Film coating structure, film coating equipment and method for high-light-transmittance lens

Abstract

The invention provides a high-light-transmittance lens coating structure which comprises a plurality of coating layers which are sequentially arranged towards the outer side along the surface of an optical lens, the thicknesses of the coating layers are sequentially reduced from the center position of the optical lens to the edge, and the coating layers are made of silicon oxide. The invention further provides coating equipment for preparing the high-light-transmittance lens coating structure. The invention further provides a film coating method for preparing the high-light-transmittance lens film coating structure. According to the invention, the reflection light leaving from the interface is easier to return to the lens direction through the coating film superposition arrangement of the plurality of layers of convex lens structures by utilizing the principles of light path reflection and refraction and matching with the shape of the coating film layer, so that the proportion of the reflection light is reduced, and the light transmittance is improved. According to the invention, the processing can be completed at one time, and multiple vacuum coating operations can be carried out without respectively using multiple evaporation sources, so that the workload is greatly reduced, and the processing efficiency is further improved.

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 method. Background Art

[0002] When light enters different transmission materials (such as from air to glass), about 5% will be reflected. There are many lenses and refractors in optical lenses, which can cause a loss of 30% to 40% of the incident light. Modern optical lenses are usually coated with single or multi-layer anti-reflection coatings. Single-layer anti-reflection coatings can reduce reflection to 1.5%, and multi-layer anti-reflection coatings can reduce reflection to 0.25%. Therefore, if the entire lens is properly coated, the light penetration rate can reach 95%.

[0003] In modern technology, coating technology is usually used to coat the surface of optical lenses or other objects, mainly including chemical coating, vacuum evaporation coating, vacuum sputtering coating and vacuum ion coating. Among them, chemical coating is a method of forming a thin film on the surface of a material through a chemical reaction. Commonly used methods include acid etching and deposition. The acid etching method is to immerse the glass parts in an acetic acid aqueous solution to form a silica gel layer on the surface, which becomes a silicon dioxide film after baking and dehydration. The deposition method is to pour a silver ammonia germanium salt solution and a reducing agent solution on clean glass, and the silver precipitated in the reaction is deposited on the glass surface as a silver film.

[0004] Vacuum evaporation coating (referred to as vacuum evaporation) is to heat the evaporated material under vacuum conditions to make it sublime, and the evaporated particles are directly shot to the substrate and deposited to form a solid film. The physical steps of this process include: evaporating the material to the substrate surface, transporting the gaseous particles to the substrate surface in a straight line, and finally condensing on the substrate surface to form a solid film. This method is often used to prepare thin films with various functions, such as reflectors, transmission optical elements, etc.

[0005] For optical lenses, vacuum evaporation is a more conventional and effective coating method. There are many types of film materials that can be evaporated, among which silicon oxide and silicon dioxide are one of the most widely used coating materials. Silicon dioxide and silicon oxide are both common coating materials. Compared with materials such as silicon nitride, magnesium fluoride and aluminum oxide, their light transmittance is still somewhat insufficient, but they have higher hardness, so they are usually used as the outermost layer of multi-layer coatings. Of course, due to the different transmittances of various materials to light of different wavelengths, different materials are generally used for multi-layer coating to achieve the best light transmission effect. However, this multi-layer coating structure also has certain problems. First, there is a certain degree of bonding between different types of film layers, and the film layers may fall off during long-term use. Second, different types of multi-layer coatings need to be processed separately, which makes the coating process too complicated and cumbersome, greatly affecting the efficiency of the entire optical lens preparation process. Summary of the invention

[0006] In view of 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 that different film layers are not tightly combined, and the multi-layer coating process is too complicated, affecting 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 a plurality of coating layers arranged sequentially along the surface of the optical lens toward the outside, and the thickness of the coating layers 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 sequentially along the surface of the optical lens toward the outside, and the thickness at any position of the outer coating layer is not less than the thickness at any position of the inner coating layer; the material of the coating layer is silicon oxide.

[0008] Furthermore, the oxygen content in the material of the coating layer increases 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, comprising a closed coating chamber, the coating chamber being a hollow environment, the coating chamber being provided with a loading plate and an evaporation source bracket which are symmetrical to each other, the loading plate and the evaporation source bracket being both arranged horizontally, the coating chamber being further provided with an oxygen delivery pipe and a protective gas delivery pipe, the loading plate being 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 being fixedly arranged.

[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 support, and an evaporation source containing box is provided above the heater, and the evaporation source containing box is located just below the center of the optical lens containing 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 a 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 receiving tank, with the surface to be coated facing downward. At the same time, place the silicon oxide evaporation source into the evaporation source receiving box, and then extend the telescopic rod to the maximum distance to minimize the distance between the optical lens receiving tank and the evaporation source receiving box. Close the coating chamber and evacuate until the vacuum degree inside the coating chamber reaches 3*10 -3 Below Pa;

[0016] S2, introducing protective gas into the coating chamber, controlling the internal pressure to 2Pa, and then turning on the heater to heat the evaporation source container, controlling the temperature to 1200°C to 1600°C;

[0017] S3. Introduce a mixed gas of oxygen and protective gas into the coating chamber, control the telescopic rod to slowly retract, increase the distance between the optical lens receiving slot and the evaporation source receiving box, and 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, open the coating chamber, and take out the optical lens that has been coated.

[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 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.

[0020] The technical principle of the present invention is: the optical lens coating structure of 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 coating layer on the outer side gradually decreases relative to the coating layer on the inner side, 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, so the reflectivity inward 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] 1. The present invention uses a multi-layer convex lens structure with a superimposed coating, utilizes the principle of light path reflection and refraction, and combines 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 further improving the light transmittance;

[0023] 2. 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, so that light can enter the coating layer from the outside more easily, and only reflects at the interface of different coating layers inside, so that the reflected light is gradually gathered in the direction of the lens, and will not be reflected away from the optical lens at the outermost layer, thereby avoiding reducing the light transmittance;

[0024] 3. The present invention only uses silicon oxide as the coating material. By using silicon oxide as the evaporation source and combining it with different oxygen concentration atmospheres, the processing can be completed at one time. 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 It is a schematic diagram of the structure of the coating equipment according to an embodiment of the present invention.

[0027] Figure 3 It is a light transmittance curve diagram of the embodiments and comparative examples in 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 slot; 51. evaporation source receiving box. DETAILED DESCRIPTION

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

[0030] Embodiment 1:

[0031] like Figure 1As shown, an embodiment of the present invention proposes a high-transmittance lens coating structure, the coating structure is arranged corresponding to the surface of the light-transmitting optical lens 1, including four coating layers 2 arranged sequentially along the surface of the optical lens 1 toward the outside, the thickness of the coating layer 2 decreases from the center position of the optical lens 1 toward the edge, and 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 which are symmetrical to each other. The loading plate 4 and the evaporation source bracket 5 are both horizontally arranged. 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 connected 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, so that the optical lens 1 can be installed on the bottom surface of the loading plate 4, and the surface of the optical lens 1 to be coated is not blocked and faces the direction of the evaporation source bracket 5. The loading plate 4 is connected to the top plate of the coating chamber 3 through a vertically arranged telescopic rod 6, and the telescopic rod 6 drives the loading plate 4 to move in the vertical direction, so as to adjust the distance between the loading plate 4 and the evaporation source bracket 5. A heater is provided below the evaporation source bracket 5, and an evaporation source receiving box 51 is provided above the heater, and the evaporation source receiving box 51 is located just 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 groove 41, with the surface to be coated facing downwards. Meanwhile, place the silicon oxide evaporation source into the evaporation source receiving box 51. Then, extend the telescopic rod 6 to the maximum distance, so that the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51 is minimized. Then, close the coating chamber 3 and evacuate the chamber until the vacuum degree inside the coating chamber 3 reaches below 3*10-3Pa.

[0036] S2, introducing a protective gas into the coating chamber 3, wherein the protective gas is nitrogen, 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 1200° C.;

[0037] S3, introduce a mixed gas of oxygen and protective gas into the coating chamber 3, control the telescopic rod 6 to slowly contract, increase the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51, and 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. During the coating process, pure protective gas is introduced in the first quarter of the time, and the oxygen content is uniformly increased from one quarter to one half of the time until the oxygen proportion is 50%, and 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. After 20 minutes, the coating chamber 3 is opened and the optical lens 1 after coating is taken out.

[0038] Embodiment 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 in the middle 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 groove 41, with the surface to be coated facing downwards. Meanwhile, place the silicon oxide evaporation source into the evaporation source receiving box 51. Then, extend the telescopic rod 6 to the maximum distance, so that the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51 is minimized. Then, close the coating chamber 3 and evacuate the chamber until the vacuum degree inside the coating chamber 3 reaches below 3*10-3Pa.

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

[0044] S3, introduce a mixed gas of oxygen and protective gas into the coating chamber 3, control the telescopic rod 6 to slowly contract, increase the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51, and 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. During the coating process, pure protective gas is introduced in the first quarter of the time, and the oxygen content is uniformly increased from one quarter to one half of the time until the oxygen proportion is 50%, and 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. After 25 minutes, the coating chamber 3 is opened and the optical lens 1 after coating is taken out.

[0045] Embodiment 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 in the middle 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 groove 41, with the surface to be coated facing downwards. Meanwhile, place the silicon oxide evaporation source into the evaporation source receiving box 51. Then, extend the telescopic rod 6 to the maximum distance, so that the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51 is minimized. Then, close the coating chamber 3 and evacuate the chamber until the vacuum degree inside the coating chamber 3 reaches below 3*10-3Pa.

[0050] S2, introducing a protective gas into the coating chamber 3, wherein the protective gas is nitrogen, 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 11600° C.;

[0051] S3, introduce a mixed gas of oxygen and protective gas into the coating chamber 3, control the telescopic rod 6 to slowly contract, increase the distance between the optical lens receiving groove 41 and the evaporation source receiving box 51, and 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. During the coating process, pure protective gas is introduced in the first quarter of the time, and the oxygen content is uniformly increased from one quarter to one half of the time until the oxygen proportion is 50%, and 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. After 30 minutes, the coating chamber 3 is opened and the optical lens 1 after coating is taken out.

[0052] Comparative Example:

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

[0054] The light 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 respectively. It can be seen that the light transmittance of the present invention is significantly higher than that of ordinary silicon dioxide coatings, especially in the high-wavelength infrared region, the light 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 solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A high-transmittance lens coating structure, the coating structure is arranged corresponding to the surface of a light-transmitting optical lens, characterized in that: It comprises a plurality of coating layers which are sequentially arranged along the surface of the optical lens toward the outside, wherein the thickness of the coating layers decreases from the center position toward the edge of the optical lens, and at the same time, the thickness of the edge positions of all the coating layers is the same, and the thickness of the middle positions decreases sequentially along the surface of the optical lens toward the outside, and the thickness of any position of the coating layer close to the outside is not less than the thickness of any position of the coating layer close to the inside; the material of the coating layer is silicon oxide.

2. The high light transmittance lens coating structure as claimed in claim 1, characterized in that: The oxygen content in the material of the coating layer increases 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 light transmittance lens coating structure as claimed in claim 1, characterized in that: The coating layer has a thickness of 80-220 nm.

4. A coating device for preparing the high-transmittance lens coating structure as claimed in 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 which 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 connected to the top plate of the coating chamber so that the loading plate can move in the vertical direction. The evaporation source bracket is fixedly arranged.

5. The coating device according to claim 4, characterized in that: 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, characterized in that: A heater is arranged at the bottom of the evaporation source bracket, and an evaporation source containing box is arranged above the heater. The evaporation source containing box is located just below the center of the optical lens containing groove.

7. The coating device according to claim 4, characterized in that: 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 receiving tank, with the surface to be coated facing downward. At the same time, place the silicon oxide evaporation source into the evaporation source receiving box, and then extend the telescopic rod to the maximum distance to minimize the distance between the optical lens receiving tank and the evaporation source receiving box. Close the coating chamber and evacuate until the vacuum degree inside the coating chamber reaches 3*10 -3 Below Pa; S2, introducing protective gas into the coating chamber, controlling the internal pressure to 2Pa, and then turning on the heater to heat the evaporation source container, controlling the temperature to 1200°C to 1600°C; S3. Introduce a mixed gas of oxygen and protective gas into the coating chamber, control the telescopic rod to slowly retract, increase the distance between the optical lens receiving slot and the evaporation source receiving box, and 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, open the coating chamber, and take out the optical lens that has been coated.

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

10. The coating method according to claim 8, characterized in that: 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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