Polishing process of infrared detector packaging window lens

Abstract

The invention relates to the technical field of infrared lens processing, in particular to a polishing process of an infrared detector packaging window lens, which comprises the following steps of: S1, cutting an initial lens into a convex-transparent hemispherical lens, and reserving an integrated circular ring on the outer ring of the convex-transparent hemispherical lens; s2, the convex-transparent hemispherical lens and the circular ring are installed on a workbench, and the circular ring is clamped through a clamp; s3, two polishing heads are adopted to polish the convex surface and the concave surface of the convex hemispherical lens at the same time; s4, cutting the polished convex-transparent hemispherical lens, and cutting off a circular ring on the outer ring of the convex-transparent hemispherical lens to obtain a polished lens; s5, cleaning the polished lens, and controlling the smooth finish of the convex surface and the concave surface of the cleaned polished lens to be 60-40 levels to obtain a cleaned lens; s6, one face of the cleaned lens is plated with a carbon film, then the other face of the cleaned lens is plated with an infrared film, the thickness of the carbon film is 1-1.5 microns, and the film layer uniformity of the carbon film is smaller than 50 nm.

Description

Technical Field

[0001] The invention relates to the technical field of infrared lens processing, and in particular to a polishing process for an infrared detector packaging window lens. Background Art

[0002] As the main product of infrared lenses, infrared window lenses are widely used, mainly in infrared security monitoring, cameras, vehicle-mounted infrared night vision, fire protection, power detection, medical thermometers, etc. Among them, short waves are mainly used in the military field, while long waves are mainly used in the civilian field. Infrared window lenses need to be coated before use. The coating types include double-sided infrared film, double-sided carbon film, infrared film + carbon film (i.e. one side is coated with carbon film and the other side is coated with infrared film) and other film structures. The infrared film + carbon film coating structure is the most mainstream usage mode. The commonly used infrared film + carbon film coating method is: after single-sided polishing, first coat one side with carbon film, then polish the other side and coat the infrared film.

[0003] In the prior art, when single-sided polishing is performed on a convex hemispherical lens, a main shaft, an upper jig, a swing arm and a grinding dish are generally used. The upper jig is used to directly apply pressure to the convex hemispherical lens to clamp it, and then the swing arm drives the convex hemispherical lens to swing so that its surface contacts the rotating grinding dish for polishing. The main problems are that the upper jig needs to directly apply clamping force to the convex hemispherical lens to prevent the convex hemispherical lens from rotating during polishing, and the polishing efficiency of single-sided polishing needs to be improved.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0005] The purpose of the present invention is to design a process that can fix a convex hemispherical lens without directly applying a clamping force to the convex hemispherical lens, and can polish both sides of the convex hemispherical lens at the same time to improve the polishing efficiency, so as to solve the above-mentioned deficiencies in the technology.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a polishing process for an infrared detector package window lens, comprising the following steps: S1. Cutting the initial lens into a convex hemispherical lens and retaining the integrated outer ring of the convex hemispherical lens; S2. Install the convex hemispherical lens and the ring on the workbench and clamp the ring with a clamp; S3. Use two polishing heads to polish the convex and concave surfaces of the convex hemispherical lens simultaneously; S4. The polished convex hemispherical lens is cut, and the outer ring of the convex hemispherical lens is cut off to obtain a polished lens; S5. Clean the polished lens, control the finish of the convex and concave surfaces of the polished lens after cleaning to 60~40 levels, and obtain a clean lens; S6. Coat one side of the cleaned lens with a carbon film, and then coat the other side with an infrared film, wherein the thickness of the carbon film is 1~1.5μm, and the film uniformity of the carbon film is less than 50nm; the thickness of the infrared film is 2~3μm, and the film uniformity of the infrared film is less than 20nm, and the film thickness of the infrared film is 1.5~2 times that of the carbon film.

[0007] Preferably, in step S3, the rotation directions of the two polishing heads are opposite, and the difference between the friction force generated when the polishing heads polish the concave surface and the friction force generated when the polishing heads polish the convex surface is smaller than the friction force applied by the fixture to the ring.

[0008] Preferably, in step S3, the polishing process uses 0.25 μm diamond polishing liquid, and the polishing speed is 500-1200 r / min.

[0009] Preferably, in step S5, ultrasonic cleaning is adopted, and the ultrasonic cleaning agent is isopropyl alcohol; the frequency of ultrasonic cleaning is 67-80 kHz, and the cleaning time is 0.5-1 h.

[0010] Preferably, in step S6, when a carbon film is coated on one side of the infrared window lens, a high temperature resistant tape is used to protect the other side of the infrared window lens; after the carbon film is coated, the high temperature resistant tape is torn off and cleaned with alcohol, and then the infrared film is coated.

[0011] Preferably, in step S6, the specific method of carbon coating is: place the infrared window material with one side facing up into the carbon film machine tray, and use the CVD deposition method to evacuate the material until the pressure reaches 3×10-3~6×10-3Pa, then turn on the radio frequency for bombardment, the time is 3~4h, and the power is 500~1500W to coat the carbon film.

[0012] Preferably, in step S6, an infrared coating machine is used to coat an infrared film, and the parameters during the coating process are set as follows: the vacuum degree is 1×10-3~3×10-3Pa, the workpiece disk speed is 10~15 rpm, the temperature is 130~160°C, the film layer is set to 9~12 layers, the coating time is 2~3h, and the coating frequency is 8~15Hz.

[0013] In the second aspect, the present invention also provides a workbench for placing the convex hemispherical lens and the ring as described in any one of claims 1 to 3, comprising a placing table, a through hole passing through the placing table, and a placing hole opened on the top surface of the placing table, wherein the shape of the placing hole matches the shape of the ring, and the convex surface of the convex hemispherical lens extends out from the through hole and contacts with the polishing head.

[0014] In the third aspect, the present invention also provides a clamp for clamping the ring described in any one of claims 1 to 3 on the workbench, comprising a threaded rod installed on the workbench, a nut threadedly connected to the top of the threaded rod, a spring sleeved on the bottom end of the threaded rod, a connecting plate fitted to the bottom end of the spring, a connecting rod passing through and slidably connected to the connecting plate, and a pressing plate fixedly connected to the bottom end of the connecting rod, the threaded rod passing through the connecting plate and slidably connected to the connecting plate, and the pressing plate fits with the top of the ring.

[0015] In the above technical solution, the technical effects and advantages provided by the present invention are: The present invention changes the process of making a convex hemispherical lens from an initial lens into a finished product. When the convex hemispherical lens is first cut out, the outer ring of the convex hemispherical lens is retained to form a ring, and then the ring is clamped with a separately designed clamp, which will not affect the polishing head to polish both sides of the convex hemispherical lens at the same time. After the polishing is completed, the ring is cut off and cleaned; When the convex hemispherical lens is clamped, the clamp is used to apply a clamping force to the ring, and the clamping force is parallel to the axis direction of the convex hemispherical lens, unlike the prior art, where a clamping force perpendicular to the axis of the convex hemispherical lens is not applied to the convex hemispherical lens, thereby preventing the polishing of the convex hemispherical lens from being affected. The present invention improves the polishing efficiency by polishing the convex surface and the concave surface of the convex hemispherical lens at the same time, and sets the rotation directions of the two polishing heads in opposite directions so that the friction forces generated when the polishing heads polish the convex hemispherical lens offset each other, so that the fixture can clamp the polishing heads with a smaller force. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is a process flow chart of the present invention; Figure 2 It is a schematic diagram of the overall structure of the present invention; Figure 3 is a cross-sectional view of a workbench of the present invention; Figure 4 It is a schematic diagram of the installation of the convex hemispherical lens and the circular ring of the present invention; Figure 5 It is a schematic diagram of polishing the polishing head and the convex hemispherical lens of the present invention.

[0018] Description of reference numerals: 1. Convex hemispherical lens; 2. Ring; 3. Workbench; 3a. Placement table; 3b. Through hole; 3c. Placement hole; 4. Clamp; 4a. Threaded rod; 4b. Nut; 4c. Spring; 4d. Connecting plate; 4e. Connecting rod; 4f. Pressing sheet; 5. Polishing head. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] like Figure 1-5 As shown: S1. First, the initial lens is cut into a convex hemispherical lens 1, but the outer part of the convex hemispherical lens 1 is retained to form a ring 2 integrated with the convex hemispherical lens 1; S2. Then move the cut convex hemispherical lens 1 to the placement table 3a, put the ring 2 into the placement hole 3c, let the convex surface of the convex hemispherical lens 1 face down and extend from the through hole 3b to ensure that the polishing head 5 can come into contact with the convex surface, then pull the connecting plate 4d upward, the connecting plate 4d compresses the spring 4c, and drives the pressing plate 4f to separate from the surface of the placement table 3a through the connecting rod 4e, then move the connecting rod 4e to move the pressing plate 4f to the top of the ring 2, then release the connecting plate 4d, let the spring 4c apply elastic force to the connecting plate 4d, The force is transmitted to the pressing sheet 4f through the connecting plate 4d and the connecting rod 4e, so that the ring 2 is clamped in the placement hole 3c by the pressing sheet 4f. The clamping force is not directly applied to the convex hemispherical lens 1 itself, but to the ring 2 cut off later. Moreover, the clamping force is applied to the ring 2 along the axial direction of the convex hemispherical lens 1, rather than perpendicular to the axial direction of the convex hemispherical lens 1. Therefore, it will not affect the convex hemispherical lens 1 itself. Therefore, while ensuring clamping, the convex hemispherical lens 1 is not subjected to force, ensuring that it will not affect the polishing. S3. Compared with the prior art that uses the coordination among the main shaft, the upper fixture, the swing arm and the grinding plate, etc. to press the convex hemispherical lens 1 on the rotating grinding plate and swing it, so as to polish one side, the present technical solution adopts two polishing heads 5 that can move up and down, that is, two grinding plates that only rotate by themselves, but one is a concave grinding plate that matches the convex shape of the convex hemispherical lens 1 and rotates forward, and the other is a convex grinding plate that matches the concave shape of the convex hemispherical lens 1 and rotates reversely, and the convex hemispherical lens 1 no longer swings, and only needs to be kept on the placement table 3a to complete the polishing, because the rotation direction of the concave grinding plate and the convex grinding plate is opposite, all the grinding plates in contact with the convex hemispherical lens 1 are in the opposite direction. The direction of the friction force generated when the two are offset is also opposite. After the two are offset, the remaining friction force is less than the friction force applied by the pressing plate 4f to the ring 2, so that the convex hemispherical lens 1 does not rotate; the friction force generated by the pressing plate 4f applying pressure to the ring 2 is less than the clamping force applied by the upper fixture to the convex hemispherical lens 1 in the prior art. When polishing, 0.25um diamond polishing liquid needs to be dripped onto the concave grinding dish and the convex grinding dish, the polishing speed is set to 1000r / min, the polishing time is set to 8h, and after polishing, it is wiped and cleaned with alcohol to reach the US military standard MIL-PRF-13830B finish 60-40 level; S4. After polishing, the ring 2 of the outer ring of the qualified convex hemispherical lens 1 is cut off, leaving only the convex hemispherical lens 1; S5. Use ultrasonic cleaning, the cleaning agent is isopropyl alcohol, the frequency of ultrasonic cleaning is 70kHz, the cleaning time is 0.5h, so that the finish reaches the 60-40 level in the US military standard MIL-PRF-13830B, and then dry; S6. Use high temperature resistant tape to stick one side of the convex hemispherical lens 1 from the edge to the middle for protection, and put the other side upwards on the tray of the carbon film machine through the CVD deposition method. First, evacuate the vacuum. When the pressure reaches a vacuum degree of 4X10`Pa, turn on the radio frequency for bombardment. Set the coating time to 3h and the power to 750W to coat the DLC film. The thickness of the carbon film layer is 1um, and the uniformity of the film layer is less than 50nm. After the carbon film is completed, tear off the high temperature tape and wipe it with a dust-free cloth dipped in alcohol. After cleaning, put it into the ring tooling and put it into the infrared coating machine for AR coating. The parameters during the coating process are set as follows: the vacuum degree is 3X10-Pa, the workpiece disk speed is 12 rpm, the temperature is 160℃, the film layer is set to 10 layers, the coating time is 3h, and the coating frequency is 8~15Hz. The thickness of the carbon film layer is 2um, and the uniformity of the film layer is less than 20nm. After cooling to 80 degrees after coating, open the furnace to take out the film to obtain the product; In combination with a polishing process for an infrared detector package window lens, the present invention further provides a workbench 3 for placing a convex semi-spherical lens 1 and a circular ring 2, comprising a placing platform 3a, a through hole 3b penetrating the placing platform 3a, and a placing hole 3c opened on the top surface of the placing platform 3a, wherein the shape of the placing hole 3c matches the shape of the circular ring 2, and the convex surface of the convex semi-spherical lens 1 extends out from the through hole 3b to contact the polishing head 5; In combination with a polishing process for a window lens of an infrared detector package, the present invention also provides a clamp 4 for clamping a ring 2 on a workbench 3, comprising a threaded rod 4a installed on the workbench 3, a nut 4b threadedly connected to the top of the threaded rod 4a, a spring 4c sleeved on the bottom end of the threaded rod 4a, a connecting plate 4d fitted to the bottom end of the spring 4c, a connecting rod 4e passing through and slidably connected to the connecting plate 4d, and a pressing plate 4f fixedly connected to the bottom end of the connecting rod 4e, the threaded rod 4a passes through the connecting plate 4d and is slidably connected to the connecting plate 4d, and the pressing plate 4f is fitted to the top of the ring 2.

[0022] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are exemplary only. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, colors, changes in orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application.

Claims

1. A polishing process for an infrared detector package window lens, characterized in that: The following steps are involved: S1. Cutting the initial lens into a convex hemispherical lens (1), and retaining the outer ring (2) of the convex hemispherical lens (1); S2. Install the convex hemispherical lens (1) and the ring (2) on the workbench (3), and clamp the ring (2) with a clamp (4); S3. Two polishing heads (5) are used to polish the convex and concave surfaces of the convex hemispherical lens (1) simultaneously; S4. The polished convex hemispherical lens (1) is cut, and the outer ring (2) of the convex hemispherical lens (1) is cut off to obtain a polished lens; S5. Clean the polished lens, control the finish of the convex and concave surfaces of the polished lens after cleaning to 60~40 levels, and obtain a clean lens; S6. Coat one side of the cleaned lens with a carbon film, and then coat the other side with an infrared film, wherein the thickness of the carbon film is 1~1.5μm, and the film uniformity of the carbon film is less than 50nm; the thickness of the infrared film is 2~3μm, and the film uniformity of the infrared film is less than 20nm, and the film thickness of the infrared film is 1.5~2 times that of the carbon film.

2. The polishing process of the infrared detector package window lens according to claim 1, characterized in that: In step S3, the two polishing heads (5) rotate in opposite directions, and the difference between the friction force generated when the polishing head (5) polishes the concave surface and the friction force generated when the polishing head (5) polishes the convex surface is smaller than the friction force applied by the fixture (4) to the ring (2).

3. The polishing process of the infrared detector package window lens according to claim 1, characterized in that: In step S3, the polishing process uses 0.25 μm diamond polishing liquid, and the polishing speed is 500-1200 r / min.

4. The polishing process of the infrared detector package window lens according to claim 1, characterized in that: In the step S5, ultrasonic cleaning is adopted, the ultrasonic cleaning agent is isopropyl alcohol; the frequency of ultrasonic cleaning is 67-80 kHz, and the cleaning time is 0.5-1 h.

5. The polishing process of the infrared detector package window lens according to claim 1, characterized in that: In step S6, when a carbon film is coated on one side of the infrared window lens, a high temperature resistant tape is used to protect the other side of the infrared window lens; after the carbon film is coated, the high temperature resistant tape is torn off and cleaned with alcohol, and then the infrared film is coated.

6. The polishing process of the infrared detector package window lens according to claim 1, characterized in that: In step S6, the specific method of carbon coating is: place the infrared window material with one side facing up into the tray of the carbon film machine, and use the CVD deposition method to evacuate the material until the pressure reaches 3×10-3~6×10-3Pa, then turn on the radio frequency for bombardment, the time is 3~4h, and the power is 500~1500W to coat the carbon film.

7. The polishing process of the infrared detector package window lens according to claim 1, characterized in that: In step S6, an infrared coating machine is used to coat an infrared film, and the parameters during the coating process are set as follows: the vacuum degree is 1×10-3~3×10-3Pa, the workpiece disk speed is 10~15 rpm, the temperature is 130~160°C, the film layer is set to 9~12 layers, the coating time is 2~3h, and the coating frequency is 8~15Hz.

8. A workbench (3) for placing the convex hemispherical lens (1) and the ring (2) as claimed in any one of claims 1 to 3, characterized in that: It comprises a placement platform (3a), a through hole (3b) penetrating the placement platform (3a), and a placement hole (3c) opened on the top surface of the placement platform (3a), wherein the shape of the placement hole (3c) matches the shape of the circular ring (2), and the convex surface of the convex hemispherical lens (1) extends out from the through hole (3b) to contact the polishing head (5).

9. A clamp (4) for clamping the ring (2) according to any one of claims 1 to 3 on the workbench (3), characterized in that: It comprises a threaded rod (4a) mounted on a workbench (3), a nut (4b) threadedly connected to the top of the threaded rod (4a), a spring (4c) sleeved on the bottom of the threaded rod (4a), a connecting plate (4d) fitted to the bottom of the spring (4c), a connecting rod (4e) passing through and slidably connected to the connecting plate (4d), and a pressing plate (4f) fixedly connected to the bottom of the connecting rod (4e), wherein the threaded rod (4a) passes through the connecting plate (4d) and is slidably connected to the connecting plate (4d), and the pressing plate (4f) is fitted to the top of the ring (2).

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