A snapshot polarization spectrum imaging method and device

Abstract

The present invention relates to a snapshot polarization spectrum imaging method and device. It aims to solve the technical problems that the spectral imaging method or device in the prior art is not suitable for the needs of dynamic target detection and real-time detection, the time-sharing period of polarization state measurement is long, the spectral aliasing phenomenon and the energy utilization rate are not high; a snapshot polarization spectrum imaging method of the present invention, after collimating the target light, interferes it through an F-P interferometer, and continuously fine-tunes the F-P interferometer, then obtains and outputs the polarization spectrum image with the spectrum band continuously changing, and then collects the polarization spectrum image; thereby realizing the ability of snapshot polarization spectrum acquisition, for this purpose, the present invention also provides a snapshot polarization spectrum imaging device for realizing the above method, the device does not have a large-stroke moving part, has very good stability, and does not need to rotate the polarization wheel or wave plate in a traditional way.

Description

Technical Field

[0001] The invention relates to a spectral imaging method and a device, and in particular to a snapshot type polarization spectral imaging method and a device. Background Art

[0002] The combination of spectral imaging and polarization imaging has formed a new optical remote sensing technology - polarization spectral imaging technology. This technology is a new detection technology that can integrate the image information, spectral information and polarization state information of the target. It has obvious advanced principles and technical advantages. Spectral imaging equipment may have the phenomenon of "same spectrum, different objects" and "same object, different spectrum", and there are certain limitations in the accuracy of target identification. After adding polarization information to the image and spectral information, the best detection and identification capabilities can be achieved. It is especially suitable for target detection under conditions such as turbid media (smoke, fog, haze, dust, water, etc.). It also has the characteristics of "weakening strong light" and "strengthening weak light" of the polarization state, which can greatly extend the detection area of ​​remote sensing dark and bright ends. At the same time, the use of polarization means can accurately characterize and discover the laws of atmospheric attenuation, which can provide an objective basis for the new atmospheric window theory.

[0003] At present, there are mainly the following methods for polarization spectrum imaging detection:

[0004] 1. Polarization spectral imaging method based on AOTF (acousto-optic tunable) and LCTF (liquid crystal tunable): The principle of this method is to use the principle of acousto-optic diffraction and the principle of liquid crystal electric tuning to select the spectral spectrum. At the same time, a combination of phase delay devices such as LCVR is used to measure the polarization state. Its disadvantage is that it can only be used to measure static targets, which does not meet the requirements of dynamic application targets and real-time performance.

[0005] 2. Computational tomography polarization spectral imaging method: Polarization state and spectral information are detected by installing multiple polarizers and wave plates with different polarization directions. Its disadvantages are that the polarization state measurement is time-divided, the measurement cycle is long, there are moving parts, and it is not applicable when there are fast-changing moving targets.

[0006] 3. Spectral polarization imaging method based on slit dispersion: This method adopts polarization-spectral intensity modulation technology and realizes the measurement of polarization state by adding a spectral modulation module in the optical path of an ordinary slit dispersion spectrometer. The disadvantage of this method is that the spectral acquisition system uses a slit, so the energy utilization rate is relatively low, and the acquired raw data has spectral aliasing.

[0007] 4. Polarization spectral imaging system based on polarization grating: This system uses a new type of transmission anisotropic polarization-sensitive grating, which can separate the polarization dimension and the spectral dimension. However, the system has aliasing phenomenon in spectrum acquisition, and the measurement of polarization state requires combined calculation. At the same time, the system has slits, the energy utilization rate is not high, and the processing and preparation process of the transmission grating is difficult.

[0008] Based on the above typical shortcomings, there is an urgent need for a spectral imaging technology with non-push-scan, snapshot, synchronous acquisition of polarization information, and programmable spectral output. Summary of the invention

[0009] The present invention aims to solve the technical problems in the prior art that the spectral imaging method or device is not suitable for the needs of dynamic target detection and real-time detection, the time-sharing period of polarization state measurement is long, the spectral aliasing phenomenon and the energy utilization rate are low, and provide a snapshot type polarization spectral imaging method and device.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A snapshot polarization spectrum imaging method, which is special in that it includes the following steps:

[0012] Step 1) collimating the target light;

[0013] Step 2) interfering the aligned target light with the FP interferometer, and continuously fine-tuning the FP interferometer so that the wavelength of the light wave outputted by it continuously changes, thereby generating a continuous spectrum with continuously changing spectrum bands;

[0014] Step 3) obtaining and outputting a polarization spectrum image with a continuously changing spectrum segment;

[0015] Step 4) Collect polarization spectrum images.

[0016] Furthermore, in the step 2), the fine-tuning of the FP interferometer is to continuously change the displacement of the micro-displacement motor in the FP interferometer.

[0017] Based on the above-mentioned snapshot polarization spectral imaging method, the present invention also provides a snapshot polarization spectral imaging device, which is special in that:

[0018] It includes a front optical telescope unit, a FP interferometer, a detection unit and a collection control unit which are sequentially arranged along the optical path;

[0019] The front optical telescope unit collimates the target light and emits it;

[0020] The FP interferometer is used to change the optical path difference of the target light;

[0021] The detection unit acquires a polarization spectrum image of the target light;

[0022] The acquisition control unit acquires polarization spectrum images and outputs different voltage signals to the FP interferometer.

[0023] Further, the detection unit includes an imaging lens group and a polarization detector;

[0024] The imaging lens group images the target light onto the polarization detector;

[0025] The polarization detector is used to obtain a polarization spectrum image.

[0026] Further, the FP interferometer includes a micro-displacement motor;

[0027] The acquisition control unit is provided with a corresponding data set of the displacement of the micro-displacement motor and the wavelength of the output light wave.

[0028] Further, the polarization detector includes a first polarization unit;

[0029] The first polarization unit is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 135 degree linear polarization direction and a non-polarization direction.

[0030] Further, the polarization detector includes a second polarization unit;

[0031] The second polarization unit is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 135 degree linear polarization direction and a circular polarization direction.

[0032] Further, the polarization detector includes a third polarization unit;

[0033] The third polarization unit is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 90 degree linear polarization direction and a 135 degree linear polarization direction.

[0034] Furthermore, the polarization detector is formed by any combination of at least one of the first polarization unit, the second polarization unit and the third polarization unit in the form of an N*N matrix;

[0035] The first polarization unit is configured in a 2*2 matrix form by a 0 degree linear deflection direction, a 45 degree linear deflection direction, a 135 degree linear deflection direction and a non-polarization direction;

[0036] The second polarization unit is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 135 degree linear polarization direction and a circular polarization direction;

[0037] The third polarization unit is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 90 degree linear polarization direction and a 135 degree linear polarization direction.

[0038] Furthermore, the front optical telescope unit includes a front lens group, a field stop and a collimating lens group which are sequentially arranged along the optical path;

[0039] The front mirror group realizes the front collection of the target light, and makes the target light incident on the field diaphragm, and the field diaphragm performs field selection adjustment on the target light, and then the target light is collimated by the collimating mirror group and emitted to the FP interferometer.

[0040] The beneficial effects of the present invention are:

[0041] 1. Compared with the traditional polarization spectrum imaging method, the spectrum imaging method of the present invention has the ability to achieve snapshot polarization spectrum acquisition and has the ability to detect moving targets.

[0042] 2. The polarization state acquisition of the present invention is synchronous acquisition, has very good real-time performance, and is a non-traditional time-sharing and asynchronous measurement.

[0043] 3. The spectral imaging device of the present invention does not have any moving parts with a large stroke and has very good stability, and does not require a rotating polarization wheel or wave plate as in the traditional method.

[0044] 4. The spectrum acquisition of the spectrum imaging device of the present invention does not use a slit, so the energy utilization rate is high and there is no spectrum aliasing phenomenon.

[0045] 5. The polarization spectrum imaging device of the present invention has the ability to select spectrum bands under different polarization state information acquisition conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural principle diagram of a snapshot type polarization spectrum imaging device of the present invention;

[0047] Figure 2 is a configuration diagram of the first polarization unit in the present invention;

[0048] Figure 3 is a configuration diagram of the second polarization unit in the present invention;

[0049] Figure 4 is a configuration diagram of the third polarization unit in the present invention;

[0050] Figure 5 It is a configuration diagram of four first polarization units combined in a 2*2 matrix form in the present invention.

[0051] In the figure, 1-front optical telescope unit, 11-front lens group, 12-field diaphragm, 13-collimation lens group, 2-FP interferometer, 3-detection unit, 31-imaging lens group, 32-polarization detector, 321-first polarization unit, 322-second polarization unit, 323-third polarization unit, 4-acquisition control unit. DETAILED DESCRIPTION

[0052] In order to make the purpose, advantages and features of the present invention clearer, a snapshot polarization spectrum imaging method and device proposed by the present invention are further described in detail below in combination with the accompanying drawings and specific embodiments. According to the following specific implementation methods, the advantages and features of the present invention will be clearer. It should be noted that: the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention; secondly, the structure shown in the drawings is often part of the actual structure.

[0053] The present invention provides a snapshot type polarization spectrum imaging device, such as Figure 1 As shown, it includes a front lens group 11, a field aperture 12, a collimating lens group 13, an FP interferometer 2, an imaging lens group 31, a polarization detector 32 and an acquisition control unit 4 which are sequentially arranged along the optical path;

[0054] The front lens group 11, the field aperture 12 and the collimating lens group 13 constitute a front optical telescope unit 1 for collimating the target light; the FP interferometer 2 is used to change the optical path difference of the target light; the imaging lens group 31 and the polarization detector 32 constitute a detection unit 3 for obtaining the polarization image of the light beam; the acquisition control unit 4 realizes the acquisition of polarization spectrum data, the control and adjustment of the detector and the micro-displacement motor.

[0055] The FP interferometer 2 includes a micro-displacement motor. Changing the displacement of the micro-displacement motor can change the wavelength of the light wave output by the FP interferometer, thereby generating a continuous spectrum with continuously changing spectrum segments.

[0056] The target light enters the front mirror group 11 to realize the front collection, and the target light is incident on the field of view aperture 12, the field of view aperture 12 selects and adjusts the field of view of the target light, and then is collimated by the collimating mirror group 13 to be emitted to the FP interferometer 2; the displacement of the micro-displacement motor in the FP interferometer 2 is controlled by the acquisition control unit 4, so as to continuously modulate and transform the spectrum, and then the image is formed on the polarization detector 32 through the imaging mirror group 31 to realize the acquisition of the polarization image of the continuous spectrum, and the polarization state adjustment of different spectrum bands can realize the acquisition of different polarization states through the change of the polarization detector.

[0057] The displacement generated by the micro-displacement motor is proportional to the optical path difference of the two interfering light beams, and the optical path difference corresponds to the wavelength generated by the interference. Therefore, the present invention provides a corresponding data set of the displacement of the micro-displacement motor and the wavelength of the light beam in the acquisition control unit 4. In use, it can be directly added to the required wavelength position as needed, without gradually scanning from the starting point, and the wavelength to be detected can be selected as needed, that is, by programming the driving voltage signal added to the micro-displacement motor, the change of the micro-displacement is realized, thereby realizing the selection and output of the wavelength, which has a relatively large advantage in application, such as achieving the detection purpose without generating a large amount of data (data cube), and greatly improving work efficiency.

[0058] The present invention provides four configurations of polarization detectors:

[0059] The first one, such as Figure 2 As shown, the polarization detector 32 includes a first polarization unit 321; the first polarization unit 321 is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 135 degree linear polarization direction and a non-polarization direction. This configuration can avoid weak incident light energy and limited target detection.

[0060] The second type, such as Figure 3 As shown, the polarization detector 32 includes a second polarization unit 322; the second polarization unit 322 is configured in a 2*2 matrix form by a 0 degree linear polarization direction, a 45 degree linear polarization direction, a 135 degree linear polarization direction and a circular polarization direction; this configuration adopts the memory effect of circular polarization information to obtain full polarization information;

[0061] The third type, such as Figure 4 As shown, the polarization detector 32 includes a third polarization unit 323; the third polarization unit 323 is configured in a 2*2 matrix form by a 0-degree linear polarization direction, a 45-degree linear polarization direction, a 90-degree linear polarization direction and a 135-degree linear polarization direction. This configuration can obtain two orthogonal linear polarization information, which correspond to different application scenario requirements.

[0062] Fourthly, the polarization detector 32 is composed of at least one of the first polarization unit 321 in the first type, the second polarization unit 322 in the second type, and the third polarization unit 323 in the third type in an N*N matrix form; that is, it can be all one of the above three types, or any two of them, or all three, and its configuration is varied. Figure 5 As shown, four first polarization units 321 are arranged in a 2*2 matrix. This arrangement can acquire polarization information of a target at any position in the field of view.

[0063] A snapshot polarization spectrum imaging method of the present invention comprises the following steps:

[0064] Step 1) The target light is collected, adjusted and collimated in sequence by the front optical telescope unit, and then incident on the FP interferometer;

[0065] Step 2) continuously modulating the FP interferometer by the acquisition control unit, thereby continuously adjusting the wavelength of the light wave output by the FP interferometer to generate a continuous spectrum with a continuously changing spectrum band;

[0066] Step 3) imaging the continuous spectrum with continuously changing spectrum bands to a polarization detector through an imaging lens group in the detection unit, and obtaining and outputting the polarization spectrum image with continuously changing spectrum bands through the polarization detector;

[0067] Step 4) collecting polarization spectrum images through the collection control unit.

Claims

1. A snapshot polarization spectrum imaging device, characterized in that: It comprises a front optical telescope unit (1), an FP interferometer (2), a detection unit (3) and a collection control unit (4) which are sequentially arranged along the optical path; The front optical telescope unit (1) collimates and emits the target light; The FP interferometer (2) is used to change the optical path difference of the target light; the FP interferometer (2) comprises a micro displacement motor; The detection unit (3) acquires a polarization spectrum image of the target light; the detection unit (3) comprises an imaging lens group (31) and a polarization detector (32); the imaging lens group (31) images the target light on the polarization detector (32); the polarization detector (32) is used to acquire a polarization spectrum image; the polarization detector (32) is composed of at least one of a first polarization unit (321), a second polarization unit (322) and a third polarization unit (323) in an N*N matrix form; the first polarization unit (321) is composed of a 0 degree linear deflection direction, a 45 degree linear deflection direction, a 135 degree linear deflection direction, and a The second polarization unit (322) is configured in the form of a 2*2 matrix consisting of a 0-degree linear deflection direction, a 45-degree linear deflection direction, a 135-degree linear deflection direction and a circular polarization direction; the third polarization unit (323) is configured in the form of a 2*2 matrix consisting of a 0-degree linear deflection direction, a 45-degree linear deflection direction, a 90-degree linear deflection direction and a 135-degree linear deflection direction; the acquisition control unit (4) acquires polarization spectrum images and outputs different voltage signals to the FP interferometer (2); and a corresponding data set of the displacement of the micro-displacement motor and the output light wavelength is provided in the acquisition control unit (4).

2. A snapshot polarization spectrum imaging device according to claim 1, characterized in that: The front optical telescope unit (1) comprises a front lens group (11), a field stop (12) and a collimating lens group (13) which are sequentially arranged along the optical path; The front mirror group (11) realizes the front collection of target light and makes the target light incident on the field diaphragm (12). The field diaphragm (12) performs field selection adjustment on the target light and then collimates the target light through the collimating mirror group (13) and emits it to the FP interferometer (2).

3. A snapshot polarization spectral imaging method, using the snapshot polarization spectral imaging device according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step 1) collimating the target light; Step 2) interfering the aligned target light with the FP interferometer, and continuously fine-tuning the FP interferometer so that the wavelength of the light wave outputted by the FP interferometer is continuously changed, thereby generating a continuous spectrum with continuously changing spectrum bands; the fine-tuning of the FP interferometer is to continuously change the displacement of the micro-displacement motor in the FP interferometer; Step 3) obtaining and outputting a polarization spectrum image with a continuously changing spectrum segment; Step 4) Collect polarization spectrum images.

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