A long focal length close-range imaging optical system for space use and an imaging device
Patent Information
- Application Number
- CN202510256702.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2026-09-08
AI Technical Summary
[0004]本申请实施例的目的在于提供一种空间用长焦距近景成像光学系统和成像装置，以解决在空间辐射环境下长焦距近景成像时物距变化带来的像质下降问题
[0024] 1. The space long focal length close-range imaging optical system and imaging device provided in the embodiments of this application have the following characteristics: the first lens of the optical system is made of radiation-resistant quartz with a thickness greater than 3 mm, and the other lenses are all made of radiation-resistant glass, which improves the radiation resistance of the optical system and makes the optical system suitable for the space environment; the focal length of the optical system is 75 mm and the F number is 4, which can produce clear images within an object distance of 1.5 m to 10 m.
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Figure CN122710322A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical imaging technology, and in particular to a long focal length close-range imaging optical system and imaging device for space applications. Background Technology
[0002] In space-based servicing, machine vision is required to perform multi-dimensional measurements on instruments and equipment in various application scenarios. Taking a large radar system as an example, after it enters orbit, the motion mechanism controlling the pointing may experience zero-position drift due to the mechanical influence of the active segment; when exposed to illumination in orbit, minute deformations may occur, causing pointing drift. Therefore, it is necessary to calibrate the pointing of the radar system. However, since radar waves are invisible, the convergence point of the antenna spherical surface cannot be directly measured. Therefore, a high-precision visual imaging measurement system is needed to measure its surface shape and convergence point.
[0003] Due to the high accuracy requirements of the measurement, a long focal length optical lens is needed for image acquisition. However, due to the limited size of the satellite and the short distance between the imaging measurement system and the radar under test, it is necessary to design a long focal length close-range imaging measurement lens that can solve the problem of image quality degradation caused by changes in object distance during long focal length close-range imaging while meeting environmental factors such as space radiation. Summary of the Invention
[0004] The purpose of this application is to provide a long focal length close-range imaging optical system and imaging device for space applications, in order to solve the problem of image quality degradation caused by changes in object distance during long focal length close-range imaging in a space radiation environment. The specific technical solution is as follows:
[0005] In a first aspect of this application, a long focal length close-up imaging optical system for space is provided. The optical system is provided with a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth cemented lens group, a sixth lens, and a seventh lens arranged coaxially along the incident direction of light. Light reaches the focal plane after passing through each lens and the aperture stop.
[0006] The first lens is made of quartz, and the radius of curvature ρ of the incident surface of the first lens is... 入1 and the radius of curvature ρ of the exit surface 出1 Satisfy: 35 mm ≥ ρ 入1 ≥30 mm, 22 mm ≥ρ 出1 ≥19 mm;
[0007] The refractive index r2 of the second lens is ≥ 1.9, and the radius of curvature ρ of the incident surface of the second lens is... 入2 and the radius of curvature ρ of the exit surface 出2 Satisfy: 20 mm ≥ ρ 入2 ≥15 mm, 20 mm ≥ρ 出2 ≥15 mm;
[0008] The refractive index r3 of the third lens is ≤1.5, and the radius of curvature ρ of the incident surface of the third lens is... 入3 and the radius of curvature ρ of the exit surface 出3 Satisfy: 18 mm ≥ ρ 入3 ≥14 mm, 150 mm ≥ρ 出3 ≥145 mm;
[0009] The refractive index r4 of the fourth lens is ≤1.5, and the radius of curvature ρ of the incident surface of the fourth lens is... 入4 and the radius of curvature ρ of the exit surface 出4 Satisfy: 15 mm ≥ ρ 入4 ≥12 mm, 70 mm ≥ρ 出4 ≥65 mm;
[0010] The fifth cemented mirror group includes a fifth cemented negative mirror and a fifth cemented positive mirror arranged coaxially along the incident light direction. The refractive index r of the fifth cemented negative mirror is... 5-1 ≥1.9, the refractive index r of the fifth cemented positive mirror 5-2 Satisfy: 1.6≥r 5-2 ≥1.5; the radius of curvature ρ of the incident surface of the fifth cemented negative mirror 入5 Satisfy: -640 mm ≥ ρ 入5 ≥-650 mm, the radius of curvature ρ of the exit surface of the fifth cemented positive mirror 出5 Satisfy: 110 mm ≥ ρ 出5 ≥105 mm, the radius of curvature ρ of the bonding surface of the fifth cemented negative mirror and the fifth cemented positive mirror 胶 Satisfy: 9 mm ≥ ρ 胶 ≥8.5 mm;
[0011] The refractive index r6 of the sixth lens is ≤1.5, and the radius of curvature ρ of the incident surface of the sixth lens is... 入6 and the radius of curvature ρ of the exit surface 出6 Satisfy: -9 mm ≥ ρ 入6 ≥-10 mm, -35 mm ≥ρ 出6 ≥-40 mm;
[0012] The refractive index r7 of the seventh lens satisfies: 1.8 ≤ r4 ≤ 1.9, and the radius of curvature ρ of the incident surface of the seventh lens... 入7 and the radius of curvature ρ of the exit surface 出7 Satisfy: 100 mm ≥ ρ 入7 ≥95 mm, -45 mm ≥ρ 出7 ≥-50 mm.
[0013] In one possible implementation, the center thickness d1 of the first lens, the second lens, and the sixth lens satisfies: 3.6 mm ≥ d1 ≥ 3.4 mm; the center thickness d2 of the third lens and the fourth lens satisfies: 3.85 mm ≥ d2 ≥ 3.65 mm; the center thickness d3 of the fifth cemented negative lens satisfies: 4.85 mm ≥ d3 ≥ 4.65 mm; the thickness d4 of the fifth cemented positive lens satisfies: 6.1 mm ≥ d4 ≥ 5.9 mm; and the center thickness d5 of the seventh lens satisfies: 5.46 mm ≥ d5 ≥ 5.26 mm.
[0014] In one possible implementation, the material of the second lens is heavy flint glass.
[0015] In one possible implementation, the fourth lens is made of fluorine crown glass.
[0016] In one possible implementation, the fifth cemented negative mirror is made of heavy lanthanum flint glass.
[0017] In one possible implementation, the fifth cemented positive mirror is made of phosphor crown glass.
[0018] In one possible implementation, the distance between the first lens and the second lens, the distance between the second lens and the third lens, and the distance between the aperture stop and the fourth lens are all 0.3 mm; the distance between the third lens and the aperture stop is 1.28 mm; the distance between the fourth lens and the fifth cemented lens group is 1.44 mm; the distance between the fifth cemented lens group and the sixth lens is 6.9 mm; the distance between the sixth lens and the seventh lens is 2 mm; and the distance between the seventh lens and the focal plane is 23.34 mm.
[0019] In one possible implementation, the first lens, the second lens, the third lens, the fourth lens, the fifth cemented lens group, the sixth lens, and the seventh lens are all spherical lenses;
[0020] The first lens has an incident surface radius of curvature of 33.14 mm and an exit surface radius of curvature of 20.14 mm; the second lens has an incident surface radius of curvature of 17.46 mm and an exit surface radius of curvature of 16.42 mm; the third lens has an incident surface radius of curvature of 15.6 mm and an exit surface radius of curvature of 148 mm; the fourth lens has an incident surface radius of curvature of 12.73 mm and an exit surface radius of curvature of 69.25 mm. The fifth cemented negative mirror has an incident surface radius of curvature of -648.32 mm, the cemented surface radius of curvature of the fifth cemented negative mirror and the fifth cemented positive mirror is 8.56 mm, and the exit surface radius of curvature of the fifth cemented positive mirror is 109.39 mm; the sixth lens has an incident surface radius of curvature of -9.82 mm and an exit surface radius of curvature of -36.42 mm; the seventh lens has an incident surface radius of curvature of 96.74 mm and an exit surface radius of curvature of -48.43 mm.
[0021] In one possible implementation, the external dimensions of the spatial long focal length close-up imaging optical system are:
[0022] A second aspect of this application provides an imaging device, the imaging device including the spatial long focal length close-up imaging optical system described in the first aspect above.
[0023] Beneficial effects of the embodiments in this application:
[0024] 1. The space long focal length close-range imaging optical system and imaging device provided in the embodiments of this application have the following characteristics: the first lens of the optical system is made of radiation-resistant quartz with a thickness greater than 3 mm, and the other lenses are all made of radiation-resistant glass, which improves the radiation resistance of the optical system and makes the optical system suitable for the space environment; the focal length of the optical system is 75 mm and the F number is 4, which can produce clear images within an object distance of 1.5 m to 10 m.
[0025] 2. The space-use long-focal-length close-range imaging optical system and imaging device provided in this application, through the reasonable setting of the refractive index, radius of curvature, and material of each lens, and the thermal design, enables the optical system to achieve clear imaging without focusing within a vacuum range of 40°C to -20°C. Furthermore, through the cooperation of radiation-resistant lenses, high-refractive-index lenses, and low-refractive-index lenses, this optical system is suitable for imaging in the visible light band and also exhibits good performance for imaging under commonly used single-wavelength illumination at 450nm, 532nm, 808nm, and 850nm.
[0026] 3. The space-use long focal length close-range imaging optical system and imaging device provided in this application all use spherical lens design, which reduces cost and facilitates small-batch production. Furthermore, the optical system exhibits a full field-of-view distortion of less than or equal to 0.1%, improving image quality and thus solving the problem of image quality degradation caused by changes in object distance during long focal length close-range imaging in a space radiation environment.
[0027] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.
[0029] Figure 1 A schematic diagram of a first structure of a long focal length close-range imaging optical system for space provided in an embodiment of this application;
[0030] Figure 2 This is a schematic diagram of a second structure of a long focal length close-range imaging optical system for space provided in an embodiment of this application;
[0031] Figure 3a The diagram shows the optical transfer function at the far end.
[0032] Figure 3b This is a graph of the mid-range optical transfer function;
[0033] Figure 3c The near-end optical transfer function is plotted.
[0034] Figure 3d The optical modulation transfer function of the optical system at -20°C in vacuum is shown.
[0035] Figure 3e The optical modulation transfer function of the optical system at 40°C above vacuum is shown in the figure.
[0036] Figure 3f Optical modulation transfer function of the optical system when the incident light wavelength is 450 nm;
[0037] Figure 3g The optical modulation transfer function of the optical system is plotted when the incident light wavelength is 532 nm.
[0038] Figure 3h The optical modulation transfer function of the optical system is plotted when the incident light wavelength is 808 nm.
[0039] Figure 3i The optical modulation transfer function of the optical system is plotted when the incident light wavelength is 850 nm.
[0040] Figure 4a for Figure 3a Equivalent diagram;
[0041] Figure 4b for Figure 3b Equivalent diagram;
[0042] Figure 4c for Figure 3c Equivalent diagram;
[0043] Figure 4d for Figure 3d Equivalent diagram;
[0044] Figure 4e for Figure 3e Equivalent diagram;
[0045] Figure 4f for Figure 3f Equivalent diagram;
[0046] Figure 4g for Figure 3g Equivalent diagram;
[0047] Figure 4h for Figure 3h Equivalent diagram;
[0048] Figure 4i for Figure 3i Equivalent diagram;
[0049] Figure 5a This is a distortion curve of the optical system at the far end;
[0050] Figure 5b This is a distortion curve of the optical system at the midpoint;
[0051] Figure 5c This is a distortion curve of the optical system at the near end;
[0052] Figure 6a , Figure 6b The diagram shown is an optical path diagram of an optical system provided in an embodiment of this application.
[0053] Figures 7a to 7f The diagram shows the optical path of the optical system provided in this application under different fields of view. Detailed Implementation
[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.
[0055] To address the image quality degradation caused by changes in object distance during long-focal-length close-up imaging in a space radiation environment, a first aspect of this application provides a space-based long-focal-length close-up imaging optical system. For example... Figure 1 The diagram shows a first structural schematic of a long focal length close-up imaging optical system for space provided in this application embodiment. The optical system includes a first lens 1, a second lens 2, a third lens 3, an aperture stop 4, a fourth lens 5, a fifth cemented lens group 6, a sixth lens 7, and a seventh lens 8 arranged coaxially along the light incident direction. When the optical system is used, the light rays pass through each lens and the aperture stop 4 before reaching the focal plane 9. The fifth cemented lens group 6 includes a fifth cemented negative lens 6-1 and a fifth cemented positive lens 6-2 arranged coaxially along the light incident direction. The aperture stop 4 is used to control the size of the incident light beam.
[0056] For ease of manufacturing, the first lens 1, the second lens 2, the third lens 3, the fourth lens 5, the fifth cemented lens group 6, the sixth lens 7, and the seventh lens 8 are all spherical lenses.
[0057] The first lens 1 is made of radiation-resistant silicon dioxide, i.e., quartz, with a refractive index of 1.544–1.553 and a dispersion coefficient of 0.013. The second lens 2, the fifth cemented negative mirror 6-1, and the seventh lens 8 are made of materials with high refractive index and low dispersion coefficient. The refractive index r2 of the second lens 2 and the refractive index r of the fifth cemented negative mirror 6-1 are... 5-1 The refractive index r7 of the seventh lens 8 is greater than or equal to 1.9, satisfying 1.8 ≤ r7 ≤ 1.9; the refractive index r3 of the third lens 3, the refractive index r4 of the fourth lens 5, the refractive index r4 of the fifth cemented positive mirror 6-2, and the refractive index r7 of the sixth lens 8 are all made of materials with low refractive index and high dispersion coefficient. Among them, the refractive indices of the third lens 3, the fourth lens 5, and the sixth lens 7 are less than or equal to 1.5, and the refractive index r4 of the fifth cemented positive mirror 6-2 is less than or equal to 1.5. 5-2 It satisfies: 1.6≥r3≥1.5.
[0058] Here, high refractive index means that the refractive index is greater than a preset refractive index threshold, low refractive index means that the refractive index is less than a preset refractive index threshold, high dispersion means that the dispersion coefficient is greater than a preset dispersion coefficient threshold, and low dispersion means that the dispersion coefficient is less than a preset dispersion coefficient threshold. The refractive index threshold and dispersion coefficient threshold are set based on actual experience. For example, the dispersion coefficient threshold can be set to 40. This application embodiment does not limit this.
[0059] Lenses typically have an entrance surface and an exit surface. The entrance surface is the surface where light enters the lens, while the exit surface is the surface where light leaves the lens after refraction within the lens. For example... Figure 2 The diagram shown is a second structural schematic of the spatial long focal length close-range imaging optical system provided in the embodiment of this application, with the light incident direction from left to right.
[0060] The radius of curvature ρ of the incident surface 11 of the first lens 1 入1 and the radius of curvature ρ of the exit surface 12 出1 Satisfy: 35 mm ≥ ρ 入1 ≥30 mm, 22 mm ≥ρ 出1 ≥19 mm; the radius of curvature ρ of the incident surface 21 of the second lens 2 入2 and the radius of curvature ρ of the exit surface 22 出2 Satisfy: 20 mm ≥ ρ 入2 ≥15 mm, 20 mm ≥ρ 出2 ≥15 mm; the radius of curvature ρ of the incident surface 31 of the third lens 3 入3 and the radius of curvature ρ of the exit surface 32 出3 Satisfy: 18 mm ≥ ρ 入3 ≥14 mm, 150 mm ≥ρ 出3 ≥145 mm; the radius of curvature ρ of the incident surface 41 of the fourth lens 5 入4 and the radius of curvature ρ of the exit surface 42 出4 Satisfy: 15 mm ≥ ρ 入4 ≥12 mm, 70 mm ≥ρ 出4 ≥65 mm; the radius of curvature ρ of the incident surface 611 of the fifth cemented negative mirror 6-1 入5 Satisfy: -640 mm ≥ ρ 入5 ≥-650 mm, the radius of curvature ρ of the exit surface 622 of the fifth cemented positive mirror 6-2. 出5 Satisfy: 110 mm ≥ ρ 出5 ≥105 mm, the radius of curvature ρ of the bonding surface 613 of the fifth cemented negative mirror 6-1 and the fifth cemented positive mirror 6-2 is... 胶 Satisfy: 9 mm ≥ ρ 胶 ≥8.5 mm; the radius of curvature ρ of the incident surface 71 of the sixth lens 7 入6 and the radius of curvature ρ of the exit surface 72 出6 Satisfy: -9 mm ≥ ρ 入6 ≥-10 mm, -35 mm ≥ρ 出6 ≥-40 mm; the radius of curvature ρ of the incident surface 81 of the seventh lens 8 入7 and the radius of curvature ρ of the exit surface 82 出7 Satisfy: 100 mm ≥ ρ 入7 ≥95 mm, -45 mm ≥ρ 出7≥-50 mm.
[0061] Understandably, the sign of the radius of curvature of a spherical lens reflects the direction of curvature and shape characteristics of the lens surface. A positive radius of curvature indicates that the surface is convex, meaning the center of the sphere is to the right of the vertex. A negative radius of curvature indicates that the surface is concave, meaning the center of the sphere is to the left of the vertex. For example... Figure 2 The radius of curvature ρ of the incident surface 71 of the sixth lens 7 入6 Satisfy: -9 mm ≥ ρ 入6 ≥-10 mm, meaning the radius of curvature of the incident surface 71 is negative, the incident surface is curved to the right, and the center of the sphere containing the incident surface is located to the left of the vertex of the sphere. Figure 2 The radius of curvature ρ of the incident surface 81 of the seventh lens 8 入7 Satisfy: 100 mm ≥ ρ 入7 ≥95 mm, meaning the radius of curvature of the incident surface 91 is positive, the incident surface is curved to the left, and the center of the sphere containing the incident surface is located to the right of the vertex of the sphere.
[0062] In an imaging system, the detector's role is to convert received light signals into electrical signals, which in turn form an image or data. To ensure that the detector can accurately receive the image focused by the optical system, the detector must be precisely aligned with the focal plane.
[0063] In order to enable the optical system provided in this application embodiment to achieve clear imaging at different object distances, in one possible implementation, the detector is aligned with the focal plane at different object distances to achieve clear imaging.
[0064] The detector can be an infrared focal plane detector, a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor, etc., and the embodiments of this application do not limit it.
[0065] In one possible implementation, the detector is 1 inch in size.
[0066] To reduce the overall weight and volume of the optical system and minimize the impact of object distance variations on image quality, in one possible implementation, the center thickness of each lens needs to meet the following requirements: the center thickness d1 of the first lens 1, the second lens 2, and the sixth lens 7 is 3.5 mm with a tolerance of ±0.1 mm, i.e., 3.6 mm ≥ d1 ≥ 3.4 mm; the center thickness d2 of the third lens 3 and the fourth lens 5 is 3.75 mm with a tolerance of ±0.1 mm, i.e., 3.85 mm ≥ d1 ≥ 3.4 mm. The thickness d3 of the fifth cemented negative lens 6-1 is 7.75 mm, with a tolerance of ±0.1 mm, which means 4.85 mm ≥ d3 ≥ 4.65 mm. The thickness d4 of the fifth cemented positive lens 6-2 is 6 mm, with a tolerance of ±0.1 mm, which means 6.1 mm ≥ d4 ≥ 5.9 mm. The thickness d5 of the seventh lens 8 is 5.36 mm, with a tolerance of ±0.1 mm, which means 5.46 mm ≥ d5 ≥ 5.26 mm.
[0067] To further improve the radiation resistance of the optical system, in one possible implementation, the second lens 2 is made of heavy flint glass with a refractive index greater than 1.9, such as heavy flint glass HZF88 (a glass grade); the third lens 3 is made of low-refractive-index, high-dispersion glass with a refractive index less than or equal to 1.5, such as silicon dioxide; the fourth lens 5 is made of low-refractive-index, high-dispersion fluorine crown glass with a refractive index less than or equal to 1.5, such as HFK61 (a glass grade); and the fifth cemented negative lens 6-1 is made of glass with a refractive index greater than or equal to 1. 9. High refractive index, low dispersion heavy lanthanum flint glass, such as HZLAF4LA (a glass grade); 6-2, the fifth cemented positive lens, uses low refractive index, high dispersion, and low softening point phosphorus crown glass with a refractive index between 1.5 and 1.6, such as DPK3 (a glass grade); 7, the sixth lens, uses low refractive index, high dispersion glass with a refractive index less than or equal to 1.5, such as silicon dioxide; 8, the seventh lens, uses high refractive index, low dispersion glass with a refractive index between 1.8 and 1.9, such as HZF52A (a glass grade).
[0068] It is understood that the optical system provided in this application embodiment has a cylindrical shape. In one possible implementation, the external dimensions of the spatial long focal length close-range imaging optical system are: in, 70 mm is the maximum diameter of the optical system, and 70 mm is the length of the optical system. The maximum diameter refers to the maximum outer diameter of each lens that makes up the optical system, and the length refers to the distance between the vertex of the incident surface of the first lens 1 and the focal plane 9.
[0069] In one specific embodiment, the parameters of each lens in the spatial long focal length close-range imaging optical system provided in this application are shown in Table 1.
[0070]
[0071] Based on Table 1, the materials of the first lens 1, the third lens 3, and the sixth lens 7 are silicon dioxide; the material of the second lens 2 is glass with grade HZF88; the material of the third lens 3 is silicon dioxide; the material of the fourth lens 5 is glass with grade HFK61; the material of the fifth cemented negative lens 6-1 is glass with grade HZLAF4LA; the material of the fifth cemented positive lens 6-2 is glass with grade DPK3; and the material of the seventh lens 8 is glass with grade HZF52A.
[0072] The radius of curvature of the incident surface 11 of the first lens 1 is 33.14 mm, and the radius of curvature of the exit surface 12 of the first lens 1 is 20.14 mm; the radius of curvature of the incident surface 21 of the second lens 2 is 17.46 mm, and the radius of curvature of the exit surface 22 of the second lens is 16.42 mm; the radius of curvature of the incident surface 31 of the third lens 3 is 15.6 mm, and the radius of curvature of the exit surface 32 of the third lens 3 is 148 mm; the radius of curvature of the incident surface 51 of the fourth lens 5 is 12.73 mm, and the radius of curvature of the exit surface 52 of the fourth lens 5 is 69.25 mm; the fifth cemented... The radius of curvature of the incident surface 611 of the negative lens 6-1 is -648.32 mm; the radius of curvature of the exit surface 622 of the fifth cemented positive lens 6-2 is 109.39 mm; and the radius of curvature of the cementing surface 613 of the fifth cemented negative lens 6-1 and the fifth cemented positive lens 6-2 is 8.56 mm. The radius of curvature of the incident surface 71 of the sixth lens 7 is -9.82 mm; the radius of curvature of the exit surface 72 of the sixth lens 7 is -36.42 mm; and the radius of curvature of the incident surface 81 of the seventh lens 8 is 96.74 mm; and the radius of curvature of the exit surface 82 of the seventh lens 8 is -48.43 mm.
[0073] The distances between the first lens 1 and the second lens 2, the second lens 2 and the third lens 3, and the aperture 4 and the fourth lens 5 are all 0.3 mm. The distance between the third lens 3 and the aperture 4 is 1.28 mm. The distance between the fourth lens 5 and the fifth cemented lens group 6 is 1.44 mm. The distance between the fifth cemented lens group 6 and the sixth lens 7 is 6.9 mm. The distance between the sixth lens 7 and the seventh lens 8 is 2 mm. The distance between the seventh lens 8 and the focal plane 9 is 23.34 mm.
[0074] Here, the spacing refers to the distance between the vertices of adjacent incident and exit surfaces of two adjacent lenses. For example, such as... Figure 2 In this context, L represents the distance between the vertex of the exit surface 622 of the fifth cemented lens group 6 and the vertex of the incident surface 71 of the sixth lens 7.
[0075] In the embodiments of this application, by limiting the center thickness of each lens, the length of the optical system can be reduced without affecting the image quality, thereby reducing the volume of the optical system.
[0076] Figure 3a , Figure 3b , Figure 3c , Figure 3d , Figure 3e , Figure 3f , Figure 3g , Figure 3h , Figure 3i The figure shown is a transfer function diagram under different conditions provided in the embodiments of this application. Figure 4a , Figure 4b , Figure 4c , Figure 4d , Figure 4e , Figure 4f , Figure 4g , Figure 4h , Figure 4i They are respectively Figure 3a , Figure 3b , Figure 3c , Figure 3d , Figure 3e , Figure 3f , Figure 3g , Figure 3h , Figure 3i Equivalent diagram, in which, Figure 3a and Figure 4a The graph shows the optical transfer function at the far end. Figure 3b and Figure 4b This is a graph of the mid-range optical transfer function. Figure 3c and Figure 4c This is a graph of the near-end optical transfer function. Figure 3d and Figure 4d The graph shows the optical modulation transfer function of the optical system at -20°C in a vacuum. Figure 3e and Figure 4e The graph shows the optical modulation transfer function of the optical system at 40°C in vacuum. Figure 3f and Figure 4f Optical modulation transfer function diagram of the optical system when the incident light wavelength is 450 nm. Figure 3g and Figure 4g The graph shows the optical modulation transfer function of the optical system when the incident light wavelength is 532 nm. Figure 3h and Figure 4h The graph shows the optical modulation transfer function of the optical system when the incident light wavelength is 808 nm. Figure 3i and Figure 4i The graph shows the optical modulation transfer function of the optical system when the incident light wavelength is 850 nm. Figures 3a to 3i and Figures 4a to 4iIn the diagram, the horizontal axis represents the spatial modulation frequency, and the vertical axis represents the optical modulation function. Each curve represents the transfer function at different image heights (i.e., different field of view angles). Specifically, the curves in the diagram represent the horizontal and vertical transfer functions at image heights of 0 mm, 1.4 mm, 2.8 mm, 5.632 mm, 6.400 mm, and 8.000 mm, respectively. Figures 3a to 3i In the diagram, the curve corresponding to "F1: Diff.Limit" is the optical transfer function curve at the diffraction limit; the curve corresponding to "F1: (RIH) 0.000mm" is the optical transfer function curve when the image height is 0.000 mm; the curve corresponding to "F2: T(RIH) 1.400mm" is the optical transfer function curve in the tangential direction when the image height is 1.400 mm; the curve corresponding to "F2: R(RIH) 1.400mm" is the optical transfer function curve in the radial direction when the image height is 1.400 mm; the curve corresponding to "F3: T(RIH) 2.800mm" is the optical transfer function curve in the tangential direction when the image height is 2.800 mm; the curve corresponding to "F3: R(RIH) 2.800mm" is the optical transfer function curve in the radial direction when the image height is 2.800 mm; and the curve corresponding to "F4: T(RIH) 0.000mm" is the optical transfer function curve in the radial direction when the image height is 2.800 mm. The curve corresponding to "F4: R(RIH) 5.632mm" is the optical transfer function curve in the tangential direction when the image height is 5.632 mm. The curve corresponding to "F5: R(RIH) 5.632mm" is the optical transfer function curve in the radial direction when the image height is 5.632 mm. The curve corresponding to "F5: T(RIH) 6.400mm" is the optical transfer function curve in the tangential direction when the image height is 6.400 mm. The curve corresponding to "F5: R(RIH) 6.400mm" is the optical transfer function curve in the radial direction when the image height is 6.400 mm. The curve corresponding to "F6: T(RIH) 8.000mm" is the optical transfer function curve in the tangential direction when the image height is 8.000 mm. The curve corresponding to "F6: R(RIH) 8.000mm" is the optical transfer function curve in the radial direction when the image height is 8.000 mm.
[0077] Understandable Figures 3a to 3i With the corresponding Figures 4a to 4i They are completely equivalent, that is... Figure 4a and Figure 3a They are completely equivalent. Figure 4b and Figure 3b They are completely equivalent, and so on.
[0078] Depend on Figures 3a to 3i and Figures 4a to 4iIt can be seen that, under different conditions, the optical system provided in this application embodiment has most optical modulation function values greater than 0.2 at different field of view angles, i.e., different spatial modulation frequencies of 90 cycles / mm. Therefore, it can be considered that the optical system provided in this application embodiment has high imaging quality under different conditions, and can meet the requirements of imaging in the visible light band of 450nm~650nm and single-band illumination imaging in the visible to near-infrared bands under vacuum low temperature conditions of -20℃, vacuum high temperature conditions of 40℃, and vacuum high temperature conditions. Moreover, according to Figures 3g to 3i and Figures 4g to 4i It can be seen that the transfer function of single-band imaging is close to the diffraction limit, resulting in better imaging performance.
[0079] This application eliminates the influence of temperature by using a combination of lenses made of materials with different thermal properties, achieving a heatless design and meeting a wide operating temperature range from -20°C to 40°C. Within this temperature range, clear imaging can be guaranteed without focusing.
[0080] Figure 5a , Figure 5b and Figure 5c The distortion curve of the optical system provided in the embodiments of this application is shown in the figure. Figure 5a This is a distortion curve of the optical system at the far end. Figure 5b This is a distortion curve of the optical system in the middle range. Figure 5c This is a distortion curve of the optical system at the near end. Figures 5a-5c The horizontal axis represents the percentage of optical distortion, and the vertical axis represents the image height of the optical system. Figures 5a-5c As can be seen, the optical system provided in this application embodiment has an absolute distortion value of less than 0.1% at the mid-range, far-range, and near-range, making it suitable for high-precision measurement.
[0081] Figure 6a The diagram shown is an optical path diagram of the optical system provided in an embodiment of this application. For ease of observation, [the diagram is omitted]. Figure 6a The simplified optical path diagram shown is obtained as follows Figure 6b The diagram shown is illustrated below, and the ray path diagrams for different fields of view are as follows: Figure 7a , Figure 7b , Figure 7c , Figure 7d , Figure 7e as well as Figure 7f As shown, by Figure 6a , Figure 6b and Figures 7a to 7f It is understood that light rays from different fields of view can be imaged on the focal plane 9 through the optical system provided in the embodiments of this application.
[0082] The space-use long-focal-length close-range imaging optical system provided in this application embodiment features a first lens made of radiation-resistant quartz with a thickness greater than 3 mm, while the other lenses are made of radiation-resistant glass. This enhances the system's radiation resistance, making it suitable for space environments. The system has a focal length of 75 mm and an F-number of 4, enabling clear imaging within an object distance of 1.5 to 10 meters. Through the rational setting of the refractive index, radius of curvature, and materials of each lens, and a heat-free design, the system can achieve clear imaging without focusing within a vacuum temperature range of 40°C to -20°C. Furthermore, the system, through the combination of radiation-resistant, high-refractive-index, and low-refractive-index lenses, is suitable for imaging in the visible light band and also exhibits good performance for imaging with commonly used single-wavelength illumination at 450 nm, 532 nm, 808 nm, and 850 nm. The use of spherical lenses in all lenses reduces cost, facilitating small-batch production. Furthermore, the optical system exhibits distortion of less than or equal to 0.1% across the entire field of view, which improves image quality and thus solves the problem of image quality degradation caused by changes in object distance when performing close-up imaging at long focal lengths in a space radiation environment.
[0083] A second aspect of the embodiments of this application provides an imaging device, which includes the spatial long focal length close-up imaging optical system of the first aspect described above.
[0084] In one possible implementation, the imaging device further includes a photosensitive chip, which is disposed in such a position as... Figure 1 The position of the central focal plane 9.
[0085] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0086] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the imaging device embodiments are basically similar to the optical system embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.
[0087] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.
Claims
1. A long focal length close-up imaging optical system for space applications, characterized in that, The optical system is provided with a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth cemented lens group, a sixth lens, and a seventh lens arranged coaxially along the incident direction of light. The light reaches the focal plane after passing through each lens and the aperture stop. The first lens is made of quartz, and the radius of curvature ρ of the incident surface of the first lens is... 入1 and the radius of curvature ρ of the exit surface 出1 Satisfy: 35 mm ≥ ρ 入1 ≥30 mm, 22 mm ≥ρ 出1 ≥19 mm; The refractive index r2 of the second lens is ≥ 1.9, and the radius of curvature ρ of the incident surface of the second lens is... 入2 and the radius of curvature ρ of the exit surface 出2 Satisfy: 20 mm ≥ ρ 入2 ≥15 mm, 20 mm ≥ρ 出2 ≥15 mm; The refractive index r3 of the third lens is ≤1.5, and the radius of curvature ρ of the incident surface of the third lens is... 入3 and the radius of curvature ρ of the exit surface 出3 Satisfy: 18 mm ≥ ρ 入3 ≥14 mm, 150 mm ≥ρ 出3 ≥145 mm; The refractive index r4 of the fourth lens is ≤1.5, and the radius of curvature ρ of the incident surface of the fourth lens is... 入4 and the radius of curvature ρ of the exit surface 出4 Satisfy: 15 mm ≥ ρ 入4 ≥12 mm, 70 mm ≥ρ 出4 ≥65 mm; The fifth cemented mirror group includes a fifth cemented negative mirror and a fifth cemented positive mirror arranged coaxially along the incident light direction. The refractive index r of the fifth cemented negative mirror is... 5-1 ≥1.9, the refractive index r of the fifth cemented positive mirror 5-2 Satisfy: 1.6≥r 5-2 ≥1.5; the radius of curvature ρ of the incident surface of the fifth cemented negative mirror 入5 Satisfy: -640 mm ≥ ρ 入5 ≥-650 mm, the radius of curvature ρ of the exit surface of the fifth cemented positive mirror 出5 Satisfy: 110 mm ≥ ρ 出5 ≥105 mm, the radius of curvature ρ of the bonding surface of the fifth cemented negative mirror and the fifth cemented positive mirror 胶 Satisfy: 9 mm ≥ ρ 胶 ≥8.5 mm; The refractive index r6 of the sixth lens is ≤1.5, and the radius of curvature ρ of the incident surface of the sixth lens is... 入6 and the radius of curvature ρ of the exit surface 出6 Satisfy: -9 mm ≥ ρ 入6 ≥-10 mm, -35 mm ≥ρ 出6 ≥-40 mm; The refractive index r7 of the seventh lens satisfies: 1.8 ≤ r7 ≤ 1.9, and the radius of curvature ρ of the incident surface of the seventh lens... 入7 and the radius of curvature ρ of the exit surface 出7 Satisfy: 100 mm ≥ ρ 入7 ≥95 mm, -45 mm ≥ρ 出7 ≥-50 mm.
2. The space-use long focal length close-up imaging optical system according to claim 1, characterized in that, The center thickness d1 of the first lens, the second lens, and the sixth lens satisfies: 3.6 mm ≥ d1 ≥ 3.4 mm; the center thickness d2 of the third lens and the fourth lens satisfies: 3.85 mm ≥ d2 ≥ 3.65 mm; the center thickness d3 of the fifth cemented negative lens satisfies: 4.85 mm ≥ d3 ≥ 4.65 mm; the thickness d4 of the fifth cemented positive lens satisfies: 6.1 mm ≥ d4 ≥ 5.9 mm; and the center thickness d5 of the seventh lens satisfies: 5.46 mm ≥ d5 ≥ 5.26 mm.
3. The space-use long focal length close-up imaging optical system according to claim 1, characterized in that, The material of the second lens is heavy flint glass.
4. The space-use long focal length close-up imaging optical system according to claim 1, characterized in that, The fourth lens is made of fluorine crown glass.
5. The space-use long focal length close-up imaging optical system according to claim 1, characterized in that, The fifth cemented negative mirror is made of heavy lanthanum flint glass.
6. The space-use long focal length close-up imaging optical system according to claim 1, characterized in that, The fifth cemented positive mirror is made of phosphor crown glass.
7. The long focal length close-up imaging optical system for space use according to claim 1, characterized in that, The distances between the first lens and the second lens, the second lens and the third lens, and the aperture stop and the fourth lens are all 0.3 mm. The distance between the third lens and the aperture stop is 1.28 mm. The distance between the fourth lens and the fifth cemented lens group is 1.44 mm. The distance between the fifth cemented lens group and the sixth lens is 6.9 mm. The distance between the sixth lens and the seventh lens is 2 mm. The distance between the seventh lens and the focal plane is 23.34 mm.
8. The space-use long focal length close-up imaging optical system according to claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth cemented lens group, the sixth lens, and the seventh lens are all spherical lenses; The first lens has an incident surface radius of curvature of 33.14 mm and an exit surface radius of curvature of 20.14 mm; the second lens has an incident surface radius of curvature of 17.46 mm and an exit surface radius of curvature of 16.42 mm; the third lens has an incident surface radius of curvature of 15.6 mm and an exit surface radius of curvature of 148 mm; the fourth lens has an incident surface radius of curvature of 12.73 mm and an exit surface radius of curvature of 69.25 mm. The fifth cemented negative mirror has an incident surface radius of curvature of -648.32 mm, the cemented surface radius of curvature of the fifth cemented negative mirror and the fifth cemented positive mirror is 8.56 mm, and the exit surface radius of curvature of the fifth cemented positive mirror is 109.39 mm; the sixth lens has an incident surface radius of curvature of -9.82 mm and an exit surface radius of curvature of -36.42 mm; the seventh lens has an incident surface radius of curvature of 96.74 mm and an exit surface radius of curvature of -48.43 mm.
9. The long focal length close-up imaging optical system for space use according to claim 1, characterized in that, The external dimensions of the space-use long focal length close-range imaging optical system are: 70 mm × 70 mm.
10. An imaging device, characterized in that, The imaging device includes the long focal length close-up imaging optical system for space as described in any one of claims 1-9.