A semi-athermal zoom lens
By designing a semi-thermal zoom lens and employing specific optical combinations and materials, the problems of large size and poor temperature adaptability of zoom lenses have been solved, achieving high performance, miniaturization, and clear imaging at both high and low temperatures.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN INST OF OPTICS & PRECISION MECHANICS CHINESE ACAD OF SCI
- Filing Date
- 2024-04-25
- Publication Date
- 2026-05-15
AI Technical Summary
Existing zoom lenses are too long and bulky, making them unsuitable for scenarios with limited space. They also have poor temperature adaptability and low overall performance.
Design a semi-thermal zoom lens that employs a front fixed group with positive optical power, a zoom group with negative optical power, and a compensation group with positive optical power. By rationally setting the optical power relationship and selecting specific optical glass materials, the lens can be used normally under high and low temperature conditions. Furthermore, the lens size can be shortened by rationally setting the aperture stop position.
It enables normal use of the lens under high and low temperature conditions, has high overall performance, a compact lens size to meet the miniaturization requirements, and good image quality. In particular, it can maintain clear imaging across the entire zoom range with slight focusing in telephoto mode.
Smart Images
Figure CN118311751B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an optical lens, specifically to a semi-thermal zoom lens. Background Technology
[0002] To achieve real-time monitoring of critical parts of specific objects at short to medium distances, zoom lenses are required. Zoom lenses can cover a wide field of view and magnify specific areas for further observation. Furthermore, such applications often require compactness and good temperature adaptability. However, existing zoom lenses have the following drawbacks: First, their emphasis on zoom ratio and telephoto resolution results in excessive length and bulk, making them unsuitable for space-constrained scenarios; second, they have poor temperature adaptability and overall low performance. Summary of the Invention
[0003] The purpose of this invention is to solve the technical problems of existing zoom lenses, such as excessive length, large size, unsuitability for space-limited scenarios, poor temperature adaptability, and low overall performance, and to provide a semi-heatless zoom lens.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] A semi-heatless zoom lens, its special feature is:
[0006] It includes a front fixed group of positive optical power, a zoom group of negative optical power, a compensation group of positive optical power, and a rear fixed group of positive optical power arranged sequentially along the direction of incident light propagation; the zoom group and the compensation group can move along the optical axis to achieve continuous zoom imaging.
[0007] The focal lengths f1 of the front fixed group, f2 of the zoom group, f3 of the compensation group, and f4 of the rear fixed group satisfy the following relationships: -0.25 ≤ f2 / f1 ≤ -0.18; 0.5 ≤ f3 / f1 ≤ 0.72; 1 ≤ f4 / f1 ≤ 1.5; 0.4 ≤ f1 / f L ≤0.5; where f L The focal length of the zoom lens when it is in telephoto mode.
[0008] The front fixing group includes a first meniscus negative lens, a first biconvex positive lens, and a first meniscus positive lens arranged sequentially along the incident light propagation direction; the first meniscus negative lens and the first biconvex positive lens are cemented together; the first biconvex positive lens and the first meniscus positive lens are both made of optical glass material with a refractive index of 1.45≤refractive index nd≤1.50 and an Abbe number of 80≤Abbe number vd≤95.
[0009] The compensation group includes a second biconvex positive lens, a second meniscus negative lens, and a third biconvex positive lens arranged sequentially along the incident light propagation direction; the second meniscus negative lens and the third biconvex positive lens are cemented together; an aperture stop is provided in the optical path between the second biconvex positive lens and the second meniscus negative lens; the third biconvex positive lens is a 12×10... -6 / K≤expansion coefficient α≤14×10 -6 / K and -9×10 -6 / K≤Temperature Refractive Index Coefficient Optical glass materials.
[0010] Furthermore, the intervals between the front fixed group and the zoom group, the intervals between the zoom group and the compensation group, and the intervals between the compensation group and the rear fixed group are 33.23mm to 33.33mm, 0.05mm to 0.15mm, and 25.09mm to 25.19mm, respectively, when the zoom lens is in telephoto mode.
[0011] The intervals between the front fixed group and the zoom group, the interval between the zoom group and the compensation group, and the interval between the compensation group and the rear fixed group are 9.32mm to 9.42mm, 48.95mm to 49.05mm, and 0.05mm to 0.15mm, respectively, when the zoom lens is in short focal length mode.
[0012] Furthermore, the zoom group includes a third meniscus negative lens, a first biconcave negative lens, a fourth biconvex positive lens, and a second biconcave negative lens arranged sequentially along the incident light propagation direction; the first biconcave negative lens and the fourth biconvex positive lens are cemented together.
[0013] The rear fixed assembly includes a second meniscus positive lens, a third biconcave negative lens, a fifth biconvex positive lens, a fourth meniscus negative lens, and a third meniscus positive lens arranged sequentially along the direction of incident light propagation; a color filter is provided in the optical path between the third meniscus positive lens and the image plane of the zoom lens.
[0014] Furthermore, the radius of curvature of the incident surface of the first meniscus negative lens is 69.240 mm to 76.530 mm, the radius of curvature of the cemented surface of the first meniscus negative lens and the first biconvex positive lens is 44.680 mm to 49.380 mm, and the radius of curvature of the exit surface of the first biconvex positive lens is -178.930 mm to -197.760 mm;
[0015] The radius of curvature of the incident surface of the first meniscus lens is 39.040 mm to 43.150 mm, and the radius of curvature of the exit surface is 155.140 mm to 171.470 mm.
[0016] The third meniscus negative lens has an incident surface radius of curvature of 210.490 mm to 232.650 mm and an exit surface radius of curvature of 27.160 mm to 30.020 mm.
[0017] The radius of curvature of the incident surface of the first biconcave negative lens is -49.840 mm to -55.090 mm, the radius of curvature of the cemented surface of the first biconcave negative lens and the fourth biconvex positive lens is 16.740 mm to 18.500 mm, and the radius of curvature of the exit surface of the fourth biconvex positive lens is -542.420 mm to -599.520 mm.
[0018] The second biconcave negative lens has an incident surface radius of curvature of -44.070 mm to -48.710 mm and an exit surface radius of curvature of 87.320 mm to 96.510 mm.
[0019] The second biconvex positive lens has an incident surface radius of curvature of 87.290 mm to 96.480 mm and an exit surface radius of curvature of -36.640 mm to -40.500 mm.
[0020] The surface radius of curvature of the aperture is infinite;
[0021] The radius of curvature of the incident surface of the second meniscus negative lens is 24.970 mm to 27.600 mm, the radius of curvature of the cemented surface of the second meniscus negative lens and the third biconvex positive lens is 14.130 mm to 15.620 mm, and the radius of curvature of the exit surface of the third biconvex positive lens is 18241.600 mm to infinity.
[0022] The second meniscus lens has an incident surface radius of curvature of 11.480 mm to 12.690 mm and an exit surface radius of curvature of 30.660 mm to 33.890 mm.
[0023] The third biconcave negative lens has an incident surface radius of curvature of -93.580 mm to -103.430 mm and an exit surface radius of curvature of 20.490 mm to 22.640 mm.
[0024] The fifth biconvex positive lens has an incident surface radius of curvature of 61.270 mm to 67.720 mm and an exit surface radius of curvature of -38.490 mm to -42.550 mm.
[0025] The incident surface radius of curvature of the fourth meniscus negative lens is 19.660 mm to 21.730 mm, and the exit surface radius of curvature is 7.670 mm to 8.480 mm.
[0026] The radius of curvature of the incident surface of the third meniscus lens is 13.270 mm to 14.670 mm, and the radius of curvature of the exit surface is 61.190 mm to 67.630 mm.
[0027] The incident and exit surfaces of the color filter have infinite radii of curvature.
[0028] Further, the intervals between adjacent surfaces along the optical path propagation direction within the front fixed group are successively 1.94mm–2.04mm, 6.02mm–6.12mm, 0.05mm–0.15mm, and 4.45mm–4.55mm; the intervals between adjacent surfaces along the optical path propagation direction within the zoom group are successively 0.75mm–0.85mm, 1.93mm–2.03mm, 0.75mm–0.85mm, 2.64mm–2.74mm, 0.64mm–0.74mm, and 0.75mm–0.85mm; and the intervals between adjacent surfaces along the optical path propagation direction within the compensation group are successively 1.39mm–1.49mm, 0.05mm–0.15mm, 0.05mm–0.15mm, and 0.75mm–0.85mm. The spacing between adjacent surfaces in the rear fixing group along the optical path propagation direction is 1.54mm-1.64mm, 0.58mm-0.68mm, 0.75mm-0.85mm, 4.32mm-4.42mm, 1.17mm-1.27mm, 0.05mm-0.15mm, 0.75mm-0.85mm, 10.69mm-10.79mm, and 1.39mm-1.49mm, respectively. The spacing between the rear fixing group and the incident surface of the color filter is 3.95mm-4.05mm. The spacing between the incident surface and the exit surface of the color filter is 1.05mm-1.15mm. The spacing between the exit surface of the color filter and the image plane of the zoom lens is 4.85mm-4.95mm.
[0029] Furthermore, both the third meniscus negative lens and the second biconcave negative lens are made of optical glass material with 1.88≤nd≤1.89 and 39≤vd≤42.
[0030] Furthermore, both the first biconvex positive lens and the first meniscus positive lens are made of optical glass material with nd = 1.496998 and vd = 81.5947; the third biconvex positive lens is made of α = 12.4 × 10⁻⁶. -6 / K and The optical glass material is as follows: the third meniscus negative lens and the second biconcave negative lens are both made of optical glass material with nd = 1.883001 and vd = 39.2253; the first meniscus negative lens, the second meniscus negative lens, and the fifth biconvex positive lens are all made of H-ZF52 material; the material of the first biconcave negative lens is the same as that of the third meniscus negative lens; the material of the fourth biconvex positive lens is H-ZF88; the material of the second biconvex positive lens is H-LAK2A; the material of the second meniscus positive lens is H-LAF3B; the material of the third biconcave negative lens is H-ZF1; the material of the fourth meniscus negative lens is H-ZLAF76; the material of the third meniscus positive lens and the color filter is H-K9L.
[0031] Furthermore, the radius of curvature of the incident surface of the first meniscus negative lens is 72.881 mm, the radius of curvature of the cemented surface of the first meniscus negative lens and the first biconvex positive lens is 47.032 mm, and the radius of curvature of the exit surface of the first biconvex positive lens is -188.345 mm.
[0032] The radius of curvature of the incident surface of the first meniscus lens is 41.094 mm, and the radius of curvature of the exit surface is 163.308 mm.
[0033] The radius of curvature of the incident surface of the third meniscus negative lens is 221.568 mm, and the radius of curvature of the exit surface is 28.587 mm.
[0034] The incident surface radius of curvature of the first biconcave negative lens is -52.467 mm, the cementation surface radius of curvature of the first biconcave negative lens and the fourth biconvex positive lens is 17.616 mm, and the exit surface radius of curvature of the fourth biconvex positive lens is -570.971 mm.
[0035] The second biconcave negative lens has an incident surface radius of curvature of -46.391 mm and an exit surface radius of curvature of 91.918 mm.
[0036] The second biconvex positive lens has an incident surface radius of curvature of 91.883 mm and an exit surface radius of curvature of -38.571 mm.
[0037] The incident surface radius of curvature of the second meniscus negative lens is 26.287 mm, the cemented surface radius of curvature of the second meniscus negative lens and the third biconvex positive lens is 14.875 mm, and the exit surface radius of curvature of the third biconvex positive lens is 19201.685 mm.
[0038] The second meniscus lens has an incident surface radius of curvature of 12.088 mm and an exit surface radius of curvature of 32.278 mm.
[0039] The third biconcave negative lens has an incident surface radius of curvature of -98.505 mm and an exit surface radius of curvature of 21.564 mm.
[0040] The fifth biconvex positive lens has an incident surface radius of curvature of 64.499 mm and an exit surface radius of curvature of -40.520 mm.
[0041] The fourth crescent negative lens has an incident surface radius of curvature of 20.695 mm and an exit surface radius of curvature of 8.075 mm.
[0042] The third meniscus lens has an incident surface radius of curvature of 13.972 mm and an exit surface radius of curvature of 64.412 mm.
[0043] Furthermore, the intervals between the front fixed group and the zoom group, the interval between the zoom group and the compensation group, and the interval between the compensation group and the rear fixed group are 33.28mm, 0.10mm, and 25.14mm, respectively, when the zoom lens is in telephoto mode.
[0044] The intervals between the front fixed group and the zoom group, the interval between the zoom group and the compensation group, and the interval between the compensation group and the rear fixed group are 9.39mm, 49.03mm, and 0.10mm, respectively, when the zoom lens is in short focal length mode.
[0045] Further, the spacing between adjacent surfaces along the optical path propagation direction within the front fixed group is successively 1.99mm, 6.07mm, 0.10mm, and 4.50mm; the spacing between adjacent surfaces along the optical path propagation direction within the zoom group is successively 0.80mm, 1.98mm, 0.80mm, 2.69mm, 0.69mm, and 0.80mm; and the spacing between adjacent surfaces along the optical path propagation direction within the compensation group is successively 1.44mm, 0.10mm, 0.10mm, and 0.80mm. 1.94mm; the spacing between adjacent surfaces in the rear fixing group along the optical path propagation direction is 1.59mm, 0.63mm, 0.80mm, 4.37mm, 1.22mm, 0.10mm, 0.80mm, 10.74mm, and 1.44mm respectively; the spacing between the rear fixing group and the incident surface of the color filter is 4.00mm; the spacing between the incident surface of the color filter and its exit surface is 1.10mm; the spacing between the exit surface of the color filter and the image plane of the zoom lens is 4.90mm.
[0046] The beneficial effects of this invention are:
[0047] 1. This invention provides a semi-thermal zoom lens, which, through reasonable setting of the optical power of each optical lens group, f1, f2, f3, f4, f... LBy carefully considering the numerical relationships and the appropriate selection of materials for the first biconvex positive lens, the first meniscus positive lens, and the third biconvex positive lens, this lens can operate normally under vacuum and high / low temperature conditions, exhibiting high temperature adaptability and overall performance. The lens achieves pyrolysis at low temperatures, and the front fixed-group focusing effectively adjusts the back focus in telephoto mode while having a much smaller impact on the depth of focus in short-focus mode. Therefore, after focusing in telephoto mode, the lens still maintains good image quality in short-focus mode. At -40℃ and +60℃, only slight focusing in telephoto mode is needed to achieve sharp target images across the entire zoom range. In its high / low temperature design, the lens forgoes investment in high / low temperature control in telephoto mode, reducing material constraints and design complexity. The aperture is positioned within the compensation group, reducing the aperture of the front fixed-group and limiting the lens size to within φ42mm×115mm. This results in a compact structure, simplified front fixed-group, and shorter overall length, achieving a balance between small size and high / low temperature performance.
[0048] 2. The focal length of this invention can reach 12mm to 140mm. In the short focal length state, the reciprocal of the relative aperture F is not less than 3.1, and in the long focal length state, the reciprocal of the relative aperture F is not less than 5.0. For a 1 / 2.35-inch target surface, the diagonal field of view reaches more than 35.5°, the full field of view distortion is less than ≤2.5%, and the spatial resolution reaches 145lp / mm. Attached Figure Description
[0049] Figure 1 This is an optical system diagram of a semi-thermal zoom lens in telephoto mode according to the present invention;
[0050] Figure 2 This is an MTF (modulation transfer function) curve of an embodiment of the present invention in the telephoto state;
[0051] Figure 3 This is a field curvature diagram of an embodiment of the present invention in a telephoto state;
[0052] Figure 4 This is a distortion image of an embodiment of the present invention in a telephoto state;
[0053] Figure 5 This is a magnification chromatic aberration curve diagram of the present invention when in telephoto mode;
[0054] Figure 6 This is an optical system diagram of an embodiment of the present invention in a short focal length state;
[0055] Figure 7 This is an MTF curve diagram of an embodiment of the present invention in a short focal length state;
[0056] Figure 8 This is a field curvature diagram of an embodiment of the present invention in a short focal length state;
[0057] Figure 9 This is a distortion image of an embodiment of the present invention in a short focal length state;
[0058] Figure 10 This is the magnification chromatic aberration curve of the present invention when in short focal length mode;
[0059] Figure 11 This is a defocused MTF curve of an embodiment of the present invention in a short focal length state at -40°C;
[0060] Figure 12 This is a defocused MTF curve of an embodiment of the present invention at +60°C in a short focal length state;
[0061] Figure 13 This is an MTF curve of an embodiment of the present invention in a telephoto state at -40°C;
[0062] Figure 14 This is an MTF curve of an embodiment of the present invention after focusing at -40°C in a telephoto state;
[0063] Figure 15 This is an MTF curve of the present invention at -40℃ in the short focal length state after telephoto focusing;
[0064] Figure 16 This is an MTF curve of an embodiment of the present invention in a telephoto state at +60°C;
[0065] Figure 17 This is an MTF curve of an embodiment of the present invention after focusing at +60°C in a telephoto state;
[0066] Figure 18 This is an MTF curve of the embodiment of the present invention at +60°C in the short focal length state after telephoto focusing;
[0067] Figure 19 The figures show the relative illumination curves of the present invention in both short-focus and long-focus states.
[0068] Explanation of reference numerals in the attached figures:
[0069] L1 - Front fixed group, 1 - First meniscus negative lens, 2 - First biconvex positive lens, 3 - First meniscus positive lens, L2 - Magnification group, 4 - Third meniscus negative lens, 5 - First biconcave negative lens, 6 - Fourth biconvex positive lens, 7 - Second biconcave negative lens, L3 - Compensation group, 8 - Second biconvex positive lens, 9 - Second meniscus negative lens, 10 - Third biconvex positive lens, SP - Aperture stop, L4 - Rear fixed group, 11 - Second meniscus positive lens, 12 - Third biconcave negative lens, 13 - Fifth biconvex positive lens, 14 - Fourth meniscus negative lens, 15 - Third meniscus positive lens, I - Image plane, 16 - Color filter. Detailed Implementation
[0070] like Figure 1 and Figure 6 As shown, a semi-heatless zoom lens includes a front fixed group L1 with positive optical power, a zoom group L2 with negative optical power, a compensation group L3 with positive optical power, and a rear fixed group L4 with positive optical power, arranged sequentially along the incident light propagation direction. The zoom group L2 and the compensation group L3 can move along the optical axis to achieve continuous zoom imaging. The focal lengths f1 of the front fixed group L1, f2 of the zoom group L2, f3 of the compensation group L3, and f4 of the rear fixed group L4 satisfy the following relationships: -0.25≤f2 / f1≤-0.18; 0.5≤f3 / f1≤0.72; 1≤f4 / f1≤1.5; 0.4≤f1 / f L ≤0.5; where f L This refers to the focal length of the zoom lens when it is in telephoto mode. In this embodiment, f2 / f1 = -0.21, f3 / f1 = 0.60, f4 / f1 = 1.19, f1 / f L =0.45. The front fixed group L1 includes a first meniscus negative lens 1, a first biconvex positive lens 2, and a first meniscus positive lens 3 arranged sequentially along the incident light propagation direction. The first meniscus negative lens 1 and the first biconvex positive lens 2 are cemented together. The first biconvex positive lens 2 and the first meniscus positive lens 3 are both made of optical glass material with a refractive index of 1.45 ≤ refractive index nd ≤ 1.50 and an Abbe number of 80 ≤ Abbe number vd ≤ 95. The zoom group L2 includes a third meniscus negative lens 4, a first biconcave negative lens 5, a fourth biconvex positive lens 6, and a second biconcave negative lens 7 arranged sequentially along the incident light propagation direction. The first biconcave negative lens 5 and the fourth biconvex positive lens 6 are cemented together. The third meniscus negative lens 4 and the second biconcave negative lens 7 are both made of optical glass material with a refractive index of 1.88 ≤ nd ≤ 1.89 and an Abbe number of 39 ≤ vd ≤ 42. Compensation group L3 includes a second biconvex positive lens 8, a second meniscus negative lens 9, and a third biconvex positive lens 10 arranged sequentially along the incident light propagation direction. The second meniscus negative lens 9 and the third biconvex positive lens 10 are cemented together. An aperture stop SP is provided in the optical path between the second biconvex positive lens 8 and the second meniscus negative lens 9. The third biconvex positive lens 10 is 12×10 -6 / K≤expansion coefficient α≤14×10 -6 / K and -9×10 -6 / K≤Temperature Refractive Index Coefficient The optical glass material is as follows. The rear fixed assembly L4 includes a second meniscus positive lens 11, a third biconcave negative lens 12, a fifth biconvex positive lens 13, a fourth meniscus negative lens 14, and a third meniscus positive lens 15 arranged sequentially along the incident light propagation direction. A color filter 16 is arranged in the optical path between the third meniscus positive lens 15 and the image plane I of the zoom lens. In this embodiment, the first biconvex positive lens 2 and the first meniscus positive lens 3 are both made of H-FK61 series optical glass material with nd=1.496998 and vd=81.5947, which can effectively suppress second-order spectral chromatic aberration and provide a basis for high-quality imaging when the zoom lens is in telephoto mode. The third meniscus negative lens 4 and the second biconcave negative lens 7 are responsible for light refraction and are both made of H-ZLAF68N optical glass material with nd=1.883001 and vd=39.2253, which reduces monochromatic aberration caused by dense optical power and also reduces the generation of chromatic aberration. The third biconvex positive lens 10 uses α = 12.4 × 10⁻⁶. -6 / K and The H-ZPK5 optical glass material improves image quality in zoom lenses at short focal lengths while also reducing heat loss in these conditions.
[0071] In this embodiment, the detailed parameter data of each lens are shown in Table 1 (telephoto mode):
[0072] Table 1
[0073]
[0074]
[0075] In this embodiment, the spacing between adjacent surfaces within each lens group along the optical path propagation direction in the short focal length state is the same as the spacing between adjacent surfaces within each lens group along the optical path propagation direction in the long focal length state. The spacing data between the front fixed group L1, zoom group L2, compensation group L3, and rear fixed group L4 in both the short focal length and long focal length states are shown in Table 2.
[0076] Table 2
[0077] Interval / mm Short focal length Telephoto mode Front fixed group L1 and variable magnification group L2 9.38988216 33.27573646 Variable-amplification group L2 and compensation group L3 49.02743989 0.099580027 Compensation group L3 and rear fixation group L4 0.10000000 25.14200556
[0078] In this embodiment, the total length TTL of the lens is equal to the focal length f when the lens is in telephoto mode. L The ratio of TTL / f L ≤0.85, the system structure is compact, which is conducive to miniaturization. The zoom ratio f of this lens is... L / f s ≥11.5, where f s This refers to the focal length when the lens is in a short focal length mode.
[0079] Figures 2 to 5This describes the primary image quality when the lens is in telephoto mode; the lens operates in the visible light band. Figure 2 It can be seen that the MTF across the entire field of view is greater than 0.28 at 145 lp / mm. Figure 3 It can be seen that the field curvature is less than 0.03 mm and the astigmatism is less than 0.1 mm. Figure 4 It can be seen that the distortion is pincushion-shaped, less than 2%. Figure 5 It can be seen that the vertical color difference is 2.6 micrometers, which is less than one pixel.
[0080] Figures 7 to 10 This describes the primary image quality when the lens is in short focal length mode; the lens operates in the visible light band. Figure 7 It can be seen that the MTF across the entire field of view is greater than 0.33 at 145 lp / mm. Figure 8 It can be seen that the field curvature is less than 0.03 mm and the astigmatism is less than 0.1 mm. Figure 9 It can be seen that the distortion is barrel distortion, less than 2%. Figure 10 It can be seen that the vertical color difference is 2.9 micrometers, which is less than one pixel.
[0081] Figures 11 to 18 This refers to high and low temperature image quality. Among them, Figure 11 , Figure 12 The MTF values are shown for the lens in short focal length mode at -40℃ and +60℃, respectively. It can be seen that the image quality of the lens does not change significantly, that is, the lens achieves heat-free operation in short focal length mode. Figure 13 The MTF (Mean Transformation Chart) is for a lens in telephoto mode at -40°C, indicating that the focal plane has shifted. Figure 14 The image quality is significantly improved after focusing, with the lens in telephoto mode and at -40°C. Figure 15 The MTF (Mean Transformation Factor) at -40℃ after adjusting from a telephoto to a short focal length still shows good performance. This means that while the focal plane changes at low temperatures in the telephoto setting, this can be compensated for by refocusing, and the refocusing process does not affect the image quality in the short focal length setting. Similarly, Figure 16 , Figure 17 The MTF (Mean Transformer) values are before and after focusing the lens in telephoto mode at +60°C. Figure 18 The MTF (Mean Transmission Factor) is the image quality of the lens in its short focal length position after telephoto focusing, at +60℃. This means the aforementioned properties still hold true at high temperatures. In summary, after focusing the lens in its telephoto position, the lens still maintains good image quality in its short focal length position. Therefore, when the lens is in its telephoto position and at -40℃ and +60℃, only a corresponding focus adjustment of -0.072mm and +0.048mm on the front fixed group L1 is needed to achieve a clear target surface across the entire zoom range.
[0082] Figure 19The relative illumination curves are shown when the lens is in short focal length and long focal length. It can be seen that the relative illumination of the entire field of view is greater than 90%, the relative illumination is uniform, there is no dark corner, which meets the requirements of most detectors.
[0083] The detector target size applicable to this invention reaches 1 / 2.35 inch, and the MTF resolution is better than 145 lp / mm.
[0084] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A semi-thermal zoom lens, characterized in that: Along the direction of incident light propagation, it consists of a front fixed group L1 with positive optical power, a zoom group L2 with negative optical power, a compensation group L3 with positive optical power, and a rear fixed group L4 with positive optical power. The zoom group L2 and the compensation group L3 can move along the optical axis to achieve continuous zoom imaging. The focal lengths f1 of the front fixed group L1, f2 of the zoom group L2, f3 of the compensation group L3, and f4 of the rear fixed group L4 satisfy the following relationships: -0.25≤f2 / f1≤-0.18; 0.5≤f3 / f1≤0.72; 1≤f4 / f1≤1.5; 0.4≤f1 / ≤0.5; where, The focal length of the zoom lens when it is in telephoto mode. The front fixed group L1 is composed of a first meniscus negative lens (1), a first biconvex positive lens (2), and a first meniscus positive lens (3) in sequence along the incident light propagation direction; the first meniscus negative lens (1) and the first biconvex positive lens (2) are cemented together; the first biconvex positive lens (2) and the first meniscus positive lens (3) are both made of optical glass material with 1.45≤nd≤1.50 and 80≤vd≤95, where nd is the refractive index of the optical glass material and vd is the Abbe number of the optical glass material; the zoom group L2 is composed of a third meniscus negative lens (4), a first biconcave negative lens (5), a fourth biconvex positive lens (6), and a second biconcave negative lens (7) in sequence along the incident light propagation direction. The compensation group L3 is composed of a second biconvex positive lens (8), a second meniscus negative lens (9), and a third biconvex positive lens (10) in sequence along the incident light propagation direction; the second meniscus negative lens (9) and the third biconvex positive lens (10) are cemented together; an aperture stop SP is provided in the optical path between the second biconvex positive lens (8) and the second meniscus negative lens (9); the third biconvex positive lens (10) adopts... and Optical glass materials, among which, The coefficient of thermal expansion of optical glass materials. The temperature refractive index coefficient of optical glass materials; The rear fixed group L4 is composed of a second meniscus positive lens (11), a third biconcave negative lens (12), a fifth biconvex positive lens (13), a fourth meniscus negative lens (14), and a third meniscus positive lens (15) in sequence along the direction of incident light propagation.
2. The semi-thermal zoom lens according to claim 1, characterized in that: The intervals between the front fixed group L1 and the zoom group L2, the intervals between the zoom group L2 and the compensation group L3, and the intervals between the compensation group L3 and the rear fixed group L4 are 33.23mm~33.33mm, 0.05mm~0.15mm, and 25.09mm~25.19mm, respectively, when the zoom lens is in telephoto mode. The intervals between the front fixed group L1 and the zoom group L2, the interval between the zoom group L2 and the compensation group L3, and the interval between the compensation group L3 and the rear fixed group L4 are 9.32mm~9.42mm, 48.95mm~49.05mm, and 0.05mm~0.15mm, respectively, when the zoom lens is in short focal length mode.
3. The semi-heatless zoom lens according to claim 1 or 2, characterized in that: The first biconcave negative lens (5) is cemented to the fourth biconvex positive lens (6); A color filter (16) is provided on the optical path between the third meniscus lens (15) and the image plane I of the zoom lens.
4. The semi-heatless zoom lens according to claim 3, characterized in that: The radius of curvature of the incident surface of the first meniscus negative lens (1) is 69.240mm~76.530mm, the radius of curvature of the cemented surface of the first meniscus negative lens (1) and the first biconvex positive lens (2) is 44.680mm~49.380mm, and the radius of curvature of the exit surface of the first biconvex positive lens (2) is -178.930mm~-197.760mm; The radius of curvature of the incident surface of the first meniscus lens (3) is 39.040 mm to 43.150 mm, and the radius of curvature of the exit surface is 155.140 mm to 171.470 mm. The incident surface radius of curvature of the third crescent negative lens (4) is 210.490mm~232.650mm, and the exit surface radius of curvature is 27.160mm~30.020mm; The incident surface radius of curvature of the first biconcave negative lens (5) is -49.840mm to -55.090mm, the cemented surface radius of curvature of the first biconcave negative lens (5) and the fourth biconvex positive lens (6) is 16.740mm to 18.500mm, and the exit surface radius of curvature of the fourth biconvex positive lens (6) is -542.420mm to -599.520mm. The second biconcave negative lens (7) has an incident surface radius of curvature of -44.070mm to -48.710mm and an exit surface radius of curvature of 87.320mm to 96.510mm. The second biconvex positive lens (8) has an incident surface radius of curvature of 87.290 mm to 96.480 mm and an exit surface radius of curvature of -36.640 mm to -40.500 mm. The surface radius of curvature of the aperture SP is infinite; The incident surface radius of curvature of the second meniscus negative lens (9) is 24.970mm~27.600mm, the cemented surface radius of curvature of the second meniscus negative lens (9) and the third biconvex positive lens (10) is 14.130mm~15.620mm, and the exit surface radius of curvature of the third biconvex positive lens (10) is 18241.600mm~infinity; The second meniscus lens (11) has an incident surface radius of curvature of 11.480 mm to 12.690 mm and an exit surface radius of curvature of 30.660 mm to 33.890 mm. The incident surface radius of curvature of the third biconcave negative lens (12) is -93.580mm to -103.430mm, and the exit surface radius of curvature is 20.490mm to 22.640mm. The fifth biconvex positive lens (13) has an incident surface radius of curvature of 61.270 mm to 67.720 mm and an exit surface radius of curvature of -38.490 mm to -42.550 mm. The incident surface radius of curvature of the fourth crescent negative lens (14) is 19.660 mm to 21.730 mm, and the exit surface radius of curvature is 7.670 mm to 8.480 mm. The radius of curvature of the incident surface of the third meniscus lens (15) is 13.270 mm to 14.670 mm, and the radius of curvature of the exit surface is 61.190 mm to 67.630 mm. The incident and exit surfaces of the color filter (16) have infinite radii of curvature.
5. The semi-heatless zoom lens according to claim 4, characterized in that: The spacing between adjacent surfaces along the optical path propagation direction in the front fixed group L1 is 1.94mm~2.04mm, 6.02mm~6.12mm, 0.05mm~0.15mm, and 4.45mm~4.55mm, respectively; the spacing between adjacent surfaces along the optical path propagation direction in the zoom group L2 is 0.75mm~0.85mm, 1.93mm~2.03mm, 0.75mm~0.85mm, 2.64mm~2.74mm, 0.64mm~0.74mm, and 0.75mm~0.85mm, respectively; and the spacing between adjacent surfaces along the optical path propagation direction in the compensation group L3 is 1.39mm~1.49mm, 0.05mm~0.15mm, 0.05mm~0.15mm, 0.75mm~0.85mm, and 1.89mm, respectively. m~1.99mm; the intervals between adjacent surfaces in the rear fixed group L4 along the optical path propagation direction are 1.54mm~1.64mm, 0.58mm~0.68mm, 0.75mm~0.85mm, 4.32mm~4.42mm, 1.17mm~1.27mm, 0.05mm~0.15mm, 0.75mm~0.85mm, 10.69mm~10.79mm, and 1.39mm~1.49mm; the interval between the rear fixed group L4 and the incident surface of the color filter (16) is 3.95mm~4.05mm; the interval between the incident surface and the exit surface of the color filter (16) is 1.05mm~1.15mm; the interval between the exit surface of the color filter (16) and the image plane I of the zoom lens is 4.85mm~4.95mm.
6. The semi-thermal zoom lens according to claim 5, characterized in that: The third meniscus negative lens (4) and the second biconcave negative lens (7) are both made of optical glass material with 1.88≤nd≤1.89 and 39≤vd≤42.
7. The semi-thermal zoom lens according to claim 6, characterized in that: The first biconvex positive lens (2) and the first meniscus positive lens (3) are both made of optical glass material with nd=1.496998 and vd=81.5947; the third biconvex positive lens (10) is made of... and The optical glass material is as follows: the third meniscus negative lens (4) and the second biconcave negative lens (7) are both made of optical glass material with nd=1.883001 and vd=39.2253; the first meniscus negative lens (1), the second meniscus negative lens (9), and the fifth biconvex positive lens (13) are all made of H-ZF52; the material of the first biconcave negative lens (5) is the same as that of the third meniscus negative lens (4); the material of the fourth biconvex positive lens (6) is H-ZF88; the material of the second biconvex positive lens (8) is H-LAK2A; The material of the second meniscus positive lens (11) is H-LAF3B; the material of the third biconcave negative lens (12) is H-ZF1; the material of the fourth meniscus negative lens (14) is H-ZLAF76; the materials of the third meniscus positive lens (15) and the color filter (16) are both H-K9L.
8. The semi-thermal zoom lens according to claim 7, characterized in that: The incident surface radius of curvature of the first meniscus negative lens (1) is 72.881 mm, the cementation surface radius of curvature of the first meniscus negative lens (1) and the first biconvex positive lens (2) is 47.032 mm, and the exit surface radius of curvature of the first biconvex positive lens (2) is -188.345 mm. The radius of curvature of the incident surface of the first meniscus lens (3) is 41.094 mm, and the radius of curvature of the exit surface is 163.308 mm. The incident surface radius of curvature of the third crescent negative lens (4) is 221.568 mm, and the exit surface radius of curvature is 28.587 mm. The incident surface radius of curvature of the first biconcave negative lens (5) is -52.467mm, the cemented surface radius of curvature of the first biconcave negative lens (5) and the fourth biconvex positive lens (6) is 17.616mm, and the exit surface radius of curvature of the fourth biconvex positive lens (6) is -570.971mm. The second biconcave negative lens (7) has an incident surface radius of curvature of -46.391 mm and an exit surface radius of curvature of 91.918 mm. The second biconvex positive lens (8) has an incident surface radius of curvature of 91.883 mm and an exit surface radius of curvature of -38.571 mm. The incident surface radius of curvature of the second meniscus negative lens (9) is 26.287 mm, the cemented surface radius of curvature of the second meniscus negative lens (9) and the third biconvex positive lens (10) is 14.875 mm, and the exit surface radius of curvature of the third biconvex positive lens (10) is 19201.685 mm. The second meniscus lens (11) has an incident surface radius of curvature of 12.088 mm and an exit surface radius of curvature of 32.278 mm. The third biconcave negative lens (12) has an incident surface radius of curvature of -98.505 mm and an exit surface radius of curvature of 21.564 mm. The fifth biconvex positive lens (13) has an incident surface radius of curvature of 64.499 mm and an exit surface radius of curvature of -40.520 mm. The incident surface radius of curvature of the fourth crescent negative lens (14) is 20.695 mm, and the exit surface radius of curvature is 8.075 mm. The radius of curvature of the incident surface of the third meniscus lens (15) is 13.972 mm, and the radius of curvature of the exit surface is 64.412 mm.
9. The semi-thermal zoom lens according to claim 2, characterized in that: The intervals between the front fixed group L1 and the zoom group L2, the intervals between the zoom group L2 and the compensation group L3, and the intervals between the compensation group L3 and the rear fixed group L4 are 33.28mm, 0.10mm, and 25.14mm, respectively, when the zoom lens is in telephoto mode. The intervals between the front fixed group L1 and the zoom group L2, the interval between the zoom group L2 and the compensation group L3, and the interval between the compensation group L3 and the rear fixed group L4 are 9.39mm, 49.03mm, and 0.10mm, respectively, when the zoom lens is in short focal length mode.
10. The semi-thermal zoom lens according to claim 5, characterized in that: The spacing between adjacent surfaces along the optical path propagation direction in the front fixed group L1 is 1.99mm, 6.07mm, 0.10mm, and 4.50mm, respectively; the spacing between adjacent surfaces along the optical path propagation direction in the zoom group L2 is 0.80mm, 1.98mm, 0.80mm, 2.69mm, 0.69mm, and 0.80mm, respectively; and the spacing between adjacent surfaces along the optical path propagation direction in the compensation group L3 is 1.44mm, 0.10mm, 0.10mm, 0.80mm, and 1.94mm, respectively. The intervals between adjacent surfaces in the rear fixed group L4 along the optical path propagation direction are 1.59mm, 0.63mm, 0.80mm, 4.37mm, 1.22mm, 0.10mm, 0.80mm, 10.74mm, and 1.44mm, respectively; the interval between the rear fixed group L4 and the incident surface of the color filter (16) is 4.00mm; the interval between the incident surface and the exit surface of the color filter (16) is 1.10mm; and the interval between the exit surface of the color filter (16) and the image plane I of the zoom lens is 4.90mm.