Hyperspectral imaging device based on dual-channel optical path splicing laminated interference

Abstract

The invention discloses a hyperspectral imaging device based on dual-channel optical path splicing laminated interference, which sequentially comprises a front imaging objective lens, a diaphragm, a collimator objective lens, a dual-channel optical path splicing laminated interference system, a liquid crystal polarization switch, a rear imaging objective lens and an area array detector along an optical path, wherein the dual-channel optical path splicing laminated interference module comprises a polarization splitting prism, a half-wave plate and a Savart single plate, different azimuth included angles are set for a birefringence device in a cutter, optical path difference adjustment corresponding to interference signals is realized, and two groups of interference signals are spliced to improve the spectral resolution index of the imaging system. Based on the technical thought of optical path difference interference modulation, a double-channel optical path splicing laminated interference method is utilized, and under the condition that the fringe contrast is guaranteed and the sampling law is met, the optical path difference of interference signals is increased, so that the spectral resolution is improved, and the hyperspectral imaging measurement performance is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of spectral imaging measurement, and in particular relates to a hyperspectral imaging device based on dual-channel optical path splicing and stacking interference. Background Art

[0002] Fourier transform hyperspectral imaging technology integrates the detection technology of the target's two-dimensional spatial information and spectral information, obtains the spectral information of the target at each spatial position with nanometer-level spectral resolution, and effectively characterizes the multi-dimensional physical and chemical properties of the target. It is a new breakthrough in the field of optical detection technology.

[0003] In order to improve the measurement performance of the device, such as expanding the imaging field of view and extending the polarization measurement function, the conventional design method is to adopt a dual detector or image plane splitting method, which will lead to an increase in system volume and low spatial resolution. In view of the shortcomings of the existing technical solutions, this paper studies a dual-channel multi-modal static interference hyperspectral imaging technology. By adopting the technical approach of dual-channel optical path stacking and birefringence shearing interference, a dual-channel optical path splicing and stacking interference hyperspectral imaging device is established. By setting the rotation angle of the Savart plate in the dual interference channel, the optical path difference range between the reflected light path and the transmitted light path is different, and there is a certain overlapping area. The two sets of interference signals are spliced ​​to increase the optical path difference, thereby improving the spectral resolution index of the imaging system. Summary of the invention

[0004] The purpose of the present invention is to provide a hyperspectral imaging device based on dual-channel optical path splicing and stacking interference to solve the technical problem of limited optical path difference range in conventional static interference spectral imaging schemes, and ultimately improve the spectral resolution of the device.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A hyperspectral imaging device based on dual-channel optical path splicing and stacking interference comprises a front imaging objective lens, an aperture, a collimating objective lens, a dual-channel optical path splicing and stacking interference module, a liquid crystal polarization switch, a rear imaging objective lens and a planar array detector; wherein in the dual-channel optical path splicing and stacking interference module, a first half-wave plate, a first Savart single plate, a second half-wave plate, a second Savart single plate, a first reflector and a fifth half-wave plate are sequentially arranged in a reflection light path of a first polarization beam splitter prism, and a third half-wave plate, a third Savart single plate, a fourth half-wave plate, a fourth Savart single plate, a second reflector and a sixth half-wave plate are sequentially arranged in a transmission light path of the first polarization beam splitter prism; and the liquid crystal polarization switch comprises a ferroelectric liquid crystal LCS and a linear polarizer.

[0007] The material and thickness of the first Savart board, the second Savart board, the third Savart board and the fourth Savart board in the dual-channel optical path splicing stacked interference module are the same, and the optical axis direction of the first Savart board is in the positive direction of the x-axis and the negative direction of the z-axis. , the optical axis direction of the second Savart board is perpendicular to the positive direction of the x and z axes , the optical axis direction of the third Savart board is in the positive direction of the x-axis and the negative direction of the z-axis. , the optical axis direction of the fourth Savart board is perpendicular to the positive direction of the x and z axes .

[0008] The first half-wave plate, the second half-wave plate, the third half-wave plate, the fourth half-wave plate, the fifth half-wave plate and the sixth half-wave plate in the above-mentioned dual-channel optical path splicing stacked interference module are all achromatic wave plates. The fast axis of the first half-wave plate is perpendicular to the x-axis and has an angle of 0.04° with the y-axis. , the fast axis of the second half-wave plate is perpendicular to the x-axis and has an angle of , the fast axis of the third half-wave plate is perpendicular to the z-axis and has an angle of , the fast axis of the fourth half-wave plate is perpendicular to the x-axis and has an angle of , the fast axis of the fifth half-wave plate is perpendicular to the z-axis and has an angle of , the fast axis of the sixth half-wave plate is perpendicular to the x-axis and has an angle of .

[0009] The above-mentioned hyperspectral imaging device based on dual-channel optical path splicing and stacking interference is characterized in that: the first Savart single plate, the second half-wave plate and the second Savart single plate in the dual-channel optical path splicing and stacking interference module are taken as a whole, and the third Savart single plate, the third half-wave plate and the fourth Savart single plate are taken as a whole, and the optical path difference range of different channels is modulated by adjusting the rotation angle of each of the two along the y-axis.

[0010] The phase delay of the ferroelectric liquid crystal FLC in the above liquid crystal polarization switch is equivalent to that of the achromatic half-wave plate when working. When the high level is controlled, the fast axis direction of the ferroelectric liquid crystal FLC is parallel to the x-axis. When the low level is controlled, the fast axis direction of the ferroelectric liquid crystal FLC is perpendicular to the z-axis, and the angle between it and the y-axis is .

[0011] The polarizer P in the above-mentioned liquid crystal polarization switch is a linear polarizer or a Glan-Taylor prism, and the transmission direction is parallel to the x-axis.

[0012] Compared with the prior art, the advantages of the present invention are:

[0013] The present invention adopts a static interference spectroscopic method, and has no slits or moving parts in the internal structure, and has the advantages of high throughput, high stability and high resolution; by designing the azimuth angle of the birefringent device in the double interference channel, the optical path difference ranges in the reflected light path and the transmitted light path are different, and at the same time have a certain overlapping area, and the two groups of interference signals are spliced ​​to achieve an increase in the optical path difference, thereby improving the spectral resolution index of the imaging system; the present invention adopts a liquid crystal polarization switch, and a single scan can synchronously obtain the interference signals of the two interference channels. Compared with the conventional reciprocating scanning and field of view segmentation method, it has higher time resolution, spatial resolution and spectral resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of a hyperspectral imaging device based on dual-channel optical path splicing and stacking interference of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Combination Figure 1 A hyperspectral imaging device based on dual-channel optical path splicing and stacking interference of the present invention comprises a front imaging objective lens 1, an aperture 2, a collimating objective lens 3, a dual-channel optical path splicing and stacking interference module 4, a liquid crystal polarization switch 5, a rear imaging objective lens 6 and a planar array detector 7; wherein in the dual-channel optical path splicing and stacking interference module 4, a first half-wave plate HP1, a first Savart single board SP1, a second half-wave plate HP2, a second Savart single board SP2, a first reflector R1 and a fifth half-wave plate HP5 are sequentially arranged in the reflection light path of the first polarization beam splitter prism BS1, and a third half-wave plate HP3, a third Savart single board SP3, a fourth half-wave plate HP4, a fourth Savart single board SP4, a second reflector R2 and a sixth half-wave plate HP6 are sequentially arranged in the transmission light path of the first polarization beam splitter prism BS1; and the liquid crystal polarization switch 5 comprises a ferroelectric liquid crystal LCS and a linear polarizer P.

[0017] The material and thickness of the first Savart board SP1, the second Savart board SP2, the third Savart board SP3 and the fourth Savart board SP4 in the dual-channel optical path splicing stacked interference module 4 are the same, and the optical axis direction of the first Savart board SP1 is in the positive direction of the x-axis and the negative direction of the z-axis. , the optical axis direction of the second Savart board SP2 is perpendicular to the positive direction of the x and z axes. The optical axis direction of the third Savart board SP3 is in the positive direction of the x-axis and the negative direction of the z-axis. The optical axis direction of the fourth Savart board SP4 is in the positive direction of the x and z axes. .

[0018] The first half-wave plate HP1, the second half-wave plate HP2, the third half-wave plate HP3, the fourth half-wave plate HP4, the fifth half-wave plate HP5 and the sixth half-wave plate HP6 in the above-mentioned dual-channel optical path splicing stacked interference module 4 are all achromatic wave plates. The fast axis of the first half-wave plate HP1 is perpendicular to the x-axis and has an angle of 0.040° with the y-axis. , the fast axis of the second half-wave plate HP2 is perpendicular to the x-axis and has an angle of , the fast axis of the third half-wave plate HP3 is perpendicular to the z-axis and has an angle of , the fast axis of the fourth half-wave plate HP4 is perpendicular to the x-axis and has an angle of , the fast axis of the fifth half-wave plate HP5 is perpendicular to the z-axis and has an angle of , the fast axis of the sixth half-wave plate HP6 is perpendicular to the x-axis and has an angle of ;

[0019] The above-mentioned hyperspectral imaging device based on dual-channel optical path splicing and stacking interference is characterized in that: the first Savart single board SP1, the second half-wave plate HP2 and the second Savart single board SP2 in the dual-channel optical path splicing and stacking interference module are taken as a whole, and the third Savart single board SP3, the third half-wave plate HP3 and the fourth Savart single board SP4 are taken as a whole, and the optical path difference range of different channels is modulated by adjusting the rotation angle of each of the two along the y-axis;

[0020] The phase delay amount of the ferroelectric liquid crystal FLC in the above-mentioned liquid crystal polarization switch 5 is equivalent to that of the achromatic half-wave plate when working. When the high-level control is performed, the fast axis direction of the ferroelectric liquid crystal FLC is parallel to the x-axis. When the low-level control is performed, the fast axis direction of the ferroelectric liquid crystal FLC is perpendicular to the z-axis, and the angle between the ferroelectric liquid crystal FLC and the y-axis is The polarizer P in the above-mentioned liquid crystal polarization switch 5 is a linear polarizer or a Glan-Taylor prism, and the transmission direction is parallel to the x-axis.

[0021] Set the azimuth angle of the two-channel birefringent devices so that the overlap area of ​​the optical path difference range of the two channels is 10%. Therefore, the total optical path difference of the splicing is 1.9 times the initial optical path difference. The imaging process is as follows:

[0022] In the first step, the incident light is imaged on the image plane through the front imaging objective lens 1, the stray light is removed through the aperture 2, and then the collimated light is formed after passing through the collimating objective lens 3;

[0023] In the second step, the collimated light beam enters the dual-channel optical path splicing and stacking interference module 4, and first passes through the polarization beam splitter prism BS1, and is divided into reflected linear polarized light and transmitted linear polarized light;

[0024] In the third step, taking the reflected light path of the polarization beam splitter BS1 as an example, the polarization direction of the reflected linear polarized light is parallel to the y-axis, and the linear polarization direction rotates after passing through the first half-wave plate HP1. , with an incident angle The linear polarized light is incident on the first Savart plate SP1; after passing through the first Savart plate SP1, it is decomposed into two linear polarized lights with equal intensity, perpendicular vibration directions, parallel emission directions, perpendicular vibration directions and separated in space, where the o light is parallel to the z axis and the e light is parallel to the y axis; after the two linear polarized lights are incident on the second half-wave plate HP2, they rotate , o light is parallel to the y axis, e light is parallel to the z axis; the two linearly polarized lights are at an incident angle When entering the second Savart single board SP2, the o-light becomes the e-light, and the e-light becomes the o-light. The optical path difference is further expanded, and it becomes two linearly polarized lights with parallel emission directions, vertical vibration directions and separated in space. After passing through the first reflector R1, the two parallel polarized lights enter the fifth half-wave plate HP5, and the polarization directions are both rotated. , and then enter the polarization beam splitter prism BS2; after the two linear polarized lights pass through the polarization beam splitter prism BS2, the linear polarization component with a vibration direction parallel to the x-axis is transmitted; similarly, the linear polarized light in the transmission light path of the polarization beam splitter prism BS1, the linear polarization component with a vibration direction parallel to the y-axis is finally reflected;

[0025] In the fourth step, the linear polarized light in the reflected light path and the linear polarized light in the transmitted light path of the dual-channel optical path splicing stacked interference module enter the liquid crystal polarization switch 5 perpendicularly to each other; when the ferroelectric liquid crystal FLC control voltage is at a high level, the linear polarized light in the reflected light path is transmitted by the linear polarizer P, and the linear polarized light in the transmitted light path is absorbed by the linear polarizer P; when the ferroelectric liquid crystal control voltage is at a low level, the linear polarized light in the reflected light path is absorbed by the linear polarizer P, and the linear polarized light in the transmitted light path is transmitted by the linear polarizer P; when the ferroelectric liquid crystal control voltage is quickly switched between the high level and the low level, high-speed alternating gating of the linear polarized light in the reflected light path and the linear polarized light in the transmitted light path can be achieved;

[0026] In the fifth step, the linearly polarized light selected by the liquid crystal polarization switch 5 passes through the rear imaging objective lens 6, is imaged on the target surface of the area array detector 7 and generates interference, and the area array detector 7 obtains the interference image information of the target, and the interference image has the spatial morphology information and interference modulation information of the detection target;

[0027] The sixth step is to use the window scanning mode to perform hyperspectral imaging of the detection target. Each time the liquid crystal polarization switch 5 switches the gating state, the area array detector 7 collects a frame of interference image. After the scanning is completed, a set of interference image sequences can be captured. The interference image sequences are grouped and the interference signals of the same image points are extracted. Based on the monochromatic fringe phase calibration technology, the two sets of interference signals are spliced ​​with high precision, and then the spectral restoration of the interference signal can obtain the spectral information of the target point corresponding to the image point. The average spectral resolution is increased from 2.48 nm to 1.31 nm.

Claims

1. A hyperspectral imaging device based on dual-channel optical path splicing and stacking interference, characterized by: The invention comprises a front imaging objective lens (1), an aperture (2), a collimating objective lens (3), a dual-channel optical path splicing and stacking interference module (4), a liquid crystal polarization switch (5), a rear imaging objective lens (6) and a planar array detector (7); wherein in the dual-channel optical path splicing and stacking interference module (4), a first half-wave plate HP1, a first Savart single plate SP1, a second half-wave plate HP2, a second Savart single plate SP2, a first reflector R1 and a fifth half-wave plate HP5 are sequentially arranged in the reflection light path of a first polarization beam splitter prism BS1, and a third half-wave plate HP3, a third Savart single plate SP3, a fourth half-wave plate HP4, a fourth Savart single plate SP4, a second reflector R2 and a sixth half-wave plate HP6 are sequentially arranged in the transmission light path of the first polarization beam splitter prism BS1; and the liquid crystal polarization switch (5) comprises a ferroelectric liquid crystal LCS and a linear polarizer P.

2. The hyperspectral imaging device based on dual-channel optical path splicing and stacking interference according to claim 1 is characterized in that: The material and thickness of the first Savart single board SP1, the second Savart single board SP2, the third Savart single board SP3 and the fourth Savart single board SP4 in the dual-channel optical path splicing and stacking interference module (4) are the same, and the optical axis direction of the first Savart single board SP1 is parallel to the positive direction of the x-axis and the negative direction of the z-axis. , the optical axis direction of the second Savart board SP2 is perpendicular to the positive direction of the x and z axes. The optical axis direction of the third Savart board SP3 is in the positive direction of the x-axis and the negative direction of the z-axis. The optical axis direction of the fourth Savart board SP4 is in the positive direction of the x and z axes. .

3. The hyperspectral imaging device based on dual-channel optical path splicing and stacking interference according to claim 1 is characterized in that: The first half-wave plate HP1, the second half-wave plate HP2, the third half-wave plate HP3, the fourth half-wave plate HP4, the fifth half-wave plate HP5 and the sixth half-wave plate HP6 in the dual-channel optical path splicing stacked interference module (4) are all achromatic wave plates. The fast axis of the first half-wave plate HP1 is perpendicular to the x-axis and has an angle of 0.040° with the y-axis. , the fast axis of the second half-wave plate HP2 is perpendicular to the x-axis and has an angle of , the fast axis of the third half-wave plate HP3 is perpendicular to the z-axis and has an angle of , the fast axis of the fourth half-wave plate HP4 is perpendicular to the x-axis and has an angle of , the fast axis of the fifth half-wave plate HP5 is perpendicular to the z-axis and has an angle of , the fast axis of the sixth half-wave plate HP6 is perpendicular to the x-axis and has an angle of .

4. The hyperspectral imaging device based on dual-channel optical path splicing and stacking interference according to claim 1 is characterized in that: In the dual-channel optical path splicing stacked interference module (4), the first Savart single plate SP1, the second half-wave plate HP2 and the second Savart single plate SP4 are taken as a whole, and the third Savart single plate SP3, the third half-wave plate HP3 and the fourth Savart single plate SP4 are taken as a whole, and the optical path difference range of different channels is modulated by adjusting the rotation angle of each of the two along the y-axis.

5. The hyperspectral imaging device based on dual-channel optical path splicing and stacking interference according to claim 1 is characterized in that: The phase delay amount of the ferroelectric liquid crystal FLC in the liquid crystal polarization switch (5) is equivalent to that of the achromatic half-wave plate when working. When the high level is controlled, the fast axis direction of the ferroelectric liquid crystal FLC is parallel to the x-axis. When the low level is controlled, the fast axis direction of the ferroelectric liquid crystal FLC is perpendicular to the z-axis and the angle between the ferroelectric liquid crystal FLC and the y-axis is .

6. The hyperspectral imaging device based on dual-channel optical path splicing and stacking interference according to claim 1 is characterized in that: The polarizer P in the liquid crystal polarization switch (5) is a linear polarizer or a Glan-Taylor prism, and the transmission direction is parallel to the x-axis.

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