradiating the photosensitive layer will change, and the two photosensitive layers output different voltages to the differential amplifier according to the light intensity they receive respectively.

[0042] The specific method for the liquid crystal layer to change the light transmittance is as follows: The network structure formed by the liquid crystal layer and the polymer is arranged along the direction perpendicular to the photosensitive layer. As Figure 2 shown, when no electric field is applied, since the refractive index of the liquid crystal matches the refractive index of the polymer network, the liquid crystal layer is in a transparent state. The antireflection layer and the photosensitive layer of this unit both use materials with excellent electrical conductivity to act as electrodes. After the photosensitive layer emits voltage under light irradiation, it outputs voltage to the antireflection layer and the photosensitive layer of another unit, forming an electric field between the two layers. As Figure 3 shown, since the liquid crystal layer is between the antireflection layer and the photosensitive layer, under the action of the electric field, the liquid crystal molecules deflect, but the elastic force of the epoxy resin in the polymer network will hinder the deflection of the liquid crystal molecules, making the overall direction of the liquid crystal molecules disordered finally, strongly scattering the incident light, and reducing the transparency of the liquid crystal layer.

[0043] After the photosensitive layer outputs the photosensitive voltage, due to the change of the light transmittance of the liquid crystal layer, the light transmittance of the liquid crystal layer where the received light is strong will increase, and the light transmittance of the liquid crystal layer where the received light is weak will decrease. That is, the light transmittance of the liquid crystal layer of the skylight detection unit where the photosensitive layer originally received stronger light is high, and the light transmittance of the liquid crystal layer of the skylight detection unit where the photosensitive layer originally received weaker light is low, further increasing the difference in the light intensity received by the two photosensitive layers. Then, the photosensitive layer outputs voltage to the differential amplifier according to the finally received light intensity, and the differential amplifier outputs the light intensity component of the preset polarization angle after enhancing the polarization degree.

[0044] Embodiment 2

[0045] Based on Embodiment 1, a method for measuring the polarization angle of skylight is provided in this embodiment. By measuring the light intensity component of the preset polarization angle to measure the polarization angle of skylight, the method includes the following steps:

[0046] Step 1: Receive the irradiation of skylight. The antireflection layer reduces the reflection of light, increases the intensity of the transmitted light, and the enhanced light enters the polarization layer;

[0047] Step 2: After the light enters the polarization layer, it is polarized by the polarization structure in the polarization layer and becomes polarized light. The polarized light passes through the liquid crystal layer and enters the photosensitive layer;

[0048] Step 3: After the light enters the photosensitive layer, the photosensitive layer outputs the photosensitive voltage according to the brightness of the light. The two skylight detection units mutually activate the liquid crystal layer, and the liquid crystal layer adjusts the light transmittance according to the received photosensitive voltage;

[0049] The stronger the light brightness received by the photosensitive layer, the lower the light transmittance of the liquid crystal layer of the other skylight detection unit; the weaker the light brightness received, the higher the light transmittance of the liquid crystal layer of the other skylight detection unit.

[0050] Step 4: According to the received light brightness, the two photosensitive layers output different photosensitive voltages to the differential amplifier. After amplifying the voltage difference at the input end, the differential amplifier outputs a measurement voltage, and the measurement voltage corresponds to the magnitude of the light intensity component of the incident light, i.e., the preset linear polarization angle of the skylight.

[0051] In Step 1, specifically, sunlight is natural light. When sunlight passes through the atmosphere, air molecules, dust, and water vapor in the atmosphere undergo diffuse reflection, and the polarization angle of the scattered sunlight at various places in the sky changes. The scattered points scattered throughout the sky form skylight. When the light irradiates the object surface, it will be reflected, increasing the difficulty of measurement. The first layer of this device uses an antireflection film to reduce the reflection of skylight, making this device more accurate.

[0052] Specifically, when the preset polarization directions of the two measurement units are perpendicular to each other. The skylight is polarized by the polarization films of the two measurement units and becomes polarized light, which enters the photosensitive layer.

[0053] The liquid crystal layer realizes the transmission and shielding of the light source. In this embodiment, the stronger the light received by the photosensitive layer, the higher the output voltage, making the light transmittance of the other liquid crystal layer lower, and vice versa. The liquid crystal layer with stronger incident light has a higher light transmittance, and the liquid crystal layer with weaker transmitted light has a lower light transmittance, increasing the difference between the two.

[0054] The above are only the preferred embodiments of the present disclosure and are not used to limit the present disclosure. For those skilled in the art, the present disclosure can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

[0055] Although the specific implementation manners of the present disclosure have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present disclosure. Those skilled in the art should understand that based on the technical solutions of the present disclosure, various modifications or deformations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present disclosure.

Claims

1. A linear polarization angle measuring device for enhancing the polarization degree of skylight reception, characterized in that: It includes two skylight detection units and a differential amplifier. The output terminals of each skylight detection unit are respectively connected to the differential amplifier, and the differential amplifier outputs the light intensity component of a preset polarization angle. The photosensitive voltage generated by one skylight detection unit is amplified and used as the control voltage of the liquid crystal layer of the other skylight detection unit. The two skylight detection units cooperate with each other to filter out the common mode components in the skylight and enhance the total polarization degree of the received transmitted light. The preset polarization angles of the two skylight detection units differ by 90 degrees. The skylight detection unit includes an antireflection layer, a polarization layer, a liquid crystal layer, and a photosensitive layer connected in sequence. The incident skylight passes through reducing reflection, filtering, adjusting the light transmittance of the liquid crystal layer, and is transmitted to the differential amplifier by the photosensitive layer in sequence.

2. The linear polarization angle measuring device for enhancing the polarization degree of received skylight according to claim 1, wherein: Antireflection layer: It is used to reduce the reflection of skylight, increase the intensity of transmitted light, enhance the light transmittance performance of the device. The light enhanced by the antireflection layer enters the polarization layer and serves as the control electrode of the liquid crystal layer. Polarization layer: It is used to polarize the skylight and filter out the light inconsistent with the preset polarization direction. Liquid crystal layer: It is used to control the light transmittance ratio. The light passing through the polarization layer will pass through the liquid crystal layer and reach the photosensitive layer. Photosensitive layer: It is used to generate a photosensitive voltage according to the received light intensity.

3. The linear polarization angle measuring device for enhancing the polarization degree of received skylight according to claim 2, wherein The antireflection layer and the photosensitive layer are made of conductive materials and act as electrodes. After receiving the voltage, an electric field is generated between the antireflection layer and the photosensitive layer. Or, when the light irradiating the photosensitive layer is bright, the photosensitive voltage generated by the photosensitive layer is high; when the light irradiating the photosensitive layer is dim, the voltage generated by the photosensitive layer is low. The liquid crystal layer adjusts the light transmittance according to the received photosensitive voltage. The higher the photosensitive voltage, the lower the light transmittance of the liquid crystal layer of the other skylight detection unit; the lower the photosensitive voltage, the higher the light transmittance of the liquid crystal layer of the other skylight detection unit.

4. The linear polarization angle measuring device for enhancing the polarization degree of sky light reception according to claim 3, wherein, The specific method for adjusting the light transmittance is: after the photosensitive layer is irradiated by light, it outputs a photosensitive voltage, which acts on the antireflection layer and the photosensitive layer of the other skylight detection unit after passing through a voltage amplifier. An electric field is formed between the antireflection layer and the photosensitive layer under the action of the photosensitive voltage, and the transparency of the liquid crystal layer changes.

5. The linear polarization angle measuring device for enhancing the polarization degree of received skylight according to claim 2, wherein: The antireflection layer adopts a titanium dioxide antireflection film. Or, the polarization layer adopts a polarizing film made with polyvinyl alcohol as the substrate. Or, the specific structure of the liquid crystal layer is: a grid structure of liquid crystal polymerized with epoxy resin. Or, the photosensitive layer adopts an amorphous silicon thin film.

6. A method for measuring the polarization angle of skylight using a device for measuring the polarization angle of skylight that enhances the polarization degree of received skylight as described in claim 1, characterized in that, It includes the following steps: Receiving the irradiation of skylight, the antireflection layer reduces the reflection of light, increases the intensity of transmitted light, and the enhanced light enters the polarization layer. After the light enters the polarization layer, it is divided into two kinds of polarized light with different directions by the polarizing film in the polarization layer. The polarized light passes through the liquid crystal layer and enters the photosensitive layer. The light enters the photosensitive layer, and the photosensitive layer outputs a photosensitive voltage according to the brightness of the light. The two sets of skylight detection units activate the liquid crystal layer mutually, and the liquid crystal layer adjusts the light transmittance according to the received photosensitive voltage. The two photosensitive layers output different photosensitive voltages to the differential amplifier according to the received light brightness. After amplifying the voltage difference at the input end, the differential amplifier outputs a measurement voltage, and the measurement voltage corresponds to the light intensity component of the incident light, that is, skylight, at a preset polarization angle.

7. The method for measuring the polarization angle of skylight according to claim 6, wherein: The liquid crystal layer adjusts the light transmittance according to the received photosensitive voltage. Specifically, the liquid crystal layer of the skylight detection unit with strong incident light has a high light transmittance, and the liquid crystal layer of the skylight detection unit with weak transmitted light has a low light transmittance, increasing the voltage difference between the outputs of the two photosensitive layers.

8. The method for measuring the polarization angle of skylight according to claim 6, wherein: The preset angles of the polarization layers of the two skylight detection units differ by 90 degrees, and the output voltages correspond to the light intensity components at the two polarization angles.

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