A method for fixing a cryogenic lens assembly resistant to mechanical vibration

Abstract

This invention discloses a method for fixing cryogenic lens assemblies resistant to mechanical vibration, applicable to the assembly of low-stress lens assemblies resistant to mechanical vibration in cryogenic applications. The lens assembly consists of a lens, a lens mount, and epoxy resin. Under the premise of ensuring heat transfer, low stress, and high reliability, the required amount of epoxy resin is determined based on the external force, adhesive strength, lens diameter, and lens mount diameter, achieving good mechanical strength and meeting strength requirements. The epoxy resin uses a four-segment symmetrical bonding method and cures at room temperature; verification has shown that the lens surface shape meets the application requirements. This invention has a simple structure, is easy to operate, has good compatibility, and high reliability. It can be applied to various cryogenic lens assembly fixing processes resistant to mechanical vibration.

Description

Technical Field

[0001] This invention relates to lens bonding technology, specifically to a method for fixing cryogenic lens assemblies resistant to mechanical vibration, which is suitable for fixing cryogenic optomechanical structures with high mechanical reliability. Background Technology

[0002] To better meet the infrared detection needs of extraterrestrial objects, high sensitivity and low noise are inevitable development trends, and cold optics technology is one of the effective means to achieve this goal. Cold optics technology involves placing all optical components and detectors of the infrared optical system in a rear optical path assembly (cold box / Dewar). The cold box lowers the temperature of these optical components and detectors to their operating temperature, thereby effectively suppressing the impact of thermal radiation and stray light from the optical components and their supporting structure on detection performance and minimizing background noise.

[0003] Compared to traditional mechanical connections, adhesive bonding results in less weight, especially beneficial for precision optical instruments. It simplifies structures, reduces weight, and increases material utilization. Due to the high flexibility of adhesives, the effects of temperature on lenses are effectively reduced during heating and cooling. Since adhesive bonding involves the connection of two bonding surfaces, the contact area is larger than in traditional mechanical connections, leading to more uniform stress distribution and smaller stress peaks on the bonding surface, resulting in better fatigue and creep resistance. Adhesive bonding can connect irregularly shaped, complex, tiny, or very thin components, as well as metals and non-metals, simplifying the manufacturing process for complex structures. Assembly using adhesive bonding requires simple equipment, is easy to operate, is noiseless, provides good working conditions, high productivity, and lower costs. Adhesive bonding offers reliable sealing; for some precision optical instruments requiring immersion to increase the refractive index of the medium, adhesive bonding effectively achieves the requirements of sealing and low stress. Operating temperatures can be modified to reach -200℃ when special requirements are needed.

[0004] With a temperature range of up to +1000℃, the operating environment for optical instruments is greatly expanded.

[0005] In the manufacturing process of lenses for low-temperature optics, various imported optical instruments commonly employ adhesive bonding technology to assemble optical components. This typically involves using epoxy resin, polyurethane rubber adhesives, cyanoacrylate hydrochloric acid adhesives, and sealants (such as silicone). For example, in the Japanese-made Uvidec-100Ⅱ ultraviolet spectrophotometer, almost all optical components (including gratings) are glued together. Furthermore, many optical instruments are evolving towards simpler structures, and adhesive bonding technology plays a crucial role in this trend. However, the adhesive bonding technology used in these products suffers from several drawbacks. The adhesive strength decreases significantly with increasing operating temperature; moreover, it exhibits poor resistance to peeling, bending, and shock, resulting in lens surfaces that do not meet usage requirements. Therefore, it is only suitable for environments with minimal impact and requires high environmental stability.

[0006] Chinese invention patent CN105700109B discloses a micro-stress support structure for a large-aperture reflector. The structure uses a mirror base and an axial fastening ring with multiple protrusions to fix the large-aperture reflector, and a stress-relieving groove is set to ensure the surface accuracy of the reflector.

[0007] Chinese invention patent with announcement number CN108227111B discloses a method for reducing the bonding stress of aspherical large-diameter hollow reflectors. The method involves using a primary mirror pressure plate and a pressure plate rubber pad for auxiliary positioning of the primary mirror, and then fixing the primary reflector by injecting glue through the glue injection hole.

[0008] The patents disclosed above focus on innovations in micro-stress structures and bonding methods to reduce stress, resulting in complex structures and cumbersome processes. They do not include specific process design and innovation for lens assemblies designed to resist mechanical vibrations in deep cryogenic environments. Summary of the Invention

[0009] The purpose of this invention is to provide a method for fixing a cryogenic lens assembly that is resistant to mechanical vibration. This method overcomes the shortcomings of existing technologies, such as large deformation of the lens surface and poor resistance to high-intensity mechanical conditions in cryogenic environments. It features a specialized process design for cryogenic lens assemblies, designs the amount of adhesive used in the lens assembly in conjunction with mechanical conditions, and innovates the implementation method.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A method for fixing a cryogenic lens assembly resistant to mechanical vibration, the lens assembly comprising a lens, a lens mount, and epoxy resin, wherein the lens mount is provided with a mounting groove for placing the lens, and an adhesive gap for filling the epoxy resin is provided between the lens and the sidewall of the mounting groove, the adhesive width for filling the epoxy resin being determined by the diameter of the lens and the diameter of the mounting groove; characterized in that: the fixing method for the lens assembly comprises the following steps:

[0012] Step 1: Determine the effective thickness H of the epoxy resin;

[0013] Step 2: Determine the adhesive bonding width W;

[0014] Step 3: Determine the filler amount Q of epoxy adhesive based on the bonding width W and the effective thickness H of epoxy adhesive;

[0015] Step four: Prepare the epoxy resin with the filler amount Q determined in step three, and fix the lens assembly.

[0016] In step one, the method for confirming the effective thickness H of the epoxy resin is as follows:

[0017] First, calculate the external force F1 acting on the lens based on the mechanical conditions and the mass m of the lens itself, and then calculate the resultant force F acting on the lens, F = F1 + mg (Formula 1).

[0018] Second, calculate the required bonding area S1 based on the shear strength σ of the epoxy adhesive, the safety factor δ, and the external force F on the lens. S1 = F * δ / σ (Formula 2).

[0019] Third, calculate the toroidal circumference L of the epoxy resin based on the lens diameter D1.

[0020] L=π*D1 Formula 3;

[0021] Fourth, calculate the theoretical filler thickness H1 of the epoxy resin based on the bonding area S1 and the circumference L of the epoxy resin ring.

[0022] H1=S1 / L=(F*δ / σ) / (π*D1)=(F1+mg)*δ / (π*D1*σ) Formula 4;

[0023] Fifth, calculate the effective filling coefficient ε of the epoxy resin based on the side filling range θ1 and the non-filling area θ2, where the side filling range θ1 and the non-filling area θ2 are set alternately.

[0024] ε = θ1 / 90 (Formula 5)

[0025] Sixth, calculate the effective thickness H of the epoxy resin based on the effective filling coefficient ε, the lens edge thickness H2, and the theoretical filling thickness H1. H2 / 5 ≤ H = H1 / ε ≤ H2, that is:

[0026] H2 / 5≤90*(F1+mg)*δ / (π*D1*σ*θ1)≤H2 Formula 6.

[0027] In step two, the adhesive bonding width W is calculated based on the lens diameter D1 and the mounting groove diameter D2, where W = (D2 - D1) / 2 (Formula 7).

[0028] The method for determining the epoxy filler amount Q in step three is as follows:

[0029] First, calculate the annular area S2 of epoxy resin 3 based on the lens diameter D1 and the mounting groove diameter D2.

[0030] S² = π((D² / 2) 2 -(D1 / 2) 2 ) Formula 8;

[0031] Second, calculate the required amount of epoxy resin Q based on the annular area S2, the effective thickness H, and the density ρ of the epoxy resin.

[0032] Q = S² * H * ρ = 90 * (D² / 2) 2 -(D1 / 2) 2 )*(F1+mg)*δ*ρ / (D1*σ*θ1) Formula 9.

[0033] The method for fixing the lens group in step four is as follows.

[0034] First, prepare the epoxy adhesive needed for bonding and let it stand at room temperature for 6-8 hours.

[0035] Second, uniformly fill the required amount of epoxy adhesive Q into the adhesive filling range θ1 on the side of the lens.

[0036] Third, use a centering device to adjust the lens and lens mount to be concentric, ensuring that the concentricity is no greater than 0.01mm. After adjustment, leave it stationary and allow it to cure at room temperature.

[0037] The adhesive bonding width W ranges from 0.1 to 0.5 mm.

[0038] The side filling range θ1 is divided into four segments, and the area between two adjacent filling ranges θ1 is the non-filling area θ2, where 15°≤θ1≤85° and θ1+θ2=90°.

[0039] This invention relates to a low-stress, high-reliability bonding process for vacuum-encapsulated infrared lenses in cold optical systems, achieving low-stress, high-reliability encapsulation of the optomechanical structure of vacuum cold optical systems. The advantages of this invention are: 1. Simple structure, convenient operation, and low cost; 2. The bonding area is calculated based on the external force on the lens and the shear strength of the epoxy adhesive according to simulation analysis or mechanical input, exhibiting good mechanical strength that meets the strength requirements of vibration under high mechanical conditions at low temperatures; 3. The epoxy adhesive in this invention uses a four-segment symmetrical bonding method and cures at room temperature. Verification shows that the lens exhibits minimal deformation at a low temperature of 77K, and its surface shape meets the application requirements. Attached Figure Description

[0040] Figure 1 This is a diagram of the lens assembly fixing structure of the present invention;

[0041] Figure 2 This is a top view of the lens assembly fixing structure of the present invention;

[0042] Figure 3 These are comparison images of the lens surface shape before and after applying the lens group fixing method of the present invention.

[0043] In the diagram: 1-lens, 2-lens mount, 21-mounting groove; 3-epoxy resin. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings. The drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0045] To simplify the description of this embodiment, some components that are well-known to those skilled in the art but are not related to the main content of this invention may be omitted in the accompanying drawings or description. Additionally, for ease of description, some components in the drawings may be omitted, enlarged, or reduced, but these do not represent the actual product dimensions or the complete structure.

[0046] This invention discloses a method for fixing a cryogenic lens assembly resistant to mechanical vibration, such as... Figure 1 As shown, the lens assembly includes a lens 1, a lens mount 2, and epoxy resin 3. The lens mount 2 has a mounting groove 21 for placing the lens 1. A bonding gap for filling the epoxy resin 3 is provided between the lens 1 and the sidewall of the mounting groove 21. The bonding width of the epoxy resin 3 is determined by the diameter of the lens 1 and the diameter of the mounting groove 21. The lens 1 is made of GE material, and the lens mount 2 is made of ceramic material. A bonding width W is left between the edge of the lens 1 and the sidewall of the mounting groove 21 to facilitate filling with epoxy resin.

[0047] The steps for fixing the lens group are as follows:

[0048] Step 1: Determine the effective thickness H of epoxy adhesive 3;

[0049] Step 2: Determine the adhesive bonding width W;

[0050] Step 3: Determine the filler amount Q of epoxy adhesive 3 based on the bonding width W and the effective thickness H of epoxy adhesive 3.

[0051] Step four: Prepare epoxy resin 3 with the filler amount Q determined in step three, and fix the lens assembly.

[0052] The specific implementation method is as follows:

[0053] In step one, the method for confirming the effective thickness H of epoxy adhesive 3 is as follows:

[0054] First, calculate the external force F1 acting on lens 1 based on the mechanical conditions, and calculate the resultant force F acting on lens 1 based on the mass m of lens 1 itself, F=F1+mg Formula 1;

[0055] The mechanical conditions are calculated as follows: the force F1 on the lens is 686.147 N, and the mass m of the lens itself is 0.35 kg. Therefore, the external force F on the lens is calculated as F = F1 + mg = 689.43 N.

[0056] Second, the required bonding area S1 is calculated based on the shear strength σ of epoxy adhesive 3, the safety factor δ, and the external force F on the lens. S1 = F * δ / σ (Formula 2).

[0057] Given the shear strength σ of epoxy adhesive 3 = 2 MPa, a safety factor δ = 1.1, and the external force F acting on the lens, the required bonding area S1 = 379.18 mm² is calculated. 2 .

[0058] Third, calculate the toroidal circumference L of epoxy resin 3 based on the diameter D1 of lens 1.

[0059] L = π * D1; Formula 3;

[0060] Lens 1 has a diameter D1 = 100 mm and an L = 314 mm.

[0061] Fourth, calculate the theoretical filler thickness H1 of epoxy adhesive 3 based on the bonding area S1 of epoxy adhesive 3 and the annular circumference L of epoxy adhesive 3, that is...

[0062] H1=S1 / L=(F*δ / σ) / (π*D1)=(F1+mg)*δ / (π*D1*σ) Formula 4;

[0063] H1 = S1 / L = 379.18mm 2 / 314mm=1.20mm.

[0064] Fifth, such as Figure 2 As shown, the effective filling coefficient ε of epoxy resin 3 is calculated based on the side filling range θ1 and the non-filling area θ2 of epoxy resin 3. The side filling range θ1 and the non-filling area θ2 are set at intervals, and ε = θ1 / 90 (Formula 5).

[0065] Preferably, the side filling range θ1 is divided into four segments, and the area between two adjacent filling ranges θ1 is a non-filling area θ2, where 15°≤θ1≤85° and θ1+θ2=90°.

[0066] The side filling area θ1 is 80°, and the non-filled area θ2 is 10°. Therefore, ε=0.89.

[0067] Epoxy Adhesive 3 uses a four-segment symmetrical bonding method. After curing at room temperature, the lens has minimal deformation at a low temperature of 77K, and its surface shape meets the application requirements.

[0068] Sixth, based on the effective filling coefficient ε of epoxy resin 3, the edge thickness H2 of lens 3, and the theoretical filling thickness H1, calculate the effective thickness H of epoxy resin 3. H2 / 5 ≤ H = H1 / ε ≤ H2, that is:

[0069] H2 / 5≤90*(F1+mg)*δ / (π*D1*σ*θ1)≤H2 Formula 6

[0070] H2 / 5≤H=1.36mm≤H2, that is, 0.77mm≤1.36mm≤3.85mm.

[0071] In step two, the adhesive bonding width W is calculated based on the diameter D1 of lens 1 and the diameter D2 of mounting groove 21, where W = (D2 - D1) / 2 (Formula 7).

[0072] Lens 1 has a diameter D1 of 100mm, and mounting groove 21 has a diameter D2 of 100.6mm. The calculated adhesive width W is 0.3mm. The adhesive width W ranges from 0.1mm to 0.5mm.

[0073] The method for determining the filler amount Q of epoxy adhesive 3 in step three is as follows:

[0074] First, calculate the annular area S2 of the epoxy resin 3 based on the diameter D1 of lens 1 and the diameter D2 of mounting groove 21.

[0075] S² = π((D² / 2) 2 -(D1 / 2) 2 ) Formula 8;

[0076] If D1 is 100mm and D2 is 100.6mm, then S2 = 94.53mm 2 .

[0077] Second, the required amount of epoxy resin 3, Q, is calculated based on the annular area S2 of epoxy resin 3, the effective thickness H of epoxy resin 3, and the density ρ of epoxy resin 3.

[0078] Q = S² * H * ρ = 90 * (D² / 2) 2 -(D1 / 2) 2 )*(F1+mg)*δ*ρ / (D1*σ*θ1) Formula 9

[0079] The density of epoxy resin 3 is ρ = 1.2 g / cm³. 3 Therefore, Q = 0.15g.

[0080] The method for fixing the lens group in step four is as follows:

[0081] First, prepare epoxy adhesive 3 for bonding and let it stand at room temperature for 6-8 hours to reduce the fluidity of the adhesive and prevent epoxy adhesive 3 from flowing to the bottom surface of lens 1.

[0082] Prepare 0.15g of epoxy adhesive 3 according to the adhesive preparation process, and let it stand at room temperature for 7 hours.

[0083] Second, the epoxy adhesive 3, with the required amount Q, is evenly filled into the adhesive filling range θ1 on the side of the lens 1.

[0084] Use a special tool to evenly fill the prepared epoxy adhesive 3 into the 80° range of the four sides of lens 1.

[0085] Third, use a centering device to adjust lens 1 and lens mount 2 to be concentric, ensuring the concentricity is no greater than 0.01mm. After adjustment, leave them stationary and cure at room temperature. Cure at room temperature for 7 days, ensuring the curing temperature is set at 26±3℃ and the humidity is controlled at 45%+3%.

[0086] like Figure 3 As shown, the left side shows the surface profile values ​​of lens 1 (bare lens) before installation, and the right side shows the surface profile values ​​of lens 1 fixed using the method of the present invention. The comparison between the two fully verifies that the surface profile of lens 1 meets the usage requirements when the fixing method of the present invention is applied.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. All equivalent changes and modifications made within the scope of the claims of this invention should be considered within the technical scope of this invention.

Claims

1. A method for fixing a cryogenic lens assembly resistant to mechanical vibration, the lens assembly comprising a lens (1), a lens mount (2), and epoxy resin (3), wherein the lens mount (2) is provided with a mounting groove (21) for placing the lens (1), and an adhesive gap for filling the epoxy resin (3) is provided between the lens (1) and the sidewall of the mounting groove (21), and the adhesive width for filling the epoxy resin (3) is set according to the diameter of the lens (1) and the diameter of the mounting groove (21); characterized in that: The steps for fixing the lens group are as follows: Step 1: Determine the effective thickness H of the epoxy adhesive (3) as follows: First, calculate the external force F1 acting on lens (1) based on the mechanical conditions, and calculate the resultant force F acting on lens (1) based on the mass m of lens (1). F = F1 + mg (Formula 1) Second, the required bonding area S1 is calculated based on the shear strength σ of the epoxy adhesive (3), the safety factor δ, and the external force F experienced by the lens. S1=F*δ / σ Formula 2; Third, calculate the toroidal circumference L of the epoxy resin (3) based on the diameter D1 of the lens (1). L=π*D1 Formula 3; Fourth, the theoretical filler thickness H1 of the epoxy adhesive (3) is calculated based on the bonding area S1 of the epoxy adhesive (3) and the circumference L of the annular surface of the epoxy adhesive (3), that is... H1=S1 / L=(F*δ / σ) / (π*D1)=(F1+mg)*δ / (π*D1*σ) Formula 4; Fifth, the effective filling coefficient ε of epoxy resin (3) is calculated based on the side filling range θ1 and the non-filling area θ2 of epoxy resin (3), wherein the side filling range θ1 and the non-filling area θ2 are set alternately. ε = θ1 / 90 (Formula 5) Sixth, calculate the effective thickness H of epoxy resin (3) based on the effective filling coefficient ε of epoxy resin (3), the edge thickness H2 of lens (1), and the theoretical filling thickness H1. H2 / 5≤H=H1 / ε≤H2, that is: H2 / 5≤90*(F1+mg)*δ / (π*D1*σ*θ1)≤H2 Formula 6; Step 2, determine the bonding width W; calculate the bonding width W based on the diameter D1 of the lens (1) and the diameter D2 of the mounting groove (21). W = (D2 - D1) / 2 (Formula 7) Step 3: Determine the filler amount Q of epoxy adhesive (3) based on the bonding width W and the effective thickness H of epoxy adhesive (3); the method for determining the filler amount Q of epoxy adhesive (3) is as follows: First, calculate the annular area S2 of epoxy resin 3 based on the diameter D1 of lens (1) and the diameter D2 of mounting groove (21). S² = π((D² / 2) 2 -(D1 / 2) 2 ) Formula 8; Second, the required amount of epoxy resin (3) Q is calculated based on the annular area S2 of the epoxy resin (3), the effective thickness H of the epoxy resin (3), and the density ρ of the epoxy resin (3). Q=S2*H*ρ=90*((D2 / 2) 2 -(D1 / 2) 2 )*(F1+mg)*δ*ρ / (D1*σ*θ1) Formula 9; Step 4: Prepare epoxy resin (3) with the filler amount Q determined in Step 3, and fix the lens assembly.

2. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 1, characterized in that: The method for fixing the lens group in step four is as follows. First, prepare the epoxy adhesive (3) required for bonding and let it stand at room temperature for 6-8 hours; Second, the epoxy adhesive (3) with the required amount Q is evenly filled into the adhesive filling range θ1 on the side of the lens (1). Third, use a centering device to adjust the lens (1) and lens mount (2) to be concentric, and ensure that the concentricity is no more than 0.01 mm. After adjustment, place it still and cure it at room temperature.

3. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 1, characterized in that: The adhesive bonding width W ranges from 0.1 to 0.5 mm.

4. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 1, characterized in that: The side filling range θ1 is divided into four segments, and the area between two adjacent filling ranges θ1 is the non-filling area θ2, where 15°≤θ1≤85° and θ1+θ2=90°.

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