CN103776445B - Design method and device of amplitude-divided polarization navigation angle sensing - Google Patents

Abstract

The invention belongs to the field of navigation and measurement and control, and relates to an amplitude-division angle sensing design method and device for navigation by using polarization information of sky scattered light. The method adopts a) an amplitude-dividing multi-channel synchronous detection mode to detect the polarization state of incident light; b) the small field telescope realizes the functions of light collection and directional measurement; c) analyzing the vibration azimuth angle of the linearly polarized light electric field vector by a Stokes vector sum matrix analysis method; d) performing system optimization design on indexes and installation and adjustment states of internal components of the sensing device by taking the condition number of the instrument matrix as an evaluation factor; e) the reference polarization state generator is used for accurately calibrating the instrument matrix of the sensing device and calibrating and inspecting the sensing device. The invention provides a new technical approach for autonomous navigation by using an optical means, can be widely applied to the navigation purpose of vehicles, ships, low-altitude aircrafts, autonomous robots and other equipment, and can also be used in the fields of polar investigation, field exploration, geological investigation and the like.

Description

Design method and device of amplitude-divided polarization navigation angle sensing

technical field

The invention belongs to the technical field of navigation and measurement and control, combines polarized light detection technology and navigation technology, and relates to a navigation angle sensing design method and device for navigation by using sky scattered light polarization information. It can be widely used in the navigation purposes of vehicles, ships, low-altitude aircraft, autonomous robots and other equipment, and can also be used in polar expeditions, field expeditions, geological surveys and other fields.

Background technique

Polarization navigation is a new navigation method that utilizes the polarization distribution pattern of scattered light in the sky for autonomous navigation. Polarization navigation was originally a bionic sensing and navigation method. It originated from the research on the polarization vision system of sand ants, bees, crickets and other insects. Through passive measurement and analysis of atmospheric scattering light polarization information, the reference axis of the carrier relative to the sun meridian is calculated. The azimuth angle, and then determine the heading angle according to the astronomical calendar and the relationship between space angles, so as to realize autonomous navigation. Polarization navigation has the characteristics of strong autonomy, good precision, no accumulation of errors over time, small size, and strong anti-electromagnetic interference. It can be used as an important supplement to existing navigation technologies, play an important role in integrated navigation systems, and can be widely used in vehicles , Ships, low-altitude aircraft, autonomous robots and other equipment for navigation purposes, and can also be used in polar expeditions, field expeditions, geological surveys and other fields.

There are mainly two kinds of angle sensing devices for polarization navigation that have been proposed in domestic and foreign literatures. A sensor device designed to imitate the biological polarization vision system as shown in Figure 1 and Figure 2, wherein Figure 1 is a schematic plan view, and Figure 2 is a schematic three-dimensional view. In Figure 1, the polarizer 1 is spliced by six small polarizers, and the main directions 2 (that is, the direction of light transmission) of the six small polarizers are different, respectively 0°, 30°, 60°, 90° °, 120°, 150°, the main directions of the two small polarizers at 0° and 90° are perpendicular to each other, the main directions of the two small polarizers at 30° and 120° are perpendicular to each other, and the two small polarizers at 60° and 150° are perpendicular to each other. The main directions of the small polarizers are perpendicular to each other. A total of six photosensitive detectors 3 are installed below each small polarizer for receiving linearly polarized light passing through the polarizer. The polarizer 1 spliced by six small pieces is installed in the lens barrel 4 . In Figure 2, after the incident light wave 5 passes through the polarizer 1, it is projected on the photosensitive detector 3 below, and the photosensitive detector 3 converts the optical signal into an electrical signal, which is supplied to the subsequent signal acquisition equipment (not shown in the figure) and calculation equipment (not shown in the figure) processing. This angle sensing device uses lens barrel 4 or an additional sleeve mechanism (not shown in the figure) to realize light collection and orientation measurement. Another angle sensor is a polarization-sensitive CMOS image sensor, which uses modern ultra-precision integrated circuit processing technology to integrate metal wire grid polarizers into each pixel of the CMOS camera. The pixel organization form of this polarization-sensitive CMOS image sensor is shown in Fig. 3. Each basic functional unit is composed of 2×2 pixels. Fig. 3(a) and Fig. 3(b) respectively show Two typical basic functional unit forms. In Figure 3(a), there is no arrow marked on pixel 6, indicating that the pixel is an ordinary pixel without integrated wire grids, and an arrow in the direction of 90° is marked on pixel 7, indicating that the pixel is integrated with The wire grid whose main direction is 90°, and the wire grid whose main direction is 0° are integrated on the pixel 8. In Figure 3(b), pixel 6 is an ordinary pixel without grids, and pixel 7, 8, and 9 are respectively integrated with wire grids whose main directions are 90°, 0°, and 45°. Because the integrated wire grid acts as a linear polarizer, this basic functional unit consisting of 2×2 pixels has the function of measuring the linear polarization azimuth angle, and can sense the linear polarization azimuth angle of the scattered light in the sky.

From the perspective of measurement mode, the above two polarization navigation angle sensors are based on the principle of sub-wave surface detection. This kind of sub-wave surface detection method is correct and feasible in theory, and the method is relatively simple, but there are many problems in the implementation technology.

For the former existing design model, technically there are weaknesses such as low measurement accuracy, low utilization rate of light energy, poor ability to resist stray light and directional monitoring. First, the measurement accuracy and sensitivity are not high. This is because six independent polarizers are required to be strictly arranged and installed at six angles of 0°, 30°, 60°, 90°, 120°, and 150° in the light transmission direction. Due to the limited precision of polarizer processing, assembly and testing, The angular accuracy of this arrangement is difficult to achieve a high level, and it will bring high requirements for instrument assembly and adjustment. In addition, dichroic iodine-impregnated polyethylene alcohol polarizers (H polarizers) or optically coated polarizers are generally used. This type of polarizer has low polarization performance, and the extinction ratio can only reach the order of 10 ^-3 . (blue-violet light) the extinction performance will be worse (10 ^-2 ). The polarizer is the core component of the direction detection of the polarization angle sensing device, and these two factors will inevitably cause the problem of low precision and sensitivity of the polarization angle sensing device. Secondly, the utilization rate of light energy is low. This is because the light beam passing through the six small polarizers is not fully utilized, only a small amount of light can be received by the six photosensitive detectors (the photosensitive surface is small), the utilization rate is very low, and most of the light is converted into background stray light , will seriously interfere with the detection process, reduce the signal-to-noise ratio, and the low utilization rate of light energy also limits the application of sensing devices in low-light environments. Finally, the ability to resist stray light and directional detection is poor. Due to the simple sleeve structure, the ability to resist stray light and directional measurement is poor. For example, as shown in FIG. 4, the detection range of the photosensitive element 10 is determined by the sleeve 11, which is actually a tapered area between the light rays 12 and 13, corresponding to a larger area in the sky, because the polarization states of each point in the sky are different. It is not the same, the large viewing angle measurement implemented by the sleeve mechanism homogenizes the polarization state of each point, and the comprehensive measurement result of the space area is obtained, which helps to improve the anti-interference performance to some extent, but leads to Measurement sensitivity and accuracy are greatly reduced. In addition, the sleeve mechanism will also generate stray light (for example, the light 14 directly shining on the inner wall of the sleeve 11 will produce diffuse reflection stray light, which has a strong polarization), which seriously interferes with the measurement process and leads to measurement accuracy. decline.

For the latter existing design model, it is completely feasible in theory, and it is easy to realize miniaturization by using integrated circuit processing technology, but there are problems of low measurement accuracy and sensitivity. This is mainly because it uses an integrated metal wire grid as a polarizer, and its polarizing performance is weak, and its extinction ratio can only reach 10- ² . The polarization extinction performance is worse in the case of short wavelengths (eg blue light, violet light). The sky scattered light has the most significant polarization characteristics in the short-wavelength band (blue-violet light), and the short-wavelength band is most suitable as the working band for polarized light navigation sensing. On the other hand, the ultra-precision and highly integrated photolithography processing technology is very complicated and the cost investment is huge. In addition, due to the 2×2 pixel detection mode, the same incident light wave is divided into four parts according to the spatial position, and each pixel detects different polarization components respectively, so the utilization rate of light energy is not high, and it is easy to cause scattering/scattering between adjacent pixels. Reflected stray light interference reduces measurement accuracy and sensitivity.

Based on the above situation, the present invention proposes an amplitude-divided polarization navigation angle sensing design method and device, which uses the divided-amplitude method to realize multi-channel synchronous and efficient detection of polarization components, and uses Stokes vector and matrix theory to realize principle analysis, Optimizing design and azimuth analysis, using a small field of view telescope to achieve light collection and directional measurement capabilities, so as to solve the above problems.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, and provide a method and device for designing an amplitude-divided polarization navigation angle sensing. The purpose of the present invention is achieved through the following technical solutions.

A kind of amplitude-divided polarization navigation angle sensing design method of the present invention is:

a) The polarization state of the incident light is detected by means of multi-channel synchronous detection with sub-amplitude;

b) Analyzing the vector vibration azimuth angle of the linearly polarized light field by using the Stokes vector and matrix analysis method;

c) Take the condition number of the instrument matrix as the evaluation factor to carry out system optimization design on the internal component indicators and adjustment status of the sensing device;

d) Accurately calibrate the instrument matrix of the sensing device by using a reference polarization generator, and perform calibration and accuracy inspection on the sensing device.

The sub-amplitudes include prism sub-amplitudes, grating sub-amplitudes, flat glass sub-amplitudes, diffractive optical element sub-amplitudes and acousto-optic device sub-amplitudes; the number of channels includes three channels or more.

The evaluation factor for system optimization design can be the condition number of the instrument matrix, or other types of mathematical measures used to determine the ill-conditioned degree of the matrix.

An optical phase retarder is used to transform the polarization state of the beam.

An amplitude-divided polarization navigation angle sensing device of the present invention includes a light collecting mirror, a bandpass filter, a modulator, a beam splitter, a first phase retarder, a second phase retarder, a first polarizing beam splitter, and a second polarizing beam splitter. Two polarizing beam splitters, the first condenser lens, the second condenser lens, the third condenser lens, the fourth condenser lens, the first pinhole stop, the second pinhole stop, the third pinhole stop, The fourth small aperture diaphragm, the first photosensitive detector, the second photosensitive detector, the third photosensitive detector, the fourth photosensitive detector, the data acquisition unit, the calculation and information display output unit; among them: light collecting mirror, band pass The optical filter is located at the forefront, and its mutual position is adjustable; the modulator is located behind the light collecting mirror and the bandpass filter; the light collecting mirror, the bandpass filter and the modulator constitute the common light entrance channel of the sensing device; the light splitter The mirror splits the incident beam into two; the first phase retarder and the second phase retarder are located in the two beam paths immediately after the beam splitter; the first polarizing beam splitter and the second polarizing beam splitter are respectively located in the first phase retarder , After the second phase retarder, its position can be intermodulated; the condenser lens is placed before the photosensitive detector, and the two are placed together at the end of the four optical path channels; the position of the aperture diaphragm is adjustable; the four photosensitive detectors lead out The electrical signal is transmitted to the data acquisition unit, and the data generated by the data acquisition unit is transmitted to the calculation and information display output unit.

The light-collecting mirror can be a Keplerian telescope with a built-in field diaphragm, or other forms of telescopes with light-collecting and directional observation capabilities;

The types of modulators include optical choppers, electro-optic modulators, photoelastic modulators, and acousto-optic modulators.

The positions of the first phase retarder and the second phase retarder can be interchanged; the types of phase retarders include wave plates, prisms, compensators, and liquid crystal devices; the number of phase retarders is not limited to two.

The types of the beam splitter, the first polarizing beam splitter, and the second polarizing beam splitter include prisms, diffraction gratings, parallel glass plates, diffractive optical elements, and acousto-optic devices; beam splitters, the first polarizing beam splitter, and the second polarizing beam splitter It can be the same device or different devices, and can also be combined into one device; the position of the first aperture diaphragm is not limited to between the first condenser lens and the first photosensitive detector; the second aperture aperture The position of the second condenser lens and the second photosensitive detector is not limited; the position of the third aperture diaphragm is not limited between the third condenser lens and the third photosensitive detector; the position of the fourth aperture diaphragm It is not limited to between the fourth condenser lens and the fourth photosensitive detector; the number of pinhole diaphragms is not limited to the number of channels.

The types of photosensitive detectors include silicon-based photodetectors, gallium phosphide photodetectors, photomultiplier tubes, avalanche photodetectors and position sensing detectors; the data acquisition unit can be an external independent collector or an integrated Into the internal circuit of the sensing device; the calculation and information display output unit can be a computer and measurement and control software, or an embedded software and hardware functional module integrated in the sensing device.

The multi-channel optical path layout form can be a planar layout form or a spatial three-dimensional layout form; other optical elements can also be arranged in the optical path of each channel, including linear polarizers, lenses, prisms, reflectors, and protective glasses.

The position sensing detector is used for sensing the lateral drift of the light spot and the alignment of the light beam.

Beneficial effect

Compared with the prior art, the present invention has the following method innovations:

1. Multi-channel synchronous measurement principle of sub-amplitude Stokes vector. The multi-channel synchronous measurement of sky polarized light Stokes vector is realized by the principle of partial amplitude, which solves the problem of insufficient sensing accuracy, serious stray light and low utilization rate of light energy in the current proposed partial wave surface polarization navigation sensor model And other issues. Designing with polarized light Stokes vector method enables the effective application of matrix theory in system analysis and optimal design, making it possible to optimize the design with the condition number of the instrument matrix as the evaluation factor. This is one of the innovations different from the existing split-wave surface polarization navigation sensing technology.

2. The optimal design method using the condition number of the instrument matrix as the evaluation factor can significantly reduce the difficulty of installation and adjustment and reduce the requirements for equipment technical indicators, while improving the sensitivity and accuracy of the sensing device. Mathematical methods such as the least squares method and neural network training method can be used to achieve accurate calibration of the instrument matrix, and then use the condition number of the instrument matrix as an evaluation factor to determine the parameter configuration and installation of the internal components of the sensing device. The optimized design of the adjustment position can greatly reduce the dependence of the measurement accuracy on the performance indicators of the internal components of the sensing device and the adjustment accuracy, and improve the measurement sensitivity and accuracy of the sensing device. This is the second innovation point that is different from the existing split-wave surface polarization navigation sensing technology.

The method and device of the present invention have the following notable features:

1. High sensing accuracy and sensitivity. A crystal-type polarization beamsplitter prism with high polarization performance is preferably used as the polarizing element. Compared with the linear polarizer used in the current proposed split-wave surface sensing device, the extinction ability can be improved by about two orders of magnitude, and the linear polarizer splicing can be avoided. Angular alignment error, effectively improving measurement accuracy and sensitivity. The optimal design of the installation and positioning ensures that the sensing device achieves the best sensing performance.

2. High utilization rate of light energy and strong ability to resist stray light. The split-amplitude multi-channel synchronous measurement method can achieve nearly complete light energy utilization, and the interference stray light generated is extremely small, which is conducive to improving the measurement signal-to-noise ratio and sensitivity, and is also conducive to the work of the sensing device in a weak light environment.

3. Strong light-gathering ability and directional measurement ability. The small field of view telescope is used as the common optical path light collector, which has strong light collection ability and less interference stray light introduced, and can be applied to weaker lighting environments; by optimizing the design of the aberrations of the telescopic objective lens, eyepiece on the axis and in the blue light band, While improving the light collection ability, it can also have better directional measurement ability, which is beneficial to improve the measurement signal-to-noise ratio and sensitivity.

4. The sensor responds quickly. The multi-channel synchronous measurement mode can achieve a fast response speed, which mainly depends on the response speed of the photodetector and the subsequent analysis and processing speed of the signal.

Description of drawings

1 is a schematic plan view of one of the currently existing polarization navigation angle sensing devices;

Fig. 2 is a three-dimensional schematic diagram of one of the currently existing polarization navigation angle sensing devices;

3 is a schematic diagram of the minimum functional unit of the second existing polarization navigation angle sensing device;

Fig. 4 is a schematic diagram of the viewing angle and stray light of the sleeve light collecting mechanism;

Fig. 5 is a schematic diagram of the principle of the design method and device of the amplitude-divided polarization navigation angle sensing;

Fig. 6 is the schematic diagram of embodiment 1;

Fig. 7 is the measured response curve of four photosensitive detectors in embodiment 1;

Fig. 8 compares the theoretical value and measured value of linear polarization azimuth angle in embodiment 1;

Fig. 9 is the measurement error of linear polarization azimuth in embodiment 1;

Figure 10 is a schematic diagram of embodiment 2;

Fig. 11 is a partition form of the upper surface of the parallel glass plate in embodiment 2.

Among them, 1-polarizer, 2-main direction of polarizer, 3-photosensitive detector, 4-lens barrel, 5-incident light, 6-common pixel, 7-integrated 90° wire grid pixel, 8-integrated 0° wire grid pixel, 9-integrated 45° wire grid pixel, 10-photosensitive detector, 11-sleeve, 12-first ray, 13-second ray, 14-third ray, 15- Collector mirror, 16-bandpass filter, 17-modulator, 18-beam splitter, 19-first phase retarder, 20-second phase retarder, 21-first polarizing beam splitter, 22-second Polarizing beam splitter, 23-first condenser lens, 24-second condenser lens, 25-third condenser lens, 26-fourth condenser lens, 27-first aperture diaphragm, 28-second small aperture Aperture diaphragm, 29-third aperture diaphragm, 30-fourth aperture diaphragm, 31-first photosensitive detector, 32-second photosensitive detector, 33-third photosensitive detector, 34-fourth Photosensitive detector, 35-data acquisition unit, 36-calculation and information display output unit, 37-reference polarization state generator, 38-first Wollaston prism, 39-second Wollaston prism, 40-parallel Glass plate, 41-first linear polarizer, 42-second linear polarizer, 43-third linear polarizer, 44-fourth linear polarizer, 45-first area, 46-second area, 47-third area , 48 - the fourth area.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

The essence of the present invention is to measure the Stokes vector of the incident light wave by means of sub-amplitude multi-channel measurement, and then calculate the "dominant" vibration direction of the electric field vector of the incident light wave relative to the reference direction according to the measured Stokes vector parameters. Azimuth, in turn, is used for polarized navigation purposes.

As shown in FIG. 5 , the light collecting mirror 15 is a Keplerian telescope, which is used to collect scattered light from the distant sky, reduce the aperture of the beam, and increase the radiation intensity of the beam. Increasing the aperture of the objective lens of the light collecting mirror can improve the light collecting ability. A field diaphragm is placed on the focal plane of the objective lens of the collecting mirror 15 to limit the field angle of the object side and realize the directional measurement function. The bandpass filter 16 selects the working wavelength range, and its working wavelength is usually short-wavelength bands (≤500nm) such as ultraviolet light, violet light, and blue light, but not limited to short-wavelength bands; under the condition of sufficient light intensity, the filter can be appropriately reduced bandwidth; the position of the bandpass filter is more flexible, but it should be placed before the beam splitter 18, that is, in the common light entrance channel. The modulator 17 modulates the intensity of the incident light wave in order to reduce the influence of ambient stray light, etc. In this way, the DC background signal of the electronic circuit can also be filtered out; if the ambient stray light, the dark current of the circuit, etc. are small, they can be ignored , the modulator 17 may not be used. The beam splitter 18 is an ordinary beam splitting prism, which splits the incident beam into two beams, one beam goes to the first phase retarder 19 , and the other beam goes to the second phase retarder 20 . The first phase retarder 19 and the second phase retarder 20 are 1/4 wave plate and 1/2 wave plate respectively. The azimuth angle of the fast axis of the first phase retarder 19 is 45°, the azimuth angle of the fast axis of the second phase retarder 20 is 22.5°, and the positions of the phase retarders 19 and 20 can be interchanged. The polarizing beam splitters 21 and 22 are prisms, which respectively separate the p and s polarization components of the two beams of light waves to form four beams of linearly polarized light, which are focused and projected on four detectors after passing through the condenser lens and the aperture diaphragm. Generates four analog electrical signals proportional to light intensity. The analog electrical signal is transmitted to the data acquisition unit 35, and the data acquisition unit 35 completes the A/D conversion of the analog electrical signal, and the generated data is then transmitted to the calculation and information display output unit 36 for processing, calculation, analysis, and display and output results. The x-y-z coordinate system in Figure 5 is the reference direction of the device.

The implementation steps of the amplitude-divided polarization navigation angle sensing design method are as follows:

The first step is to calibrate the instrument constants. Construct the sensing device according to Fig. 5, and the reference polarization state generator generates N incident light waves with polarization states S _k = [s _k0 s _k1 s _k2 s _k3 ] ^T (k=1,2,3... N, N≥4), and sequentially lead into the sensing device. The signals detected by the four detectors (31-34) are respectively

I _k0 ＝a ₀₀ s _k0 +a ₀₁ s _k1 +a ₀₂ s _k2 +a ₀₃ s _k3

I _k1 ＝a ₁₀ s _k0 +a ₁₁ s _k1 +a ₁₂ s _k2 +a ₁₃ s _k3

I _k2 ＝a ₂₀ s _k0 +a ₂₁ s _k1 +a ₂₂ s _k2 +a ₂₃ s _k3

I _k3 ＝a ₃₀ s _k0 +a ₃₁ s _k1 +a ₃₂ s _k2 +a ₃₃ s _k3

This system of linear equations can also be expressed in matrix form I _k ＝AS _k , where I _k ＝[I _k0 I _k1 I _k2 I _k3 ] ^T , a _ij (i=0…3, j=0…3) are instrument constants Matrix element of matrix A. According to the known polarization state Stokes parameter data S _k and the light intensity data I _k measured by the detector, the instrument matrix parameter a _ij can be calibrated by the least square method. Compute the condition number K(A) of the instrumentation matrix.

The second step is to adjust the internal parameter configuration and adjustment status of the sensing device, such as light splitting ratio, phase delay, angular position alignment, lateral position alignment, electronic device magnification, etc., and repeat the first step to determine the instrument matrix Whether the condition number K(A) of is reduced.

The third step is to optimize the sensing device. Repeat the first step and the second step to make the condition number K(A) of the instrument matrix as small as possible, so that the sensor device can achieve the optimal detection performance. Record the instrument matrix value at this time, as the fourth step of actual measurement and calculation.

The fourth step, the actual measurement. Use the optimized and adjusted sensor device for sky scattered light measurement,

According to the signal data measured by the photosensitive detector, the Stokes vector of the measured light is calculated according to the following formula

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{\left[\begin{array}{cccc}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 01</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 02</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 03</span>}}\\ {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}\\ {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 20</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; three</span>}}\\ {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 30</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 31</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}& {\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}\end{array}\right]}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\end{array}\right]$

then by The azimuth α between the reference direction of the sensing device and the "dominant" vibration direction of the electric field vector of the measured light wave can be calculated.

Example 1

As shown in Fig. 6, a kind of amplitude-divided polarization navigation angle sensing device. The second phase retarder is not included in the device of this embodiment, and the first phase retarder 19 used is a half-wave plate, and the azimuth angle of the fast axis is adjusted to about 22.5°; the reference polarization generator 37 is used to generate a reference for a known polarization state Polarized light; the bandpass filter 16 is a dielectric film filter with a central wavelength of 633nm and a full width at half maximum (FWHM) of 10nm; the modulator 17 is an optical chopper, and the modulation frequency is set at 120Hz; the beam splitter 18 is a common type of light splitter Prism, the splitting ratio is about 50:50; the first polarization beam splitter 38 and the second polarization beam splitter 39 are all Wollaston prisms; photosensitive detectors 31-34 are all silicon-based amplifying detectors, and the analog voltage signals generated Passed to the data acquisition unit 35, the data acquisition unit 35 is an A/D data collector with 16bit precision, and the analog voltage signal is digitized and then transmitted to the computer 36, which is equipped with specially designed measurement and control software.

First, the reference polarization state generator 37 generates 21 reference linear polarization states at intervals of 5° (that is, the azimuth angles are 0°, 5°, 10°...100°), which are used to calibrate the instrument matrix and optimize the device in this embodiment. design. The measurement and control software automatically completes the control of the rotation angle of the electric control turntable, the collection of four detection signals, and the analysis and processing of data. Adjust the parameter configuration, installation status, etc. of the internal components of the device in the embodiment, calibrate the instrument matrix and make the condition number of the instrument matrix reach a smaller value. Finally, the instrument matrix obtained by calibration is

$\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{cccc}\mathrm{<span\; class="notranslate">\; 2.7953</span>}& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2614</span>}& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2.7075</span>}& <span\; class="notranslate">\; \&CenterDot;</span>\\ \mathrm{<span\; class="notranslate">\; 2.7883</span>}& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.2927</span>}& \mathrm{<span\; class="notranslate">\; 2.7290</span>}& <span\; class="notranslate">\; \&Center\; Dot;</span>\\ \mathrm{<span\; class="notranslate">\; 3.2540</span>}& \mathrm{<span\; class="notranslate">\; 3.2570</span>}& <span\; class="notranslate">\; -</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 00030</span>}& <span\; class="notranslate">\; \&Center\; Dot;</span>\\ \mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 8649</span>}& <span\; class="notranslate">\; -</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 28705</span>}& \mathrm{<span\; class="notranslate">\; 0.0709</span>}& <span\; class="notranslate">\; \&Center\; Dot;</span>\end{array}\right]$

Since only the linear polarization state is used for calibration in this embodiment, the value of the fourth column element of the instrument matrix cannot be obtained, but this does not affect the detection of the polarization azimuth angle of the linearly polarized light.

Then, the actual test is carried out. Let the reference polarization generator 37 sequentially generate linearly polarized light to be measured at 31 kinds of known azimuth angles (at intervals of 6°, 0°, 6°, 12°...180°). Use the calibrated device of this embodiment to detect the 31 kinds of linearly polarized light to be measured, and perform calculations in sequence according to the data measured by the four photosensitive detectors and the calibrated instrument matrix A, and obtain the 31 kinds of polarized lights to be measured. Azimuth measurement.

FIG. 7 shows the magnitudes of the light intensity signals sensed by the four photosensitive detectors 31 to 34 during the actual test (corresponding to the curves D1 to D4 in the figure respectively).

Fig. 8 shows the theoretical curve and the measured value of the azimuth angle of the measured linearly polarized light. It can be seen that the coincidence degree of the theoretical curve and the measured value is very high, indicating that the measurement accuracy of this embodiment is very good.

Figure 9 shows the azimuth measurement error of the measured linearly polarized light, and the measurement error is better than ±0.2°. It can be seen that this embodiment has very good measurement accuracy and sensitivity of the polarization azimuth angle.

Example 2

As shown in Figure 10, in this embodiment, a parallel glass plate 40 is used to replace the beam splitter 18, the first polarizing beam splitting prism 38, and the second polarizing beam splitting prism 39 in Embodiment 1 to perform amplitude splitting without phase delay. device. The upper surface of the parallel glass plate 40 is coated with a dielectric film, and the lower surface is coated with a high-reflectivity metal film. The parallel thin beams coming from the band-pass filter 16 and the modulator 17 enter the parallel glass plate 40 in an oblique incidence mode, multiple internal reflections occur in the parallel glass plate 40, and multiple times occur on the upper surface of the parallel glass plate 40 Partially transmitted, resulting in multiple parallel, equally spaced reflected beams. In this embodiment, detection is performed using the first four reflected light beams generated. The upper surface of the parallel glass plate 40 can be divided into four regions according to the mode of Fig. 11: the first region 45, the second region 46, the third region 47 and the fourth region 48, each region is plated with a dielectric film of different reflectivity, in order to The reflection coefficient and light intensity ratio of each beam of reflected light are optimized, and the fourth area 48 can be coated with an anti-reflection film to fully utilize the remaining light waves. In the four light beams generated by the reflection of the parallel glass plate 40 in this embodiment, a first linear polarizer 41, a second linear polarizer 42, a third linear polarizer 43, and a fourth linear polarizer 44 are respectively arranged, and their main directions are relative to the reflecting surface. The azimuth angles can be 0°, 45°, 90°, 135° respectively. The technical steps of calibration and precision inspection in this embodiment are the same as those in Embodiment 1. By adjusting the reflectivity of each area on the upper surface of the parallel glass plate 40, this embodiment can achieve high light energy utilization; through calibration and performance optimization design, this embodiment can achieve high measurement accuracy and sensitivity.

The specific embodiment of the present invention has been described above in conjunction with the accompanying drawings, but these descriptions can not be interpreted as limiting the scope of the present invention, the protection scope of the present invention is defined by the appended claims, any claims on the basis of the present invention The changes made are within the protection scope of the present invention.

Claims (6)

1. A method for designing a sub-amplitude polarization navigation angle sensing, the specific steps are: a) The polarization state of the incident light is detected by means of multi-channel synchronous detection with sub-amplitude; b) Analyzing the vector vibration azimuth angle of the linearly polarized light field by using the Stokes vector and matrix analysis method; c) Take the condition number of the instrument matrix as the evaluation factor to carry out system optimization design on the internal component indicators and adjustment status of the sensing device; d) Accurately calibrate the instrument matrix of the sensing device by using a reference polarization generator, and perform calibration and accuracy inspection on the sensing device; It is characterized in that the amplitude-divided polarization navigation angle sensing device for realizing the design method includes: a light collecting mirror (15), a bandpass filter (16), a modulator (17), a beam splitter (18), a first phase Retardator (19), second phase retarder (20), first polarization beam splitter (21), second polarization beam splitter (22), first condenser lens (23), second condenser lens (24) , the 3rd condenser lens (25), the 4th condenser lens (26), the first aperture aperture (27), the second aperture aperture (28), the 3rd aperture aperture (29), the 3rd aperture aperture Four aperture apertures (30), the first photosensitive detector (31), the second photosensitive detector (32), the third photosensitive detector (33), the fourth photosensitive detector (34), the data acquisition unit (35 ), calculation and information display output unit (36); wherein: light collecting mirror (15), bandpass filter (16) are positioned at the front end, and its mutual position is adjustable; modulator (17) is positioned at light collecting mirror (15 ), after the band-pass filter (16); the light-collecting mirror (15), the band-pass filter (16), and the modulator (17) constitute the common light-incoming channel of the sensing device; the beam splitter (18) will incident The light beam is divided into two; the first phase retarder (19), the second phase retarder (20) are located in the two beam paths behind the beam splitter (18); the first polarizing beam splitter (21), the second polarizing The spectroscopic mirror (22) is respectively located behind the first phase retarder (19) and the second phase retarder (20), and its positions can be intermodulated; the condenser lens is placed in front of the photosensitive detector, and the two are placed together in four optical paths The end of the channel; the position of the aperture diaphragm is adjustable; the four electrical signals drawn by the four photosensitive detectors are transmitted to the data acquisition unit (35), and the data generated by the data acquisition unit (35) are transmitted to the calculation and information display output unit ( 36). 2. The sub-amplitude polarization navigation angle sensing device of a kind of sub-amplitude polarization navigation angle sensing design method according to claim 1, characterized in that: the collecting mirror (15) can be an opening with a built-in field of view diaphragm The Puller telescope can also be other forms of telescopes with light-collecting and directional observation capabilities; the modulator (17) is an optical chopper, or an electro-optic modulator, or a photoelastic modulator, or an acousto-optic modulator. 3. the sub-amplitude polarization navigation angle sensing device of a kind of sub-amplitude polarization navigation angle sensing design method according to claim 1, is characterized in that: the first phase retarder (19), the second phase retarder (20 ) are interchanged or not; the phase retarder is a wave plate or a prism, or a compensator, or a liquid crystal device; the number of phase retarders is not limited to two. 4. the amplitude-divided polarization navigation angle sensing device of a kind of amplitude-divided polarization navigation angle sensing design method according to claim 1, is characterized in that: beam splitter (18), the first polarization beam splitter (21), the second The two polarization beamsplitters (22) are prisms or diffraction gratings, or parallel glass plates; the beamsplitter (18), the first polarization beamsplitter (21), and the second polarization beamsplitter (22) can be the same device, or Different devices can also be combined into one device; the position of the first small aperture stop (27) is not limited to between the first condenser lens (23) and the first photosensitive detector (31); the second small hole stop The position of (28) is not limited between the second condenser lens (24) and the second photosensitive detector (32); The position of the 3rd pinhole diaphragm (29) is not limited to the 3rd condenser lens (25) and the Between the three photosensitive detectors (33); the position of the fourth aperture diaphragm (30) is not limited between the fourth condenser lens (26) and the fourth photosensitive detector (34); the quantity of the aperture aperture is not limited Limited to the number of channels. 5. The sub-amplitude polarization navigation angle sensing device of a kind of sub-amplitude polarization navigation angle sensing design method according to claim 1, characterized in that: the photosensitive detector is a silicon-based photodetector or a gallium phosphide photodetector , or photomultiplier tubes, or avalanche photodetectors, or position sensing detectors; the data acquisition unit (35) can be an external independent collector, or can be integrated into the internal circuit of the sensing device; calculation and information display output The unit (36) can be a computer and measurement and control software, or an embedded software and hardware functional module integrated in the sensing device. 6. The sub-amplitude polarization navigation angle sensing device of a kind of sub-amplitude polarization navigation angle sensing design method according to claim 1, characterized in that: the multi-channel optical path layout form is a planar layout form or a spatial three-dimensional layout form; Other optical elements are arranged in the optical path of each channel, which are polarizers or lenses, or prisms, or mirrors, or protective glass.