High-transmittance lens coating structure, coating equipment and method

Abstract

The present invention provides a high-transmittance lens coating structure, comprising a plurality of coating layers sequentially arranged along the surface of the optical lens toward the outside, the thickness of the coating layers sequentially decreasing from the center position of the optical lens toward the edge, and the material of the coating layers is silicon oxide. The present invention also provides a coating device for preparing the above-mentioned high-transmittance lens coating structure; the present invention also provides a coating method for preparing the above-mentioned high-transmittance lens coating structure. The present invention superimposes the coating of a multi-layer convex lens structure, utilizes the principle of light path reflection and refraction, and cooperates with the shape of the coating layer to make it easier for the reflected light leaving the interface to return to the direction of the lens, thereby reducing the proportion of reflected light and thereby improving the transmittance. The present invention can complete the processing at one time, without the need to use multiple evaporation sources separately for multiple vacuum coating operations, which greatly reduces the workload and thereby improves the processing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of coating technology, and in particular to a high-transmittance lens coating structure, coating equipment, and coating method. Background Art

[0002] When light enters various transmissive materials (such as from air to glass), approximately 5% is reflected. Optical lenses contain many lenses and refractors, which together can cause a loss of 30% to 40% of the incident light. Modern optical lenses are typically coated with single or multi-layer antireflection coatings. A single layer of antireflection coating can reduce reflection to 1.5%, while a multi-layer antireflection coating can reduce reflection to 0.25%. Therefore, if the entire lens is properly coated, the light transmission rate can reach 95%.

[0003] In modern technology, coating techniques are commonly used to coat the surfaces of optical lenses or other objects. These techniques include chemical plating, vacuum evaporation, vacuum sputtering, and vacuum ion plating. Chemical plating forms a thin film on a material's surface through a chemical reaction. Common methods include acid etching and deposition. The acid etching method involves immersing glass parts in an aqueous acetic acid solution, which forms a silica gel layer on the surface. This layer is then baked and dehydrated to form a silicon dioxide film. Deposition methods involve pouring a silver ammonia germanium salt solution and a reducing agent solution onto clean glass. The silver precipitated during the reaction deposits as a silver film on the glass surface.

[0004] Vacuum evaporation coating (also known as vacuum evaporation) involves heating a vaporized material under vacuum conditions to cause it to sublime. The evaporated particles are then directed toward the substrate, where they are deposited to form a solid thin film. The physical steps of this process include: vaporization of the material onto the substrate surface, linear transport of the gaseous particles to the substrate surface, and finally, condensation onto the substrate surface to form a solid thin film. This method is commonly used to produce thin films with various functionalities, such as reflectors and transmissive optical components.

[0005] Vacuum evaporation is a common and effective coating method for optical lenses. A wide variety of film materials can be deposited using this method, with silicon oxide and silicon dioxide being among the most widely used. Silicon dioxide and silicon oxide are both common coating materials. While their light transmittance is somewhat limited compared to materials like silicon nitride, magnesium fluoride, and aluminum oxide, they offer greater hardness, making them commonly used as the outermost layer of multilayer coatings. Of course, due to differences in transmittance of different materials for different wavelengths of light, multiple layers of coating are typically constructed using different materials to achieve optimal light transmission. However, this multilayer coating structure also presents certain challenges. First, there are issues with the adhesion between the different layers, leading to potential for layer detachment with long-term use. Second, each layer requires separate processing, making the coating process complex and cumbersome, significantly impacting the efficiency of the entire optical lens manufacturing process. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides a high-transmittance lens coating structure, coating equipment and method, which solve the problems in the prior art of insufficient tight bonding of different film layers and the overly complicated multi-layer coating process, which affects production efficiency.

[0007] In the first aspect, the present invention proposes a high-transmittance lens coating structure, which is arranged corresponding to the surface of a translucent optical lens, including several coating layers arranged in sequence along the surface of the optical lens toward the outside, and the thickness of the coating layer decreases from the center position of the optical lens toward the edge. At the same time, in all the coating layers, the thickness at the edge position is the same, and the thickness at the middle position decreases along the surface of the optical lens toward the outside; the material of the coating layer is silicon oxide.

[0008] Furthermore, the oxygen content in the material of the coating layer increases gradually along the surface of the optical lens toward the outside, that is, the silicon oxide content is the highest in the coating layer close to the optical lens, and the silicon dioxide content is the highest in the coating layer farthest from the optical lens.

[0009] Preferably, the coating layer has a thickness of 80-220 nm.

[0010] In the second aspect, the present invention proposes a coating device for preparing the above-mentioned high-transmittance lens coating structure, including a closed coating chamber, which is a hollow environment. The coating chamber is provided with a mutually symmetrical loading plate and an evaporation source bracket, and the loading plate and the evaporation source bracket are both arranged horizontally. The coating chamber is also provided with an oxygen delivery pipe and a protective gas delivery pipe. The loading plate is movably linked to the top plate of the coating chamber so that the loading plate can move in the vertical direction, and the evaporation source bracket is fixed.

[0011] Furthermore, an optical lens receiving groove is provided on the bottom surface of the loading plate, so that the optical lens can be installed on the bottom surface of the loading plate, and the surface of the optical lens to be coated is not blocked and faces the direction of the evaporation source bracket.

[0012] Furthermore, a heater is provided at the bottom of the evaporation source bracket, and an evaporation source receiving box is provided above the heater. The evaporation source receiving box is located just below the center of the optical lens receiving groove.

[0013] Furthermore, the loading plate is connected to the top plate of the coating chamber via a vertically arranged telescopic rod, and the telescopic rod drives the loading plate to move in the vertical direction, thereby adjusting the distance between the loading plate and the evaporation source bracket.

[0014] In a third aspect, the present invention further proposes a coating method for preparing the above-mentioned high-transmittance lens coating structure, comprising the following steps:

[0015] S1. After cleaning the surface of the optical lens, place it into the optical lens holding tank with the surface to be coated facing downward. At the same time, place the silicon oxide evaporation source into the evaporation source holding box. Then, extend the telescopic rod to the maximum distance to minimize the distance between the optical lens holding tank and the evaporation source holding box. Close the coating chamber and evacuate the chamber until the vacuum level inside the coating chamber reaches below 3*10-3Pa.

[0016] S2. Shielding gas is introduced into the coating chamber to control the internal pressure to 2 Pa, and then the heater is turned on to heat the evaporation source container to control the temperature to 1200°C to 1600°C;

[0017] S3. Introduce a mixture of oxygen and protective gas into the coating chamber, control the telescopic rod to slowly retract, and increase the distance between the optical lens receiving tank and the evaporation source receiving box. At the same time, continuously adjust the proportion of oxygen in the mixed gas so that the mixed gas gradually changes from pure protective gas to pure oxygen. Continue for 20-30 minutes, then open the coating chamber and take out the coated optical lens.

[0018] Preferably, in steps S2 and S3, the protective gas includes one of nitrogen and argon.

[0019] Furthermore, in step S3, during the coating process, pure protective gas is introduced in the first quarter of the time, the oxygen content is uniformly increased from one quarter to one half of the time until the oxygen proportion is 50%, the oxygen content is uniformly increased from one half to three quarters of the time until the oxygen proportion is 100%, and pure oxygen is introduced in the last quarter of the time.

[0020] The technical principle of the present invention is: the optical lens coating structure in the present invention has multiple layers of silicon oxide coating layers of the same material, wherein each coating layer is in a shape in which the thickness of the outer edge is less than that of the center position, that is, a convex structure. At the same time, the convexity of each outer coating layer relative to the inner coating layer gradually decreases, so that when the incident light enters the interface of the adjacent coating layer, most of it is refracted, and a small part of the reflected light is reflected toward the edge due to the convex structure of the coating layer. Since the thickness of the coating layer at the edge is the same in the present invention, the closer to the edge, the greater the curvature, and therefore the reflectivity toward the inside is higher, then the reflected light leaving the interface is more likely to be reflected back to the direction of the lens again, thereby reducing the proportion of reflected light leaving the lens and physically improving the transmittance.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention utilizes the principles of light reflection and refraction by stacking multiple layers of convex lens structures and the shape of the coating layers to make it easier for reflected light leaving the interface to return to the lens direction, thereby reducing the proportion of reflected light and improving light transmittance.

[0023] The coating layer material of the present invention gradually changes from silicon oxide to silicon dioxide from the inside to the outside, and its light transmittance gradually increases, allowing light to enter the coating layer from the outside more easily. It is only reflected at the interface between different coating layers inside, thereby gradually converging the reflected light in the direction of the lens, and not reflecting away from the optical lens at the outermost layer, thus avoiding a reduction in light transmittance.

[0024] The present invention only uses silicon oxide as the coating material, uses silicon oxide as the evaporation source, and combines it with different oxygen concentration atmospheres to complete the processing in one go. There is no need to use multiple evaporation sources for multiple vacuum coating operations, which greatly reduces the workload and improves the processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the cross section of the coating layer according to an embodiment of the present invention.

[0026] Figure 2 Schematic diagram of the structure of the coating equipment according to an embodiment of the present invention.

[0027] Figure 3 Graph showing light transmittance of the embodiments and comparative examples of the present invention.

[0028] In the above drawings: 1. optical lens; 2. coating layer; 3. coating chamber; 4. loading plate; 5. evaporation source bracket; 6. telescopic rod; 7. connecting rod; 31. oxygen delivery pipe; 32. protective gas delivery pipe; 41. optical lens receiving tank; 51. evaporation source receiving box. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0030] Example 1:

[0031] like Figure 1As shown, an embodiment of the present invention proposes a high-transmittance lens coating structure, which is arranged on the surface of a translucent optical lens 1, and includes four coating layers 2 arranged sequentially along the surface of the optical lens 1 toward the outside, and the thickness of the coating layer 2 decreases from the center position of the optical lens 1 toward the edge. At the same time, the thickness of the edge position of all the coating layers 2 is the same, and the thickness of the middle position decreases sequentially along the surface of the optical lens 1 toward the outside, and the thickness of any position of the coating layer 2 close to the outside is not less than the thickness of any position of the coating layer 2 close to the inside. In this embodiment, the edge thickness of the coating layer 2 is 80nm, and the thickness of the middle position is 180, 160, 140, and 120nm respectively. The material of the coating layer 2 is silicon oxide, and the oxygen content increases sequentially along the surface of the optical lens 1 toward the outside, that is, the silicon oxide content in the coating layer 2 close to the optical lens 1 is the highest, and the silicon dioxide content in the coating layer 2 farthest from the optical lens 1 is the highest.

[0032] like Figure 2 As shown, the coating equipment of this embodiment includes a closed coating chamber 3, which is a hollow environment. The coating chamber 3 is provided with a loading plate 4 and an evaporation source bracket 5 that are symmetrical to each other. The loading plate 4 and the evaporation source bracket 5 are both arranged horizontally. The coating chamber 3 is also provided with an oxygen delivery pipe 31 and a protective gas delivery pipe 32. The loading plate 4 is movably linked to the top plate of the coating chamber 3 so that the loading plate 4 can move in the vertical direction. The evaporation source bracket 5 is fixed in the middle of the coating chamber 3 by a connecting rod.

[0033] The bottom surface of the loading plate 4 is provided with an optical lens receiving groove 41, allowing the optical lens 1 to be mounted thereon, with the surface of the optical lens 1 to be coated facing unobstructed toward the evaporation source holder 5. The loading plate 4 is connected to the top plate of the coating chamber 3 via a vertical telescopic rod 6, which drives the loading plate 4 to move vertically, thereby adjusting the distance between the loading plate 4 and the evaporation source holder 5. A heater is provided below the evaporation source holder 5, and an evaporation source receiving box 51 is located above the heater, directly below the center of the optical lens receiving groove 41.

[0034] The coating method of this embodiment includes the following steps:

[0035] S1. After cleaning the surface of the optical lens 1, place it into the optical lens receiving tank 41 with the surface to be coated facing downward. Simultaneously, place the silicon oxide evaporation source into the evaporation source receiving box 51. Then, extend the telescopic rod 6 to its maximum distance to minimize the distance between the optical lens receiving tank 41 and the evaporation source receiving box 51. Close the coating chamber 3 and evacuate the chamber until the vacuum level inside the coating chamber 3 reaches below 3*10-3Pa.

[0036] S2, introducing nitrogen as a protective gas into the coating chamber 3, controlling the internal pressure to 2 Pa, and then turning on the heater to heat the evaporation source container 51, controlling the temperature to 1200° C.;

[0037] S3. A mixture of oxygen and protective gas is introduced into the coating chamber 3. The telescopic rod 6 is controlled to slowly retract, increasing the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51. At the same time, the proportion of oxygen in the mixed gas is continuously adjusted so that the mixed gas gradually changes from pure protective gas to pure oxygen. During the coating process, pure protective gas is introduced for the first quarter of the time. The oxygen content is uniformly increased from one quarter to one half of the time until the oxygen content reaches 50%. The oxygen content is uniformly increased from one half to three quarters of the time until the oxygen content reaches 100%. Pure oxygen is introduced for the last quarter of the time. This process continues for 20 minutes, and the coating chamber 3 is opened to remove the coated optical lens 1.

[0038] Example 2:

[0039] The thickness of the coating layer 2 in this embodiment is as follows: the thickness of the edge of the coating layer 2 is 120 nm, and the thicknesses at the middle position are 200, 180, 160, and 140 nm, respectively.

[0040] The coating equipment in this embodiment is the same as that in embodiment 1.

[0041] The coating method of this embodiment includes the following steps:

[0042] S1. After cleaning the surface of the optical lens 1, place it into the optical lens receiving tank 41 with the surface to be coated facing downward. Simultaneously, place the silicon oxide evaporation source into the evaporation source receiving box 51. Then, extend the telescopic rod 6 to its maximum distance to minimize the distance between the optical lens receiving tank 41 and the evaporation source receiving box 51. Close the coating chamber 3 and evacuate the chamber until the vacuum level inside the coating chamber 3 reaches below 3*10-3Pa.

[0043] S2, introducing a protective gas into the coating chamber 3, the protective gas being argon, and controlling the internal pressure to be 2 Pa, and then turning on the heater to heat the evaporation source container 51, and controlling the temperature to be 1400° C.;

[0044] S3. A mixture of oxygen and protective gas is introduced into the coating chamber 3. The telescopic rod 6 is controlled to slowly retract, increasing the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51. At the same time, the proportion of oxygen in the mixed gas is continuously adjusted so that the mixed gas gradually changes from pure protective gas to pure oxygen. During the coating process, pure protective gas is introduced for the first quarter of the time. The oxygen content is uniformly increased from one quarter to one half of the time until the oxygen content reaches 50%. The oxygen content is uniformly increased from one half to three quarters of the time until the oxygen content reaches 100%. Pure oxygen is introduced for the last quarter of the time. This process continues for 25 minutes, and the coating chamber 3 is opened to remove the coated optical lens 1.

[0045] Example 3:

[0046] The thickness of the coating layer 2 in this embodiment is as follows: the thickness of the edge of the coating layer 2 is 160 nm, and the thicknesses at the middle position are 220, 200, 180, and 160 nm, respectively.

[0047] The coating equipment in this embodiment is the same as that in embodiment 1.

[0048] The coating method of this embodiment includes the following steps:

[0049] S1. After cleaning the surface of the optical lens 1, place it into the optical lens receiving tank 41 with the surface to be coated facing downward. Simultaneously, place the silicon oxide evaporation source into the evaporation source receiving box 51. Then, extend the telescopic rod 6 to its maximum distance to minimize the distance between the optical lens receiving tank 41 and the evaporation source receiving box 51. Close the coating chamber 3 and evacuate the chamber until the vacuum level inside the coating chamber 3 reaches below 3*10-3Pa.

[0050] S2, introducing nitrogen as a protective gas into the coating chamber 3, controlling the internal pressure to 2 Pa, and then turning on the heater to heat the evaporation source container 51, controlling the temperature to 11600° C.;

[0051] S3. A mixture of oxygen and protective gas is introduced into the coating chamber 3. The telescopic rod 6 is controlled to slowly retract, increasing the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51. At the same time, the proportion of oxygen in the mixed gas is continuously adjusted so that the mixed gas gradually changes from pure protective gas to pure oxygen. During the coating process, pure protective gas is introduced for the first quarter of the time. The oxygen content is uniformly increased from one quarter to one half of the time until the oxygen content reaches 50%. The oxygen content is uniformly increased from one half to three quarters of the time until the oxygen content reaches 100%. Pure oxygen is introduced for the last quarter of the time. This process continues for 30 minutes, and the coating chamber 3 is opened to remove the coated optical lens 1.

[0052] Comparative Example:

[0053] The comparative example uses a silicon dioxide coating with a thickness of 480 nm.

[0054] The transmittance of Examples 1-3 and the comparison was tested. The results are as follows: Figure 3 shown.

[0055] Figure 3 In the figure, S1 is a comparative example, and S2-S4 are examples 1-3. It can be seen that the transmittance of the present invention is significantly higher than that of ordinary silicon dioxide coatings, especially in the high-wavelength infrared region, where the transmittance of the present invention is greatly improved.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high-transmittance lens coating structure, the coating structure being disposed on a surface of a light-transmitting optical lens, characterized in that: It comprises several coating layers arranged in sequence along the surface of the optical lens toward the outside, and the thickness of each coating layer decreases from the center position of the optical lens toward the edge. At the same time, the thickness of all coating layers is the same at the edge position, and the thickness at the middle position decreases along the surface of the optical lens toward the outside; the material of the coating layer is silicon oxide.

2. The high-transmittance lens coating structure according to claim 1, wherein: The oxygen content in the material of the coating layer increases gradually along the surface of the optical lens toward the outside, that is, the silicon oxide content is the highest in the coating layer close to the optical lens, and the silicon dioxide content is the highest in the coating layer farthest from the optical lens.

3. The high-transmittance lens coating structure according to claim 1, wherein: The coating layer has a thickness of 80-220 nm.

4. A coating device for preparing the high-transmittance lens coating structure according to claim 1, characterized in that: It includes a closed coating chamber, which is a hollow environment. The coating chamber is provided with a loading plate and an evaporation source bracket that are symmetrical to each other. The loading plate and the evaporation source bracket are both arranged horizontally. The coating chamber is also provided with an oxygen delivery pipe and a protective gas delivery pipe. The loading plate is movably linked to the top plate of the coating chamber so that the loading plate can move in the vertical direction. The evaporation source bracket is fixed.

5. The coating device according to claim 4, wherein: The bottom surface of the loading plate is provided with an optical lens receiving groove, so that the optical lens can be installed on the bottom surface of the loading plate, and the surface of the optical lens to be coated is not blocked and faces the direction of the evaporation source bracket.

6. The coating device according to claim 4, wherein: A heater is provided at the bottom of the evaporation source bracket, and an evaporation source receiving box is provided above the heater. The evaporation source receiving box is located just below the center of the optical lens receiving groove.

7. The coating device according to claim 4, wherein: The loading plate is connected to the top plate of the coating chamber via a vertically arranged telescopic rod, and the telescopic rod drives the loading plate to move in a vertical direction, thereby adjusting the distance between the loading plate and the evaporation source bracket.

8. A coating method for preparing the high-transmittance lens coating structure according to claim 1, characterized in that: The steps include: S1. After cleaning the surface of the optical lens, place it into the optical lens holding tank with the surface to be coated facing downward. At the same time, place the silicon oxide evaporation source into the evaporation source holding box. Then, extend the telescopic rod to the maximum distance to minimize the distance between the optical lens holding tank and the evaporation source holding box. Close the coating chamber and evacuate the chamber until the vacuum level inside the coating chamber reaches below 3*10-3Pa. S2. Shielding gas is introduced into the coating chamber to control the internal pressure to 2 Pa, and then the heater is turned on to heat the evaporation source container to control the temperature to 1200°C to 1600°C; S3. Introduce a mixture of oxygen and protective gas into the coating chamber, control the telescopic rod to slowly retract, and increase the distance between the optical lens receiving tank and the evaporation source receiving box. At the same time, continuously adjust the proportion of oxygen in the mixed gas so that the mixed gas gradually changes from pure protective gas to pure oxygen. Continue for 20-30 minutes, then open the coating chamber and take out the coated optical lens.

9. The coating method according to claim 8, wherein: In steps S2 and S3, the protective gas includes one of nitrogen and argon.

10. The coating method according to claim 8, wherein: In step S3, during the coating process, pure protective gas is introduced in the first quarter of the time, the oxygen content is uniformly increased from one quarter to one half of the time until the oxygen content is 50%, the oxygen content is uniformly increased from one half to three quarters of the time until the oxygen content is 100%, and pure oxygen is introduced in the last quarter of the time.

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