CN110081978A - A kind of multispectral polarization imaging device of transient state and its imaging method - Google Patents

Abstract

The invention discloses a transient multispectral polarization imaging device and an imaging method thereof. The device comprises an imaging objective lens, a diaphragm, a collimating objective lens, a filter array, a microlens array and an area array detector arranged in sequence. The method includes the following steps: the incident light is imaged on the diaphragm through the imaging objective lens, and then incident on the filter array in the form of a collimated beam through the collimating objective lens; the collimated beam is divided into a plurality of collimated beams of different wavelength bands, and the Incident to the microlens array, the filter and the position of the microlens correspond one-to-one; multiple collimated beams are respectively imaged on different areas of the target surface of the area array detector through the microlens array, and the images on the area array detector are collected to obtain Spectral polarization images of multiple bands; using the collected spectral polarization images of multiple spectral bands to synthesize color spectral polarization images. The invention can realize the synchronous real-time measurement of the spectral information and the polarization information of the detection target, and has the advantages of compact structure, low complexity, high integration and high measurement efficiency.

Description

A transient multispectral polarization imaging device and imaging method thereof

technical field

The invention belongs to the field of optical imaging detection, in particular to a transient multispectral polarization imaging device and an imaging method thereof.

Background technique

Spectral polarization imaging technology is a new optical detection technology that integrates imaging technology, spectral technology and polarization technology. This technology can obtain the data hypercube of the measured target, including the image information of the measured target and the spectral information of each point and polarization information for each spectral band. Spectral polarization imaging technology can detect multi-dimensional optical information that cannot be obtained by conventional optical instruments. Therefore, it has broad application prospects in the fields of atmospheric detection, biomedicine, target detection and identification, and astronomical observation.

At present, multispectral polarization imaging technology can be mainly divided into dispersion type, interference type and filter type according to the different ways of spectral spectroscopy. Dispersive multispectral polarization imaging technology uses prisms or gratings as light-splitting elements to disperse the incident light passing through the slits according to wavelength, and then the imaging system images the slits at different positions of the detector according to wavelengths; As a spectroscopic element, the instrument uses the principle of double-beam interference to obtain the interferogram of the incident slit, and then restores the spectrum of the slit from the interferogram through Fourier transform. Both the dispersive and interferometric multispectral polarization imaging technologies obtain the spectral polarization image information of the two-dimensional target by means of push-broom and swing-sweep, which require high stability of the platform, and acquire the spectra of all spectral bands in the same exposure. Polarization information. The filter-type multispectral polarization imaging technology is to add filters to the polarization imaging optical path. Currently, the commonly used liquid crystal tunable filters (LCTF) and acousto-optic tunable filters ( Acousto-Optic Tunable Filter, AOTF) two methods make the mechanism simpler and the detection speed faster, so it is widely used.

The Japan National Aviation Laboratory proposed a spectral polarization imaging method based on spectral filtering and polarizer rotation. This method introduces LCTF to realize spectral modulation and polarization modulation. The system has a compact structure and can be used for water pollution detection, agricultural disaster census and other work. The U.S. Army Research Laboratory proposed a spectral polarization imaging method based on spectral filtering and liquid crystal phase retardation modulation technology. The system uses AOTF as the spectral filter element and single-chip LCVR as the phase delay time-division modulation element. , the detection efficiency is high, but the acousto-optic device is more sensitive to noise, and the imaging signal-to-noise ratio is low. Based on the idea of spectral filtering and phase delay time division modulation, Xi'an Institute of Optics and Mechanics adopts LCTF as the spectral filter element and two liquid crystal variable retarders (LCVR) as the phase delay time division modulation element. The fast axis direction of the LCVR is fixed, and the phase delay changes regularly with the input voltage. In the process of scanning and imaging, by adjusting the control voltage of the LCVR, the two LCVRs have four different combinations of phase delays. Finally, by analyzing the four The information of interference fringes of different polarization modulation states can be obtained, and the full Stokes vector information of each spectral band of the imaging target can be obtained. North Central University proposed a new spectral polarization imaging method based on AOTF and photoelastic modulators. Three photoelastic modulators are used for difference frequency modulation. The three polarization parameters I, Q and U in the Stokes vector can be obtained in a single measurement. , and then by adjusting the transmission wavelength of the AOTF, the spectral polarization information of the detection target can be obtained. The above methods use two optical devices, LCTF and AOTF, for spectral spectroscopy. LCTF has the disadvantages of high cost and low spectral transmittance; while AOTF is more sensitive to noise and has a low imaging signal-to-noise ratio.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device and method capable of realizing real-time measurement of target spectrum and polarization information with low cost, compact structure, stable performance and high imaging signal-to-noise ratio.

The technical solution to achieve the purpose of the present invention is: a transient multispectral polarization imaging device, comprising an imaging objective lens, a diaphragm, a collimating objective lens, a filter array, a microlens array and an area array detector arranged in sequence along the optical axis The imaging surface of the imaging objective lens coincides with the front focal surface of the collimating objective lens; the diaphragm is located on the imaging surface of the imaging objective lens; the target surface of the area array detector is located at the image surface position of the microlens array;

The filter array includes m coplanar filters with different wavelength bands, the microlens array includes m identical microlenses coplanar, and the filters are in one-to-one correspondence with the positions of the microlenses;

The incident light is imaged on the diaphragm by the imaging objective lens, and then incident on the filter array in the form of a collimated beam through the collimating objective lens, and is divided into m collimated beams with different wavelength bands, and m beams of collimated beams are respectively incident on the micrometer. The microlenses corresponding to the lens array are then respectively imaged on m mutually separated regions on the target surface of the area array detector.

A transient multispectral polarization imaging method, comprising the following steps:

Step 1. The incident light is imaged on the diaphragm through the imaging objective lens, and then incident on the filter array in the form of a collimated beam through the collimating objective lens; the filter array includes m coplanar filters with different wavelength bands ;

Step 2, the incident collimated light beam is divided into m beams of collimated light beams with different wavelength bands after passing through the filter array, and is incident on the microlens array; the microlens array includes m identical microlenses coplanar, and The filters correspond to the positions of the microlenses one-to-one;

Step 3, m beams of collimated light beams are respectively imaged on different areas of the target surface of the area array detector after passing through the microlens array, the images on the area array detector are collected, and spectral polarization images of m bands are obtained;

Step 4: Synthesize a color spectral polarization image by using the collected spectral polarization images of multiple spectral segments.

Compared with the prior art, the present invention has the following significant advantages: 1) In the form of a combination of a filter array and a microlens array, the spectral images of multiple spectral bands of the target can be obtained simultaneously in a single acquisition, and the present invention has the advantages of high spectral transmittance, The advantages of high detection efficiency and low cost; 2) Using a polarization camera as an area array detector, it can obtain the polarization information of the detection target in real time, and has the advantages of stable performance, high imaging signal-to-noise ratio, and real-time imaging; 3) Using optical filters The combination of array and polarization camera for spectral polarization imaging detection has the advantages of simple structure, small size and low cost, and is suitable for various light and small instrument imaging applications such as some handheld instruments and small unmanned aerial vehicles.

The present invention will be described in further detail below with reference to the accompanying drawings.

Description of drawings

FIG. 1 is a schematic structural diagram of a transient multispectral polarization imaging device of the present invention.

FIG. 2 is a schematic diagram of the structure of a 2×2 filter array of the present invention.

FIG. 3 is a schematic structural diagram of a 2×2 microlens array according to the present invention.

Detailed ways

1, a transient multi-spectral polarization imaging device of the present invention includes an imaging objective lens 1, a diaphragm 2, a collimating objective lens 3, a filter array 4, a microlens array 5 and an area array detector arranged in sequence along the optical axis. The imaging surface of the imaging objective lens 1 coincides with the front focal surface of the collimating objective lens 3; the diaphragm 2 is located on the imaging surface of the imaging objective lens 1; the target surface of the area array detector 6 is located on the image surface of the microlens array 5 Location.

The filter array 4 includes m coplanar filters of different wavelength bands, the microlens array 5 includes m identical microlenses coplanar, and the filters correspond to the positions of the microlenses one-to-one;

The incident light is imaged on the diaphragm 2 through the imaging objective lens 1, and then enters the filter array 4 in the form of a collimated beam through the collimating objective lens 3, and is divided into m collimated beams of different wavelength bands, and m beams of collimated beams They are incident on the corresponding microlenses of the microlens array 5 respectively, and then each image is imaged in m mutually separated regions on the target surface of the area array detector 6 .

Further, the filter array 4 and the microlens array 5 are both n×n arrays, and m=n ² .

Further preferably, with reference to FIGS. 2 and 3 , the filter array 4 and the microlens array 5 are both 2×2 arrays, and m=4.

Further, the filter array 4 includes red band, green band, blue band and near-infrared band filters.

Exemplarily and preferably, the filters of the red wavelength band, the green wavelength band, the blue wavelength band and the near-infrared wavelength band are sequentially arranged in a clockwise or counterclockwise direction.

Further preferably, the area array detector 6 specifically adopts a polarization camera. It is to set a micro-polarization array in front of the target as a polarization modulation device, and the micro-polarization array is mainly composed of several identical polarization modulation units. Each polarization modulation unit includes four linear polarization sub-units with different polarization directions, and each sub-unit corresponds to the pixels on the target surface of the detector one-to-one. By combining and analyzing the signal of the same polarization modulation unit, the polarization information of the target point can be calculated and obtained, and the information of the four spectral channels can be combined to realize the simultaneous real-time measurement of the spectral information and polarization information of the detection target.

A transient multispectral polarization imaging method, comprising the following steps:

Step 1, the incident light is imaged on the diaphragm 2 through the imaging objective lens 1, and then incident on the filter array 4 in the form of a collimated beam through the collimating objective lens 3; the filter array 4 includes m different coplanar band filter;

Step 2, the incident collimated light beam is divided into m beams of collimated light beams with different wavebands after passing through the filter array 4, and is incident on the microlens array 5; the microlens array 5 includes m identical microlens coplanar lens, and the filter corresponds to the position of the microlens one-to-one;

Step 3, m beams of collimated light beams are respectively imaged on different areas of the target surface of the area array detector 6 after passing through the microlens array 5, and the images on the area array detector 6 are collected to obtain spectral polarization images of m bands;

Step 4: Synthesize a color spectral polarization image by using the collected spectral polarization images of multiple spectral segments.

Further, the filter array 4 and the microlens array 5 are both n×n arrays, and m=n ² .

Further preferably, n=2, and the filter array 4 includes red band, green band, blue band and near-infrared band filters.

Further, step 4 utilizes the collected spectral polarization images of multiple spectral bands to synthesize color spectral polarization images, specifically: using the spectral polarization images of the red band, green band, and blue band to synthesize color spectral polarization images.

The transient multi-spectral polarization imaging device and the imaging method of the present invention can realize the simultaneous real-time measurement of the spectral information and polarization information of the detection target by combining the filter array, the microlens array and the polarization camera for spectral polarization imaging detection. , has the advantages of compact structure, low complexity, high integration and high measurement efficiency.

Claims (10)

1. a kind of multispectral polarization imaging device of transient state, which is characterized in that including set gradually along optical axis image-forming objective lens (1), Diaphragm (2), collimator objective (3), filter arrays (4), microlens array (5) and planar array detector (6)；The image-forming objective lens (1) imaging surface is overlapped with the front focal plane of collimator objective (3)；Diaphragm (2) is located on the imaging surface of image-forming objective lens (1)；Face battle array is visited The target surface for surveying device (6) is located at the image planes position of microlens array (5)；

The filter arrays (4) include the optical filter of m coplanar different-waveband, and microlens array (5) includes coplanar m Identical lenticule, and the position of optical filter and lenticule corresponds；

Incident light is imaged on diaphragm (2) by image-forming objective lens (1), then is entered in the form of collimated light beam collimator objective (3) Filter arrays (4) are incident upon, the collimated light beam of m different-waveband is divided into, m beam collimated light beam is incident on microlens array respectively (5) corresponding lenticule is respectively imaged on the m regions being separated from each other of planar array detector (6) target surface later.

2. the multispectral polarization imaging device of transient state according to claim 1, which is characterized in that the filter arrays (4), Microlens array (5) is n × n array, m=n²。

3. the multispectral polarization imaging device of transient state according to claim 2, which is characterized in that the n=2.

4. the multispectral polarization imaging device of transient state according to claim 3, which is characterized in that the filter arrays (4) Including red band, green band, blue wave band and near infrared band optical filter.

5. the multispectral polarization imaging device of transient state according to claim 4, which is characterized in that the red band, green The optical filter of wave band, blue wave band and near infrared band is set gradually clockwise or counterclockwise.

6. the multispectral polarization imaging device of transient state according to claim 5, which is characterized in that the planar array detector (6) It is specific to use polarization camera.

7. a kind of multispectral polarization imaging method of transient state, which comprises the following steps:

Step 1, incident light are imaged on diaphragm (2) by image-forming objective lens (1), then by collimator objective (3) with collimated light beam Form is incident to filter arrays (4)；The filter arrays (4) include the optical filter of m coplanar different-waveband；

Step 2, incident collimated light beam are divided into the collimated light beam of m beam different-waveband after filter arrays (4), and are incident on Microlens array (5)；The microlens array (5) includes coplanar m identical lenticules, and the position of optical filter and lenticule Set one-to-one correspondence；

Step 3, m beam collimated light beam are imaged on the different zones of planar array detector (6) target surface respectively after microlens array (5), The image on planar array detector (6) is acquired, the spectrum polarizing image of m wave band is obtained；

Step 4 utilizes the spectrum polarizing image of collected multiple spectral coverages, synthesis chromatic spectrum polarization image.

8. the multispectral polarization imaging method of transient state according to claim 7, which is characterized in that the filter arrays (4), Microlens array (5) is n × n array, m=n²。

9. the multispectral polarization imaging method of transient state according to claim 8, which is characterized in that the n=2, optical filter battle array Arranging (4) includes red band, green band, blue wave band and near infrared band optical filter.

10. the multispectral polarization imaging method of transient state according to claim 9, which is characterized in that utilize acquisition described in step 4 The spectrum polarizing image of the multiple spectral coverages arrived, synthesize chromatic spectrum polarization image, specifically: using red band, green band, The spectrum polarizing image of blue wave band synthesizes chromatic spectrum polarization image.