Super-wide-working-distance long-focal-length continuous zooming visible light optical system with reverse scanning function

Abstract

The invention discloses an ultra-wide working distance band reverse-scanning long-focal-length continuous zooming visible light optical system. The system comprises a front fixed group lens, a zoom group lens, a compensation group lens, a first rear fixed group lens, a reverse-scanning group lens, a second rear fixed group lens, a reflex mirror and an optical filter group lens which are sequentially arranged from an object space to an image space along an optical axis, wherein the front fixed group lens, the zoom group lens, the compensation group lens, the first rear fixed group lens, the reverse-scanning group lens, the second rear fixed group lens, the reflex mirror and the optical filter group lens are arranged in sequence; wherein the first rear fixed group lens comprises a first rear group lens, a second rear group lens and a focusing assembly consisting of two glued negative lenses. According to the long-focal-length optical system, the focusing assembly composed of the glued negative lens is added to the rear fixing assembly, so that the drift of an image plane in an ultra-close working distance and high-low-temperature working environment when the optical system is in a long focal length can be supplemented, and therefore, the working distance of clear imaging of the long-focal-length optical system reaches infinity from 50m, and the imaging precision of the long-focal-length optical system is improved. Clear imaging from a short-distance target to a long-distance target is realized.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to an ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system. Background Technology

[0002] With the increasing demand for long-range target detection and identification, long-focal-length optical systems have become an indispensable component of various optoelectronic payloads. However, these optical systems are limited by depth of field, making it difficult to achieve clear imaging of close-range targets. But certain special applications require the identification and detection of minute targets, such as foreign object (screw) detection on airport runways. Therefore, an optical system capable of clear imaging of targets ranging from close to long distances is needed. Summary of the Invention

[0003] To address the shortcomings of existing technologies in achieving clear imaging of close-range targets, this invention provides an ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system, enabling clear imaging of targets ranging from close to distant.

[0004] Therefore, the technical solution adopted by the present invention is as follows: An ultra-wide working distance long focal length continuous zoom visible light optical system with reverse scanning is provided, including a front fixed group lens, a zoom group lens, a compensation group lens, a first rear fixed group lens, a reverse scanning group lens, a second rear fixed group lens, a folding mirror and a filter group lens arranged sequentially along the optical axis from the object side to the image side. The first rear fixed lens group includes a first rear lens group, a second rear lens group, and a focusing assembly composed of two cemented negative lenses. The object-side imaging beam passes sequentially through the front fixed lens group, the zoom lens group, the compensation lens group, the first rear fixed lens group, the reverse scanning lens group, the second rear fixed lens group, and then through the folding mirror and the filter lens group to form an image on the detector. Continuous zoom is achieved by moving the zoom lens and compensation lens back and forth relative to each other along the optical axis, and the image sharpness is adjusted by moving the focusing assembly back and forth along the optical axis.

[0005] According to the above scheme, the front fixed lens group includes a first front lens group, a second front lens group, a third front lens group, and a fourth front lens group; the zoom lens group includes a first zoom lens group, a second zoom lens group, and a third zoom lens group; the compensation lens group includes a first compensation lens group, a second compensation lens group, a third compensation lens group, and a fourth compensation lens group; and the second rear fixed lens group includes a third rear lens group and a fourth rear lens group.

[0006] According to the above scheme, the first front lens is specifically a biconvex fluorine crown positive lens, the second front lens is specifically a meniscus heavy crown negative lens, the third front lens is specifically a meniscus fluorine crown positive lens, and the fourth front lens is specifically a meniscus heavy lanthanum flint negative lens; the first zoom lens is specifically a meniscus heavy phosphorus crown negative lens, the second zoom lens is specifically a heavy phosphorus crown-heavy flint cemented negative lens, and the third zoom lens is specifically a heavy crown biconcave negative lens; the first compensation lens is specifically a biconvex fluorine crown positive lens, the second compensation lens is specifically a meniscus heavy phosphorus crown positive lens, the third compensation lens is specifically a meniscus lanthanum flint negative lens, and the fourth compensation lens is specifically a heavy phosphorus crown-heavy lanthanum flint cemented positive lens; the third rear lens is specifically a meniscus flint negative lens, and the fourth rear lens is specifically a biconvex light crown positive lens.

[0007] According to the above scheme, the reverse scanning lens group specifically includes an azimuth reverse scanning mirror and a pitch reverse scanning mirror, and the azimuth reverse scanning mirror and the pitch reverse scanning mirror are located in the parallel optical path; the azimuth reverse scanning mirror and the pitch reverse scanning mirror are specifically made of SiC material.

[0008] According to the above scheme, the first rear lens group is a heavy phosphorus crown plano-concave negative lens, the second rear lens group is a heavy crown meniscus positive lens, and the two cemented negative lenses are a lanthanum flint-light flint cemented negative lens and a lanthanum flint-crown cemented negative lens, respectively.

[0009] According to the above scheme, the folding mirror is specifically made of quartz material, and the angle between the normal of the folding mirror and the optical axis is 45°.

[0010] According to the above scheme, the filter group lens is specifically one of the following: a filter with a wavelength range of 450nm~950nm, a filter with a wavelength range of 850nm±20nm, and a polarizer.

[0011] According to the above scheme, the focal length range of the continuous zoom visible light optical system is 95mm~2000mm continuous zoom, and the working wavelength is 0.45μm~0.95μm.

[0012] A detector is also provided for sensing the emitted light of the ultrawide working distance band reverse scanning long focal length continuous zoom visible light optical system described above.

[0013] According to the above scheme, the resolution of the detector is 3840×2160, and the pixel size is 4μm×4μm.

[0014] The beneficial effects of this invention are as follows: By adding a focusing assembly composed of cemented negative lenses to the rear fixed group, this invention can compensate for the image plane drift when the optical system is at a long focal length, under ultra-close working distances and high and low temperature working environments, thereby enabling the working distance for clear imaging of the long focal length optical system to reach infinity from 50m, achieving clear imaging from close-range targets to distant targets.

[0015] Furthermore, by setting up a reverse scanning lens group consisting of an azimuth reverse scanning mirror and a pitch reverse scanning mirror in the parallel optical path, the present invention can achieve the functions of reverse scanning and image stabilization, which can significantly reduce the control accuracy requirements of the servo in the optical system and achieve a balance between system performance and economy. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the optical system in the short focal length 95mm position according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical system in an embodiment of the present invention at a focal length of 2000mm. Figure 3(a) is a transfer function curve of the short focal length optical system of the present invention at 50 lp / mm; Figure 3(b) is a transfer function curve of the central focal optical system of this embodiment at 50 lp / mm; Figure 3(c) is a transfer function curve of the telephoto optical system of this embodiment at 50 lp / mm; Figure 3(d) is a transfer function curve of the ultra-long focal length optical system of this embodiment at 50 lp / mm; Figure 3(e) is a transfer function curve of the ultra-long focal length optical system of the present invention at 50 lp / mm when the object-side reverse scanning is 0.02°; Figure 3(f) is a transfer function curve of the ultra-long focal length optical system of this invention when imaging a target at a close distance of 50m at 50lp / mm. Figure 4(a) is a blur pattern of the short focal length optical system according to an embodiment of the present invention; Figure 4(b) is a diffusion pattern of the central focal optical system according to an embodiment of the present invention; Figure 4(c) is a blur pattern of the telephoto optical system according to an embodiment of the present invention; Figure 4(d) is a blur pattern of the ultra-long focal length optical system according to an embodiment of the present invention; Figure 4(e) is a blur pattern of the ultra-long focal length optical system of the present invention when the object side is back-scanned at 0.02°. Figure 4(f) is a blur pattern of the ultra-long focal length optical system of this invention when imaging a target at a close distance of 50m.

[0017] In the diagram: 1-Front fixed lens group; 11-First front lens group; 12-Second front lens group; 13-Third front lens group; 14-Fourth front lens group; 2-Zoom lens group; 21-First zoom lens group; 22-Second zoom lens group; 23-Third zoom lens group; 3-Compensation lens group; 31-First compensation lens group; 32-Second compensation lens group; 33-Third compensation lens group; 34-Fourth compensation lens group; 4-First rear fixed lens group; 41-First rear lens group; 42-Second rear lens group; 43-First cemented negative lens group; 44-Second cemented negative lens group; 5-Azimuth counterscanning mirror; 6-Pitch counterscanning mirror; 7-Second rear fixed lens group; 71-Third rear lens group; 72-Fourth rear lens group; 8-Folding mirror; 9-Filter lens group; 10-Detector. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] This invention provides an ultra-wide working distance long focal length continuous zoom visible light optical system with reverse scanning. A focusing component is designed in the continuous zoom telescope system to compensate for the image plane drift of the long focal length optical system at ultra-close working distances and in high and low temperature working environments. It can achieve clear imaging of targets from 50m to infinity with an optical system with a focal length of 2000mm.

[0020] like Figure 1 As shown, this continuous zoom visible light optical system mainly includes a front fixed lens group 1, a zoom lens group 2, a compensation lens group 3, a first rear fixed lens group 4, a reverse scanning lens group, a second rear fixed lens group 7, a folding mirror 8, and a filter lens group 9 arranged sequentially from the object side to the image side along the optical axis. The first rear fixed lens group 4 includes a first rear lens group 41, a second rear lens group 42, and a focusing assembly composed of a first cemented negative lens 43 and a second cemented negative lens 44, used to compensate for image plane drift during high / low temperature and close-range imaging. When the optical system images at close range, the inherent depth of field causes image focus drift. The focusing lens group moves along the optical axis towards the image plane to bring the optimal image plane to the detector's photosensitive surface. When the optical system images under high / low temperature conditions, the refractive index of the optical materials and the thermal expansion of the structural components cause image focus drift. The focusing lens group moves along the optical axis closer to and further away from the image plane to bring the optimal image plane to the detector's photosensitive surface.

[0021] The object-side imaging beam passes sequentially through the front fixed group lens 1, the zoom group lens 2, the compensation group lens 3, the first rear fixed group lens 4, the reverse scanning group lens, and the second rear fixed group lens 7 to form an image once. Then, it passes through the folding mirror 8 and the filter group lens 9 to form a second image on the detector 10. During continuous zoom, the zoom lens 2 and the compensation lens 3 are moved back and forth relative to each other along the optical axis to achieve continuous zoom, and the image sharpness is adjusted by moving the focusing assembly back and forth along the optical axis.

[0022] Specifically, the front fixed lens group 1 consists of four lenses with an optical power of "positive-negative-positive-negative" and a focal length of 502.8mm; including the first front lens group 11, the second front lens group 12, the third front lens group 13 and the fourth front lens group 14. Specifically, the first front lens 11 is a biconvex fluorine crown positive lens, the second front lens 12 is a meniscus crown negative lens, the third front lens 13 is a meniscus fluorine crown positive lens, and the fourth front lens 14 is a meniscus lanthanum flint negative lens.

[0023] Specifically, the zoom lens group 2 consists of three lens groups with a focal length of -75.9mm and a travel distance of 232.7mm; including a first zoom lens 21, a second zoom lens 22, and a third zoom lens 23; Specifically, the first zoom lens 21 is a meniscus heavy phosphorus crown negative lens, the second zoom lens 22 is a heavy phosphorus crown-heavy flint cemented negative lens, and the third zoom lens 23 is a heavy crown biconcave negative lens.

[0024] Specifically, the compensation lens group 3 consists of four lenses with a focal length of 103.7 mm and a travel distance of 100.9 mm; including a first compensation lens 31, a second compensation lens 32, a third compensation lens 33 and a fourth compensation lens 34. Specifically, the first compensation lens 31 is a biconvex fluorine crown positive lens, the second compensation lens 32 is a meniscus heavy phosphorus crown positive lens, the third compensation lens 33 is a meniscus lanthanum flint negative lens, and the fourth compensation lens 34 is a heavy phosphorus crown-heavy lanthanum flint cemented positive lens.

[0025] Specifically, the second rear fixed lens group 7 consists of two lenses with a focal length of 103.6mm, including the third rear lens group 71 and the fourth rear lens group 72. Among them, the third rear lens group 71 is specifically a crescent firestone negative lens, and the fourth rear lens group 72 is specifically a biconvex light crown positive lens.

[0026] Specifically, the focal length of the first rear fixed group 4 is -46.7mm. The first rear group lens 41 is a heavy phosphorus crown plano-concave negative lens, and the second rear group lens 42 is a heavy crown meniscus positive lens. Among the two cemented negative lenses, the first cemented negative lens 43 is a lanthanum flint-light flint cemented negative lens, and the second cemented negative lens 44 is a lanthanum flint-crown cemented negative lens.

[0027] Specifically, the reverse scanning lens group includes an azimuth reverse scanning mirror 5 and a pitch reverse scanning mirror 6, and the azimuth reverse scanning mirror 5 and the pitch reverse scanning mirror 6 are located in a parallel optical path; the azimuth reverse scanning mirror 5 and the pitch reverse scanning mirror 6 are specifically made of SiC material.

[0028] Specifically, the folding mirror 8 is made of quartz material, and the angle between the normal of the folding mirror 8 and the optical axis is 45°, which is used to fold the optical path, thereby improving the space utilization rate.

[0029] Specifically, the filter group lens 9 is one of the following: a filter with a wavelength range of 450nm~950nm, a filter with a wavelength range of 850nm±20nm, and a polarizer. Custom filters can be replaced according to different working conditions.

[0030] Specifically, the focal length range of the continuous zoom visible light optical system in this embodiment is 95mm~2000mm continuous zoom, and the working wavelength is 0.45μm~0.95μm.

[0031] The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system of this invention adopts a single-imaging structure. The optical system consists of a continuous zoom telescope system, a scanning mirror group, and a rear fixed group. The scanning mirror group lens is located in the parallel optical path, which can realize the functions of scanning and image stabilization, and can significantly reduce the control accuracy requirements of the servo. This optical system incorporates a focusing mirror in the continuous zoom telescope system to compensate for image plane drift in ultra-close working distances and high and low temperature operating environments of the long focal length optical system.

[0032] Specifically, the optical system design parameters of this embodiment are shown in the table below.

[0033] Table 1 Optical System Design Parameters

[0034] Specifically, as shown in the table below, these are the optical transfer function values ​​of the optical system in this embodiment at different focal lengths.

[0035] Table 2. Optical system transfer function values

[0036] Specifically, the schematic diagrams of the optical system in the embodiment of the present invention at the short focal length of 95mm and the long focal length of 2000mm are respectively as follows: Figure 1 and Figure 2 As shown.

[0037] In addition, Figures 3(a) to 3(f) and Figures 4(a) to 4(f) are optical simulation data diagrams of the optical system of this invention. Among them, Figure 3(a) is the transfer function curve of the short focal length optical system (95mm) at 50 lp / mm, Figure 3(b) is the transfer function curve of the medium focal length optical system (600mm) at 50 lp / mm, Figure 3(c) is the transfer function curve of the long focal length optical system (1200mm) at 50 lp / mm, Figure 3(d) is the transfer function curve of the super long focal length optical system (2000mm) at 50 lp / mm, Figure 3(e) is the transfer function curve of the super long focal length optical system (2000mm) at 50 lp / mm with object-side reverse scanning of 0.02°, and Figure 3(f) is the transfer function curve of the super long focal length optical system (2000mm) at 50 lp / mm with object-side reverse scanning of 0.02°. The transfer function curves of the short focal length optical system (95mm) at 50 lp / mm when imaging a target at a close distance of 50m are shown in Figure 4(a), Figure 4(b) is the blur pattern of the medium focal length optical system (600mm) of this invention, Figure 4(c) is the blur pattern of the long focal length optical system (1200mm) of this invention, Figure 4(d) is the blur pattern of the ultra-long focal length optical system (2000mm) of this invention, Figure 4(e) is the blur pattern of the ultra-long focal length optical system (2000mm) with an object-side backscan of 0.02°, and Figure 4(f) is the blur pattern of the ultra-long focal length optical system (2000mm) when imaging a target at a close distance of 50m.

[0038] In addition, this embodiment of the invention also provides a detector for sensing the emitted light of the ultra-wide working distance band reverse scanning long focal length continuous zoom visible light optical system described in this embodiment; and the detector has a resolution of 3840×2160 and a pixel size of 4μm×4μm.

[0039] The present invention provides an ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system. By adding a focusing assembly composed of cemented negative lenses to the rear fixed group, the image plane drift caused by the optical system at long focal lengths under ultra-close working distances and high and low temperature working environments can be compensated. This allows the working distance for clear imaging of the long focal length optical system to reach infinity from 50m, realizing clear imaging from near-distance targets to far-distance targets.

[0040] Furthermore, by setting up a reverse scanning lens group composed of an azimuth reverse scanning mirror and a pitch reverse scanning mirror in the parallel optical path, the present invention can achieve the functions of reverse scanning and image stabilization, which can significantly reduce the control accuracy requirements of the servo in the optical system and achieve a balance between system performance and economy.

[0041] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0042] The sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0043] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A visible light optical system with ultra-wide working distance, reverse scanning, and continuous zoom at long focal length, characterized in that: It includes a front fixed lens group, a zoom lens group, a compensation lens group, a first rear fixed lens group, a reverse scanning lens group, a second rear fixed lens group, a folding mirror, and a filter lens group arranged sequentially along the optical axis from the object side to the image side. The first rear fixed lens group includes a first rear lens group, a second rear lens group, and a focusing assembly composed of two cemented negative lenses. The object-side imaging beam passes sequentially through the front fixed lens group, the zoom lens group, the compensation lens group, the first rear fixed lens group, the reverse scanning lens group, and the second rear fixed lens group, and then through the folding mirror and the filter lens group to form an image on the detector. Continuous zoom is achieved by moving the zoom lens and compensation lens back and forth relative to each other along the optical axis, and the image sharpness is adjusted by moving the focusing assembly back and forth along the optical axis.

2. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 1, characterized in that, The front fixed lens group includes a first front lens group, a second front lens group, a third front lens group, and a fourth front lens group; the zoom lens group includes a first zoom lens group, a second zoom lens group, and a third zoom lens group; the compensation lens group includes a first compensation lens group, a second compensation lens group, a third compensation lens group, and a fourth compensation lens group; and the second rear fixed lens group includes a third rear lens group and a fourth rear lens group.

3. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 3, characterized in that, The first front lens is a biconvex fluorine crown positive lens; the second front lens is a meniscus heavy crown negative lens; the third front lens is a meniscus fluorine crown positive lens; and the fourth front lens is a meniscus heavy lanthanum flint negative lens. The first zoom lens is a meniscus heavy phosphorus crown negative lens; the second zoom lens is a heavy phosphorus crown-heavy flint cemented negative lens; and the third zoom lens is a heavy crown biconcave negative lens. The first compensation lens is a biconvex fluorine crown positive lens; the second compensation lens is a meniscus heavy phosphorus crown positive lens; the third compensation lens is a meniscus lanthanum flint negative lens; and the fourth compensation lens is a heavy phosphorus crown-heavy lanthanum flint cemented positive lens. The third rear lens is a meniscus flint negative lens; and the fourth rear lens is a biconvex light crown positive lens.

4. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 1, characterized in that, The reverse scanning lens group specifically includes an azimuth reverse scanning mirror and a pitch reverse scanning mirror, and the azimuth reverse scanning mirror and the pitch reverse scanning mirror are located in a parallel optical path; the azimuth reverse scanning mirror and the pitch reverse scanning mirror are specifically made of SiC material.

5. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 1, characterized in that, The first rear lens group is a heavy phosphorus crown plano-concave negative lens, the second rear lens group is a heavy crown meniscus positive lens, and the two cemented negative lenses are a lanthanum flint-light flint cemented negative lens and a lanthanum flint-crown cemented negative lens, respectively.

6. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 1, characterized in that, The folding mirror is made of quartz material, and the angle between the normal of the folding mirror and the optical axis is 45°.

7. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 1, characterized in that, The filter group lens is specifically one of the following: a filter with a wavelength range of 450nm~950nm, a filter with a wavelength range of 850nm±20nm, and a polarizer.

8. The ultra-wide working distance band-scanning long focal length continuous zoom visible light optical system according to claim 1, characterized in that, The continuously zoom visible light optical system has a focal length range of 95mm to 2000mm and an operating wavelength range of 0.45μm to 0.95μm.

9. A detector, characterized in that, The detector is used to sense the emitted light of the ultrawide working distance band-scanning long focal length continuous zoom visible light optical system as described in any one of claims 1-8.

10. The detector according to claim 9, characterized in that, The detector has a resolution of 3840×2160 and a pixel size of 4μm×4μm.

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