Fixing method of deep hypothermia lens group capable of resisting mechanical vibration

Abstract

The invention discloses a fixing method of a mechanical vibration resistant profound hypothermia lens group. The fixing method is suitable for assembling a mechanical vibration resistant low-stress lens group applied to profound hypothermia. The lens group is composed of a lens, a lens seat and epoxy glue. On the premise that heat transmission, low stress and high reliability are ensured, the required glue filling amount is determined according to the borne external force, the glue joint strength, the lens diameter and the lens base diameter, good mechanical strength can be achieved, and the strength requirement can be met; the epoxy glue adopts four-section symmetrical glue joint and is cured at room temperature, and the surface type of the lens meets the use requirement after verification; the device is simple in structure, convenient to operate, good in compatibility and high in reliability. The method can be applied to various mechanical vibration resistant profound hypothermia lens group fixing processes.

Description

Technical Field

[0001] The invention relates to a lens bonding process, and in particular to a method for fixing a deep-cryogenic lens group resistant to mechanical vibration, which is suitable for fixing a deep-cryogenic optical-mechanical structure with high mechanical resistance and reliability. Background Art

[0002] In order to better meet the infrared detection needs of extraterrestrial objects, high sensitivity and low noise are inevitable development trends, and cold optical technology is one of the effective means to achieve this goal. Cold optical technology is to place all optical elements and detectors belonging to the infrared optical system in the rear optical path assembly (cold box / dewar), and use the cold box to reduce the temperature of these optical elements and detectors to the operating temperature, thereby effectively suppressing the influence of thermal radiation and stray light of the optical elements and their supporting structures on the detection performance, and greatly reducing the background noise.

[0003] Compared with traditional mechanical connection, adhesive bonding has a smaller mass, especially for precision optical instruments, it can simplify the structure and reduce the mass, and the material utilization rate is higher; because the adhesive has a higher flexibility, it can effectively reduce the impact of temperature on the lens when the temperature rises or falls; because adhesive bonding is a connection between two adhesive bonding surfaces, the contact area is larger than that of traditional mechanical connection, so the stress distribution is more uniform, and the stress peak on the bonding surface is relatively small, so the fatigue resistance and creep resistance are better. Adhesive bonding can connect special-shaped, complex, tiny or very thin components and metals and non-metals to each other, simplifying the process of complex structures; using adhesive bonding, the equipment required for assembly is simple, easy to operate, noiseless, good working conditions, high labor productivity, and low cost; the sealing of adhesive bonding is reliable. For some precision optical instruments, in order to increase the refractive index of the medium, immersion technology is required, and adhesive bonding technology can well achieve the requirements of sealing and low stress; the working temperature can be modified to reach -200℃ when there are special requirements.

[0004] ~+1000℃, greatly expanding the use environment of optical instruments.

[0005] In the manufacturing process of low-temperature optical lenses, various optical instruments imported from abroad generally use bonding technology to assemble optical parts, usually using epoxy resin, polyurethane rubber adhesive, cyanoacrylate hydrochloric acid adhesive and sealant (silicone, etc.). For example, the uvidec-100Ⅱ ultraviolet spectrophotometer made in Japan, almost all optical parts are assembled by bonding (including gratings). In addition, many optical instruments are developing in the direction of structural simplification, in which the application of bonding technology plays a very important role. However, the bonding technology of the above products has the problem that when the working temperature rises, the bonding strength of the adhesive will decrease significantly with the increase of temperature; moreover, the anti-peeling, anti-bending and impact and vibration performance is poor, resulting in the lens surface shape not meeting the use requirements. Therefore, it is only suitable for environments with little impact and has high requirements for environmental stability.

[0006] The Chinese invention patent with announcement number CN105700109B discloses a micro-stress support structure for a large-aperture reflector, which uses a mirror seat and an axial fastening ring with multiple protrusions to fix the large-aperture reflector, and ensures the surface accuracy of the reflector by setting stress relief grooves.

[0007] The Chinese invention patent with announcement number CN108227111B discloses a method for reducing the bonding stress of a large-aperture aspherical hollow reflector, wherein the main mirror is assisted in positioning by a main mirror pressure plate and a pressure plate rubber pad, and the main reflector is fixed by injecting glue through the glue injection hole.

[0008] The above patents focus on the innovation of micro-stress structure and the innovation of bonding method in combination with structure in reducing stress, but the structure is complex and the process is complicated. No special process design and innovation are made for the lens group resistant to mechanical vibration for deep cryogenic use. Summary of the invention

[0009] The purpose of the present invention is to provide a method for fixing a cryogenic lens group that is resistant to mechanical vibration, which overcomes the defects of the prior art in that the lens surface deforms greatly and has poor resistance to high-strength mechanical conditions under low-temperature environments. A special process design is carried out for the cryogenic lens group, and the amount of glue for the lens group is designed in combination with the mechanical conditions, and an innovation is made in the implementation method.

[0010] To achieve the above object, the technical solution of the present invention is:

[0011] A method for fixing a cryogenic lens group resistant to mechanical vibration, the lens group comprises a lens, a lens seat and epoxy glue, the lens seat is provided with a mounting groove for placing the lens, a bonding gap for filling the epoxy glue is provided between the lens and the side wall of the mounting groove, and the bonding width filled with the epoxy glue is set according to the diameter of the lens and the diameter of the mounting groove; the method is characterized in that the steps of the lens group fixing method are as follows:

[0012] Step 1, determine the effective thickness H of the epoxy adhesive;

[0013] Step 2, determine the bonding width W;

[0014] Step 3, determining the epoxy glue filling amount Q according to the bonding width W and the effective thickness H of the epoxy glue;

[0015] Step 4: Prepare epoxy glue with the fill amount Q determined in step 3 and fix the lens group.

[0016] In step 1, the method for confirming the effective thickness H of the epoxy adhesive is as follows:

[0017] First, calculate the external force F1 on the lens according to the mechanical conditions and the mass m of the lens itself to calculate the resultant force F on the lens, F = F1 + mg, formula 1;

[0018] Second, the required bonding area S1 is calculated based on the shear strength σ of the epoxy glue, the safety factor δ, and the external force F exerted on the lens, S1 = F*δ / σ, formula 2;

[0019] Third, calculate the annular circumference L of the epoxy glue according to the lens diameter D1.

[0020] L=π*D1 Formula 3;

[0021] Fourth, the theoretical thickness H1 of the epoxy glue filling is calculated based on the epoxy glue bonding area S1 and the annular circumference L of the epoxy glue, that is,

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

[0023] Fifth, the effective coefficient ε of the epoxy glue filling is calculated according to the side glue filling range θ1 and the non-glue filling area θ2 of the epoxy glue, wherein the side glue filling range θ1 and the non-glue filling area θ2 are arranged at intervals.

[0024] ε=θ1 / 90 Formula 5;

[0025] Sixth, the effective thickness H of the epoxy glue is calculated according to the effective coefficient ε of the epoxy glue filling, the lens edge thickness H2 and the theoretical thickness H1 of the filling glue, H2 / 5≤H=H1 / ε≤H2, that is:

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

[0027] In the step 2, the bonding width W is calculated according to the lens diameter D1 and the diameter D2 of the mounting groove, W=(D2-D1) / 2 (Formula 7).

[0028] In step 3, the method for determining the epoxy glue filling amount Q is as follows:

[0029] First, calculate the annular surface area S2 of the epoxy glue 3 according to the lens diameter D1 and the diameter D2 of the mounting groove.

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

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

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

[0033] In step 4, the method of fixing the lens group is as follows:

[0034] First, prepare the epoxy glue required for bonding and let it stand at room temperature for 6-8 hours;

[0035] Second, evenly fill the epoxy glue with the required glue amount Q into the side glue filling range θ1 of the lens;

[0036] Third, use the centering equipment to adjust the lens and lens holder to be concentric, and ensure that the concentricity is no more than 0.01 mm. After adjustment, leave it still and cure it at room temperature.

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

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

[0039] The present invention is a low-stress and high-reliability infrared lens bonding process for vacuum packaging in a cold optical system, which realizes low-stress and high-reliability packaging of the optical-mechanical structure of the vacuum cold optical system. The advantages of the present invention are: 1. Simple structure, convenient operation, and low cost; 2. The bonding area is calculated based on the external force on the lens according to simulation analysis or mechanical input and the shear strength of the epoxy glue, and it has good mechanical strength and can meet the strength requirements of vibration under high mechanical conditions at low temperatures; 3. The epoxy glue in the present invention adopts four-stage symmetrical bonding and is cured at room temperature. After verification, the lens has a small deformation at a low temperature of 77K, and its surface shape meets the use requirements. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0042] Figure 3 The figure is a comparison diagram of lens surface shapes before and after applying the lens group fixing method of the present invention.

[0043] In the figure: 1-lens, 2-lens seat, 21-mounting groove; 3-epoxy glue. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with the accompanying drawings, which are only used for exemplary description and cannot be understood as limiting the present invention.

[0045] In order to more concisely describe the present embodiment, some parts known to those skilled in the art but not related to the main content of the present invention are omitted in the drawings or descriptions. In addition, for the convenience of description, some parts in the drawings are omitted, enlarged or reduced, but they do not represent the size or entire structure of the actual product.

[0046] The present invention discloses a method for fixing a deep cryogenic lens group resistant to mechanical vibration, such as Figure 1 As shown, the lens assembly includes a lens 1, a lens holder 2 and epoxy glue 3. The lens holder 2 is provided with a mounting groove 21 for placing the lens 1. A bonding gap for filling the epoxy glue 3 is provided between the lens 1 and the side wall of the mounting groove 21. The bonding width filled with the epoxy glue 3 is set according to the diameter of the lens 1 and the diameter of the mounting groove 21. The lens 1 is made of GE material, the lens holder 2 is made of ceramic material, and a bonding width W is left between the edge of the lens 1 and the side wall of the mounting groove 21 to facilitate the filling of glue.

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

[0048] Step 1, determining the effective thickness H of the epoxy adhesive 3;

[0049] Step 2, determine the bonding width W;

[0050] Step 3, determining the filling amount Q of the epoxy glue 3 according to the bonding width W and the effective thickness H of the epoxy glue 3;

[0051] Step 4: prepare epoxy glue 3 with the filling amount Q determined in step 3, and fix the lens group.

[0052] The specific implementation methods are as follows:

[0053] In the step 1, the method for confirming the effective thickness H of the epoxy adhesive 3 is as follows:

[0054] First, the external force F1 acting on the lens 1 is calculated according to the mechanical conditions, and the mass m of the lens 1 itself is used to calculate the resultant force F acting on the lens 1, F=F1+mg, formula 1;

[0055] The force F1 on the lens is calculated by mechanical conditions = 686.147N. The mass m of the lens itself is 0.35kg. The external force F on the lens is calculated to be F = F1 + mg = 689.43N.

[0056] 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 exerted on the lens, S1 = F*δ / σ, formula 2;

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

[0058] Third, calculate the annular circumference L of the epoxy adhesive 3 according to the diameter D1 of the lens 1,

[0059] L = π * D1; Formula 3;

[0060] The diameter of lens 1 is D1=100 mm, and L=314 mm.

[0061] Fourth, the theoretical thickness H1 of the epoxy glue 3 is calculated according to the bonding area S1 of the epoxy glue 3 and the circumference L of the ring surface of the epoxy glue 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, if Figure 2 As shown, the effective coefficient ε of the epoxy glue 3 is calculated according to the side glue filling range θ1 and the non-glue filling area θ2 of the epoxy glue 3, wherein the side glue filling range θ1 and the non-glue filling area θ2 are set at intervals, ε=θ1 / 90 Formula 5;

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

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

[0067] Epoxy glue 3 adopts four-stage symmetrical bonding. After curing at room temperature, the lens is deformed less at a low temperature of 77K, and its surface shape meets the use requirements.

[0068] Sixth, the effective thickness H of the epoxy glue 3 is calculated according to the effective coefficient ε of the epoxy glue 3, the edge thickness H2 of the lens 3 and the theoretical thickness H1 of the epoxy glue, 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 the second step, the bonding width W is calculated according to the diameter D1 of the lens 1 and the diameter D2 of the mounting groove 21, W=(D2-D1) / 2, Formula 7,

[0072] The diameter D1 of the lens 1 is 100 mm, the diameter D2 of the mounting groove 21 is 100.6 mm, and the calculated bonding width W is 0.3 mm. The bonding width W has a value range of 0.1-0.5 mm.

[0073] In step 3, the method for determining the filling amount Q of the epoxy adhesive 3 is as follows:

[0074] First, the annular surface area S2 of the epoxy adhesive 3 is calculated according to the diameter D1 of the lens 1 and the diameter D2 of the mounting groove 21.

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

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

[0077] Second, the required amount Q of epoxy glue 3 is calculated according to the annular surface area S2 of epoxy glue 3, the effective thickness H of epoxy glue 3 and the density ρ of epoxy glue 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 adhesive 3 is ρ = 1.2 g / cm 3 , then, Q = 0.15g.

[0080] In step 4, the method for fixing the lens group is as follows:

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

[0082] According to the glue preparation process, 0.15g of epoxy glue 3 required for bonding was prepared and allowed to stand at room temperature for 7 hours.

[0083] Second, the epoxy glue 3 with the required glue amount Q is evenly filled in the glue filling range θ1 of the side of the lens 1;

[0084] The prepared epoxy glue 3 is evenly filled into the four side glue filling ranges of the lens 1 within 80° using a special tool.

[0085] Third, use the centering equipment to adjust the lens 1 and the lens holder 2 to be concentric, and ensure that the concentricity is not greater than 0.01mm. After adjustment, leave it alone and cure it at room temperature. Curing at room temperature for 7 days, and ensure that 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 is the surface shape value of the unmounted lens 1 - bare lens, and the right side is the surface shape value of the lens 1 fixed by the method of the present invention. The comparison between the two fully verifies that the surface shape of the lens 1 meets the use requirements by applying the fixing method of the present invention.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. That is, any equivalent changes and modifications made according to the content of the patent application scope of the present invention should be within the technical scope of the present invention.

Claims

1. A method for fixing a cryogenic lens group resistant to mechanical vibration, the lens group comprising a lens (1), a lens seat (2) and epoxy glue (3), the lens seat (2) being provided with a mounting groove (21) for placing the lens (1), a bonding gap for filling the epoxy glue (3) being provided between the lens (1) and the side wall of the mounting groove (21), the bonding width filled with the epoxy glue (3) being 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, determining the effective thickness H of the epoxy adhesive (3); Step 2, determine the bonding width W; Step 3, determining the filling amount Q of the epoxy glue (3) according to the bonding width W and the effective thickness H of the epoxy glue (3); Step 4: Prepare epoxy glue (3) with the glue filling amount Q determined in step 3, and fix the lens group.

2. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 1, characterized in that: In the step 1, the method for confirming the effective thickness H of the epoxy adhesive (3) is as follows: First, the external force F1 acting on the lens (1) is calculated according to mechanical conditions, and the mass m of the lens (1) itself is used to calculate the resultant force F acting on the 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 exerted on the lens, S1 = F*δ / σ, formula 2; Third, the circumference L of the ring surface of the epoxy glue (3) is calculated according to the diameter D1 of the lens (1). L=π*D1 Formula 3; Fourth, the theoretical thickness H1 of the epoxy glue 3 is calculated based on the bonding area S1 of the epoxy glue (3) and the circumference L of the ring surface of the epoxy glue (3), that is, H1=S1 / L=(F*δ / σ) / (π*D1)=(F1+mg)*δ / (π*D1*σ) Formula 4; Fifth, the effective coefficient ε of the epoxy glue (3) is calculated according to the side glue filling range θ1 and the non-glue filling area θ2 of the epoxy glue (3), wherein the side glue filling range θ1 and the non-glue filling area θ2 are arranged at intervals, ε=θ1 / 90 Formula 5; Sixth, the effective thickness H of the epoxy glue (3) is calculated according to the effective coefficient ε of the epoxy glue (3), the edge thickness H2 of the lens (1) and the theoretical thickness H1 of the epoxy glue, H2 / 5≤H=H1 / ε≤H2, that is: H2 / 5≤90*(F1+mg)*δ / (π*D1*σ*θ1)≤H2 Formula 6.

3. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 2, characterized in that: In the step 2, the bonding width W is calculated according to the diameter D1 of the lens (1) and the diameter D2 of the mounting groove (21), W=(D2-D1) / 2 (Formula 7).

4. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 3, characterized in that: In step 3, the method for determining the filling amount Q of the epoxy glue (3) is as follows: First, the annular surface area S2 of the epoxy adhesive 3 is calculated according to the diameter D1 of the lens (1) and the diameter D2 of the mounting groove (21). S2=π((D2 / 2) 2 -(D1 / 2) 2 ) Formula 8; Second, the required amount Q of epoxy glue (3) is calculated according to the annular surface area S2 of epoxy glue (3), the effective thickness H of epoxy glue (3) and the density ρ of epoxy glue (3). Q=S2*H*ρ=90*((D2 / 2) 2 -(D1 / 2) 2 )*(F1+mg)*δ*ρ / (D1*σ*θ1)Formula 9.

5. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 4, characterized in that: In step 4, the method of fixing the lens group is as follows: First, prepare the epoxy glue (3) required for bonding and let it stand at room temperature for 6-8 hours; Second, the epoxy glue (3) with the required glue amount Q is evenly filled into the glue filling range θ1 on the side of the lens (1); Third, the lens (1) and the lens holder (2) are adjusted concentrically using a centering device, and the concentricity is ensured to be no greater than 0.01 mm. After adjustment, they are left stationary and cured at room temperature.

6. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 2, characterized in that: The bonding width W ranges from 0.1 to 0.5 mm.

7. The method for fixing a cryogenic lens assembly resistant to mechanical vibration according to claim 3, characterized in that: The side glue filling range θ1 is divided into four sections, and the area between two adjacent glue filling ranges θ1 is a non-glue filling area θ2, wherein 15°≤θ1≤85°, θ1+θ2=90°.

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