A high-resolution wide-band optical imaging system

Abstract

The present invention relates to a high-resolution wide-band optical imaging system, wherein the optical system is provided with a fixed first lens group, a second lens group moving forward and backward along the optical axis, an aperture and a fixed third lens group in sequence along the optical axis from the object side to the image side; the first lens group includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens, the second lens group includes a sixth lens, and the third lens group includes a seventh lens, an eighth lens, a ninth lens and a tenth lens; the aperture is fixed between the sixth lens and the seventh lens; except that the front surface of the first lens is a plane, the other surfaces are spherical. The optical imaging system of the present invention has a wide working band range, high resolution, can clearly image tiny targets within a wide temperature range and has low distortion, better corrects chromatic aberration and other monochromatic aberrations, has a long back intercept, and is conducive to the placement of other optical components such as a spectroscopic element or a mechanical component.

Description

Technical Field

[0001] The invention belongs to the technical field of imaging optical system design, and in particular relates to a high-resolution wide-band optical imaging system. Background Art

[0002] As a new type of remote sensing platform, drones have become increasingly popular in recent years, and the demand for optical imaging systems mounted on drone platforms in the fields of agriculture, forestry, environmental monitoring, emergency disaster warning monitoring, national security, scientific research, etc. is also increasing. The spectral response range of ordinary cameras is the visible light range of 400 to 700nm. In order to make drone optical imaging systems play a role in more fields, the working band of the optical system usually covers the spectral range of 400 to 1000nm. In addition to the wide working band range, the optical imaging system must also continue to meet the requirements of small size, light weight, high resolution, low distortion, and wide applicable ambient temperature range. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-resolution wide-band optical imaging system, the working band of which covers a spectral region of 400 to 1000 nm and the imaging resolution can reach 2600×2160.

[0004] In order to solve the above technical problems, the high-resolution wide-band optical imaging system of the present invention is composed of a fixed first lens group arranged in sequence from the object side to the image side along the optical axis, a second lens group moving forward and backward along the optical axis, an aperture and a fixed third lens group; the first lens group is composed of a first lens G1, a second lens G2, a third lens G3, a fourth lens G4 and a fifth lens G5 arranged in sequence from the object side to the image side along the optical axis, and the five lenses of the lens group are a plano-concave lens, a biconvex lens, a negative optical power meniscus lens with the convex surface facing the object side, A double concave lens and a double convex lens; the second lens group is provided with a sixth lens G6, which is a positive light focal length meniscus lens with a convex surface facing the object; the third lens group is composed of a seventh lens G7, an eighth lens G8, a ninth lens G9 and a tenth lens G10 which are arranged in sequence from the object side to the image side along the optical axis, and the four lenses of this lens group are a negative light focal length meniscus lens with a convex surface facing the object side, a double convex lens, a negative light focal length meniscus lens with a concave surface facing the object side, and a double convex lens in sequence; except that the front surface of the first lens G1 is a plane, the other surfaces are spherical surfaces.

[0005] Further, the front surface curvature radius of the first lens G1 is ∞, and the rear surface curvature radius is 15.87-19.29 mm; the front and rear surface curvature radii of the second lens G2 are 20.92-71.59 mm and -47.58--26.73 mm respectively; the front and rear surface curvature radii of the third lens G3 are 36.72-51.82 mm and 10.85-11.91 mm respectively; the front and rear surface curvature radii of the fourth lens G4 are -15.56--12.05 mm and 22.65-30.16 mm respectively; the front and rear surface curvature radii of the fifth lens G5 are 28.93-35.85 mm and -26.89--24.46 mm respectively; The front and rear surface curvature radii of lens G6 are 19.42-21.67 mm and 23.02-25.21 mm respectively; the front and rear surface curvature radii of the seventh lens G7 are 26.23-33.44 mm and 13.55-16.64 mm respectively; the front and rear surface curvature radii of the eighth lens G8 are 16.82-22.32 mm and -13.96--11.81 mm respectively; the front and rear surface curvature radii of the ninth lens G9 are -11.63--10.44 mm and -25.41--24.03 mm respectively; the front and rear surface curvature radii of the tenth lens G10 are 54.51-66.22 mm and -14.16--13.98 mm respectively.

[0006] Furthermore, the center thickness of the first lens G1 is 1.70-1.72 mm; the center thickness of the second lens G2 is 3.78-3.82 mm; the center thickness of the third lens G3 is 1.60-1.70 mm; the center thickness of the fourth lens G4 is 1.68-1.75 mm; the center thickness of the fifth lens G5 is 3.48-3.52 mm; the center thickness of the sixth lens G6 is 1.65-1.72 mm; the center thickness of the seventh lens G7 is 1.68-1.72 mm; the center thickness of the eighth lens G8 is 5.45-5.52 mm; the center thickness of the ninth lens G9 is 1.08-1.13 mm; and the center thickness of the tenth lens G10 is 4.35-4.42 mm.

[0007] Furthermore, the central air interval between the first lens G1 and the second lens G2 is 3.00-3.05 mm; the central air interval between the second lens G2 and the third lens G3 is 0.50-0.52 mm; the central air interval between the third lens G3 and the fourth lens G4 is 4.05-4.12 mm; the central air interval between the fourth lens G4 and the fifth lens G5 is 0.75-0.80 mm; when the sixth lens G6 is at the initial position, the central air interval between the fifth lens G5 and the sixth lens G6 is 13.75-13.80 mm, and the sixth lens G6 is 13.75-13.80 mm. The central air distance between the lens G6 and the aperture is 19.58-19.63 mm; the central air distance between the aperture and the seventh lens G7 is 0.80-0.82 mm; the central air distance between the seventh lens G7 and the eighth lens G8 is 0.44-0.48 mm; the central air distance between the eighth lens G8 and the ninth lens G9 is 0.68-0.72 mm; the central air distance between the ninth lens G9 and the tenth lens G10 is 0.10-0.14 mm, and the central air distance from the tenth lens G10 to the image plane is 36.54-38.22 mm.

[0008] Furthermore, the refractive index of the material of the first lens G1 and the second lens G2 is 1.6-1.9, and the dispersion coefficient is 28-55; the refractive index of the material of the third lens G3 and the fourth lens G4 is 1.5-1.7, and the dispersion coefficient is 60-75; the refractive index of the material of the seventh lens G7 and the ninth lens G9 is 1.7-1.9, and the dispersion coefficient is 40-55; the refractive index of the material of the eighth lens G8 and the tenth lens G10 is 1.4-1.5, and the dispersion coefficient is 90-95; the refractive index of the material of the fifth lens G5 and the sixth lens G6 is 1.5-1.7, and the dispersion coefficient is 35-65.

[0009] Furthermore, the rear working distance of the optical imaging system is greater than 36 mm to 38 mm, and the total optical length (the distance from the central vertex of the front surface of the first lens G1 to the image plane) is less than 106 mm to 110 mm.

[0010] When imaging in a working environment of -40℃ to 60℃, the first lens group, the aperture, the third lens group, and the image plane remain fixed, and the second lens group moves back and forth along the optical axis to compensate for thermal defocus caused by temperature. During the movement, the distance from the sixth lens G6 to the aperture ranges from 17.32 to 23.22 mm.

[0011] The beneficial effects of the present invention are as follows: the optical system has a wide operating band range and can simultaneously image the visible light spectrum region and the near-infrared spectrum region of the target, thereby improving the optical system's ability to observe the target and expanding its application field; the optical system has a high resolution and can clearly image tiny targets within a wide temperature range with low distortion; the optical system has better corrected chromatic aberration and other monochromatic aberrations; the back intercept is long, which is conducive to the placement of other optical components such as spectroscopic elements or mechanical components; the optical system uses all spherical glass lenses without using cemented lenses, thereby reducing the difficulty of lens processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic structural diagram of a high-resolution wide-band optical imaging system of the present invention;

[0013] Figure 2 is a modulation transfer function curve diagram of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention at 20°C;

[0014] Figure 3 is a point diagram of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention at 20°C;

[0015] Figure 4 is a distortion curve diagram of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention at 20°C;

[0016] Figure 5 is a modulation transfer function curve diagram of -40°C of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention;

[0017] Figure 6 is a point diagram of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention at -40°C;

[0018] Figure 7 is a distortion curve diagram of -40°C of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention;

[0019] Figure 8 is a modulation transfer function curve diagram of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention at 60°C;

[0020] Fig. 9 is a point diagram of embodiment 1 of the high-resolution wide-band optical imaging system of the present invention at 60°C;

[0021] Fig.10 is a distortion curve diagram of the high-resolution wide-band optical imaging system embodiment 1 of the present invention at 60°C;

[0022] Figure 1 In the middle, 0 is the aperture and 1 is the image plane. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, the high-resolution wide-band optical imaging system of the present invention is provided with a fixed first lens group, a second lens group moving forward and backward along the optical axis, an aperture and a fixed third lens group in sequence along the optical axis from the object side to the image side; the first lens group is composed of a first lens G1, a second lens G2, a third lens G3, a fourth lens G4 and a fifth lens G5, the second lens group adopts a sixth lens G6, and the third lens group is composed of a seventh lens G7, an eighth lens G8, a ninth lens G9 and a tenth lens G10; the aperture is fixed and is located between the sixth lens G6 and the seventh lens G7; except that the front surface of the first lens G1 is a plane, the other surfaces are all spherical.

[0025] The first lens G1 is a plano-concave lens with its plane facing the object; the second lens G2 is a biconvex lens; the third lens G3 is a negative power meniscus lens with its convex surface facing the object; the fourth lens G4 is a biconcave lens; the fifth lens G5 is a biconvex lens; the sixth lens G6 is a positive power meniscus lens with its convex surface facing the object; the seventh lens G7 is a negative power meniscus lens with its convex surface facing the object; the eighth lens G8 is a biconvex lens; the ninth lens G9 is a negative power meniscus lens with its concave surface facing the object; the tenth lens G10 is a biconvex lens; the well-known plano-concave lens and biconcave lens are both negative power lenses, and the biconvex lens is a positive power lens.

[0026] When the high-resolution wide-band optical imaging system of the present invention forms images under a working environment of -40°C to 60°C, the first lens group, the aperture, the third lens group, and the image plane remain fixed, and the second lens group moves back and forth along the optical axis to compensate for thermal defocus caused by temperature. During the movement, the distance between the sixth lens G6 and the aperture is in the range of 17.32 to 23.22 mm.

[0027] Embodiment 1:

[0028] Specific parameters of each lens in this embodiment are shown in Table 1 (wherein the central air interval between the fifth lens G5 and the sixth lens G6, and the central air interval between the sixth lens G6 and the aperture are all data when the sixth lens G6 is at the initial position).

[0029] Table 1

[0030]

[0031]

[0032] In this embodiment, the working band of the high-resolution wide-band optical imaging system is 400-1000nm, the effective focal length is 12.5mm, the F number is 2.8, the maximum diagonal half field angle is 18.6°, the adapted detector array is 2600×2160, the pixel size is 2.5μm×2.5μm, the working temperature is -40°C to 60°C, the rear working distance is 37.98mm, and the total optical length (the distance from the central vertex of the front surface of the first lens G1 to the image plane) is 108.57mm.

[0033] like Figure 2 The figure shows the modulation transfer function curve of the optical imaging system of this embodiment at 20°C. The modulation transfer function value of the central field of view at the cutoff frequency of 200lp / mm is better than 0.48; the modulation transfer function value of the maximum field of view at the cutoff frequency of 200lp / mm is better than 0.36, which fully meets the resolution requirements of the optical system.

[0034] like Figure 3 The point diagram of the optical imaging system of this embodiment at 20°C is shown. The Airy disk radius is 2.43 μm, and the RMS radius of each field of view is close to the Airy disk radius and the size of a single pixel. The light focusing ability is good and the chromatic aberration correction is good.

[0035] like Figure 4 The figure shows the distortion curve of the optical imaging system of this embodiment at 20°C. The maximum distortion of the full field of view at each wavelength is less than |-2.1%|, and the fidelity is good, which can meet the distortion requirements of the optical system.

[0036] like Figure 5 The figure shows the modulation transfer function curve of the optical imaging system of this embodiment at -40°C. The modulation transfer function value of the central field of view at the cutoff frequency of 200lp / mm is better than 0.43; the modulation transfer function value of the maximum field of view at the cutoff frequency of 200lp / mm is better than 0.33, which fully meets the resolution requirements of the optical system.

[0037] like Figure 6 The figure shows the spot diagram of the optical imaging system of this embodiment at -40°C. The RMS radius of each field of view is close to the radius of the Airy disk and the size of a single pixel, and the light focusing ability is good and the chromatic aberration correction is good.

[0038] like Figure 7 The figure shows the distortion curve of the optical imaging system of this embodiment at -40°C. The maximum distortion of the full field of view at each wavelength is less than |-2.1%|, and the fidelity is good, which can meet the distortion requirements of the optical system.

[0039] like Figure 8The figure shows the modulation transfer function curve of the optical imaging system of this embodiment at 60°C. The modulation transfer function value of the central field of view at the cutoff frequency of 200lp / mm is better than 0.43; the modulation transfer function value of the maximum field of view at the cutoff frequency of 200lp / mm is better than 0.33, which meets the resolution requirement of the optical system.

[0040] like Fig. 9 The figure shows the spot diagram of the optical imaging system of this embodiment at 60°C. The RMS radius of each field of view is close to the radius of the Airy disk and the size of a single pixel, and the light focusing ability is good and the chromatic aberration correction is good.

[0041] like Fig.10 The figure shows the distortion curve of the optical imaging system of this embodiment at 60°C. The maximum distortion of the full field of view at each wavelength is less than |-2.1%|, and the fidelity is good, which can meet the distortion requirements of the optical system.

[0042] Example 2

[0043] Specific parameters of each lens in this embodiment are shown in Table 2 (wherein the central air interval between the fifth lens G5 and the sixth lens G6, and the central air interval between the sixth lens G6 and the aperture are all data when the sixth lens G6 is at the initial position).

[0044] Table 2

[0045]

[0046] In this embodiment, the working band of the high-resolution wide-band optical imaging system is 400-1000nm, the effective focal length is 12.5mm, the F number is 2.8, the diagonal maximum half field angle is 18.6°, the adapted detector array is 2600×2160, the pixel size is 2.5μm×2.5μm, the working temperature is -40°C to 60°C, the rear working distance is 36.54mm, and the total optical length (the distance from the central vertex of the front surface of the first lens G1 to the image plane) is 106.64mm.

[0047] The high-resolution wide-band optical imaging system provided in this embodiment has a full field of view value at a cutoff frequency of 200lp / mm at 20°C that is better than 0.25, an RMS radius of each field of view that is close to the Airy disk radius, and a full field of view maximum distortion of each wavelength that is less than |-2.3%|.

[0048] Example 3

[0049] Specific parameters of each lens in this embodiment are shown in Table 3 (wherein the central air interval between the fifth lens G5 and the sixth lens G6, and the central air interval between the sixth lens G6 and the aperture are all data when the sixth lens G6 is at the initial position).

[0050] Table 3

[0051]

[0052] In this embodiment, the working band of the high-resolution wide-band optical imaging system is 400-1000nm, the effective focal length is 12.5mm, the F number is 2.8, the maximum diagonal half field angle is 18.6°, the adapted detector array is 2600×2160, the pixel size is 2.5μm×2.5μm, the working temperature is -40°C to 60°C, the rear working distance is 38.22mm, and the total optical length (the distance from the central vertex of the front surface of the first lens G1 to the image plane) is 109.32mm.

[0053] The high-resolution wide-band optical imaging system provided in this embodiment has a modulation transfer function value of better than 0.22 at a cutoff frequency of 200lp / mm for the full field of view at 20°C, an RMS radius of each field of view close to the Airy disk radius, and a maximum distortion of the full field of view at each wavelength less than |-2.5%|.

Claims

1. A high-resolution, wide-band optical imaging system, Features A fixed first lens group, a second lens group moving forward and backward along the optical axis, an aperture and a fixed third lens group are sequentially arranged along the optical axis from the object side to the image side; the first lens group includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4 and a fifth lens G5, the second lens group includes a sixth lens G6, and the third lens group includes a seventh lens G7, an eighth lens G8, a ninth lens G9 and a tenth lens G10; the aperture is fixed and is located between the sixth lens G6 and the seventh lens G7; except that the front surface of the first lens G1 is a plane, the other surfaces are spherical; The first lens G1 is a negative power meniscus lens, the second lens G2 is a positive power biconvex lens, the third lens G3 is a negative power meniscus lens with the convex surface facing the object, the fourth lens G4 is a negative power biconcave lens, the fifth lens G5 is a positive power biconvex lens, the sixth lens G6 is a positive power meniscus lens with the convex surface facing the object, the seventh lens G7 is a negative power meniscus lens with the convex surface facing the object, the eighth lens G8 is a positive power biconvex lens, the ninth lens G9 is a negative power meniscus lens with the concave surface facing the object, and the tenth lens G10 is a positive power biconvex lens.

2. The high-resolution broadband optical imaging system according to claim 1, Features The first lens G1 has a front surface curvature radius of ∞ and a rear surface curvature radius of 15.87-19.29 mm; the front and rear surface curvature radii of the second lens G2 are 20.92-71.59 mm and -47.58--26.73 mm respectively; the front and rear surface curvature radii of the third lens G3 are 36.72-51.82 mm and 10.85-11.91 mm respectively; the front and rear surface curvature radii of the fourth lens G4 are -15.56--12.05 mm and 22.65-30.16 mm respectively; the front and rear surface curvature radii of the fifth lens G5 are 28.93-35.85 mm and -26.89--24.46 mm respectively; the sixth lens The front and rear surface curvature radii of G6 are 19.42-21.67mm and 23.02-25.21mm respectively; the front and rear surface curvature radii of the seventh lens G7 are 26.23-33.44mm and 13.55-16.64mm respectively; the front and rear surface curvature radii of the eighth lens G8 are 16.82-22.32mm and -13.96--11.81mm respectively; the front and rear surface curvature radii of the ninth lens G9 are -11.63--10.44mm and -25.41--24.03mm respectively; the front and rear surface curvature radii of the tenth lens G10 are 54.51-66.22mm and -14.16--13.98mm respectively.

3. The high-resolution broadband optical imaging system according to claim 2, Features The center thickness of the first lens G1 is 1.70-1.72 mm; the center thickness of the second lens G2 is 3.78-3.82 mm; the center thickness of the third lens G3 is 1.60-1.70 mm; the center thickness of the fourth lens G4 is 1.68-1.75 mm; the center thickness of the fifth lens G5 is 3.48-3.52 mm; the center thickness of the sixth lens G6 is 1.65-1.72 mm; the center thickness of the seventh lens G7 is 1.68-1.72 mm; the center thickness of the eighth lens G8 is 5.45-5.52 mm; the center thickness of the ninth lens G9 is 1.08-1.13 mm; and the center thickness of the tenth lens G10 is 4.35-4.42 mm.

4. The high-resolution broadband optical imaging system according to claim 1, Features The central air interval between the first lens G1 and the second lens G2 is 3.00-3.05 mm; the central air interval between the second lens G2 and the third lens G3 is 0.50-0.52 mm; the central air interval between the third lens G3 and the fourth lens G4 is 4.05-4.12 mm; the central air interval between the fourth lens G4 and the fifth lens G5 is 0.75-0.80 mm; the central air interval between the fifth lens G5 and the sixth lens G6 is 13.75-13.80 mm; the central air interval between the sixth lens G6 and the aperture is 13.75-13.80 mm; the central air interval between the sixth lens G6 and the aperture is 13.75-13.80 mm; the central air interval between the sixth lens G6 and the aperture is 13.75-13.80 mm; the central air interval between the third lens G3 and the fourth lens G4 is 13.75-13.80 mm; the central air interval between the fifth lens G5 and the sixth lens G6 is 13.75-13.80 mm; the central air interval between the sixth lens G6 and the aperture is 13.75-13.80 mm; the central air interval between the fifth lens G5 and the sixth lens G6 ... The central air interval of the lens is 19.58-19.63mm; the central air interval of the aperture and the seventh lens G7 is 0.80-0.82mm; the central air interval of the seventh lens G7 and the eighth lens G8 is 0.44-0.48mm; the central air interval of the eighth lens G8 and the ninth lens G9 is 0.68-0.72mm; the central air interval of the ninth lens G9 and the tenth lens G10 is 0.10-0.14mm, and the central air interval from the tenth lens G10 to the image plane is 36.54-38.22mm.

5. The high-resolution broadband optical imaging system according to claim 1, Features The first lens G1 and the second lens G2 are made of materials with high refractive index and low dispersion coefficient; the third lens G3 and the fourth lens G4 are made of materials with low refractive index and high dispersion coefficient; the seventh lens G7 and the ninth lens G9 are made of materials with high refractive index and low dispersion coefficient; the eighth lens G8 and the tenth lens G10 are made of materials with low refractive index and high dispersion coefficient.

6. The high-resolution broadband optical imaging system according to claim 1, Features When the optical imaging system forms images under a working environment of -40°C to 60°C, the first lens group, the aperture, the third lens group, and the image plane remain fixed, and the second lens group moves back and forth along the optical axis to compensate for thermal defocus caused by temperature. During the movement, the distance between the sixth lens G6 and the aperture is in the range of 17.32 to 23.22 mm.

7. The high-resolution broadband optical imaging system according to claim 1, Features The rear working distance of the optical imaging system is greater than 35 mm, and the total optical length is less than 110 mm.

Images