Thermal infrared imager for time-space synchronous acquisition of spectral polarization information

Abstract

The invention discloses a thermal infrared imager for synchronously acquiring spectral polarization information in a time-space manner. The thermal infrared imager comprises a medium-wave infrared optical system, a refrigeration medium-wave infrared focal plane array detector, a circuit system and an upper computer, the medium-wave infrared optical system collects spectral polarization information from a target, and collected optical signals are converted into electric signals through the refrigeration medium-wave infrared focal plane array detector and output to the circuit system through the detector interface. The circuit system is used for supplying power to other equipment and forwarding an electric signal to the upper computer; and the upper computer pre-processes the electric signal and then outputs an image signal. The super-surface array is combined with a traditional thermal infrared imager, synchronous acquisition of target spectrum polarization information is achieved, and the problem that the radiation information of a detected target of an existing thermal infrared imager is limited is solved.

Description

Technical Field

[0001] The invention relates to an infrared thermal imager for synchronously acquiring spectral polarization information in time and space, and belongs to the field of infrared detection imaging. Background Art

[0002] Infrared thermal imagers detect infrared radiation emitted by targets in a passive way. Since they are not affected by factors such as smoke and dust, they can be used all day long. Compared with other active imaging systems, they are more concealed. Therefore, they have extremely high application value in the military field and can be used for night vision observation, precision guidance, weapon sights, search and tracking equipment, etc. Among them, the cooled infrared detector has the advantages of high sensitivity, fast response speed and long detection distance, and is often used in high-end military fields such as airborne, shipborne, and missile-borne that have high performance requirements.

[0003] However, in complex environments and under strong artificial interference, the single-information infrared optoelectronic system is limited by the detection system and information technology level. Its detection accuracy, distance and resolution capabilities are insufficient and cannot meet the target imaging perception requirements in different scenarios. It is necessary to expand the detection information dimension of current optoelectronic equipment. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose an infrared thermal imager that can synchronously acquire spectral polarization information in space and time. By combining a metasurface array with a traditional infrared thermal imager, the synchronous acquisition of target spectral polarization information is achieved, thereby solving the problem of limited target radiation information detected by existing infrared thermal imagers.

[0005] The technical solution of the present invention is: an infrared thermal imager for synchronously acquiring spectral polarization information in time and space, comprising: a medium-wave infrared optical system, a refrigerated medium-wave infrared focal plane array detector, a circuit system and a host computer; the medium-wave infrared optical system collects spectral polarization information from a target, and the collected optical signal is converted into an electrical signal by the refrigerated medium-wave infrared focal plane array detector, and is output to the circuit system through a detector interface; the circuit system is responsible for supplying power to other devices and forwarding the electrical signal to the host computer; the host computer pre-processes the electrical signal and outputs an image signal.

[0006] The medium-wave infrared optical system is used to obtain spectral polarization information of targets within the field of view, the detection band is medium-wave 3.7-4.8 μm, and the detection linear polarization angles are 0°, 45° and 90°.

[0007] The medium-wave infrared optical system includes a head cover, a first aspheric lens, a second aspheric lens, a third aspheric lens, a lens array, and a metasurface array, which are arranged in sequence from the optical axis direction; external input light enters the head cover and then transmits the medium-wave infrared, and then passes through the first aspheric lens, the second aspheric lens, and the third aspheric lens in sequence to correct the aberration, and then the light is converged on the lens array for splitting, and after the splitting is completed, the spectral polarization imaging is completed through the metasurface array to obtain spectral polarization information.

[0008] The head cover is a concentric spherical lens, which is made of fluorine glass; the first aspheric lens is a positive lens, which is made of germanium glass; the second aspheric lens is a positive lens, which is made of chalcogenide glass; the third aspheric lens is a positive lens, which is made of chalcogenide glass; the lens array is composed of four sub-lenses, all of which are spherical positive lenses with the same aperture, and are made of chalcogenide glass.

[0009] The metasurface array is composed of a series of dielectric nano-units arranged on a substrate, which are divided into four sub-metasurfaces; wherein,

[0010] The first sub-metasurface is a spectral detection area, in which the dielectric nanounits are cylindrical structures with different diameters;

[0011] The second sub-metasurface is a 0° polarization angle detection area, where the dielectric nanounits are rectangular parallelepiped structures with different lengths and widths;

[0012] The third sub-metasurface is a 45° polarization angle detection area, where the dielectric nanounits are rectangular structures with different lengths and widths.

[0013] The fourth sub-metasurface is a 90° polarization angle detection area, in which the dielectric nanounits are rectangular structures with different lengths and widths.

[0014] When infrared radiation passes through any dielectric nanounit, the phase Should meet:

[0015]

[0016] Where (x, y) is the position of the nanounit in the coordinate system, A i are polynomial coefficients, R is the normalized radius value, i=1, 2, 3, ... n, and n is the maximum number of terms in the phase distribution.

[0017] The materials of the substrate and the dielectric nano-unit are both single crystal silicon; the thickness of the substrate is 0.725 mm, the height of the dielectric nano-unit is 6 μm, the diameter distribution range of the cylindrical dielectric nano-unit is 700-1400 nm, and the length and width distribution range of the rectangular dielectric nano-unit is 600-1400 nm.

[0018] The cold aperture of the cooled MWIR focal plane array detector consists of four channels with the same aperture, which are respectively distributed in four quadrants. The F / # of each channel is 1.7. The first channel corresponds to the spectral detection channel, the second channel corresponds to the 0° polarization angle detection channel, the third channel corresponds to the 45° polarization angle detection channel, and the fourth channel corresponds to the 90° polarization angle detection channel.

[0019] The circuit system consists of a power management circuit and an information preprocessing circuit; the power management circuit supplies power to the information preprocessing circuit, and the information preprocessing circuit is responsible for collecting and outputting detector signals and interacting with the information processing circuit to receive data.

[0020] The host computer receives the signal output by the information preprocessing circuit in the circuit system, completes the image preprocessing process, modifies the detector display frame rate and integration time, and realizes the synchronous display of four images of the detector signal. The four images envelop one spectral image and three polarization images.

[0021] The advantages of the present invention compared with the prior art are:

[0022] 1) Currently, most infrared thermal imagers can only detect and image a single physical quantity, and very few solutions can sense and detect multiple physical quantities of the target light field. This technology introduces metasurface array elements based on traditional thermal imagers, builds a medium-wave infrared system that uses refractive lenses to provide basic focusing and imaging capabilities, and uses metasurface arrays to achieve fine aberration correction and spectral polarization perception capabilities, and simultaneously obtains the spectral polarization information of the target.

[0023] 2) The infrared thermal imager can solve the problems of insufficient detection accuracy, distance and resolution of traditional civilian infrared thermal imagers, meet the target imaging perception in different scenarios, expand the detection information dimension of current optoelectronic equipment, and improve the detection performance of infrared systems. The infrared thermal imager can also improve the probability of target detection and recognition in complex natural environments and complex artificial bait interference. This technology is expected to be applied to high-end military fields such as airborne, shipborne, and missile-borne. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of an infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to the present invention;

[0025] Figure 2 It is a schematic diagram of the mid-wave infrared multi-dimensional optical imaging system of the present invention;

[0026] Figure 3 Schematic diagram of each functional area of ​​the metasurface array of the present invention;

[0027] Figure 4Schematic diagram of the structure of the nanometer unit in the spectral functional area of ​​the metasurface array of the present invention, wherein D represents the diameter of the nanometer unit and H represents the height of the nanometer unit;

[0028] Figure 5 It is a schematic diagram of the structure of the nano-unit in the polarization function area of ​​the metasurface array of the present invention, wherein L represents the length of the nano-unit, W represents the width of the nano-unit, and H represents the height of the nano-unit.

[0029] Figure 6 It is a schematic diagram of the structure of the cold stop in the cooled medium-wave infrared focal plane array detector of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below by describing a preferred specific embodiment in detail in conjunction with the accompanying drawings.

[0031] like Figure 1 As shown, an infrared thermal imager for synchronously acquiring spectral polarization information in space and time of the present invention comprises a medium-wave infrared optical system 1, a refrigerated medium-wave infrared focal plane array detector 2, a circuit system 3 and a host computer software 4 system. The spectral polarization information from the target will be collected by the medium-wave infrared optical system 1, and the collected optical signal will be converted into an electrical signal by the refrigerated medium-wave infrared focal plane array detector 2. The circuit system 3 is composed of a power management circuit 3-1 and an information preprocessing circuit 3-2, which completes the collection and output of the electrical signal. The host computer 4 preprocesses the signal and outputs the image signal.

[0032] like Figure 2 As shown, the mid-wave infrared multi-dimensional optical system 1 of this embodiment adopts a channel-by-channel design method to obtain the spectral polarization information of the target within the 3°×3° field of view. The system uses a refractive lens to provide basic focusing and imaging capabilities, and is supplemented by a metasurface array to achieve fine aberration correction and spectral polarization perception capabilities. The detection band is mid-wave 3.7-4.8μm, and the detection linear polarization angles are 0°, 45° and 90°.

[0033] The infrared thermal imager for synchronously acquiring spectral polarization information in space and time of this embodiment comprises a head cover 1-1, a first aspheric lens 1-2, a second aspheric lens 1-3, a third aspheric lens 1-4, a lens array 1-5, a metasurface array 1-6, and a cooled medium-wave infrared focal plane array detector 2, which are arranged in sequence from the optical axis direction.

[0034] In the medium-wave infrared multi-dimensional optical imaging system 1 of this embodiment, the head cover 1-1 is a concentric spherical lens, and the material is fluorine glass; the first aspheric lens 1-2 is a positive lens, and the material is germanium glass; the second aspheric lens 1-3 is a positive lens, and the material is chalcogenide glass; the third aspheric lens 1-4 is a positive lens, and the material is chalcogenide glass; the lens array 1-5 is composed of four sub-lenses, all of which are spherical positive lenses and have the same aperture, and are made of chalcogenide glass; the metasurface array 1-6 is composed of four sub-metasurfaces.

[0035] like Figure 3 As shown, the metasurface array 1-6 of this embodiment is composed of a series of dielectric nano-units arranged on a substrate, wherein the first sub-metasurface 1-6-1 is a spectral detection area, and the nano-units in this area are cylindrical structures with different diameters; the second sub-metasurface 1-6-2 is a 0° polarization angle detection area, and the nano-units in this area are rectangular structures with different lengths and widths; the third sub-metasurface 1-6-3 is a 45° polarization angle detection area, and the nano-units in this area are rectangular structures with different lengths and widths; the fourth sub-metasurface 1-6-4 is a 90° polarization angle detection area, and the nano-units in this area are rectangular structures with different lengths and widths. When the target infrared radiation passes through any dielectric nano-unit, the phase generated by the nano-unit Should meet:

[0036]

[0037] Where (x, y) is the position of the dielectric nanounit in the coordinate system, A i (i=1, 2, 3, ... n) are polynomial coefficients, R is the normalized radius value, and n is the maximum number of terms in the phase distribution.

[0038] like Figure 4 As shown, in the sub-metasurface 1-6-1 of this embodiment, the substrate material and the cylindrical nano-unit material are both single crystal silicon, which has a high refractive index, transmittance and good conductivity in the infrared band. The thickness of the substrate is 0.725mm, the height of the nano-unit is 6μm, and the diameter distribution range of the cylindrical nano-unit is 700-1400nm.

[0039] like Figure 5 As shown, in the sub-supersurface 1-6-2, sub-supersurface 1-6-3 and sub-supersurface 1-6-4 of this embodiment, the substrate material and the square column nano-unit material are all single crystal silicon, which has a high refractive index, transmittance and good conductivity in the infrared band. The thickness of the substrate is 0.725mm, the height of the nano-unit is 6μm, and the length and width distribution range of the rectangular nano-unit is 600-1400nm.

[0040] like Figure 6As shown, the cooled medium-wave infrared focal plane array detector 2 of this embodiment has a cold aperture 2-1 composed of four channels respectively distributed in four quadrants and with the same aperture, and the F / # of each channel is 1.7, wherein the first channel 2-1-1 corresponds to the spectral detection channel, the second channel 2-1-2 corresponds to the 0° polarization angle detection channel, the third channel 2-1-3 corresponds to the 45° polarization angle detection channel, and the fourth channel 2-1-4 corresponds to the 90° polarization angle detection channel, and the F / # of each channel is 1.7; the chip size of the focal plane array 2-2 is 640*512, and the pixel size is 15μm*15μm. Its main function is to convert the target infrared spectrum polarization radiation information into a detectable electrical signal, and output it to the circuit system through the detector interface.

[0041] The circuit system 3 of this embodiment is composed of a power management circuit 3-1 and an information preprocessing circuit 3-2. The power management circuit 3-1 supplies power to the information preprocessing circuit. The main function of the information preprocessing circuit 3-2 is to collect and output detector signals and to receive data in interaction with the information processing circuit.

[0042] The host computer software system 4 of this embodiment receives the signal output by the information preprocessing circuit 3-2 in the circuit system 3, completes the image preprocessing process, modifies the detector display frame rate / integration time, and realizes the synchronous display of four images of the detector signal. The four images include one spectral image and three polarization images.

[0043] The present invention introduces a metasurface array element based on a traditional thermal imager to construct a multi-dimensional infrared optical system model of a refractive-metahybrid system, which can synchronously obtain the spectral polarization information of the target. In addition, the present invention meets the requirements of target imaging perception in different scenarios, expands the detection information dimension of current optoelectronic equipment, and can significantly improve the target detection and recognition capabilities of infrared optoelectronic systems.

[0044] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. An infrared thermal imager for synchronously acquiring spectral and polarization information in time and space, characterized in that: include: A medium-wave infrared optical system (1), a cooled medium-wave infrared focal plane array detector (2), a circuit system (3) and a host computer (4); the medium-wave infrared optical system (1) collects spectral polarization information from a target, and the collected optical signal is converted into an electrical signal by the cooled medium-wave infrared focal plane array detector (2), and is output to the circuit system (3) through a detector interface; the circuit system (3) is used to supply power to other devices and forward the electrical signal to the host computer (4); the host computer (4) pre-processes the electrical signal and outputs an image signal.

2. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 1, characterized in that: The medium-wave infrared optical system (1) is used to obtain spectral polarization information of a target within a field of view, the detection band is a medium-wave 3.7-4.8 μm, and the detection linear polarization angles are 0°, 45° and 90°.

3. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 2, characterized in that: The medium-wave infrared optical system (1) comprises a head cover, a first aspheric lens, a second aspheric lens, a third aspheric lens, a lens array, and a metasurface array, which are arranged in sequence from the optical axis direction; external input light enters the head cover and then transmits the medium-wave infrared, and then passes through the first aspheric lens, the second aspheric lens, and the third aspheric lens in sequence to correct the aberration, and then the light is converged on the lens array for splitting, and after the splitting is completed, the spectral polarization imaging is completed through the metasurface array to obtain spectral polarization information.

4. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 3, characterized in that: The head cover is a concentric spherical lens made of fluorine glass; the first aspheric lens is a positive lens made of germanium glass; the second aspheric lens is a positive lens made of chalcogenide glass; The third aspherical lens is a positive lens, and its material is chalcogenide glass; the lens array is composed of four sub-lenses, and all of the sub-lenses are spherical positive lenses with the same aperture, and their materials are all chalcogenide glass.

5. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 3, characterized in that: The metasurface array is composed of a series of dielectric nano-units arranged on a substrate, which are divided into four sub-metasurfaces; wherein, The first sub-metasurface is a spectral detection area, in which the dielectric nanounits are cylindrical structures with different diameters; The second sub-metasurface is a 0° polarization angle detection area, where the dielectric nanounits are rectangular parallelepiped structures with different lengths and widths; The third sub-metasurface is a 45° polarization angle detection area, where the dielectric nanounits are rectangular structures with different lengths and widths. The fourth sub-metasurface is a 90° polarization angle detection area, in which the dielectric nanounits are rectangular structures with different lengths and widths.

6. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 5, characterized in that: When infrared radiation passes through any dielectric nanounit, the phase Should meet: Where (x, y) is the position of the nanounit in the coordinate system, A i are polynomial coefficients, R is the normalized radius value, i=1, 2, 3, ... n, and n is the maximum number of terms in the phase distribution.

7. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 5, characterized in that: The materials of the substrate and the dielectric nano-unit are both single crystal silicon; the thickness of the substrate is 0.725 mm, the height of the dielectric nano-unit is 6 μm, the diameter distribution range of the cylindrical dielectric nano-unit is 700-1400 nm, and the length and width distribution range of the rectangular dielectric nano-unit is 600-1400 nm.

8. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 5, characterized in that: The cold aperture (2-1) of the cooled medium-wave infrared focal plane array detector (2) is composed of four channels respectively distributed in four quadrants and having the same aperture, and the F / # of each channel is 1.7, wherein the first channel (2-1-1) corresponds to a spectrum detection channel, the second channel (2-1-2) corresponds to a 0° polarization angle detection channel, the third channel (2-1-3) corresponds to a 45° polarization angle detection channel, and the fourth channel (2-1-4) corresponds to a 90° polarization angle detection channel.

9. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 5, characterized in that: The circuit system (3) is composed of a power management circuit (3-1) and an information preprocessing circuit (3-2); the power management circuit (3-1) supplies power to the information preprocessing circuit (3-2), the information preprocessing circuit (3-2) is responsible for collecting and outputting detector signals, and performs data exchange reception with the information processing circuit (3-2).

10. The infrared thermal imager for synchronously acquiring spectral and polarization information in time and space according to claim 9, characterized in that: The host computer (4) receives the signal output by the information preprocessing circuit (3-2) in the circuit system (3), completes the image preprocessing process, modifies the detector display frame frequency and integration time, and realizes the synchronous display of four images of the detector signal, wherein the four images include one spectral image and three polarization images.

Images