Low-light multispectral imaging device under low illumination at night

Abstract

The invention provides a low-light multispectral imaging device under low illumination at night, which is used for solving the problem that spectral characteristic information of a target cannot be acquired by adopting a low-light detection system in a low-illumination environment at night at present. And a visible near-infrared spectrum imager cannot be used for imaging or cannot be used for acquiring a high-contrast image for target detection and identification. According to the low-light-level multispectral imaging device, the electric filter wheel is arranged between the low-light-level imaging lens and the low-light-level detector, hardware external synchronization is arranged between the electric filter wheel and the low-light-level detector, switching of one narrow-band optical filter is completed every time the rotating structure rotates once, switching of one spectral band channel is achieved, and switching of the low-light-level imaging lens and the low-light-level detector is achieved. At the moment, through hardware external synchronization between the electric filter wheel and the low-light detector, the low-light detector synchronously exposes once; according to the invention, through coupling of a low-light imaging technology and a light splitting technology of a plurality of narrow-band optical filters, information of a plurality of spectrum band channels of a detected target is obtained, and efficient detection under low illumination at night is realized.

Description

Technical Field

[0001] The invention relates to a nighttime imaging device, and in particular to a low-light multi-spectral imaging device under low illumination at night. Background Art

[0002] Night reconnaissance and night target identification have important military application value. The existing means of night reconnaissance and night target identification are mainly detected through medium-wave infrared imaging technology or long-wave infrared imaging technology. However, the above infrared detection technology has the following main problems: (1) The detector needs to be set as a cooled infrared detector to reduce the thermal radiation of the imaging system itself, so as to obtain a high signal-to-noise ratio image. However, the cooled infrared detector will make the entire detection system expensive, heavy and bulky. (2) The array size of the cooled infrared detector is small. The current largest array size is 640×512 pixels, which leads to a small field of view and limited imaging area. (3) The image obtained by infrared detection is a black and white image without the texture information of the visible light image, which is not conducive to target identification. (4) Infrared detection is based on the temperature difference between the detection target and the background environment. It is impossible to obtain the spectral characteristics of the target and is easily interfered by other objects of the same temperature. (5) The maximum frame rate of the existing cooled infrared detector is 100Hz, which cannot meet the high-precision measurement requirements of high-speed moving targets at night.

[0003] At present, the highest frame rate of the low-light detection system can reach 500Hz, and the array size is large, which can achieve high-precision imaging measurement of high-speed moving targets at night, but it is limited by the low-light environment at night and cannot obtain the spectral characteristic information of the target and realize target recognition. Although the visible near-infrared spectral imager can obtain the spectral characteristic information of the target at night, it is limited by the low-light environment and cannot form an image or obtain a high-contrast image for target detection and recognition. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems that the spectral characteristic information of the target cannot be obtained by using a low-light detection system in a low-light environment at night, and that a visible near-infrared spectral imager cannot form an image or obtain a high-contrast image for target detection and identification, and to provide a low-light multi-spectral imaging device under low-light conditions at night.

[0005] In order to achieve the above purpose, the technical solution provided by the present invention is as follows:

[0006] A low-light multi-spectral imaging device under low illumination at night, which is special in that it comprises a box body and a low-light imaging lens, an electric filter wheel, a low-light detector, a communication and control module and a power module arranged in the box body;

[0007] The low-light imaging lens is used to capture light under low-light conditions at night and perform gain amplification on it;

[0008] The electric filter wheel comprises a filter wheel housing, a rotating structure arranged in the filter wheel housing, and a driving structure for driving the rotating structure to rotate circumferentially; a front through hole and a rear through hole are respectively provided at corresponding positions of the front and rear end surfaces of the filter wheel housing;

[0009] The light outlet of the low-light imaging lens is connected to the position corresponding to the front through hole on the filter wheel housing; the light inlet of the low-light detector is connected to the position corresponding to the rear through hole on the filter wheel housing;

[0010] At least six narrow-band filters with different wavelengths are arranged on the rotating structure in each circumferential direction. Each time the driving structure drives the rotating structure to rotate once, a narrow-band filter is switched to correspond to the front through hole and the rear through hole, thereby completing the switching of a spectral spectrum channel.

[0011] The electric filter wheel and the low-light detector are provided with hardware external synchronization, and each time the driving structure drives the rotating structure to rotate once, the low-light detector is synchronously exposed once;

[0012] The communication and control module is electrically connected to the low-light detector, and is used to send control instructions and parameter setting instructions to the low-light detector, and to perform image acquisition and transmission;

[0013] The power supply module is electrically connected to the electric filter wheel and the faint light detector respectively, and is used to supply power to the driving structure of the electric filter wheel and the faint light detector respectively.

[0014] Furthermore, the box body is a rectangular box body enclosed by a left side panel, a front side panel, a right side panel, a rear side panel, a top panel and a bottom panel;

[0015] A glass mounting hole is axially opened on the front side plate, and a window glass is mounted in the glass mounting hole;

[0016] The light inlet of the low-light imaging lens is fixed at a position corresponding to the window glass on the inner side wall of the front side plate;

[0017] The electric filter wheel is mounted on the bottom plate through a filter wheel bracket;

[0018] The communication and control module and the power supply module are respectively mounted on the bottom plate.

[0019] Further, it also includes a sunshade;

[0020] The sunshade is arranged on the outer side wall of the front side plate at a position corresponding to the window glass.

[0021] Furthermore, it also includes a glass pressing ring;

[0022] The window glass is pressed and fixed by a glass pressing ring.

[0023] Furthermore, the F number of the low-light imaging lens is 1.4.

[0024] Furthermore, an axially hollow mounting boss is extended outwardly on the front side plate, and a circle of grooves is provided on the inner side wall of the outer end of the mounting boss, and the grooves form the glass mounting holes;

[0025] A circle of first sealing grooves is provided on the mounting boss at the bottom of the groove corresponding to the groove, and a first sealing ring is arranged in the first sealing groove to achieve sealing between the mounting boss and the window glass through the first sealing ring.

[0026] Furthermore, the bottom plate, the left side plate, the front side plate and the right side plate are an integrated structure;

[0027] The rear side panel is detachably connected to the left side panel, the right side panel and the bottom panel, a second sealing groove is provided at the position where the left side panel, the right side panel and the bottom panel are connected to the rear side panel, and a second sealing ring is provided in the second sealing groove for achieving sealing between the rear side panel and the left side panel, the right side panel and the bottom panel through the second sealing ring;

[0028] The top plate is detachably connected to the left side plate, the front side plate and the right side plate. A third sealing groove is provided at the position where the left side plate, the front side plate and the right side plate are connected to the top plate. A third sealing ring is provided in the third sealing groove for achieving sealing between the top plate and the left side plate, the front side plate and the right side plate through the third sealing ring.

[0029] Further, the micro-light imaging lens comprises a lens barrel and a first micro-light lens, a second micro-light lens, a third micro-light lens, a fourth micro-light lens, a fifth micro-light lens, a sixth micro-light lens and a seventh micro-light lens which are sequentially installed in the lens barrel along the light transmission direction;

[0030] The first micro-lens, the second micro-lens and the fourth micro-lens are made of CaF2 material;

[0031] The third micro-light lens and the seventh micro-light lens are made of N-KZFS4 material;

[0032] The fifth micro-light lens and the sixth micro-light lens are made of N-LAK9 material;

[0033] One side of the light outlet of the lens barrel is fixedly connected to a position of the filter wheel housing corresponding to the front through hole.

[0034] Further, a trimming pad is included;

[0035] The trimming pad is arranged at the connection between the lens barrel and the filter wheel housing, and is used to adjust the optical interval between the low-light imaging lens and the electric filter wheel.

[0036] Furthermore, the window glass is made of YAG transparent ceramic material and can achieve an underwater pressure resistance of 120 MPa.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The present invention provides a low-light multi-spectral imaging device under low illumination at night, which adopts low-light imaging technology and arranges an electric filter wheel between a low-light imaging lens and a low-light detector. Each time the driving structure of the electric filter wheel drives the rotating structure to rotate once, a narrow-band filter is switched, and a spectral band channel is switched. At this time, the low-light detector is synchronously exposed once through hardware external synchronization between the electric filter wheel and the low-light detector. The present invention couples the low-light imaging technology with the spectroscopic technology of multiple narrow-band filters to obtain multiple spectral band channel information of the detection target, realizes efficient detection under a high frame rate ambient illumination of 10-5Lux at night, and completes camouflage exposure and target recognition. The device has both daytime and nighttime imaging capabilities, and overcomes the defect that traditional visible near-infrared multi-spectral imagers can only image during the day.

[0039] 2. The present invention provides a low-light multi-spectral imaging device under low illumination at night, which couples low-light imaging technology with the spectroscopic technology of multiple narrow-band filters. It can not only achieve efficient detection under high frame rate ambient illumination of 10-5Lux, but also achieve large-array detection of 2028×2048, and simultaneously complete spectral imaging better than six channels, overcoming the imaging defects caused by small field of view angle and low frame rate when using existing infrared detection technology for night reconnaissance and night target recognition.

[0040] 3. The present invention provides a low-light multi-spectral imaging device under low illumination at night, which uses an electric filter wheel to switch filters of different wavelengths, and can realize remote unattended imaging through an internal communication and control module and a power module.

[0041] 4. The F number of the low-light imaging lens in the present invention is set to 1.4, so that it has a large relative aperture and low distortion, and can achieve clear imaging under low illumination at night.

[0042] 5. The present invention arranges a low-light imaging lens, an electric filter wheel, a low-light detector, a communication and control module, and a power module in a box, and seals each joint of the box with a sealing ring, so that remote-controlled imaging at 500 meters underwater can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The structure of a low-light multi-spectral imaging device under low illumination at night is shown in FIG. Figure 1 ;

[0044] Figure 2 for Figure 1 A top view of (top plate not shown);

[0045] Figure 3 Schematic diagram of the connection relationship between the low-light-level imaging lens, the electric filter wheel and the low-light-level detector in an embodiment of the present invention;

[0046] Figure 4 is an axial cross-sectional view of a low-light-level imaging lens, a motorized filter wheel, and a low-light-level detector in an embodiment of the present invention;

[0047] Figure 5 It is a longitudinal cross-sectional view of the box body and the light shield in the embodiment of the present invention.

[0048] The specific reference numerals are as follows:

[0049] 1-light shield; 2-low-light imaging lens, 21-first low-light lens, 22-second low-light lens, 23-third low-light lens, 24-fourth low-light lens, 25-fifth low-light lens, 26-sixth low-light lens, 27-seventh low-light lens, 28-trimming pad; 3-box, 31-left side plate, 32-front side plate, 33-right side plate, 34-rear side plate, 35-top plate, 36-bottom plate, 37-first sealing groove, 38-second sealing groove, 39-third sealing groove; 4-communication and control module; 5-power module; 6-electric filter wheel; 7-filter wheel bracket; 8-low-light detector; 9-window glass; 10-glass pressure ring. DETAILED DESCRIPTION

[0050] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] like Figure 1-Figure 3 As shown, a low-light multi-spectral imaging device under low illumination at night includes a box 3, a low-light imaging lens 2, an electric filter wheel 6, a low-light detector 8, a communication and control module 4, a power module 5 and a sunshade 1.

[0052] The box body 3 is a rectangular box body surrounded by a left side plate 31, a front side plate 32, a right side plate 33, a rear side plate 34, a top plate 35 and a bottom plate 36. An axially hollow mounting boss is extended outwardly on the front side plate 32, and a circle of grooves is provided on the inner side wall of the outer end of the mounting boss to form a glass mounting hole; a window glass 9 is installed in the glass mounting hole, and the window glass 9 is pressed and fixed by a glass pressing ring 10. Preferably, the window glass 9 is made of high-strength special glass, such as YAG transparent ceramic material, which has the ability to withstand high water pressure in deep water areas and can be used for detection in deep water areas. The low-light imaging lens 2, the electric filter wheel 6, the low-light detector 8, the communication and control module 4 and the power module 5 are located in the box body 3, and the light shield 1 is arranged outside the box body 3.

[0053] The low-light imaging lens 2 is a large-aperture imaging lens used to capture light under low-light conditions at night and amplify it. The low-light imaging lens 2 includes a lens barrel, a plurality of mounting frames sequentially installed in the lens barrel along the light transmission direction, and low-light lenses respectively installed in the corresponding mounting frames; the mounting frames and the corresponding low-light lenses are fixed by means of glue injection and pressing with a pressing ring after centering. Figure 4 As shown, the F number of the micro-light imaging lens 2 in this embodiment is 1.4, the focal length is 55mm, the field angle is ±24°, and the micro-light lens includes a first micro-light lens 21, a second micro-light lens 22, a third micro-light lens 23, a fourth micro-light lens 24, a fifth micro-light lens 25, a sixth micro-light lens 26 and a seventh micro-light lens 27 which are arranged in sequence according to the transmission direction of light; wherein the first micro-light lens 21, the second micro-light lens 22 and the fourth micro-light lens 24 are made of CaF2 material, the third micro-light lens 23 and the seventh micro-light lens 27 are made of N-KZFS4 material, and the fifth micro-light lens 25 and the sixth micro-light lens 26 are made of N-LAK9 material. A lens trimming pad is arranged between two adjacent mounting frames, which is used to ensure the optical spacing between the lenses by adjusting the thickness of the lens trimming pad.

[0054] The light inlet of the lens barrel of the low-light imaging lens 2 is fixed at a position corresponding to the window glass 9 on the inner side wall of the front side plate 32. The light shield 1 is arranged at a position corresponding to the window glass 9 on the outer side wall of the front side plate 32, and in this embodiment, is connected to the outer side wall of the front side plate 32 by threads to prevent stray light from entering the low-light imaging lens 2.

[0055] The electric filter wheel 6 includes a filter wheel housing, a rotating structure rotatably arranged in the filter wheel housing, and a driving structure for driving the rotating structure to rotate circumferentially. The filter wheel housing is mounted on the bottom plate 36 through a filter wheel bracket 7, and corresponding positions of the two end faces of the filter wheel housing are respectively provided with a front through hole and a rear through hole; the light outlet of the lens barrel of the low-light imaging lens 2 is fixedly connected to the position corresponding to the front through hole of the filter wheel housing by screws, and a trimming pad 28 is provided at the connection between the light outlet of the lens barrel and the filter wheel housing, which is used to adjust the optical interval between the low-light imaging lens 2 and the electric filter wheel 6 by adjusting the thickness of the trimming pad 28, and the position and posture of the lens barrel of the low-light imaging lens 2 can also be adjusted by the trimming pad 28. The light inlet of the low-light detector 8 is fixedly connected to the position corresponding to the rear through hole of the filter wheel housing through a connecting flange.

[0056] In the present embodiment, six narrow-band filters 61 with different wavelengths are arranged on the rotating structure in all directions, that is, six spectral band channels are formed, and the acquisition of images with different spectral bandwidths in different spectral band channels can be achieved by replacing different narrow-band filters 61; at the same time, hardware external synchronization is arranged between the electric filter wheel 6 and the low-light detector 8, and each time the driving structure drives the rotating structure to rotate once, a narrow-band filter 61 is switched to correspond to the front through hole and the rear through hole, that is, the switching of a spectral band channel is completed, and the low-light detector 8 is synchronously exposed once. After the six narrow-band filters 61 are switched for one circle, six spectral images with different bandwidths are obtained.

[0057] The communication and control module 4 is fixed on the base plate 36 by screw connection, and is electrically connected to the low-light detector 8 for transmitting low-light imaging control instructions and sending setting instructions such as camera switch, frame rate, integration time, etc. It also has image acquisition and transmission functions.

[0058] The power module 5 is fixed on the bottom plate 36 by screw connection, and is electrically connected to the electric filter wheel 6 and the low-light detector 8 respectively, for providing 12V power output to the driving structure of the electric filter wheel 6 and the low-light detector 8 respectively.

[0059] like Figure 5 As shown, in order to ensure the sealing performance of the box body 3, a first sealing groove 37 is provided at the bottom of the groove corresponding to the groove on the mounting boss, and a first sealing ring is provided in the first sealing groove 37, which is used to achieve the sealing between the mounting boss and the window glass 9 through the first sealing ring. At the same time, the bottom plate 36, the left side plate 31, the front side plate 32 and the right side plate 33 are an integrated structure, and specifically, they can be manufactured or welded into one. In order to facilitate the assembly and maintenance of the low-light imaging lens 2, the electric filter wheel 6, the low-light detector 8, the communication and control module 4 and the power module 5, the rear side plate 34 is detachably connected to the left side plate 31, the right side plate 33 and the bottom plate 36, and the top plate 35 is detachably connected to the left side plate 31, the front side plate 32 and the right side plate 33. A second sealing groove 38 is provided at the position where the left side plate 31, the right side plate 33 and the bottom plate 36 are connected to the rear side plate 34, and a second sealing ring is provided in the second sealing groove 38, which is used to achieve sealing between the rear side plate 34 and the left side plate 31, the right side plate 33 and the bottom plate 36 through the second sealing ring; a third sealing groove 39 is provided at the position where the left side plate 31, the front side plate 32 and the right side plate 33 are connected to the top plate 35, and a third sealing ring is provided in the third sealing groove 39, which is used to achieve sealing between the top plate 35 and the left side plate 31, the front side plate 32 and the right side plate 33 through the third sealing ring.

[0060] The low-light-level multi-spectral imaging device of the present invention adopts low-light-level imaging technology, and an electric filter wheel 6 is arranged between a low-light-level imaging lens 2 and a low-light detector 8. Each time the driving structure of the electric filter wheel 6 drives the rotating structure to rotate once, a spectral channel is switched by switching a narrow-band filter 61. At the same time, the low-light detector is synchronously exposed once through hardware external synchronization between the electric filter wheel 6 and the low-light detector 8. The present invention couples low-light-level imaging technology with the spectroscopic technology of multiple filters, and can not only complete efficient detection under a high frame rate ambient illumination of 10-5Lux at night, but also obtain multiple spectral spectrum channel information of the detection target, thereby realizing camouflage exposure and target recognition under low illumination at night. The device has both daytime and nighttime imaging capabilities, and overcomes the defect that traditional visible near-infrared multi-spectral imagers can only image during the day.

[0061] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A low-light multi-spectral imaging device under low illumination at night, characterized in that: It comprises a box (3) and a low-light imaging lens (2), an electric filter wheel (6), a low-light detector (8), a communication and control module (4) and a power module (5) arranged in the box (3); The low-light imaging lens (2) is used to capture light under low-light conditions at night and perform gain amplification on it; The electric filter wheel (6) comprises a filter wheel housing, a rotating structure arranged in the filter wheel housing, and a driving structure for driving the rotating structure to rotate circumferentially; a front through hole and a rear through hole are respectively provided at corresponding positions of the front and rear end surfaces of the filter wheel housing; The light outlet of the low-light imaging lens (2) is connected to a position on the filter wheel housing corresponding to the front through hole; the light inlet of the low-light detector (8) is connected to a position on the filter wheel housing corresponding to the rear through hole; At least six narrow-band filters (61) with different wavelengths are arranged on the rotating structure in a circumferential direction, and each time the driving structure drives the rotating structure to rotate once, a narrow-band filter (61) is switched to correspond to the front through hole and the rear through hole, thereby completing the switching of a spectral spectrum channel; A hardware external synchronization is provided between the electric filter wheel (6) and the low-light detector (8), and each time the driving structure drives the rotating structure to rotate once, the low-light detector (8) is synchronously exposed once; The communication and control module (4) is electrically connected to the low-light detector (8) and is used to send control instructions and parameter setting instructions to the low-light detector (8) and to perform image acquisition and transmission; The power module (5) is electrically connected to the electric filter wheel (6) and the faint light detector (8) respectively, and is used to supply power to the driving structure of the electric filter wheel (6) and the faint light detector (8) respectively.

2. The low-light multi-spectral imaging device under low illumination at night according to claim 1, characterized in that: The box body (3) is a rectangular box body enclosed by a left side plate (31), a front side plate (32), a right side plate (33), a rear side plate (34), a top plate (35) and a bottom plate (36); The front side plate (32) is provided with a glass mounting hole in an axial direction, and a window glass (9) is mounted in the glass mounting hole; The light inlet of the low-light imaging lens (2) is fixed at a position corresponding to the window glass (9) on the inner side wall of the front side plate (32); The electric filter wheel (6) is mounted on the bottom plate (36) via a filter wheel bracket (7); The communication and control module (4) and the power module (5) are respectively mounted on the base plate (36).

3. The low-light multi-spectral imaging device under low illumination at night according to claim 2, characterized in that: Also includes a light shield (1); The light shield (1) is arranged on the outer side wall of the front side plate (32) at a position corresponding to the window glass (9).

4. The low-light multi-spectral imaging device under low illumination at night according to claim 3, characterized in that: Also includes a glass pressing ring (10); The window glass (9) is pressed and fixed by a glass pressing ring (10).

5. The low-light multi-spectral imaging device under low illumination at night according to claim 1, characterized in that: The F number of the low-light imaging lens (2) is 1.

4.

6. The low-light multi-spectral imaging device under low illumination at night according to claim 4, characterized in that: An axially hollow mounting boss is extended outwardly from the front side plate (32), and a circle of grooves is provided on the inner side wall of the outer end of the mounting boss, and the grooves form the glass mounting holes; A circle of first sealing grooves (37) are provided at the bottom of the groove corresponding to the groove on the mounting boss, and a first sealing ring is arranged in the first sealing groove (37) for achieving sealing between the mounting boss and the window glass (9) through the first sealing ring.

7. The low-light multi-spectral imaging device under low illumination at night according to claim 6, characterized in that: The bottom plate (36), the left side plate (31), the front side plate (32) and the right side plate (33) are an integrated structure; The rear side plate (34) is detachably connected to the left side plate (31), the right side plate (33) and the bottom plate (36); a second sealing groove (38) is provided at the position where the left side plate (31), the right side plate (33) and the bottom plate (36) are connected to the rear side plate (34); a second sealing ring is provided in the second sealing groove (38) for achieving sealing between the rear side plate (34) and the left side plate (31), the right side plate (33) and the bottom plate (36); The top plate (35) is detachably connected to the left side plate (31), the front side plate (32) and the right side plate (33); a third sealing groove (39) is provided at the position where the left side plate (31), the front side plate (32) and the right side plate (33) are connected to the top plate (35); a third sealing ring is provided in the third sealing groove (39) for achieving sealing between the top plate (35) and the left side plate (31), the front side plate (32) and the right side plate (33) through the third sealing ring.

8. A low-light multi-spectral imaging device at night under low illumination according to any one of claims 1 to 7, characterized in that: The micro-light imaging lens (2) comprises a lens barrel and a first micro-light lens (21), a second micro-light lens (22), a third micro-light lens (23), a fourth micro-light lens (24), a fifth micro-light lens (25), a sixth micro-light lens (26) and a seventh micro-light lens (27) which are sequentially mounted in the lens barrel along a light transmission direction; The first micro-lens (21), the second micro-lens (22) and the fourth micro-lens (24) are made of CaF2 material; The third micro-lens (23) and the seventh micro-lens (27) are made of N-KZFS4 material; The fifth micro-lens (25) and the sixth micro-lens (26) are made of N-LAK9 material; One side of the light outlet of the lens barrel is fixedly connected to a position of the filter wheel housing corresponding to the front through hole.

9. The low-light multi-spectral imaging device under low illumination at night according to claim 8, characterized in that: Also included is a trimming pad (28); The trimming pad (28) is arranged at the connection between the lens barrel and the filter wheel housing, and is used to adjust the optical interval between the low-light imaging lens (2) and the electric filter wheel (6).

10. The low-light multi-spectral imaging device at night under low illumination according to claim 2, characterized in that: The window glass (9) is made of YAG transparent ceramic material.

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