Snapshot type broadband full stokes vector measuring instrument and measuring method

Abstract

The invention discloses a snapshot type broadband full stokes vector measuring instrument and a measuring method, and belongs to the field of micro-nano optics. The snapshot type broadband full stokes vector measuring instrument comprises a wave plate array, a linear polaroid, a light intensity detector and a data processing module; the linear polaroid is installed on the light intensity detector, the wave plate array is installed on the linear polaroid, and the size of the wave plate array is not larger than that of the linear polaroid; and the light intensity detector is electrically connected with the data processing module. The wave plate array is completely arranged on the linear polarizer, the alignment precision during use is reduced, in addition, the small areas of the photosensitive area correspondingly capture light intensity values under different polarization modulations through the wave plate array, calculation inversion can be carried out on the polarization state under single measurement, and the real-time performance of a measurement result is guaranteed. Meanwhile, in combination with the broadband characteristic of the sub-wavelength medium wire grating, the defect that the working bandwidth is limited in the existing full Stokes vector measurement technology is overcome.

Description

Technical Field

[0001] The invention belongs to the field of micro-nano optics and relates to a measuring instrument, in particular to a snapshot-type broadband full-Stokes vector measuring instrument and a measuring method. Background Art

[0002] Polarimeter is an optical instrument used for analysis and characterization of optical properties. When light is reflected, transmitted or scattered in a medium, it will produce polarization state changes that are clearly related to its structural properties, material type, surface roughness and texture characteristics. By accurately measuring the polarization state change information generated by the signal light modulated by the medium, and based on the quantitative model of the interaction between light and matter, non-contact characteristic analysis and characterization of the medium can be achieved. It has a wide range of application scenarios in optical sensing, laser communication and semiconductor industry.

[0003] At present, the technical solutions for measuring the polarization state of incident light are mainly divided into time-sharing type, amplitude-sharing type, Fourier type and focal plane-sharing type. Patent No. CN201820907945.5 provides a time-sharing polarization state measurement device. This method combines a phase retarder and a linear polarizer, collects the light intensity values ​​received by the detector at different phase retarder azimuths, and uses these light intensity values ​​to reconstruct the Stokes vector of the incident light; Patent No. CN202310966473.6 provides an amplitude-sharing full-Stokes parameter polarization measurement system and method. This method is based on a Michelson interferometer device, which divides the incident light into four beams according to the amplitude and passes through the analyzer and imaging module in turn, and obtains the full Stokes vector of the entire beam to be measured in a wide band by analyzing the polarization interference pattern on the detector; Patent No. CN202010446907.6 provides a basic A light wave polarization state detection device and method based on Fourier analysis, which converts incident light of unknown polarization state into a specific vector polarized light field through a zero-order vortex half-wave plate, and forms a light intensity mapping with a wedge-shaped distribution of bright and dark on the detector after modulation by a polarizer. The light intensity distribution and the initial polarization state satisfy the scalar diffraction theorem. The initial polarization state of the incident light can be calculated by preprocessing the light intensity image collected by the detector and performing Fourier analysis; Patent No. CN201810111548.1 proposes a compact polarization state measuring instrument based on a dielectric metasurface, which uses nanoantennas to form a polarization-specific lens array, places the detector array at the focal length of the lens array, and calculates the Stokes vector of the incident light by extracting the focusing intensity of different nanoantenna array areas. These existing technologies can measure the Stokes parameters of the incident light, but they have the following shortcomings: (1) The core of the time-sharing polarization detection technology is to modulate the intensity of the incident light by controlling the rotation of the phase delay device. In principle, it is impossible to achieve real-time measurement of the polarization state. (2) The amplitude-sharing type requires the use of a polarization beam splitter to separate the two orthogonal polarization state beams and then obtain and process the polarization information through multiple detectors or interference structures. Therefore, the entire system structure is very large and difficult to calibrate. (3) The Fourier type polarization detection technology first loads the incident light into a specific complex amplitude distribution to form an incident light field, so that its polarization state and the far-field diffraction light intensity distribution show a corresponding relationship. Therefore, the system requires sufficient optical path or lens combination, the entire structure is difficult to integrate, and the method is not effective in a wide band. (4) Although the focal plane type polarization detection technology based on nanoantenna arrays can achieve snapshot polarization detection, the nanoantenna structure usually has a low extinction ratio, which means that the efficiency is not high when separating and detecting light signals of different polarization states, thereby affecting the detection accuracy and sensitivity to weak signals. At the same time, due to the resonant characteristics of nanoantennas, their operating wavelength range is in principle limited to narrowband incident light, making it difficult to operate effectively over a wide spectral range.These limitations significantly reduce the practical applicability of this technology in multi-band and wide-band applications, limiting its widespread use in various complex optical environments. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a snapshot-type broadband full-Stokes vector measurement instrument and measurement method to solve the technical problem that the prior art cannot simultaneously achieve wide-band, high extinction ratio full-Stokes vector measurement.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems: A snapshot broadband full-Stokes vector measuring instrument, comprising a wave plate array, a linear polarizer, a light intensity detector and a data processing module; The linear polarizer is installed on the light intensity detector, and the wave plate array is installed on the linear polarizer, and the size of the wave plate array is not greater than the size of the linear polarizer; The light intensity detector is electrically connected to the data processing module.

[0006] The present invention also includes the following technical features: The wave plate array comprises basic units, each of which includes a dielectric substrate and a sub-wavelength dielectric wire grating arranged on the dielectric substrate; the phase delay amount of each sub-wavelength dielectric wire grating is constant, and the azimuth angle of each sub-wavelength dielectric wire grating relative to the transmission direction of the linear polarizer is different, wherein, , is a set of positive integers. The distance between the light-sensitive area of ​​the light intensity detector and the linear polarizer Satisfies the following formula:

[0007] in: is the side length of the basic unit of the wave plate array, m; is the working wavelength of the light intensity detector, nm.

[0008] The period of the sub-wavelength dielectric line grating of the wave plate array is less than the working wavelength λ; the extinction ratio of each basic unit and linear polarizer is greater than 1000:1.

[0009] The material of the sub-wavelength dielectric wire grid of the wave plate array is silicon nitride, silicon carbide or titanium dioxide; the material of the dielectric substrate is quartz, sapphire or N-BK7.

[0010] A photoresist layer is provided at the edge of one side of the wave plate array close to the linear polarizer; The linear polarizer has a unique transmission direction.

[0011] The material of the photoresist layer is SU8.

[0012] A snapshot broadband full-Stokes vector measurement method is based on the snapshot broadband full-Stokes vector measurement instrument, and specifically comprises the following steps: Step 1, the light to be measured is incident on the wave plate array of the snapshot broadband full-Stokes vector measuring instrument; Step 2: The light intensity detector transmits the collected light intensity value to the data processing module, and the data processing module calculates the Stokes vector of the light to be measured using the following formula: ;

[0013] in: For the The light intensity value detected by the light intensity detector photosensitive area corresponding to each basic unit, W / m²; For the The azimuth angle of the sub-wavelength dielectric wire grating of the basic unit, rad; is the phase delay of each sub-wavelength dielectric wire grating, rad.

[0014] In step 2, the azimuth and phase delay The solution is as follows: S1, double-layer sub-wavelength gratings with different basic units decompose the light to be measured into a set of elliptical polarization states ; The elliptical polarization state Not coplanar on the Poincare sphere; S2, according to the elliptical polarization state Coordinates on the Poincare sphere , calculated by the Davidson formula or the cross product method from the elliptical polarization state The volume of the polyhedron formed ;

[0015]

[0016]

[0017] S3, using particle swarm algorithm to perform global traversal and optimization in parameter space to obtain the maximum volume discriminant function ; The azimuth of the parameter space is And the phase delay is ; S4, through and Multiple iterations and global searches are performed to obtain the maximum volume discriminant function The best With the best .

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: (I) The wave plate array in the present invention is completely set on the linear polarizer, which reduces the alignment accuracy during use. In addition, through the wave plate array, each small area of ​​the photosensitive area can capture the light intensity value under different polarization modulation, which can realize the calculation and inversion of the polarization state in a single measurement, ensuring the real-time measurement results. At the same time, combined with the broadband characteristics of the sub-wavelength dielectric wire grid, the defect of limited working bandwidth in the existing full Stokes vector measurement technology is overcome.

[0019] (II) In the structure of the present invention, by optimizing the basic parameters such as the phase delay and azimuth of the subwavelength dielectric wire grating, the elliptic modulation basis vectors of each region are optimally distributed on the Poincare sphere surface, which greatly reduces the influence of factors such as light intensity jitter and noise error on the polarization state recovery of the polarization measurement system, and improves the measurement accuracy and anti-noise capability of the system. In addition, compared with the metasurface structure, the subwavelength dielectric wire grating has a higher polarization extinction ratio, and the polarization conversion is more accurate, which reduces the calibration pressure of the system as much as possible, and solves the technical problem that the existing technology cannot simultaneously achieve full Stokes vector measurement with a wide band and a high extinction ratio.

[0020] (III) The present invention is highly integrated and independent. It realizes multifunctional integration, such as polarization state detection and real-time computational inversion, through multiple sub-wavelength dielectric wire gratings, avoiding the traditional system's dependence on external devices such as wave plates and spectrometers, thereby simplifying the system architecture and improving operational convenience. At the same time, the system does not require high-energy consumption equipment and has the advantage of low power consumption, making it suitable for energy-constrained scenarios such as drone remote sensing and portable medical imaging. In addition, as a miniaturized, integrated independent component, the present invention can provide a modular, lightweight solution for the polarization state analysis system to meet the application requirements with strict space and energy consumption constraints. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the snapshot type broadband full-Stokes vector measuring instrument of the present invention; Figure 2 Schematic diagram of the distribution of polarization basis vectors on the Poincare sphere under different detection times; Figure 3 The figure is the curve of the merit function of the measuring instrument under different detection times; FIG4 (a) is a schematic diagram of the working crosstalk of a snapshot broadband full-Stokes vector measurement instrument; FIG4( b ) is a side view of the snapshot broadband full-Stokes vector measuring instrument; FIG5( a ) is a schematic diagram of the structure of a sub-wavelength dielectric wire grating; Figure 5 (b) is a schematic diagram of the azimuth angle of the sub-wavelength dielectric wire grating; Figure 6 is the phase delay curve of the polarization modulation basic unit; Figure 7 This is the broadband full-Stokes vector detection result; Figure 8 is the noise immunity curve of full Stokes vector recovery.

[0022] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0023] It should be noted that, unless otherwise specified, all components in the present invention are components known in the art.

[0024] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0025] The present invention provides a snapshot broadband full-Stokes vector measuring instrument, comprising a wave plate array 1, a linear polarizer 2, a light intensity detector 3 and a data processing module 4; A linear polarizer 2 is mounted on the light intensity detector 3, and a wave plate array 1 is mounted on the linear polarizer 2. The size of the wave plate array 1 is not greater than the size of the linear polarizer 2. The light intensity detector 3 and the data processing module 4 are electrically connected.

[0026] In the above technical solution, the wave plate array 1 is used to provide a specific phase delay amount, realize the modulation of any polarization state of the incident light, and convert it into the corresponding elliptical polarization state, laying the foundation for subsequent measurements; the linear polarizer 2 is used to convert the elliptical polarized light modulated by the wave plate array 1 into a uniform linear polarized light, and present the polarization information in the form of intensity change by selectively transmitting light in a specific direction, so as to be received by the light intensity detector; the light intensity detector 3 is used to receive the light intensity after passing through the above two structures (wave plate array 1, linear polarizer 2); the data processing module 4 is used to analyze and process the received and collected light intensity data, and use the full Stokes vector recovery method mentioned in the present invention to complete the calculation and inversion of the full Stokes vector of the incident light.

[0027] The wave plate array 1 is completely set on the linear polarizer 2, which reduces the alignment accuracy during use. In addition, through the wave plate array, each small area of ​​the photosensitive area can capture the light intensity value under different polarization modulation, which can realize the calculation and inversion of the polarization state in a single measurement, ensuring the real-time measurement results. At the same time, combined with the broadband characteristics of the sub-wavelength dielectric wire grid, it overcomes the defect of limited working bandwidth in the existing full Stokes vector measurement technology.

[0028] Wave plate array 1 includes basic units, each basic unit includes a dielectric substrate and a sub-wavelength dielectric wire grating arranged on the dielectric substrate; the phase delay amount of each sub-wavelength dielectric wire grating is constant, and the azimuth angle of each sub-wavelength dielectric wire grating relative to the transmission direction of the linear polarizer 2 is different, wherein, , is a set of positive integers. In the above technical solution, the photosensitive surface is divided into N units by using the wave plate array 1, so that snapshot measurement of the full polarization state can be achieved; the phase delay amount is only related to the parameters of the subwavelength dielectric wire grating, and the value is controlled to be constant in order to unify the process parameters and reduce the difficulty of manufacturing the wave plate array.

[0029] Among them, all basic units are squares with equal sides.

[0030] The distance between the photosensitive area of ​​the light intensity detector 3 and the linear polarizer 2 Satisfies the following formula:

[0031] in: is the side length of the basic unit of the wave plate array 1, m; is the working wavelength of the light intensity detector 3, nm.

[0032] The period of the sub-wavelength dielectric wire grating of the wave plate array 1 is smaller than the working wavelength λ; the extinction ratio of each basic unit and the linear polarizer 2 is greater than 1000:1.

[0033] In the above technical solution, the distance between the photosensitive area and the linear polarizer is limited to reduce the intensity crosstalk caused by the diffraction effect; and the extinction ratio is controlled to ensure its polarization modulation performance.

[0034] The material of the sub-wavelength dielectric wire grid of the wave plate array 1 is silicon nitride, silicon carbide or titanium dioxide; the material of the dielectric substrate is quartz, sapphire or N-BK7.

[0035] In the above technical solution, the low loss characteristics of the material of the subwavelength dielectric wire grating and the slow change of the refractive index are suitable for micro-nano processing technology; the material of the dielectric substrate is mainly the commonly used material of the existing optical window glass.

[0036] A photoresist layer is provided on the edge of the side of the wave plate array 1 close to the linear polarizer 2 .

[0037] In the above technical solution, since the subwavelength dielectric wire grating is a micro-nano structure and is very fragile and cannot directly contact other linear polarizers, a photoresist layer with a height higher than the subwavelength dielectric wire grating is set around its micro-nano structure as a wall.

[0038] The linear polarizing plate 2 has a unique transmission direction.

[0039] In the above technical solution, it is defined that the polarizer is a whole and not an array structure like a sub-wavelength dielectric wire grid.

[0040] The material of the photoresist layer is SU8.

[0041] In the above technical solution, the commonly used photoresist material is used as the wall of the sub-wavelength dielectric wire grating to play a protective and supporting role.

[0042] The present invention also provides a snapshot broadband full-Stokes vector measurement method, which is based on a snapshot broadband full-Stokes vector measurement instrument and specifically includes the following steps: Step 1, the light to be measured is incident on the wave plate array 1 of the snapshot broadband full-Stokes vector measuring instrument; Step 2: The light intensity detector 3 transmits the collected light intensity value to the data processing module, and the data processing module calculates the Stokes vector of the light to be measured using the following formula: ;

[0043] in: For the The light intensity value detected by the light intensity detector 3 photosensitive area corresponding to each basic unit, W / m²; For the The azimuth angle of the sub-wavelength dielectric wire grating of the basic unit, rad; is the phase delay of each sub-wavelength dielectric wire grating, rad.

[0044] In the above technical solution, by optimizing the basic parameters such as the phase delay and azimuth of the subwavelength dielectric wire grating, the elliptic modulation basis vectors of each region are optimally distributed on the Poincare sphere surface, which greatly reduces the influence of factors such as light intensity jitter and noise error on the polarization state recovery of the polarization measurement system, and improves the measurement accuracy and anti-noise capability of the system. In addition, compared with the metasurface structure, the subwavelength dielectric wire grating has a higher polarization extinction ratio, and the polarization conversion is more accurate, which reduces the calibration pressure of the system as much as possible.

[0045] In step 2, the azimuth and phase delay The solution is as follows: S1, double-layer sub-wavelength gratings with different basic units decompose the light to be measured into a set of elliptical polarization states ; Elliptical polarization state Not coplanar on the Poincare sphere; S2, according to the elliptical polarization state Coordinates on the Poincare sphere , calculated by the Davidson formula or the cross product method from the elliptical polarization state The volume of the polyhedron formed , that is, using Calculation of elliptical polarization states The volume of the polyhedron formed ;

[0046]

[0047]

[0048] S3, using particle swarm algorithm to perform global traversal and optimization in parameter space to obtain the maximum volume discriminant function ; The azimuth in parameter space is And the phase delay is ; S4, through and Multiple iterations and global searches are performed to obtain the maximum volume discriminant function The best With the best .

[0049] in, is a function mapping, representing a and The function of is different when the number of basic units is different. The expressions are different; In the above technical solution, the phase delay and azimuth angle selection of the wave plate array are crucial to the robustness of full Stokes vector recovery. Full Stokes vector detection as a typical linear system can be written as .in, Indicates the Stokes parameter of the incident light to be measured After analyzing the matrix Obviously, the full Stokes vector of the incident light to be measured can be expressed as the analysis matrix The inverse of the intensity vector is multiplied on the left, that is, A noise factor is introduced in the process of acquiring the intensity vector If so, The recovery of will inevitably introduce deviation, that is, Therefore, a reasonable study and design of the analysis matrix is ​​conducted to reduce the error caused by intensity disturbance or noise in Stokes vector restoration on the one hand, and to make the designed polarization detection basis vector cover the entire surface of the Poincare sphere as much as possible on the other hand. This embodiment uses the Equally Weighted Variance (EWV) merit function as the judgment criterion, that is:

[0050] in, Representation analysis matrix According to the details shown in the content of the invention, the above formula can be equivalent to the position coordinates of the pixel point of a single polarization state detection on the Poincare sphere. Therefore, the method for solving the above discriminant merit function is converted into the minimum volume of the polyhedron surrounded by several points on the Poincare sphere corresponding to the analysis matrix, that is, it satisfies:

[0051] in, Represented by the set of polarization states The volume of a polyhedron composed of , and the polyhedron is inscribed in the Poincare sphere with radius R = 1, that is .

[0052] Figure 2 The distribution of polarization detection basis vectors on the Poincare sphere according to the merit function EWV is shown in the case where the number of detections N is 4, 6, 7, and 8. According to geometric theory, among the polyhedrons inscribed in the unit sphere, the inscribed regular polyhedron has the largest volume. Obviously, the distribution of polarization detection basis vectors on the Poincare sphere calculated according to the merit function EWV is consistent with the geometric theory.

[0053] Figure 3 The figure shows the change curve of the merit function of the system under different detection times N. In the figure, the conventional structure is that the phase delay of the wave plate used in the detection system is λ / 4, and the azimuth angle of different detection times is 2π / N, that is, it is equally divided on the unit circle according to the detection times. Obviously, compared with the test structure and measurement principle of the conventional polarimeter, the structure of the present invention has more advantages in stability and noise robustness.

[0054] In addition, since the size of the components involved in this scheme is in the micron level, special attention should be paid to the diffraction effect of the components. As shown in Figure 4 (a), the incident light first passes through the polarization modulation array (i.e., the wave plate array 1 and the linear polarizer 2) and then propagates a certain distance before being received by the photosensitive area of ​​the light intensity detector 3. Due to the existence of the diffraction effect, each basic unit will have a certain degree of crosstalk in the photosensitive area. Figure 4 (b) is a side view of the structure of Figure 4 (a), and the shaded part is the spatial position of the light to be measured and the photosensitive surface of the light intensity detector 3 after the propagation distance. , in order to minimize the impact of diffraction effects.

[0055] Example: In this embodiment, a four-time detection structure is adopted, that is, N=4, and the polarization modulation transmission matrix model under this condition can be expressed as:

[0056] According to the above formula, the last three elements in each row of the polarization modulation transmission matrix model are taken as the Poincare sphere , and The normalized coordinates on the axis are substituted into the merit function of the equal weighted variance coefficient (EWV), and the particle swarm optimization algorithm is used to find the minimum value of the tetrahedron composed of the four points. and .

[0057] After optimization, in this embodiment, the fixed phase delay amount , that is, the range is controlled between [0.6π, 0.9π], and the major axis azimuths of the four groups of wave plates also have a certain corresponding relationship, that is, the polyhedron of each polarization basis vector on the Poincare sphere is a regular tetrahedron, that is, the azimuth , , and The ranges are [0.2π,0.3π], [0.4π,0.5π], [0.6π,0.7π] and [0.8π,0.9π] respectively.

[0058] The above-mentioned polarization basis vector refers to the structure composed of four wave plate phase delays and corresponding azimuth angles included in each superpixel in the embodiment. This structure is completely transparent to a certain polarization state and has a modulation efficiency of 100%, so it is called a basis vector here.

[0059] In order to achieve the device effect proved by the above noise resistance theory, we use the FDTD (Finite-Difference Time-Domain) method to model and simulate the wave plate based on the subwavelength grating theory. Figure 5 (a) shows the structural schematic diagram of the subwavelength dielectric wire grating, where p is the period of the subwavelength dielectric wire grating. is the width of the subwavelength dielectric wire grating, and h is the thickness of the subwavelength dielectric wire grating. Taking the vertical incidence of the light beam as an example, in the FDTD simulation, the phase delay of a pair of orthogonal polarization states (TE light and TM light) after the incident light passes through the grating model is obtained respectively. In the wide band of 450~650nm, the five wavelengths are achromatically designed to achieve a specific uniform phase delay in the entire visible spectrum. After sampling and selection, it is finally determined that the subwavelength dielectric wire grating and the substrate material are fused quartz, the period p is 400nm, the subwavelength dielectric wire grating thickness h is 2.5μm, and the subwavelength dielectric wire grating width is 1.3μm. Figure 5(b) is a schematic diagram of the azimuth angle of the sub-wavelength dielectric wire grating. Figure 6 : is the phase delay curve of the subwavelength dielectric wire grating under this structure. It can be seen from the figure that under the incidence of TE light and TM light, the phase delay in the visible light range is controlled at around 0.73π, indicating that in this embodiment, the phase delay of the subwavelength dielectric wire grating has certain broadband characteristics in the visible light range of 450nm~650nm.

[0060] The broadband full Stokes vector detection results in this embodiment are as follows Figure 7 As shown, (a), (b) and (c) are the detection results under incident light of wavelengths of 450nm, 550nm and 650nm respectively. In order to describe the polarization response of the broadband full-Stokes vector detection chip, this embodiment uses four polarization basis vectors (Ⅰ, Ⅱ, Ⅲ and Ⅳ) to illuminate it, and their Stokes parameters are , , and For each polarization state of the incident light, the light intensities of the four pixels obtained after modulation are different.

[0061] In addition, we also use four groups of ellipsometric states (V, VI, VII and VIII) that are orthogonal to the basic unit polarization basis vector to verify the function, which are , , and ,like Figure 7As shown, (d), (e) and (f) are the detection results under incident light with wavelengths of 450nm, 550nm and 650nm, respectively. It can be seen that there is an obvious extinction phenomenon under the designed polarization basis vector. This embodiment can quantify the intensity distribution of the four polarization components by normalizing the intensity information recorded by each pixel, and substitute it into the polarization transmission matrix model given above, and reconstruct the full polarization information of the incident light based on this. Table 1 is the full Stokes vector result measured in this embodiment when irradiated with the above-mentioned polarization state of the light to be measured, indicating that the broadband full Stokes vector measuring instrument based on this embodiment has higher accuracy without additional polarization calibration.

[0062] Table 1 Full Stokes vector recovery results

[0063] Verification example: In order to verify the robustness of the full Stokes parameter recovery of the measuring instrument when the detection intensity is disturbed or the detector noise cannot be suppressed in this embodiment, we randomly select a point on the Poincare sphere to For example, Gaussian noise with different weights is added Introduce the detection intensity distribution results and define the Stokes parameters before and after recovery The relative error of is used as the criterion, which can be written as , for the Stokes parameter, the polarization detection structure optimized by this embodiment and the traditional structure are used for recovery, such as Figure 8 As shown, it can be seen that when random noise is introduced into the optimized structure, as the noise weight increases, the recovery error of the Stokes parameter is approximately linear, and as the noise weight increases, the robustness change represented by its slope is significantly improved compared with the traditional structure.

Claims

1. A snapshot broadband full-Stokes vector measuring instrument, characterized in that: It comprises a wave plate array (1), a linear polarizer (2), a light intensity detector (3) and a data processing module (4); The linear polarizer (2) is mounted on the light intensity detector (3), the wave plate array (1) is mounted on the linear polarizer (2), and the size of the wave plate array (1) is not greater than the size of the linear polarizer (2); The light intensity detector (3) and the data processing module (4) are electrically connected.

2. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 1, characterized in that: The wave plate array (1) comprises basic units, each of which comprises a dielectric substrate and a sub-wavelength dielectric wire grating arranged on the dielectric substrate; the phase delay amount of each sub-wavelength dielectric wire grating is constant, and the azimuth angle of each sub-wavelength dielectric wire grating relative to the transmission direction of the linear polarizer (2) is different, wherein: , is a set of positive integers.

3. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 2, characterized in that: The distance between the light-sensitive area of ​​the light intensity detector (3) and the linear polarizer (2) Satisfies the following formula: in: is the side length of the basic unit of the wave plate array (1), m; is the operating wavelength of the light intensity detector (3), nm.

4. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 2, characterized in that: The period of the sub-wavelength dielectric line grating of the wave plate array (1) is less than the working wavelength λ; and the extinction ratio of each basic unit and the linear polarizer (2) is greater than 1000:

1.

5. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 2, characterized in that: The material of the sub-wavelength dielectric wire grid of the wave plate array (1) is silicon nitride, silicon carbide or titanium dioxide; the material of the dielectric substrate is quartz, sapphire or N-BK7.

6. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 2, characterized in that: A photoresist layer is provided on the edge of a side of the wave plate array (1) close to the linear polarizer (2).

7. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 2, characterized in that: The linear polarizing plate (2) has a unique vibration transmission direction.

8. The snapshot broadband full-Stokes vector measuring instrument as claimed in claim 6, characterized in that: The material of the photoresist layer is SU8.

9. A snapshot broadband full-Stokes vector measurement method, characterized in that: The snapshot broadband full-Stokes vector measuring instrument according to any one of claims 2 to 8 specifically comprises the following steps: Step 1, the light to be measured is incident on the wave plate array (1) of the snapshot broadband full-Stokes vector measuring instrument; Step 2: The light intensity detector (3) transmits the collected light intensity value to the data processing module, and the data processing module calculates the Stokes vector of the light to be measured using the following formula: ; in: For the The light intensity value detected by the light intensity detector (3) corresponding to the basic unit in the photosensitive area, W / m²; For the The azimuth angle of the sub-wavelength dielectric wire grating of the basic unit, rad; is the phase delay of each sub-wavelength dielectric wire grating, rad.

10. The snapshot broadband full-Stokes vector measurement method according to claim 9, characterized in that: In step 2, the azimuth and phase delay The solution is as follows: S1, double-layer sub-wavelength gratings with different basic units decompose the light to be measured into a set of elliptical polarization states ; The elliptical polarization state Not coplanar on the Poincare sphere; S2, according to the elliptical polarization state Coordinates on the Poincare sphere , calculated by the Davidson formula or the cross product method from the elliptical polarization state The volume of the polyhedron formed ; S3, using particle swarm algorithm to perform global traversal and optimization in parameter space to obtain the maximum volume discriminant function ; The azimuth of the parameter space is And the phase delay is ; S4, through and Multiple iterations and global searches are performed to obtain the maximum volume discriminant function The best With the best .

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