CN112166684B - Liquid crystal multispectral scanning imaging system - Google Patents
Liquid crystal multispectral scanning imaging system Download PDFInfo
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- CN112166684B CN112166684B CN200910121509.0A CN200910121509A CN112166684B CN 112166684 B CN112166684 B CN 112166684B CN 200910121509 A CN200910121509 A CN 200910121509A CN 112166684 B CN112166684 B CN 112166684B
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- 239000000463 material Substances 0.000 claims description 3
- 238000013480 data collection Methods 0.000 claims 1
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Abstract
The invention provides a liquid crystal multispectral scanning imaging system which comprises a liquid crystal adjustable optical filter, a CCD (charge coupled device) camera, a driving controller and image data acquisition equipment. Compared with the traditional multispectral imaging system, the liquid crystal multispectral scanning imaging system has the advantages of small volume, light weight, simple structure, lower cost, narrow bandwidth, wide tuning range, low spectral addressing voltage, large clear aperture and the like, and has wide application potential in the fields of remote sensing imaging, optical fiber communication, astronomical observation, environmental protection, color display, medical diagnosis and the like.
Description
Technical Field
The invention belongs to the technical field of devices or devices for controlling the color of light, and particularly relates to a liquid crystal multispectral scanning imaging system. The multispectral scanning imaging system based on the liquid crystal has high spectral resolution and spectral sampling rate, can obtain a large amount of information, and has wide application prospects in the aspects of military reconnaissance, astronomical observation, biochemistry, medical diagnosis, environmental monitoring, archaeology, cultural relic protection, agriculture and forestry quality control and the like.
Background
Multispectral imaging devices that have been developed so far can be basically classified into wavelength scanning, spatial scanning, temporal scanning and the like, wherein the wavelength scanning device only measures the whole image at one wavelength at each moment; spatial scanning devices use dispersive elements, such as gratings or prisms, to scan an image along at least one axis, or point-by-point on a confocal microscope with dispersive elements; the time scanning device uses an interferometer or other optical elements to obtain spectral information of each point in the image through some mathematical transformation (e.g., fourier transform). The existing multispectral imaging device has no fundamental change in the past decades and has the defects of complex structure, high price, large volume and weight and the like.
Disclosure of Invention
The invention aims to provide a liquid crystal multispectral scanning imaging system.
The liquid crystal multispectral scanning imaging system comprises a liquid crystal adjustable optical filter, a CCD camera, a driving controller and image data acquisition equipment.
The liquid crystal adjustable optical filter and the CCD camera are respectively connected with the driving controller; under the action of the driving controller, the liquid crystal tunable filter selectively transmits a specific spectral passband and suppresses light with other wavelengths outside the passband, so as to provide a CCD camera with a light signal with a specific spectrum from a scene.
The CCD camera receives an optical signal passing through the liquid crystal adjustable optical filter, realizes scene imaging, and provides scene image data for the image data acquisition equipment through the video output terminal; the CCD camera and the liquid crystal adjustable optical filter are respectively connected with the image data acquisition equipment.
The driving controller comprises a control module and a multi-channel driving source, and the liquid crystal adjustable optical filter, the driving controller and the image data acquisition equipment are sequentially connected; the control module receives a control instruction of the image data acquisition equipment, and a driving signal is output to the liquid crystal adjustable optical filter by the multi-channel driving source, so that the liquid crystal adjustable optical filter realizes spectrum scanning.
The image data acquisition equipment comprises control acquisition software, a computer, an RS232 port and an image acquisition card; the computer is connected with the driving controller through an RS232 port and sends an instruction to the driving controller to enable the liquid crystal adjustable filter to carry out spectrum scanning; the image acquisition card is inserted into a PCI slot of a computer, is connected with the CCD camera and receives image data output by the CCD camera; the control acquisition software arranged in the computer sends an instruction to the drive controller through the RS232 port, and stores the image data received by the image acquisition card on a hard disk of the computer.
The liquid crystal adjustable filter comprises an electric control liquid crystal wave plate and a polaroid, wherein the electric control liquid crystal wave plate and the polaroid are filled with nematic liquid crystal materials in a multistage mode; the electric control liquid crystal wave plate provides controllable phase delay, the fast axis direction of the electric control liquid crystal wave plate forms an angle of 45 degrees with the transmission polarized light direction of the polaroid, and the polarization state of incident light can be controlled; the polaroid and the electric control liquid crystal wave plate are arranged in parallel and stacked at intervals, the directions of the transmitted polarized light are parallel to each other, and the light in a specific polarization state can be selectively transmitted.
The control acquisition software sends a control instruction to the drive controller through an RS232 port of the computer, drives the liquid crystal adjustable optical filter to select and transmit a specific wavelength, and realizes spectrum scanning in a certain spectrum band; and controlling the acquisition software to simultaneously control the image acquisition card, acquiring the scene image from the CCD camera, and storing the scene image in a hard disk of a computer to obtain a multispectral image sequence of the scene.
The working process of the liquid crystal multispectral scanning imaging system is as follows:
the image data acquisition equipment sends an instruction to the drive controller through a computer RS232 interface; a control module of the driving controller receives a control instruction sent by the image data acquisition equipment, and the multi-channel driving source outputs a group of low-voltage alternating signals according to the instruction to drive the liquid crystal adjustable optical filter; the liquid crystal adjustable filter filters the optical signal from the scenery under the action of the driving controller, and the central wavelength of the selective transmission is lambda0The spectrum has a certain bandwidth, and other wavelengths outside the band are highly inhibited; the CCD camera receives an optical signal from a scene which penetrates through the liquid crystal adjustable filter to image the scene, and outputs an image signal to image data acquisition equipment through a video terminal; the image data acquisition equipment receives an image signal of the CCD camera by using an image acquisition card, and controls acquisition software to acquire and store a frame of image on a computer hard disk. Repeating the above process, and allowing the liquid crystal tunable filter to transmit the center wavelength λ of the passband under the control of the drive controller0Performing a spectral scan within a particular spectral band, image dataThe acquisition equipment synchronously records and stores the image data to obtain a multispectral image sequence of the scenery. The image sequence not only contains the spatial distribution of the object/scene, but also contains the spectral information of the object scene.
The liquid crystal multispectral scanning imaging system adopts the liquid crystal adjustable optical filter, and the structure of the multispectral imaging system is greatly simplified due to the unique advantages of the liquid crystal adjustable optical filter. The liquid crystal adjustable optical filter has the characteristics of a conventional optical filter, and can also rapidly change the position of a spectral passband of the liquid crystal adjustable optical filter by adjusting voltage, so that the liquid crystal adjustable optical filter is different from the traditional multispectral imaging system, the liquid crystal multispectral scanning imaging system does not need the support of a mechanical part, multispectral imaging can be realized by controlling related software and hardware, and the liquid crystal adjustable optical filter has the characteristics of simple structure, small volume, light weight, narrow bandwidth, less energy consumption, wide tuning range, low driving voltage and the like.
Drawings
FIG. 1 is a structural block diagram of a liquid crystal multispectral scanning imaging system of the present invention
FIG. 2 is a schematic diagram of a liquid crystal tunable filter according to the present invention
FIG. 3 is a schematic diagram of an electrically controlled liquid crystal waveplate structure according to the present invention
FIG. 4 is a block diagram of a driving controller according to the present invention
FIG. 5 is a block diagram showing the configuration of an image data acquisition apparatus according to the present invention
FIG. 6 is a transmission spectrum sequence obtained by using the liquid crystal tunable filter of the present invention
FIG. 7 is a full color image of a scene (a) and multispectral images of the scene (b), (c), (d) measured using the present invention
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Fig. 1 is a structural block diagram of a liquid crystal multispectral scanning imaging system of the invention, which comprises a liquid crystal adjustable filter 1, a CCD camera 2, a drive controller 3 and an image data acquisition device 4. The liquid crystal adjustable optical filter 1 is connected with the CCD camera 2 and the drive controller 3; the image data acquisition device 4 is connected with the CCD camera 2 and the drive controller 3.
The CCD camera 2 can adopt a black-and-white CCD camera or a color CCD camera, and the standard can be PAL or NTSC. In this embodiment, a Sony black-and-white CCD camera of PAL system, model XC-ST30, is used. The optical lens of the CCD camera adopts a C-mount interface and can be conveniently connected with the liquid crystal adjustable optical filter 1; outputting video signals through a BNC connector, wherein the frame frequency is 25 frames per second; the gain adjusting device has a gain adjusting function, and different gains can be selected according to the illumination intensity of incident light.
Fig. 2 is a schematic diagram of the structure of the liquid crystal tunable filter 1 of the present invention, which includes electrically controlled liquid crystal waveplates (11, 12, 13, 14, 15) and polarizers (5, 6, 7, 8, 9, 10). Wherein the directions of transmitted polarized light of the polarizing plates (5, 6, 7, 8, 9, 10) are parallel to each other; the fast axis direction of the electric control liquid crystal wave plates (11, 12, 13, 14, 15) forms an angle of 45 degrees with the transmission polarized light direction of the polarizing plates (5, 6, 7, 8, 9, 10); the polaroids (5, 6, 7, 8, 9, 10) and the electric control liquid crystal wave plates (11, 12, 13, 14, 15) are arranged in parallel and are stacked at intervals. The extinction ratio of the polarizers (5, 6, 7, 8, 9, 10) is a relatively critical parameter for the liquid crystal tunable filter 1, and directly determines the suppression effect outside the passband of the liquid crystal tunable filter 1.
Fig. 3 is a schematic structural diagram of an electrically controlled liquid crystal wave plate (11, 12, 13, 14, 15), which includes a glass substrate (16, 17), an ITO transparent conductive film layer (18, 19), a PI alignment film layer (20, 21), a liquid crystal layer 22 and a thickness control spacer (23, 24). The ITO transparent conductive film layers (18 and 19) are connected with the multi-channel driving source 26 through electrodes, an electric field is provided for the liquid crystal layer 22, the direction of liquid crystal molecules is rotated, the phase delay of the electric control liquid crystal wave plates (11, 12, 13, 14 and 15) is changed, and therefore the polarization state of incident light is controlled; the PI orientation film layers (20, 21) are coated on the inner surfaces of the glass substrates (23, 24), and after the PI orientation film layers are subjected to baking, rubbing and other process treatment, liquid crystal molecules in the liquid crystal layer 22 can be induced to be arranged according to a specific direction, so that the electric control liquid crystal wave plate has the birefringence optical characteristics of crystals; the liquid crystal layer 22 is formed by pouring nematic liquid crystal material between the glass substrates, the thickness of the liquid crystal layer 22 is controlled by the thickness control spacers (23, 24), and the refractive index difference Deltan is between 0.08 and 0.25. The thickness control spacers (23, 24) can be made of glass fiber, glass beads or plastic beads.
Fig. 4 is a block diagram of the structure of the drive controller 3, including the control module 25 and the multi-channel drive source 26. After receiving the instruction of the image data acquisition device 4, the control module 25 outputs a driving signal to the liquid crystal tunable filter 1 by the multi-channel driving source 26. The maximum output channel number of the multichannel output signal source 26 of the driving controller 2 in this embodiment is 32, the frequency of the output signal can be selected between 1kHz and 10kHz, and the signal amplitude is continuously variable between 0V and 10V.
Fig. 5 is a block diagram of the image data acquisition device 4, including control acquisition software, a computer 27, an RS232 port 28, and an image acquisition card 29. The image acquisition card 29 is inserted in the PCI slot of the computer 27, and its video input terminal is connected to the BNC video output terminal of the CCD camera 2. The RS232 port 28 of the computer 27 is connected to the control module 25 of the drive controller 2. The control acquisition software sends a control instruction to the drive controller 2 through the RS232 port 28 to drive the liquid crystal tunable filter 1 to selectively transmit a specific wavelength, and spectrum scanning in a certain spectrum band is realized. The control acquisition software simultaneously controls the image acquisition card 29 to acquire the scenery image from the CCD camera 2 and store the scenery image on the hard disk of the computer 27 to obtain the multispectral image sequence of the scenery.
Fig. 6 is a sequence of transmission spectra of the liquid crystal tunable filter 1. In this embodiment, the thickness of the liquid crystal layer 22 of the electrically controlled liquid crystal wave plates (11, 12, 13, 14, 15) used in the liquid crystal tunable filter 1 is between 5 μm and 80 μm, the frequency of the driving signal output by the driving controller 3 is 1kHz, and the amplitude varies between 1V and 5V.
FIG. 7 is a sequence of multispectral images of a scene obtained using the liquid crystal multispectral scanning imaging system of the present invention, wherein FIG. 7(a) is a full-color image of the scene, wherein the primary colors are red, green and blue; fig. 7(b) to 7(d) are images obtained by the liquid crystal multispectral scanning imaging system of the present invention when the transmission center wavelengths of the liquid crystal tunable filter 1 are 662nm, 580nm, and 461nm, respectively.
Claims (3)
1. The utility model provides a multispectral scanning imaging system of liquid crystal, includes liquid crystal tunable filter (1), CCD camera (2), drive controller (3) and image data collection equipment (4), its characterized in that: the liquid crystal multispectral scanning imaging system
The liquid crystal adjustable optical filter (1) and the CCD camera (2) are respectively connected with the driving controller (3); under the action of the driving controller (3), the liquid crystal tunable filter (1) selectively transmits a specific spectrum passband, suppresses light with other wavelengths outside the passband, and provides a CCD camera (2) with a light signal with a specific spectrum from a scene;
the CCD camera (2) receives an optical signal passing through the liquid crystal adjustable optical filter (1), realizes scene imaging, and provides scene image data for the image data acquisition equipment (4) through a video output terminal; the CCD camera (2) and the liquid crystal adjustable optical filter (1) are respectively connected with the image data acquisition equipment (4);
the driving controller (3) comprises a control module (25) and a multi-channel driving source (26), and the liquid crystal adjustable optical filter (1), the driving controller (3) and the image data acquisition equipment (4) are sequentially connected; the control module (25) receives a control instruction of the image data acquisition equipment (4), and a multi-channel driving source (26) outputs a driving signal to the liquid crystal adjustable optical filter (1) to enable the liquid crystal adjustable optical filter (1) to realize spectrum scanning;
the image data acquisition equipment (4) comprises control acquisition software, a computer (27), an RS232 port (28) and an image acquisition card (29); the computer (27) is connected with the driving controller (3) through an RS232 port (28) and sends an instruction to the driving controller (3) to enable the liquid crystal tunable filter (1) to carry out spectrum scanning; the image acquisition card (29) is inserted into a PCI slot of the computer (27), is connected with the CCD camera (2) and receives image data output by the CCD camera (2); the control acquisition software arranged in the computer (27) sends instructions to the drive controller (3) through the RS232 port (28), and stores the image data received by the image acquisition card (29) on the hard disk of the computer (27).
2. The liquid crystal multispectral scanning imaging system of claim 1, wherein: the liquid crystal tunable filter (1) comprises electric control liquid crystal wave plates (11, 12, 13, 14, 15) and polarizing plates (5, 6, 7, 8, 9, 10) which are filled with nematic liquid crystal materials in a multistage mode; the electric control liquid crystal wave plates (11, 12, 13, 14, 15) provide controllable phase retardation, the fast axis direction of the electric control liquid crystal wave plates forms an angle of 45 degrees with the transmission polarized light direction of the polarizing plates (5, 6, 7, 8, 9, 10), and the polarization state of incident light can be controlled; the polaroids (5, 6, 7, 8, 9, 10) and the electric control liquid crystal wave plates (11, 12, 13, 14, 15) are arranged in parallel and stacked at intervals, and the transmission polarization directions are parallel to each other so as to selectively transmit light in a specific polarization state.
3. The liquid crystal multispectral scanning imaging system of claim 1, wherein: the control acquisition software sends a control instruction to the drive controller (3) through an RS232 port (28) of the computer (27), drives the liquid crystal tunable filter (1) to selectively transmit a specific wavelength and realizes spectrum scanning in a certain spectrum band; the control acquisition software controls the image acquisition card (29) at the same time, acquires the scenery image from the CCD camera (2), and stores the scenery image on the hard disk of the computer (27) to obtain the multispectral image sequence of the scenery.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910121509.0A CN112166684B (en) | 2009-06-03 | 2009-06-03 | Liquid crystal multispectral scanning imaging system |
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| CN200910121509.0A CN112166684B (en) | 2009-06-03 | 2009-06-03 | Liquid crystal multispectral scanning imaging system |
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| CN112166684B true CN112166684B (en) | 2013-04-10 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113325648A (en) * | 2021-07-07 | 2021-08-31 | 台州安奇灵智能科技有限公司 | Spectral imaging system based on guest-host liquid crystal tunable filter |
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2009
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113325648A (en) * | 2021-07-07 | 2021-08-31 | 台州安奇灵智能科技有限公司 | Spectral imaging system based on guest-host liquid crystal tunable filter |
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