CN210774359U - Convergent light-splitting aperture multispectral imaging optical system - Google Patents
Convergent light-splitting aperture multispectral imaging optical system Download PDFInfo
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- CN210774359U CN210774359U CN201921521387.XU CN201921521387U CN210774359U CN 210774359 U CN210774359 U CN 210774359U CN 201921521387 U CN201921521387 U CN 201921521387U CN 210774359 U CN210774359 U CN 210774359U
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Abstract
In order to solve the problems of larger volume and smaller field angle of the existing aperture-dividing spectral imaging optical system, the utility model provides a convergent aperture-dividing multispectral imaging optical system, which comprises a former imaging objective and a lens array; the front imaging objective is used for compressing the light beam and forming a convergent light beam, and eliminating field curvature and chromatic aberration within a spectral range required by design; the lens array is positioned in the convergent light beam and comprises N lenses, wherein N is an integer greater than or equal to 2; the N lenses are coplanar close to the mirror surfaces of the front group of imaging objective lenses and vertical to the optical axis of the front group of imaging objective lenses; the N lenses are respectively coated with filter films with different spectral sections to form N spectral light splitting modules; the distance between the adjacent spectral light splitting modules ensures that images formed on the detector do not interfere with each other; the imaging quality of the N spectral light splitting modules is close to the diffraction limit. The utility model discloses saved the eyepiece, utilized preceding component image objective to compress infinity parallel light into telecentric convergence pencil, reduced the lens array volume, whole optical system volume is less.
Description
Technical Field
The utility model belongs to the technical field of the multispectral formation of image of snapshot type, a convergence light divides multispectral formation of image optical system in aperture is related to.
Background
The spectral imaging technology is a high and new technology integrating optics, spectroscopy, electronic technology, computer technology and precision machinery, which appears in the 80 s of the 20 th century. The method can obtain rich information of the space and the spectrum of the target to be detected, so the method has important application value in the aspects of aerospace remote sensing, reconnaissance and mapping, environmental monitoring, resource surveying and the like.
The spectral imaging remote sensing integrates the traditional image dimension and the spectral dimension information, obtains the continuous spectral information of the target while obtaining the target space image, and thereby identifies different targets according to different spectral characteristics. Each pixel or pixel group of each object in the spectral image comprises a specific continuous light (wave) spectrum, and the light (wave) spectrum can be used as a characteristic parameter for identifying the feature after being corrected by atmosphere, so that the time, where, which attribute and what change of an observed target occur can be quantitatively described, and therefore, the spectral image is more and more valued by various countries.
The existing spectral imaging technology mainly has a time push-scan type, a space push-scan type and a snapshot type without push-scan. The snapshot type spectral imaging technology is to acquire two-dimensional spatial information and one-dimensional spectral information of a target simultaneously within the time when a detector acquires a frame of image, and because space push-broom and time push-broom are not needed, the snapshot type spectral imaging technology becomes a research hotspot of the spectral imaging technology at present, and the snapshot type spectral imaging technology of various principles emerges endlessly.
Due to the different principles of the snapshot type spectral imaging technology, the optical system used in the snapshot type spectral imaging technology has different structural patterns according to different principles. For the snapshot type spectral imaging technology of the aperture multiplexing principle, there are two types of optical systems at present:
one is that a plurality of lenses form a lens array directly, the detector connected with the rear end of the lens array has two forms, one is to connect a large area array detector, the structural form has the defect that the lens is limited by the size of the target surface of the detector, and the relative aperture can only be small under the condition of a certain focal length; the other is that each lens in the lens array is connected with a detector, the structural form forms a camera array, the whole volume is large, and the synchronization and image matching technology among the cameras is very complex.
Another optical system is shown in fig. 1 and is formed by simply connecting a telescopic system and a lens array in series, wherein the telescopic system is used for compressing an imaging light beam to output a parallel light beam, and then the lens array formed by a plurality of lenses 103 is used for imaging the parallel light beam onto a detector 105; the telescope system is composed of a front-mounted imaging objective lens 101 and a front-mounted imaging eyepiece lens 102, so that the telescope system is complex in structure, small in view field and large in size, and is limited to be used in application occasions with certain requirements on size.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem that the present aperture-dividing spectral imaging optical system is bulky, the angle of field is less, the utility model provides a convergence aperture-dividing multispectral imaging optical system.
The technical solution of the utility model is that:
the multi-spectral imaging optical system with the converged light split aperture is characterized in that: comprises a front imaging objective lens and a lens array;
the front imaging objective is used for compressing light beams and forming convergent light beams, and eliminating field curvature and chromatic aberration within a spectral range required by design;
the lens array is positioned in the convergent light beam and is an aperture diaphragm of the integral optical system;
the lens array comprises N independent lenses, wherein N is an integer greater than or equal to 2; the N lenses are close to the mirror surfaces of the front group of imaging objective lenses to be coplanar and are vertical to the optical axis of the front group of imaging objective lenses; the N lenses are plated with filter films, and the filter films on the lenses have different spectral bands to form N spectral splitting modules;
an enough distance is reserved between two adjacent spectrum light splitting modules to ensure that images formed on the detector do not interfere with each other;
the imaging quality of the N spectral light splitting modules is close to the diffraction limit, wherein the close to the diffraction limit means that the MTF of the spectral light splitting modules is not lower than 95% of the diffraction limit of the MTF of the whole optical system.
Furthermore, the front group image objective and the lens array are designed integrally to form an image objective.
Further, the N spectrum light splitting modules are uniformly distributed.
Further, the structures of the N lenses are the same.
Further, the materials of the N lenses are the same.
Furthermore, the front imaging objective lens comprises a first imaging lens, a second imaging lens, a third imaging lens and a fourth imaging lens which are sequentially arranged along the same optical axis; the first imaging lens and the second imaging lens form a double cemented lens.
Further, the front group image objective lens further includes a protective glass disposed at a front end of the first imaging lens.
Further, the first imaging lens, the third imaging lens and the lens array are all made of ZK11 material, and the second imaging lens and the fourth imaging lens are all made of ZF3 material.
Furthermore, one of the N spectral light splitting modules is coaxial with the front imaging objective and is positioned in the center of a meridian plane and an isolated sagittal plane of the optical system, and the rest N-1 spectral light splitting modules have different off-axes relative to the front imaging objective.
Furthermore, the filter film is a narrow band-pass filter film and is plated by adopting a Fabry-Perot interference principle.
Compared with the prior art, the utility model discloses following beneficial effect has:
1. the optical system of the utility model combines the lens array and the former imaging objective, realizes aperture multiplexing, realizes snapshot type spectral imaging, and can perform spectral imaging on a moving target; compared with the structure of the existing telescope and lens array, the utility model saves the ocular lens in the telescope system, integrally designs the front image objective lens and the lens array, jointly realizes the imaging function and reduces the volume of the optical system; the utility model discloses the formation image objective compresses the parallel light of infinity for the telecentric convergence pencil before utilizing, has guaranteed that lens array has great relative aperture, reduces lens array's volume simultaneously, and then has reduced the volume of whole equipment.
2. Because the lens array of the utility model directly forms the image in the front of the convergent beam of the image objective lens, the utility model has the advantage of large field angle.
3. The N lenses of the lens array of the utility model have consistent materials and structures, thereby reducing the processing and adjusting difficulty; if the spectrum section needs to be changed, only one of the N lenses needs to be changed, and the whole system has strong flexibility and mobility.
4. The utility model discloses directly plate the system filter coating on lens array's camera lens, saved the precision problem that camera lens and light filter matched, saved the structure of fixed light filter, whole precision is higher.
5. The utility model discloses an optical system cooperates ordinary detector just can realize the spectral imaging of target in detector collection frame image time, does not have special requirement to the stability of carrying on the platform.
6. The utility model discloses can select suitable spectral band according to spectral camera's different application occasions, only need change the camera lens in the lens array if need change the spectral band, and these camera lenses all install alone fixedly, and it is very convenient to change.
7. Because the lens surface of the lens array close to the front group of imaging objective lenses serves as an aperture diaphragm of the integral optical system, and light rays of all fields of view are imaged simultaneously through the N lenses, images formed by the N lenses are the same field of view, the consistency of image space positions of different spectral bands is ensured, and characteristic images can be directly fused without complex image processing.
8. The utility model discloses among the optical system, only used two kinds of common materials preparation lens, it is with low costs, the engineering is realized.
Drawings
Fig. 1 is a schematic diagram of a conventional spectroscopic imaging optical system with a split aperture.
Fig. 2 is a schematic diagram of the optical system of the present invention.
Fig. 3 is a schematic structural diagram of an embodiment of the optical system of the present invention.
Fig. 4 is a distribution diagram of nine lenses in a lens array according to an embodiment of the present invention.
Fig. 5 shows the imaging quality of the intermediate lens in the lens array according to the embodiment of the present invention.
Fig. 6 shows the imaging quality of the edge lens in the lens array according to the embodiment of the present invention.
Fig. 7 is a diagram of an imaging point array of an edge lens in a lens array according to an embodiment of the present invention.
Description of reference numerals:
101-a pre-imaging objective lens; 102-a front imaging eyepiece; 103-a lens; 104-an optical filter; 105-a detector;
201-protective glass; 202-a first imaging lens; 203-a second imaging lens; 204-a third imaging lens; 205-fourth imaging lens, 206-lens array, 207-aperture diaphragm, 208-detector, 209-front image objective.
Detailed Description
The present invention will be further explained with reference to the accompanying drawings.
Referring to fig. 2 and 3, an optical system provided by the embodiment of the present invention includes an objective lens 209 and a lens array 206 formed before installation;
the front image objective lens 209 is mainly used for compressing parallel light beams and forming convergent light beams so as to ensure that the lens array 206 has a larger relative aperture and reduce the volume of the lens array 206; the front imaging objective 209 can also eliminate chromatic aberration in the spectral range of 400nm-1000 nm; in this embodiment, the front imaging objective 209 includes a protective glass 201, a first imaging lens 202, a second imaging lens 203, a third imaging lens 204, and a fourth imaging lens 205, which are sequentially disposed along the same optical axis, wherein the first imaging lens 202 and the second imaging lens 203 constitute a double cemented lens;
in order to make the best use of the target surface of the detector 208, the lens array 206 is made up of nine separate lenses (in other embodiments, the lens array 6 may also be made up of four or another number of lenses); the nine lenses are made of the same material and structure, and have the same corresponding view fields, so that the processing and adjusting difficulty is reduced; the nine lenses are respectively coated with a filter film, the filter film on different lenses has different spectral bands to form nine spectral light splitting modules, and the incidence surfaces of the nine spectral light splitting modules are respectively used as aperture diaphragms 207 of the whole optical system, so that nine images with completely same view fields are formed; specifically, the filter coatings coated on the lenses are narrow-band-pass filter coatings, each filter coating is coated by adopting a Fabry-Perot interference principle, and spectral light splitting and spatial light splitting are combined;
among the nine spectral light splitting modules, one spectral light splitting module is positioned on a main optical axis and is coaxial with the front imaging objective and is positioned in the center of a meridian plane and an isolated sagittal plane of an optical system of the front imaging objective, the other eight spectral light splitting modules have different off-axes in different positions relative to the main optical axis, the off-axis amount mainly depends on the size of a target surface of the detector 208, the off-axis amount is large when the target surface of the detector 208 is large, and the off-axis amount is small when the target surface of the detector 208 is small; in this embodiment, the eight spectrum splitting modules have two off-axis parameters, which are 6mm and 8.5mm, respectively, and the specific positions and off-axis quantities thereof are shown in fig. 4.
The imaging quality of the nine spectral splitting modules can reach 0.4 at a 90lp/mm MTF (modulation transfer function), and the MTFs are close to diffraction limits, so that the same field of view and imaging quality of each spectral band are ensured, and further, a subsequent recovery algorithm is simple, and convenience is brought to later-stage data processing;
nine spectrum spectral module correspond nine formation of image passageways respectively, and nine formation of image passageways can be simultaneously in a detector 208 [ detector 208 is not the utility model discloses optical system's part, the utility model discloses an optical system + detector 8+ recovery algorithm can constitute spectral imager together and carry out the spectral imaging to form the different spectral band pictures of same target in the different positions of detector 208, realize video multispectral formation of image; in specific applications, only the lens of the corresponding spectral band in the lens array 206 needs to be replaced when different spectral bands are replaced according to actual requirements.
Because the light rays of all spectral bands enter the optical system through the front imaging objective lens which has better achromatic capability in the spectral band range of 400nm-1000nm, the integral optical system can ensure good imaging quality in the spectral band range of 400nm-1000nm no matter which nine spectral bands are replaced by the nine spectral splitting modules.
As can be seen from fig. 5, 6, and 7, although the lenses in the lens array 206 in the optical system of the present embodiment are located at different positions and have different aberration characteristics, the imaging modulation transfer function of the middle lens and the imaging modulation transfer function of the edge lens are both close to the diffraction limit, the imaging scattering points of the edge lens are both within the diffuse spot, the imaging quality is close to the diffraction limit, and the imaging quality is good.
The imaging range of the optical system of the embodiment is a visible light near-infrared spectrum band, and in other embodiments, the imaging range can be expanded to medium-wave infrared and long-wave infrared spectrum bands by replacing lens materials and plating filter films in corresponding spectrum band ranges.
In consideration of cost, processing, achromatization, and the like, only two materials are used in the entire optical system, except for the cover glass 201, wherein: the first imaging lens 202, the third imaging lens 204, and the lens array 206 are all made of ZK11 material, and the second imaging lens 203 and the fourth imaging lens 205 are all made of ZF3 material.
Claims (10)
1. The multi-spectral imaging optical system with the converged light split aperture is characterized in that: comprises a front imaging objective lens and a lens array;
the front imaging objective is used for compressing the light beam to form a convergent light beam, and eliminating field curvature and chromatic aberration within a spectral range required by design;
a lens array positioned in the converging light beam to act as an aperture stop for the integral optical system;
the lens array comprises N independent lenses, wherein N is an integer greater than or equal to 2; the N lenses are close to the mirror surfaces of the front group of imaging objective lenses to be coplanar and are vertical to the optical axis of the front group of imaging objective lenses; the N lenses are plated with filter films, and the filter films on the lenses have different spectral bands to form N spectral splitting modules;
an enough distance is reserved between two adjacent spectrum light splitting modules to ensure that images formed on the detector do not interfere with each other;
the imaging quality of the N spectral light splitting modules is close to the diffraction limit.
2. The converging light aperture multispectral imaging optical system of claim 1, wherein: the former image objective and the lens array are designed integrally to form an imaging objective.
3. The converging light aperture multispectral imaging optical system of claim 1, wherein: the N spectrum light splitting modules are uniformly distributed.
4. The converging light-splitting aperture multispectral imaging optical system according to claim 1, 2 or 3, wherein: the N lenses have the same structure.
5. The converging light aperture multispectral imaging optical system of claim 4, wherein: the N lenses are made of the same material.
6. The converging light-splitting aperture multispectral imaging optical system according to claim 1, 2 or 3, wherein: the front imaging objective lens comprises a first imaging lens, a second imaging lens, a third imaging lens and a fourth imaging lens which are sequentially arranged along the same optical axis; the first imaging lens and the second imaging lens form a double cemented lens.
7. The converging light aperture multispectral imaging optical system of claim 6, wherein: the front group image objective lens further comprises a protective glass arranged at the front end of the first imaging lens.
8. The converging light aperture multispectral imaging optical system of claim 7, wherein: the first imaging lens, the third imaging lens and the lens array are all made of ZK11 material, and the second imaging lens and the fourth imaging lens are all made of ZF3 material.
9. The converging light-splitting aperture multispectral imaging optical system according to claim 1, 2 or 3, wherein: one of the N spectral light splitting modules is coaxial with the front imaging objective and is positioned in the center of a meridian plane and an isolated sagittal plane of the optical system, and the rest N-1 spectral light splitting modules have different off-axes relative to the front imaging objective.
10. The converging light-splitting aperture multispectral imaging optical system according to claim 1, 2 or 3, wherein: the filter film is a narrow band-pass filter film and is plated by adopting a Fabry-Perot interference principle.
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| CN110631701A (en) * | 2019-09-12 | 2019-12-31 | 中国科学院西安光学精密机械研究所 | Convergent light-splitting aperture multispectral imaging optical system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110631701A (en) * | 2019-09-12 | 2019-12-31 | 中国科学院西安光学精密机械研究所 | Convergent light-splitting aperture multispectral imaging optical system |
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