Non-angle sensitive silicon-based video multispectral imaging system

Abstract

The invention relates to the technical field of spectral imaging, in particular to a non-angle-sensitive silicon-based video multispectral imaging system, which comprises a first lens, a second lens, an aperture diaphragm, a triplet lens, a doublet lens, a third lens and a beam splitting module which are sequentially arranged along an optical axis from an object plane to an image plane, an incident light beam sequentially passes through the first lens, the second lens, the aperture diaphragm, the triplet lens, the doublet lens and the third lens to enter the beam splitting module for beam splitting, and a first light beam and a second light beam are obtained. The first camera receives the first light beam and performs imaging, and the second camera receives the second light beam and performs imaging. According to the invention, the influence of the light included angle can be eliminated through the optical structure, additional calculation of the spectral image is not needed, and the spectral measurement precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of spectral imaging, and in particular to a non-angle-sensitive silicon-based video multi-spectral imaging system. Background Art

[0002] Spectral imaging technology is a new type of multi-dimensional information acquisition technology that combines spectral analysis technology with imaging technology. It is one of the research hotspots of modern remote sensing and has been widely used in meteorology, oceanography, biomedicine and military fields. Traditional hyperspectral imaging systems usually need to scan the detection target point by point or line by line to obtain the spectral information of the image. It takes a long time to obtain an image. The video-level multispectral imaging system can directly collect scene information within the integration time of a shutter, and can effectively suppress the reconstructed image error caused by push-broom detection and the blur caused by the rapid movement of the target. Its ability to quickly obtain the target's spatial spectral information can be widely used in the acquisition of video-level spectral images. However, although the existing video-level multispectral system can obtain multispectral images, due to the spacing between the pixel-level spectral filter and the imaging chip of the video-level multispectral imaging system, when there is an angle between the incident light, part of the spectral information will enter the adjacent pixels, resulting in inaccurate spectral measurement. At present, if this effect is to be eliminated, additional spectral calculations are required, but this calculation will lead to a decrease in the real-time acquisition frame rate. Post-processing while ensuring the frame rate cannot achieve real-time output of multispectral images. Summary of the invention

[0003] In view of this, the present invention aims to provide a non-angle-sensitive silicon-based video multispectral imaging system to solve the spectral inaccuracy caused by the excessively large incident angle of the image plane in the existing optical system, and the need to spend additional computing time for spectral solution, which greatly reduces the acquisition frame rate of video-level multispectral images. The present invention can eliminate the influence of the light angle through its own optical structure, without the need for additional calculation of the spectral image, thereby improving the spectral measurement accuracy.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows: A non-angle-sensitive silicon-based video multispectral imaging system, comprising: A first lens, a second lens, an aperture stop, a triplet lens, a doublet lens, a third lens and a beam splitting module are sequentially arranged along the optical axis from the object plane to the image plane, and an incident light beam is sequentially incident on the beam splitting module through the first lens, the second lens, the aperture stop, the triplet lens, the doublet lens and the third lens to be split, thereby obtaining a first light beam and a second light beam; A first camera and a second camera, the first camera receives the first light beam and forms an image, and the second camera receives the second light beam and forms an image; The aperture stop is placed on the image focal plane of the first camera and the second camera.

[0005] Further, the first camera is one of a first type camera and a second type camera, the second camera is the other of the first type camera and the second type camera, the first type camera is a silicon-based video multispectral camera, and the second type camera is a grayscale camera or a color camera or a silicon-based video multispectral camera.

[0006] Furthermore, the air gap between the first lens and the second lens is 4.45 mm; the air gap between the second lens and the aperture stop is 8.66 mm; the air gap between the aperture stop and the triplet lens is 18 mm; the air gap between the triplet lens and the doublet lens is 0.68 mm; the air gap between the doublet lens and the third lens is 6.08 mm; and the air gap between the third lens and the beam splitting module is 22 mm.

[0007] Furthermore, the first lens is a first biconvex lens; the second lens is a plano-concave lens, and the concave surface of the plano-concave lens faces away from the object plane of the silicon-based video multi-spectral imaging system; the triplet lens includes a biconcave lens, a crescent plano-convex lens and a second biconvex lens arranged in sequence along the optical axis from the object plane to the image plane, and the convex surface of the crescent plano-convex lens faces the object plane of the silicon-based video multi-spectral imaging system; the doublet lens includes a third biconvex lens and a crescent concave lens arranged in sequence along the optical axis from the object plane to the image plane, and the concave surface of the crescent concave lens faces the object plane of the silicon-based video multi-spectral imaging system; the third lens is a fourth biconvex lens.

[0008] Furthermore, the radius of curvature of the lens close to the object plane in the first biconvex lens is 61.269 mm, and the radius of curvature of the lens far from the object plane in the first biconvex lens is -169.04 mm; The curvature radius of the lens close to the object plane in the plano-concave lens is ∞mm, and the curvature radius of the lens far from the object plane in the plano-concave lens is 13.397mm; The radius of curvature of the lens close to the object plane in the biconcave lens is -92.92mm, and the radius of curvature of the lens far from the object plane in the biconcave lens is 21.803mm; The radius of curvature of the lens close to the object plane in the crescent plano-convex lens is 21.803 mm, and the radius of curvature of the lens far from the object plane in the crescent plano-convex lens is 33.1 mm; The curvature radius of the lens close to the object plane in the second biconvex lens is 33.1 mm, and the curvature radius of the lens far from the object plane in the second biconvex lens is -26.626 mm; The curvature radius of the lens close to the object plane in the third biconvex lens is 154.9 mm, and the curvature radius of the lens far from the object plane in the third biconvex lens is -17.014 mm; The radius of curvature of the lens close to the object plane in the meniscus concave lens is -17.014mm, and the radius of curvature of the lens far from the object plane in the meniscus concave lens is -35.544mm; The curvature radius of the lens close to the object plane in the fourth biconvex lens is 342.673 mm, and the curvature radius of the lens far from the object plane in the fourth biconvex lens is -212.43 mm.

[0009] Further, the refractive index of the first biconvex lens is 1.5407 and the Abbe number is 47.23; The refractive index of the plano-concave lens is 1.4565 and the Abbe number is 90.27; The refractive index of the biconcave lens is 1.6477 and the Abbe number is 33.842; The refractive index of the crescent plano-convex lens is 1.9229, and the Abbe number is 20.882; The refractive index of the second biconvex lens is 1.4565 and the Abbe number is 90.27; The refractive index of the third biconvex lens is 1.4565 and the Abbe number is 90.27; The refractive index of the meniscus lens is 1.575 and the Abbe number is 41.507; The refractive index of the fourth biconvex lens is 1.575 and the Abbe number is 41.507.

[0010] Furthermore, the material of the plano-concave lens, the second biconvex lens and the third biconvex lens is H-FK71, the material of the crescent concave lens and the fourth biconvex lens is H-QF3, the material of the first biconvex lens is H-QF8, the material of the biconcave lens is H-ZF1, and the material of the crescent plano-convex lens is H-ZF62.

[0011] Furthermore, the beam splitting module includes a non-polarizing beam splitter and a dichroic mirror assembly.

[0012] Compared with the prior art, the invention can achieve the following beneficial effects: (1) The present invention creates the non-angle-sensitive silicon-based video multi-spectral imaging system, which places the aperture stop on the image-side focal plane of the optical system, so that the main ray of the outgoing light is always parallel to the optical axis, thereby eliminating the influence of the light angle on the spectral accuracy.

[0013] (2) The non-angle-sensitive silicon-based video multispectral imaging system created by the present invention can obtain spectral videos with extremely high frame rates without the need for additional spectral calculations, thus giving full play to the technical advantages of silicon-based video multispectral camera chips.

[0014] (3) The non-angle-sensitive silicon-based video multispectral imaging system created by the present invention has a long back intercept while achieving "telecentricity", and can be widely used in application scenarios where a two-branch optical path is formed with the help of a color splitter or a beam splitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 Schematic diagram of the non-angle-sensitive silicon-based video multi-spectral imaging system described in an embodiment of the present invention.

[0016] Description of reference numerals: 1. First lens; 2. Second lens; 3. Aperture stop; 4. Triplet lens; 5. Doublet lens; 6. Third lens; 7. Beam splitting module; 8. First camera; 9. Second camera. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0019] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0020] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0021] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0022] like Figure 1 As shown, the non-angle-sensitive silicon-based video multispectral imaging system provided by the present invention comprises: A first lens 1, a second lens 2, an aperture stop 3, a triplet lens 4, a doublet lens 5, a third lens 6 and a beam splitting module 7 are arranged in sequence along the optical axis from the object plane to the image plane. An incident light beam is incident on the beam splitting module 7 through the first lens 1, the second lens 2, the aperture stop 3, the triplet lens 4, the doublet lens 5 and the third lens 6 in sequence to be split, thereby obtaining a first light beam and a second light beam; A first camera 8 and a second camera 9, the first camera 8 receives the first light beam and forms an image, and the second camera 9 receives the second light beam and forms an image; The aperture stop 3 is placed on the image focal plane of the first camera 8 and the second camera 9, so that the main ray of the outgoing light is always parallel to the optical axis, thereby eliminating the influence of the angle of the light on the spectral accuracy. In addition, the aperture stop 3 can also effectively control the aperture of the second lens 2.

[0023] The first camera 8 is one of a first type camera and a second type camera, and the second camera 9 is the other of the first type camera and the second type camera. The first type camera is a silicon-based video multispectral camera, and the second type camera is a grayscale camera or a color camera or a silicon-based video multispectral camera.

[0024] The beam splitting module 7 includes a non-polarizing beam splitter and a dichroic mirror assembly.

[0025] When the light beam is incident on the splitting surface of the beam splitting module 7 at an incident angle of 45 degrees, different splitting ratios can be obtained by a non-polarizing dichroic mirror. The non-polarizing beam splitter is used when one of the two cameras is a spectral camera and the other is a color camera / grayscale camera. The splitting ratio is determined by the grayscale response ratio of the two cameras in the silicon-based video multi-spectral imaging system. If the same target is photographed, at the same exposure time and gain, the response of camera A is 70 and the response of camera B is 30, then the splitting ratio is 70:30. Usually, the splitting ratio includes but is not limited to the following cases: 70:90 (R:T), 90:10 (R:T), 30:70 (R:T), 10:90 (R:T), 50:50 (R:T), where R represents the reflected light beam and T represents the transmitted light beam.

[0026] The dichroic mirror makes the reflected light and the transmitted light formed by the incident light beam have different spectral components, and is used in the scene where both cameras are silicon-based video multispectral cameras. The starting (cut-off) wavelength of the dichroic mirror is determined by the spectral range of the two silicon-based video multispectral cameras, and the dichroic mirror makes the spectral range of the reflected light and the transmitted light between the working spectral ranges of the two silicon-based video multispectral cameras.

[0027] The air gap between the first lens 1 and the second lens 2 is 4.45mm; the air gap between the second lens 2 and the aperture stop 3 is 8.66mm; the air gap between the aperture stop 3 and the triplet lens 4 is 18mm; the air gap between the triplet lens 4 and the doublet lens 5 is 0.68mm; the air gap between the doublet lens 5 and the third lens 6 is 6.08mm; the air gap between the third lens 6 and the beam splitting module 7 is 22mm.

[0028] The first lens 1 is a first biconvex lens; the second lens 2 is a plano-concave lens, and the concave surface of the plano-concave lens faces away from the object plane of the silicon-based video multi-spectral imaging system; the triplet lens 4 includes a biconcave lens, a crescent plano-convex lens and a second biconvex lens arranged in sequence along the optical axis from the object plane to the image plane, and the convex surface of the crescent plano-convex lens faces the object plane of the silicon-based video multi-spectral imaging system; the doublet lens 5 includes a third biconvex lens and a crescent concave lens arranged in sequence along the optical axis from the object plane to the image plane, and the concave surface of the crescent concave lens faces the object plane of the silicon-based video multi-spectral imaging system; the third lens 6 is a fourth biconvex lens.

[0029] The curvature radius of the lens close to the object plane in the first biconvex lens is 61.269 mm, and the curvature radius of the lens far from the object plane in the first biconvex lens is -169.04 mm; The curvature radius of the lens close to the object plane in the plano-concave lens is ∞mm, and the curvature radius of the lens far from the object plane in the plano-concave lens is 13.397mm; The radius of curvature of the lens close to the object plane in the biconcave lens is -92.92mm, and the radius of curvature of the lens far from the object plane in the biconcave lens is 21.803mm; The radius of curvature of the lens close to the object plane in the crescent plano-convex lens is 21.803 mm, and the radius of curvature of the lens far from the object plane in the crescent plano-convex lens is 33.1 mm; The curvature radius of the lens close to the object plane in the second biconvex lens is 33.1 mm, and the curvature radius of the lens far from the object plane in the second biconvex lens is -26.626 mm; The curvature radius of the lens close to the object plane in the third biconvex lens is 154.9 mm, and the curvature radius of the lens far from the object plane in the third biconvex lens is -17.014 mm; The radius of curvature of the lens close to the object plane in the meniscus concave lens is -17.014mm, and the radius of curvature of the lens far from the object plane in the meniscus concave lens is -35.544mm; The curvature radius of the lens close to the object plane in the fourth biconvex lens is 342.673 mm, and the curvature radius of the lens far from the object plane in the fourth biconvex lens is -212.43 mm.

[0030] The refractive index of the first biconvex lens is 1.5407 and the Abbe number is 47.23; The refractive index of the plano-concave lens is 1.4565 and the Abbe number is 90.27; The refractive index of the biconcave lens is 1.6477 and the Abbe number is 33.842; The refractive index of the meniscus plano-convex lens is 1.9229, and the Abbe number is 20.882; The refractive index of the second biconvex lens is 1.4565 and the Abbe number is 90.27; The refractive index of the third biconvex lens is 1.4565 and the Abbe number is 90.27; The refractive index of the meniscus lens is 1.575 and the Abbe number is 41.507; The refractive index of the fourth biconvex lens is 1.575 and the Abbe number is 41.507.

[0031] The material of the plano-concave lens, the second biconvex lens and the third biconvex lens is H-FK71, the material of the crescent concave lens and the fourth biconvex lens is H-QF3, the material of the first biconvex lens is H-QF8, the material of the biconcave lens is H-ZF1, and the material of the crescent plano-convex lens is H-ZF62.

[0032] The lens composed of the first lens 1, the second lens 2, the aperture stop 3, the triplet lens 4, the doublet lens 5, the third lens 6 and the beam splitter module 7 adopts a Gaussian-like structure, which balances the lens sizes of the front group (the first lens 1 and the second lens 2) and the rear group (the triplet lens 4, the doublet lens 5 and the third lens 6) while ensuring a sufficiently large field of view. The use of two types of glass, H-Fk71 and H-ZF62, meets the need to correct the secondary spectrum within the required wide spectrum range. The use of the triplet lens ensures the assembly accuracy of the lens without increasing the mechanical structure.

[0033] When two silicon-based video multispectral cameras or a silicon-based video multispectral camera is integrated with a traditional grayscale camera or a color camera, a two-branch optical path is formed with the help of a color splitter or a beam splitter. This requires that the lens of the silicon-based video multispectral imaging system has a long back focus while being telecentric. Currently, there is no such telecentric lens on the market. Based on the above design, the present invention designs the optical path structure in front of the camera so that the optical path structure in front of the camera has the characteristics of a long back focus and can be applied to dual-camera spectroscopy.

[0034] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0035] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-angle-sensitive silicon-based video multispectral imaging system, characterized in that: include: A first lens, a second lens, an aperture stop, a triplet lens, a doublet lens, a third lens and a beam splitting module are sequentially arranged along the optical axis from the object plane to the image plane, and an incident light beam is sequentially incident on the beam splitting module through the first lens, the second lens, the aperture stop, the triplet lens, the doublet lens and the third lens to be split, thereby obtaining a first light beam and a second light beam; A first camera and a second camera, wherein the first camera receives the first light beam and performs imaging, and the second camera receives the second light beam and performs imaging; Wherein, the aperture stop is placed on the image-side focal plane of the first camera and the second camera.

2. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 1, characterized in that: The first camera is one of a first type camera and a second type camera, the second camera is the other of the first type camera and the second type camera, the first type camera is a silicon-based video multispectral camera, and the second type camera is a grayscale camera or a color camera or a silicon-based video multispectral camera.

3. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 1, characterized in that: The air gap between the first lens and the second lens is 4.45mm; the air gap between the second lens and the aperture stop is 8.66mm; the air gap between the aperture stop and the triplet lens is 18mm; the air gap between the triplet lens and the doublet lens is 0.68mm; the air gap between the doublet lens and the third lens is 6.08mm; the air gap between the third lens and the beam splitting module is 22mm.

4. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 1, characterized in that: The first lens is a first biconvex lens; the second lens is a plano-concave lens, and the concave surface of the plano-concave lens faces away from the object plane of the silicon-based video multi-spectral imaging system; the triplet lens includes a biconcave lens, a crescent plano-convex lens and a second biconvex lens arranged in sequence along the optical axis from the object plane to the image plane, and the convex surface of the crescent plano-convex lens faces the object plane of the silicon-based video multi-spectral imaging system; the biconvex lens includes a third biconvex lens and a crescent concave lens arranged in sequence along the optical axis from the object plane to the image plane, and the concave surface of the crescent concave lens faces the object plane of the silicon-based video multi-spectral imaging system; the third lens is a fourth biconvex lens.

5. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 4, characterized in that: The curvature radius of the lens of the first biconvex lens close to the object plane is 61.269 mm, and the curvature radius of the lens of the first biconvex lens far from the object plane is -169.04 mm; The curvature radius of the lens close to the object plane in the plano-concave lens is ∞ mm, and the curvature radius of the lens far from the object plane in the plano-concave lens is 13.397 mm; The curvature radius of the lens of the biconcave lens close to the object plane is -92.92 mm, and the curvature radius of the lens of the biconcave lens far from the object plane is 21.803 mm; The curvature radius of the lens of the crescent plano-convex lens close to the object plane is 21.803 mm, and the curvature radius of the lens of the crescent plano-convex lens far from the object plane is 33.1 mm; The curvature radius of the lens of the second biconvex lens close to the object plane is 33.1 mm, and the curvature radius of the lens of the second biconvex lens far from the object plane is -26.626 mm; The radius of curvature of the lens of the third biconvex lens close to the object plane is 154.9 mm, and the radius of curvature of the lens of the third biconvex lens far from the object plane is -17.014 mm; The curvature radius of the lens of the crescent-shaped concave lens close to the object plane is -17.014 mm, and the curvature radius of the lens of the crescent-shaped concave lens far from the object plane is -35.544 mm; The curvature radius of the lens of the fourth biconvex lens close to the object plane is 342.673 mm, and the curvature radius of the lens of the fourth biconvex lens far from the object plane is -212.43 mm.

6. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 4, characterized in that: The refractive index of the first biconvex lens is 1.5407 and the Abbe number is 47.23; The refractive index of the plano-concave lens is 1.4565, and the Abbe number is 90.27; The refractive index of the biconcave lens is 1.6477 and the Abbe number is 33.842; The refractive index of the crescent plano-convex lens is 1.9229, and the Abbe number is 20.882; The refractive index of the second biconvex lens is 1.4565 and the Abbe number is 90.27; The refractive index of the third biconvex lens is 1.4565, and the Abbe number is 90.27; The refractive index of the meniscus lens is 1.575, and the Abbe number is 41.507; The refractive index of the fourth biconvex lens is 1.575, and the Abbe number is 41.

507.

7. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 4, characterized in that: The material of the plano-concave lens, the second biconvex lens and the third biconvex lens is H-FK71, the material of the crescent concave lens and the fourth biconvex lens is H-QF3, the material of the first biconvex lens is H-QF8, the material of the biconcave lens is H-ZF1, and the material of the crescent plano-convex lens is H-ZF62.

8. The non-angle-sensitive silicon-based video multispectral imaging system according to claim 1, characterized in that: The beam splitting module includes a non-polarizing beam splitter and a dichroic mirror assembly.

Images