A zoom radiation-hardened lens

Abstract

The application discloses a zooming radiation-resistant lens, which comprises a first lens group, a second lens group and a third lens group arranged in sequence from an object side to an image side, and a lens structure member arranged outside the lens groups for fixing the lens groups and shielding the lens groups from light, wherein the three lens groups are respectively composed of a plurality of lens pieces with different double-side curved surface shapes, and the types of the lens pieces for composing the lens groups include but are not limited to heavy flint glass doped with a weight percentage of a tantalum element of λ1, heavy flint glass doped with a weight percentage of a titanium element of λ2, heavy crown glass doped with a weight percentage of a barium element of λ3 and heavy lanthanum flint glass doped with a weight percentage of a cerium element of λ4, so as to meet the requirements of refractive index and dispersion coefficient. 6 In the application, the radiation-resistant lens is designed by using the four kinds of radiation-resistant glasses, supports a dose rate (Co60) of 3000Gy / h, supports a total dose (Co60) of 1x10 6 Gy, and the light transmittance after radiation does not decrease by more than 50%.

Description

Technical Field

[0001] This invention relates to the field of zoom optical lens technology, and more particularly to a zoom radiation-resistant lens. Background Technology

[0002] Zoom optical lenses require up to dozens of optical glass elements to form a complete product. Optical glass is made by mixing high-purity oxides of silicon, boron, sodium, potassium, zinc, magnesium, calcium, barium, lead, etc., according to a specific formula and then melting them at high temperature.

[0003] In nuclear radiation environments, video surveillance is required for critical areas, such as the nuclear island area of ​​nuclear power plants, underwater inspection operations of reactor fuel assemblies, nuclear fuel enrichment areas, nuclear waste disposal areas, radioactive medical material storage areas, nuclear weapons storage areas, high-energy nuclear physics research and experimental areas, and high-energy nuclear areas in outer space. In these environments, the free electrons generated by nuclear radiation ionization can cause browning of the color centers in optical glass; in simpler terms, the lens darkens and its transmittance decreases significantly, resulting in weakened optical performance. Summary of the Invention

[0004] To address the technical problems mentioned in the background section, a zoom radiation-resistant lens is proposed. Conventional radiation-resistant optical glass incorporates lanthanide elements such as cerium or heavy metals such as lead. However, this method of addition cannot fully meet the requirements of low dispersion and high refractive index required for optical glass. Therefore, we need to select various materials to match the requirements of different refractive indices and dispersion coefficients.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A zoom radiation-resistant lens includes a first lens group, a second lens group, and a third lens group arranged sequentially from the object side to the image side, as well as lens structural components disposed outside the lens groups for fixing the lens groups and shielding them from light. Each of the three lens groups consists of several groups of lenses with different double-sided curved surface shapes. The types of lenses constituting the lens groups include, but are not limited to, heavy flint glass with a tantalum doping weight percentage of λ1, heavy flint glass with a titanium doping weight percentage of λ2, heavy crown glass with a barium doping weight percentage of λ3, and heavy lanthanum flint glass with a cerium doping weight percentage of λ4, to meet the requirements of refractive index and dispersion coefficient, wherein the value of λ ranges from 2 to 5%.

[0007] High refractive index and moderate dispersion are achieved using heavy flint glass doped with tantalum. Titanium-doped heavy flint glass is indispensable for radiation-resistant lens design. Barium-doped crown glass has a low refractive index but extremely low dispersion and is the most frequently used type of glass in lenses. Cerium-doped lanthanum-doped heavy flint glass has a high refractive index and very low dispersion, making it the most important radiation-resistant glass affecting the optical resolution of the entire lens. Furthermore, lead-doped glass grades should be avoided in the design process to prevent the overall glass from yellowing due to lead doping.

[0008] As a further description of the above technical solution:

[0009] The lenses that make up the first lens group include heavy flint glass doped with tantalum, heavy crown glass doped with barium, heavy flint glass doped with titanium, and heavy lanthanum flint glass doped with cerium.

[0010] The lenses that make up the second lens group include heavy flint glass doped with tantalum, heavy flint glass doped with titanium, and heavy crown glass doped with barium.

[0011] The lenses that make up the third lens group include heavy flint glass doped with tantalum, heavy crown glass doped with barium, and heavy lanthanum flint glass doped with cerium.

[0012] As a further description of the above technical solution:

[0013] Along the object-to-image direction, the first lens group consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens is heavy flint glass doped with tantalum, the second lens is heavy crown glass doped with barium, the third lens is heavy lanthanum flint glass doped with cerium, the fourth lens is heavy flint glass doped with titanium, the fifth lens is heavy crown glass doped with barium, and the sixth lens is heavy flint glass doped with tantalum.

[0014] The second lens group consists of a seventh lens, an eighth lens, and a ninth lens. The seventh lens is heavy flint glass doped with tantalum, the eighth lens is heavy crown glass doped with barium, and the ninth lens is heavy flint glass doped with titanium.

[0015] The third lens group consists of a tenth lens, an eleventh lens, and a twelfth lens. The tenth lens is heavy lanthanum flint glass doped with cerium, the eleventh lens is heavy crown glass doped with barium, and the twelfth lens is heavy flint glass doped with tantalum.

[0016] As a further description of the above technical solution:

[0017] In the first lens group, the object side of the first lens is convex, the image side of the first lens is concave curved, the object side of the second lens is convex curved, the image side of the second lens is flat, the object side of the third lens is convex curved, the image side of the third lens is flat, the object side of the fourth lens is flat, the image side of the fourth lens is concave curved, the fifth lens is double-sided concave curved, and the object side of the sixth lens is convex curved, the image side of the sixth lens is flat.

[0018] In the second lens group, the seventh lens is a double-sided convex curved surface, the eighth lens is a double-sided convex curved surface, and the ninth lens is a double-sided concave curved surface.

[0019] In the third lens group, the object side of the tenth lens is flat, the image side of the tenth lens is convex curved, the eleventh lens is double-convex, the object side of the twelfth lens is concave curved, and the image side of the first lens is flat.

[0020] As a further description of the above technical solution:

[0021] The focal length of the radiation-resistant lens is 15-150mm, wherein the focal length a of the third lens group is no greater than 15mm.

[0022] In summary, due to the adoption of the above technical solutions, the beneficial effects of this invention are as follows: High refractive index and moderate dispersion are achieved through heavy flint glass doped with tantalum; heavy flint glass doped with titanium is indispensable for radiation-resistant optical lens design; heavy crown glass doped with barium has a low refractive index but extremely low dispersion, and is the most frequently used type in the entire lens; heavy lanthanum flint glass doped with cerium has a high refractive index and very low dispersion, making it the most important radiation-resistant glass affecting the optical resolution of the entire radiation-resistant lens. Radiation-resistant lenses designed using the aforementioned four types of radiation-resistant glass support a dose rate of 3000 Gy / h (Co60) and support 1×10⁻⁶... 6 The total Gy dose (Co60) resulted in a transmittance decrease of no more than 50% after irradiation. Attached Figure Description

[0023] Figure 1 A schematic diagram of the structure of a zoom radiation-resistant lens according to an embodiment of the present invention is shown.

[0024] Legend:

[0025] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Ninth lens; 10. Tenth lens; 11. Eleventh lens; 12. Twelfth lens; 13. Image sensor. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] Please see Figure 1 The present invention provides a technical solution: a zoom radiation-resistant lens, comprising a first lens group, a second lens group and a third lens group arranged sequentially from the object side to the image side, and a lens structure component disposed outside the lens group for fixing the lens group and shielding the lens group from light. The three lens groups are each composed of several groups of lenses with different double-sided curved surface shapes.

[0029] like Figure 1 As shown, in the first lens group, the object side of the first lens 1 is convex, the image side of the first lens 1 is concave curved, the object side of the second lens 2 is convex curved, the image side of the second lens 2 is flat, the object side of the third lens 3 is convex curved, the image side of the third lens 3 is flat, the object side of the fourth lens 4 is flat, the image side of the fourth lens 4 is concave curved, the fifth lens 5 is double-sided concave curved, and the object side of the sixth lens 6 is convex curved, the image side of the sixth lens 6 is flat.

[0030] In the second lens group, the seventh lens 7 has a double-sided convex curved surface shape, the eighth lens 8 has a double-sided convex curved surface shape, and the ninth lens 9 has a double-sided concave curved surface shape.

[0031] In the third lens group, the object side of the tenth lens 10 is flat, the image side of the tenth lens 10 is convex curved, the eleventh lens 11 is double-convex, the object side of the twelfth lens 12 is concave curved, and the image side of the first lens 1 is flat.

[0032] Conventional radiation-resistant optical glass incorporates lanthanide elements like cerium or lead, but this method alone cannot fully meet the low dispersion and high refractive index requirements of optical glass. Therefore, we need to select various materials to match different refractive indices and Abbe numbers, especially tantalum-doped radiation-resistant glass grade G1, which achieves high refractive index and moderate dispersion. Lead-doped glass grades should be avoided in the design process to prevent yellowing of the glass. Titanium-doped materials provide another required grade, G2, which is indispensable for radiation-resistant optical lens design. Barium-doped glass grade G3, a crown glass with a low refractive index but extremely low dispersion, is the most frequently used type in lenses. Cerium-doped glass grade G4, with its high refractive index and very low dispersion, is the most important grade affecting the optical resolution of the entire radiation-resistant lens.

[0033] Based on the design objectives of this design, four types of radiation-resistant optical materials, as shown in Table 1 below, are selected to design a radiation-resistant lens.

[0034]

[0035] Table 1

[0036] This design requires a total of 12 glass elements. The lens optical design diagram is as follows: Figure 1 As shown. To match the image sensor 13, the back focal distance a is designed to be 14mm. Light enters from the left and converges onto the image sensor surface on the right side 1.7. The glass elements are numbered 1-12 from left to right, and the lens numbers are shown in Table 2 below.

[0037] Glass serial number Glass grade number 1 G1 2 G3 3 G4 4 G2 5 G3 6 G1 7 G1 8 G3 9 G2 10 G4 11 G3 12 G1

[0038] Table 2

[0039] Considering that some metals (such as cobalt and zinc) can be activated under nuclear neutron radiation, and subsequently become radioactive, the next step after completing the optical design is to consider the structural design. In the structural design, the first step is to determine what materials to use to fabricate the lens structural components. The lens structural components serve two purposes: first, to secure the glass used on the optical lens; and second, to shield against external light, preventing stray light from entering the lens. Considering that nuclear radiation can cause rapid aging of polymer materials, this design specifically chooses a robust tungsten-nickel alloy that is free of cobalt and zinc to fabricate the structural components. The alloy contains 90% tungsten and 10% nickel.

[0040] To prevent stray light from entering the lens, i.e., to block external light, we need to blacken the inner surface of the tungsten-nickel alloy during the design process. Blackening is a process that creates a dense black oxide layer on the alloy surface, preventing light reflection. We use a special oxidizing agent for optical lenses for high-temperature treatment, specifically a concentrated solution of NaNO+ and NaOH. The workpiece to be blackened is placed in this solution and boiled at approximately 140°C for 2 hours. This process creates a dense oxide layer on the metal surface, effectively preventing light reflection.

[0041] After the lens design and fabrication were completed, we irradiated it with gamma rays using a Co60 radiation source at a dose rate of 3000 Gy / h. After 334 hours of irradiation, the total dose reached 1 × 10⁻⁶. 6 Gy. After irradiation, the lens image remained intact. Immediately after the experiment, the lens transmittance was tested, and the comparison of lens transmittance before and after irradiation is shown in Table 3 below.

[0042] Before irradiation After irradiation Percentage decrease in transmittance before and after irradiation Light transmittance 92％ 52％ 43％

[0043] Table 3

[0044] The data in Table 3 shows that after the lens was subjected to high-intensity irradiation, the light transmittance decreased by only 43%. The design target has been achieved.

[0045] The zoom radiation-resistant optical specifications in this embodiment are shown in Table 4 below.

[0046] focal length 15~150mm Through band 400~700mm Diagonal image height 21.6mm F-number 2.8 Maximum aperture 85mm TTL 195mm Number of lenses 12

[0047] Table 4

[0048] In summary, this embodiment has the following advantages: (1) a direct-view lens, requiring no additional shielding or refraction; (2) a high dose, supporting a dose rate of 3000 Gy / h (Co60), and supporting 1×10 6 (2) Total Gy dose (Co60), transmittance decreases by no more than 50% after irradiation; (3) Requires few materials, simple design, and low cost; (4) Large imaging surface, imaging circle greater than φ21.6mm, covering up to 4 / 3 of the sensor, with high compatibility; (5) Zoom design, focal length 15-150mm, which can simultaneously cover large angle and long distance observation; (6) Large aperture design, F=2.8; (7) High resolution, higher than 4 million pixels, which is better than the resolution of current radiation-resistant lenses in the industry, realizing high-definition monitoring.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A zoom radiation-resistant lens, comprising a first lens group, a second lens group, and a third lens group arranged sequentially from the object side to the image side, and a lens structure component disposed outside the lens groups for fixing the lens groups and shielding them from light, characterized in that, The three lens groups are each composed of several groups of lenses with different double-sided curved surface shapes; Along the object-to-image direction, the first lens group consists of a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), and a sixth lens (6). The first lens (1) is heavy flint glass doped with tantalum, the second lens (2) is heavy crown glass doped with barium, the third lens (3) is heavy lanthanum flint glass doped with cerium, the fourth lens (4) is heavy flint glass doped with titanium, the fifth lens (5) is heavy crown glass doped with barium, and the sixth lens (6) is heavy flint glass doped with tantalum. The second lens group consists of a seventh lens (7), an eighth lens (8) and a ninth lens (9). The seventh lens (7) is heavy flint glass doped with tantalum, the eighth lens (8) is heavy crown glass doped with barium, and the ninth lens (9) is heavy flint glass doped with titanium. The third lens group consists of a tenth lens (10), an eleventh lens (11) and a twelfth lens (12). The tenth lens (10) is heavy lanthanum flint glass doped with cerium, the eleventh lens (11) is heavy crown glass doped with barium, and the twelfth lens (12) is heavy flint glass doped with tantalum. In the first lens group, the object side of the first lens (1) is convex, the image side of the first lens (1) is concave curved, the object side of the second lens (2) is convex curved, the image side of the second lens (2) is flat, the object side of the third lens (3) is convex curved, the image side of the third lens (3) is flat, the object side of the fourth lens (4) is flat, the image side of the fourth lens (4) is concave curved, the fifth lens (5) is double-sided concave curved, the object side of the sixth lens (6) is convex curved, and the image side of the sixth lens (6) is flat; In the second lens group, the seventh lens (7) is a double-sided convex curved surface, the eighth lens (8) is a double-sided convex curved surface, and the ninth lens (9) is a double-sided concave curved surface. In the third lens group, the object side of the tenth lens (10) is flat, the image side of the tenth lens (10) is convex curved, the eleventh lens (11) is double-sided convex, the object side of the twelfth lens (12) is concave curved, and the image side of the first lens (1) is flat. The refractive index of the tantalum-doped heavy flint glass is Nd1, and 1.7 < Nd1 < 1.9, and the dispersion coefficient is Vd1, and 18 < Vd1 < 30. The refractive index of the titanium-doped heavy flint glass is Nd2, and 1.7 < Nd2 < 1.9, and the dispersion coefficient is Vd2, and 20 < Vd2 < 35. The refractive index of the barium-doped crown glass is Nd3, and 1.5 < Nd3 < 1.65, and the dispersion coefficient is Vd3, and 45 < Vd3 < 70. The cerium-doped heavy lanthanum flint glass has a refractive index of Nd⁴, where 1.7 < Nd⁴ < 1.9, and a dispersion coefficient of Vd⁴, where 35 < Vd⁴ < 55.

2. The zoom radiation-resistant lens according to claim 1, characterized in that, The focal length of the radiation-resistant lens is 15-150mm, wherein the focal length a of the third lens group is no greater than 15mm.

3. A zoom radiation-resistant lens according to claim 2, characterized in that, The lens structure is made of tungsten-nickel alloy with a blackened inner surface.

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