Lens shading film and preparation method and application thereof

Abstract

The invention belongs to the technical field of endoscope lens coating, and particularly relates to a lens shading film and a preparation method and application thereof. The lens shading film provided by the invention comprises a light absorbing layer, a reflecting layer and an insulating layer which are sequentially stacked, and the light absorbing layer is in contact with a lens substrate; the material of the light absorption layer comprises chromium and / or titanium; the reflecting layer is made of aluminum and / or silver; and the material of the insulating layer comprises silicon dioxide and / or silicon nitride. Through the synergistic effect of the light absorbing layer and the reflecting layer, the shading performance of the shading film is remarkably improved; meanwhile, the lens shading film provided by the invention is good in uniformity, so that the optical performance of the lens is not influenced. In conclusion, the coating of the lens shading film provided by the invention is compact and uniform and can reach over OD2, and the average transmittance in a visible light range has a shading effect of less than 0.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of endoscope lens coating, and in particular relates to a lens shading film and a preparation method and application thereof. Background Art

[0002] With the rapid development of medicine and the continuous improvement of people's medical requirements, endoscope lenses are key components in medical devices, and the surface shading film is the basis for their high-quality imaging. The main function of the shading film is to reduce the reflection and glare of the lens in a high-brightness environment and improve the contrast and clarity of the image. The quality of the shading film is crucial to the overall quality of the endoscope lens.

[0003] At present, the surface treatment method used for shading of endoscope lenses is mostly ink spraying, but the shading performance is still poor. Summary of the invention

[0004] The object of the present invention is to provide a lens shading film and a preparation method thereof. The lens shading film provided by the present invention can significantly improve the shading performance of an endoscope lens.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a lens shading film, comprising a light absorbing layer, a reflective layer and an insulating layer which are stacked in sequence, wherein the light absorbing layer is in contact with the endoscope lens substrate; the material of the light absorbing layer comprises chromium and / or titanium; the material of the reflective layer comprises aluminum and / or silver; and the material of the insulating layer comprises silicon dioxide and / or silicon nitride.

[0007] Preferably, the light absorbing layer has a thickness of 5 to 15 μm.

[0008] Preferably, the thickness of the reflective layer is 3-15 μm.

[0009] Preferably, the thickness of the insulating layer is 2-10 μm.

[0010] Preferably, the thickness of the lens shading film is 10-40 μm.

[0011] The present invention provides a method for preparing the lens shading film described in the above technical solution, comprising the following steps:

[0012] A light absorbing layer, a reflecting layer and an insulating layer are sequentially deposited on the side of the lens by a vapor deposition method, so that the lens light-shielding film is obtained on the side of the lens.

[0013] Preferably, the conditions for the vapor deposition include: a vacuum value of 1.0×10 -4 ~1.3×10 -3Pa; the endoscope lens rotates, and the rotation speed is 25-80 rpm; the purity of the target material used for the vapor deposition is greater than 99.99%.

[0014] Preferably, the vapor deposition includes magnetron sputtering or electron beam vacuum evaporation;

[0015] The magnetron sputtering conditions include: the power for depositing the light absorbing layer is 1-12 kW, and the time is 30-60 min; the power for depositing the reflective layer is 3-12 kW, and the time is 20-70 min; the power for depositing the insulating layer is 3-14 kW, and the time is 5-30 min, and the flow rate of the reaction gas is 50-120 sccm;

[0016] The conditions for the electron beam vacuum evaporation include: the current for depositing the light absorbing layer is 200-800 mA, and the time is 15-45 min; the current for depositing the reflective layer is 200-1000 mA, and the time is 30-60 min; the current for depositing the insulating layer is 100-500 mA, and the time is 10-50 min, and the flow rate of the reaction gas is 30-100 sccm.

[0017] Preferably, before depositing the light absorbing layer, the method further comprises: plasma cleaning the endoscope lens, wherein the gas used for the plasma cleaning comprises an inert gas, wherein the inert gas comprises argon and / or helium, and the purity of the argon or helium is greater than 99.99%; and the flow rate of the inert gas is 10 to 90 sccm;

[0018] After the insulating layer is deposited, the method further includes: cooling the deposited sample to obtain the lens shading film; the cooling time is 10 to 60 minutes.

[0019] The present invention provides application of the lens shading film described in the above technical solution or the lens shading film prepared by the preparation method described in the above technical solution in an endoscope lens shading film.

[0020] The present invention provides a lens shading film, comprising a light absorbing layer, a reflective layer and an insulating layer stacked in sequence, wherein the light absorbing layer is in contact with the lens substrate; the material of the light absorbing layer comprises chromium and / or titanium; the material of the reflective layer comprises aluminum and / or silver; the material of the insulating layer comprises silicon dioxide and / or silicon nitride. The present invention significantly improves the light shading performance of the shading film through the synergistic effect of the light absorbing layer and the reflective layer; at the same time, the lens shading film provided by the present invention has good uniformity, thereby ensuring that the optical performance of the lens is not affected; the present invention sets a reflective layer on the surface (outer surface, the surface away from the head base) of the light absorbing layer, and the main function of the reflective layer is to reflect light and reduce the light entering the interior of the lens; since the reflective layer is on the outer surface of the light absorbing layer, it also has the function of protecting the light absorbing layer; in addition, the special physical properties of the reflective layer (aluminum or silver) itself can reflect its corrosion resistance in the special case where the insulating layer is damaged. The present invention sets an insulating layer on the surface of the reflective layer (the outer surface, the surface away from the base of the head), and uses the insulating layer as a protective layer for the light-absorbing layer and the reflective layer, so as to protect the endoscope lens (i.e., the lens substrate), the light-absorbing layer and the reflective layer from scratches, abrasion and chemical corrosion, thereby extending the service life; at the same time, the insulating layer can also achieve good insulation between the protective lens and the circuit or the housing, prevent phenomena such as electrical breakdown, and improve the safety of the product; in addition, the insulating layer has good stability, so that the lens can be used under harsh conditions such as high temperature. In summary, the lens shading film provided by the present invention has a dense and uniform coating, which can reach OD2 or above, and the average transmittance in the visible light range has a shading effect of less than 0.5%; at the same time, the lens shading film has excellent wear resistance and corrosion resistance, and the film layer has a long service life.

[0021] The present invention provides a method for preparing the lens shading film described in the above technical solution, comprising the following steps: using a physical vapor deposition method to sequentially deposit a light absorbing layer, a reflective layer and an insulating layer on the side of the lens, and obtaining the lens shading film on the side of the lens. The present invention uses a physical vapor deposition method to achieve multi-angle coating on the side of the endoscope lens, thereby uniformly forming a film on the side of the endoscope lens, improving the overall uniformity of the lens shading film, and ensuring that the optical performance of the lens is not affected. The present invention uses a physical vapor deposition method, the operation steps are simple, and batch products can be prepared at the same time, which speeds up the preparation speed of the lens shading film and solves the problem of low production efficiency.

[0022] The present invention provides the application of the lens shading film described in the above technical solution or the lens shading film prepared by the preparation method described in the above technical solution in the endoscope lens shading film. The lens shading film provided by the present invention has a wide range of applications and is suitable for various types of lenses, such as endoscope lenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A macroscopic schematic diagram showing a comparison before and after the light shielding film is prepared for the endoscope lens provided by an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the film structure of the lens shading film;

[0025] Figure 3 The light-shielding film transmittance curves of the endoscope lens light-shielding films prepared in Examples 1 and 2 of the present invention;

[0026] In the figure: 1 is the light absorbing layer, 2 is the reflecting layer, 3 is the insulating layer, and 4 is the metal layer. DETAILED DESCRIPTION

[0027] The present invention provides a lens shading film, comprising a light absorbing layer, a reflective layer and an insulating layer which are stacked in sequence, wherein the light absorbing layer is in contact with the lens substrate; the material of the light absorbing layer comprises chromium and / or titanium; the material of the reflective layer comprises aluminum and / or silver; and the material of the insulating layer comprises silicon dioxide and / or silicon nitride.

[0028] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0029] Figure 2 The structure diagram of the lens shading film provided by the present invention is shown below in combination with Figure 2 The lens shading film provided by the present invention is described in detail.

[0030] The lens shading film provided by the present invention includes a light absorbing layer 1. In the present invention, the light absorbing layer 1 is in contact with the lens substrate. One surface of the light absorbing layer 1 is in contact with the lens substrate. The material of the light absorbing layer 1 includes chromium and / or titanium, and can be chromium in the embodiment. In the present invention, metal chromium (Cr) has light absorbing properties, mainly absorbs visible light and ultraviolet light, can reduce the reflection and transmission of light, and is not oxidized at room temperature and has stable chemical properties. In the present invention, the thickness of the light absorbing layer is preferably 5 to 15 μm, and can be 15 μm in the embodiment. The function of the light absorbing layer 1 is to absorb visible light and ultraviolet light, and can reduce the reflection and transmission of light.

[0031] The lens shading film provided by the present invention comprises a reflective layer 2 arranged on the other surface of the light absorbing layer 1. In the present invention, the reflective layer 2 is an intermediate layer, one surface of the reflective layer 2 is in contact with the light absorbing layer 1, and the other surface of the reflective layer 2 is in contact with the insulating layer 3. The material of the reflective layer 2 comprises aluminum and / or silver, and in the embodiment, it can be aluminum. In the present invention, metal aluminum (Al) has high reflectivity in the ultraviolet light, visible light and infrared light bands, can further reflect part of the light passing through the light absorbing layer 1, and has good chemical stability. In the present invention, the thickness of the reflective layer is preferably 3 to 15 μm, and in the embodiment, it can be 10 μm or 15 μm. In the present invention, the reflective layer mainly functions to reflect light and reduce the light entering the interior of the lens; since the reflective layer is on the outer surface of the light absorbing layer, it also has the function of protecting the light absorbing layer; in addition, the special physical properties of the reflective layer (aluminum or silver) itself can reflect its corrosion resistance in the special case where the insulating layer is damaged.

[0032] The lens shading film provided by the present invention includes an insulating layer 3 arranged on the surface of the reflective layer 2. In the present invention, the material of the insulating layer 3 includes silicon dioxide and / or silicon nitride, and in the embodiment it can be silicon dioxide. In the present invention, the silicon dioxide has extremely high chemical stability and insulation. In the present invention, the thickness of the insulating layer 3 is 2 to 10 μm, and in the embodiment it can be 5 μm. In the present invention, the insulating layer 3 serves as a protective layer to protect the endoscope lens, the light absorbing layer and the reflective layer from scratches, wear and chemical corrosion, thereby extending the service life; the insulating layer 3 is used to protect the good insulation between the lens and the circuit or the housing, prevent electrical breakdown and other phenomena, and improve the safety of the product; in addition, the insulating layer 3 has good stability, so that the lens can be used under harsh conditions such as high temperature.

[0033] In the present invention, the thickness of the lens shading film is preferably 10 to 40 μm, and in the embodiment, it can be 30 μm or 35 μm. The light absorbing layer 1 and the reflective layer 2 in the lens shading film are collectively referred to as the metal layer 4. The lens shading film provided by the present invention has a dense and uniform coating, which can reach OD2 or above, and the average transmittance in the visible light range has a shading effect of less than 0.5%.

[0034] The present invention provides a method for preparing the lens shading film described in the above technical solution, comprising the following steps:

[0035] A physical vapor deposition method is adopted to sequentially deposit a light absorbing layer, a reflective layer and an insulating layer on the side of the lens, so as to obtain the lens light-shielding film on the side of the lens.

[0036] The present invention adopts a physical vapor deposition method to prepare a lens shading film, and can use multi-angle coating on the endoscope lens to achieve uniform film formation on its surface, thereby obtaining a dense and uniform lens shading film. In the present invention, the implementation steps of the physical vapor deposition preferably include:

[0037] Step 1: In the vacuum chamber, cover both ends of the endoscope lens and fix it on the fixture, place it on the rotating workpiece in the vacuum chamber, install the target material of the light-absorbing layer, the target material of the reflective layer and the target material of the insulating layer on the vacuum coating equipment respectively, and then evacuate the vacuum chamber of the coating equipment until the set vacuum degree is reached;

[0038] Step 2: A film is deposited on the side of the endoscope lens by a physical vapor deposition method. The fixture rotates at a constant speed on a rotating table. In the first stage, an inert gas is introduced for plasma cleaning to obtain a clean endoscope lens. In the second stage, a light-absorbing layer is deposited on the four sides of the endoscope lens. In the third stage, a reflective layer is deposited on the four sides of the endoscope lens. In the fourth stage, an insulating layer is deposited on the four sides of the endoscope lens to obtain an endoscope lens with a light-shielding film deposited on all four sides.

[0039] Step 3: After the sample prepared in step 2 is cooled along with the equipment, the vacuum chamber is opened to obtain a lens shading film.

[0040] In the present invention, the vacuum value obtained by vacuuming in step 1 is preferably 1.0×10 -4 ~1.3×10 -3 Pa, specifically 1.0×10 -3 Pa or 1.0×10 -4 Pa.

[0041] In the present invention, before depositing the light absorbing layer, the present invention preferably further comprises: plasma cleaning the endoscope lens. In the present invention, the gas used for the plasma cleaning preferably comprises an inert gas, and the inert gas preferably comprises argon and / or helium, and in the embodiment it may be argon. The purity of the argon or helium is preferably >99.99%; the flow rate of the inert gas is preferably 10 to 90 sccm, and in the embodiment it is specifically 90 sccm or 10 sccm. In the present invention, the gas used for the plasma cleaning preferably also comprises oxygen, and when the gas used for the plasma cleaning also comprises oxygen, the flow rate of the oxygen is preferably 10 to 60 sccm, and in the embodiment it may be 60 sccm.

[0042] In the present invention, the conditions for physical vapor deposition preferably include: a vacuum value of 1.0×10 -4 ~1.3×10 - 3 Pa, specifically 1.0×10-3 Pa or 1.0×10 -4 Pa. The endoscope lens rotates, and the rotation speed is preferably 25-80 rpm, and in the embodiment can be 80 rpm or 30 rpm. The purity of the target material used for physical vapor deposition is preferably >99.99%.

[0043] In the present invention, the physical vapor deposition preferably includes magnetron sputtering or electron beam vacuum evaporation.

[0044] In the present invention, the conditions of the magnetron sputtering preferably include: the power for depositing the light absorbing layer is preferably 1-12 kW, which may be 6 kW in the embodiment, and the time is preferably 30-60 min, which may be 40 min in the embodiment; the power for depositing the reflective layer is preferably 3-12 kW, which may be 5 kW in the embodiment, and the time is preferably 20-70 min, which may be 30 min in the embodiment; the power for depositing the insulating layer is preferably 3-14 kW, which may be 5 kW in the embodiment, and the time is preferably 5-30 min, which may be 10 min in the embodiment; the reaction gas used for depositing the insulating layer is preferably oxygen, and the flow rate of the reaction gas is preferably 50-120 sccm, which may be 80 sccm in the embodiment. In the present invention, when the lens shading film is prepared by the magnetron sputtering, the gas used for the plasma cleaning is an inert gas, and the conditions of the plasma cleaning preferably include: the flow rate of the inert gas is more preferably 50-90 sccm, which may be 90 sccm in the embodiment, and the ICP power is preferably 0.1-0.8 kW, which may be 0.6 kW in the embodiment.

[0045] In the present invention, the conditions of the electron beam vacuum evaporation preferably include: the current for depositing the light absorbing layer is preferably 200-800 mA, which may be 500 mA in the embodiment, and the time is preferably 15-45 min, which may be 30 min in the embodiment; the current for depositing the reflective layer is preferably 200-1000 mA, which may be 400 mA in the embodiment, and the time is preferably 30-60 min, which may be 45 min in the embodiment; the current for depositing the insulating layer is preferably 100-500 mA, which may be 200 mA in the embodiment, and the time is preferably 10-50 min, which may be 20 min in the embodiment; the reaction gas used for depositing the insulating layer is preferably oxygen, and the flow rate of the reaction gas is preferably 30-100 sccm, which may be 80 sccm in the embodiment. In the present invention, when the lens shading film is prepared by the electron beam vacuum evaporation, the gas used for the plasma cleaning is an inert gas and oxygen, and the conditions of the plasma cleaning preferably include: the flow rate of the inert gas is more preferably 10-20 sccm, which may be 10 sccm in the embodiment. The flow rate of the oxygen gas is preferably 10 to 60 sccm, and in the embodiment, may be 60 sccm.

[0046] In the present invention, after the insulating layer is deposited, the present invention preferably further comprises: cooling the deposited sample to obtain the lens shading film; the cooling time is preferably 10 to 60 minutes. By controlling the cooling time, the present invention can better ensure that a lens shading film product with good performance is obtained.

[0047] The present invention adopts physical vapor deposition coating to speed up the preparation of lens shading film, solving the problem of low production efficiency; at the same time, multi-angle deposition of film layers is adopted to achieve uniform film formation on the surface of the lens shading film, ensuring that the optical performance of the lens is not affected.

[0048] The present invention provides application of the lens shading film described in the above technical solution or the lens shading film prepared by the preparation method described in the above technical solution in an endoscope lens shading film.

[0049] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0050] Figure 1 This is a macroscopic schematic diagram comparing the endoscope lens before and after the light-shielding film is prepared in Examples 1 and 2 of the present invention.

[0051] Example 1

[0052] The present embodiment provides a method for preparing a light-shielding film for an endoscope lens. The present embodiment adopts a vacuum coating method, and a light-shielding film with a total thickness of 30 μm is coated on the surface of the endoscope lens by magnetron sputtering. The thickness of the chromium (Cr) light absorption layer is 15 μm; the thickness of the aluminum (Al) reflective layer is 10 μm; and the thickness of the silicon dioxide insulating layer is 5 μm.

[0053] Magnetron sputtering specifically includes the following steps:

[0054] In the vacuum chamber, the ends of the endoscope lens are covered and fixed on the fixture, and then placed on the rotating workpiece in the vacuum chamber. The light-absorbing layer target (chromium, purity>99.99%), the reflective layer target (Al, purity>99.99%) and the insulating layer target (Si, purity>99.99%) are installed on the vacuum coating equipment respectively, and then the vacuum chamber of the coating equipment is evacuated until the set vacuum degree of 1.0×10 -3 Pa;

[0055] The film layer is deposited on the four sides of the endoscope lens by magnetron sputtering. The fixture rotates at a constant speed of 80rpm on the rotating table. In the first stage, an inert gas (argon) is introduced with a flow rate of 90sccm and an ICP power of 0.6kW for plasma cleaning to obtain a clean endoscope lens; in the second stage, the light-absorbing layer is deposited on the four sides of the endoscope lens; in the third stage, the reflective layer is deposited on the four sides of the endoscope lens; in the fourth stage, an insulating layer is deposited on the four sides of the endoscope lens; an endoscope lens with a light-shielding film deposited on all four sides is obtained; wherein, the conditions for magnetron sputtering light-shielding film deposition include: vacuum degree: 1.0×10 -3 Pa; chromium (Cr) light absorbing layer power 6kW, time 40min; aluminum (Al) reflective layer power 5kW, time 30min; silicon dioxide insulating layer power 5kW, time 10min, the reaction gas for depositing the silicon dioxide insulating layer is oxygen, and the flow rate of oxygen introduced for the reaction is 80sccm.

[0056] After the prepared endoscope lens light-shielding film was cooled along with the equipment for 30 minutes, the vacuum chamber was opened to obtain the endoscope lens light-shielding film.

[0057] After testing, the test results are as follows Figure 3 As shown, the endoscope lens shading film prepared in this embodiment has a good shading effect, while the optical performance remains unchanged.

[0058] Example 2

[0059] The present embodiment provides a method for preparing a light-shielding film for an endoscope lens. The present embodiment adopts a vacuum coating method. A light-shielding film with a total thickness of 35 μm is coated on the surface of the endoscope lens by electron beam vacuum evaporation coating. The thickness of the chromium (Cr) light-absorbing layer is 15 μm; the thickness of the aluminum (Al) reflective layer is 15 μm; and the thickness of the silicon dioxide insulating layer is 5 μm.

[0060] Electron beam vacuum evaporation coating specifically includes the following steps:

[0061] In the vacuum chamber, the ends of the endoscope lens are covered and fixed on the fixture, and then placed on the rotating workpiece in the vacuum chamber. The light-absorbing layer target (chromium, purity>99.99%), the reflective layer target (Al, purity>99.99%) and the insulating layer target (Si, purity>99.99%) are installed on the vacuum coating equipment respectively, and then the vacuum chamber of the coating equipment is evacuated until the set vacuum degree of 1.0×10 -4 Pa;

[0062] Electron beam vacuum evaporation coating was used to deposit film layers on the four sides of the endoscope lens. The fixture rotated at a constant speed of 30 rpm on the rotating table. In the first stage, an inert gas (argon) was introduced with a flow rate of 10 sccm and oxygen 60 sccm for plasma cleaning to obtain a clean endoscope lens; in the second stage, the light-absorbing layer was deposited on the four sides of the endoscope lens; in the third stage, the reflective layer was deposited on the four sides of the endoscope lens; in the fourth stage, an insulating layer was deposited on the four sides of the endoscope lens; an endoscope lens with a light-shielding film deposited on all four sides was obtained; wherein, the conditions for preparing the light-shielding film by electron beam vacuum evaporation coating include: vacuum degree: 1.0×10 -4 Pa; chromium (Cr) light absorption layer current 500mA, time 30min; aluminum (Al) reflective layer current 400mA, time 45min; silicon dioxide insulating layer current 200mA, time 20min; the reaction gas for depositing the silicon dioxide insulating layer is oxygen, and the flow rate of oxygen introduced for the reaction is 80sccm.

[0063] After the prepared endoscope lens light-shielding film was cooled along with the equipment for 30 minutes, the vacuum chamber was opened to obtain the endoscope lens light-shielding film.

[0064] After testing, the test results are as follows Figure 3 As shown, the endoscope lens shading film prepared in this embodiment has excellent shading effect while the optical performance remains unchanged.

[0065] In the present invention, the film layers prepared in Example 1 and Example 2 are prepared by two different processes, magnetron sputtering and electron beam evaporation coating, and the organizational structure of the film layers is different, and the thickness of the prepared film layers is different, so the transmittance is different. However, the transmittance data below 0.1% is a very small value. When the Y-axis transmittance is magnified, there is a certain difference between Example 1 and Example 2, but the overall difference between the two is small below 0.1%.

[0066] It can be seen from the above embodiments that the present invention has the following advantages compared with the prior art:

[0067] The lens shading film prepared by the present invention has good shading effect: the present invention significantly improves the shading performance of the lens through the synergistic effect of the light absorbing layer and the reflective layer.

[0068] The lens shading film prepared by the present invention has strong durability: the reflective layer can effectively protect the light-absorbing layer, improve the wear resistance and corrosion resistance of the film layer, and extend the service life of the film layer.

[0069] The lens shading film prepared by the present invention has a wide range of applications and is suitable for various types of lenses, such as endoscope lenses.

[0070] The present invention adopts a physical vapor deposition method to deposit film layers at multiple angles and accurately control the thickness of the film layers, thereby achieving uniform film formation on the lens surface, improving the uniformity of the lens shading film, ensuring that the optical performance of the lens is not affected, and being able to prepare a large number of products at the same time with high production efficiency.

[0071] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A lens shading film, characterized in that: It comprises a light absorbing layer, a reflective layer and an insulating layer which are stacked in sequence, wherein the light absorbing layer is in contact with a lens substrate; the material of the light absorbing layer comprises chromium and / or titanium; the material of the reflective layer comprises aluminum and / or silver; the material of the insulating layer comprises silicon dioxide and / or silicon nitride.

2. The lens shading film according to claim 1, wherein: The thickness of the light absorbing layer is 5 to 15 μm.

3. The lens shading film according to claim 1, wherein: The thickness of the reflective layer is 3-15 μm.

4. The lens shading film according to claim 1, wherein: The thickness of the insulating layer is 2-10 μm.

5. The lens shading film according to any one of claims 1 to 4, characterized in that: The thickness of the lens shading film is 10 to 40 μm.

6. The method for preparing a lens shading film according to any one of claims 1 to 5, characterized in that: The following steps are involved: A physical vapor deposition method is adopted to sequentially deposit a light absorbing layer, a reflective layer and an insulating layer on the side of the lens, so as to obtain the lens light-shielding film on the side of the lens.

7. The preparation method according to claim 6, characterized in that: The conditions of the physical vapor deposition include: a vacuum value of 1.0×10 -4 ~1.3×10 -3 Pa; the endoscope lens rotates, and the rotation speed is 25-80 rpm; the purity of the target material used in the physical vapor deposition is greater than 99.99%.

8. The preparation method according to claim 6 or 7, characterized in that: The physical vapor deposition includes magnetron sputtering or electron beam vacuum evaporation; The magnetron sputtering conditions include: the power for depositing the light absorbing layer is 1-12 kW, and the time is 30-60 min; the power for depositing the reflective layer is 3-12 kW, and the time is 20-70 min; the power for depositing the insulating layer is 3-14 kW, and the time is 5-30 min, and the flow rate of the reaction gas is 50-120 sccm; The conditions for the electron beam vacuum evaporation include: the current for depositing the light absorbing layer is 200-800 mA, and the time is 15-45 min; the current for depositing the reflective layer is 200-1000 mA, and the time is 30-60 min; the current for depositing the insulating layer is 100-500 mA, and the time is 10-50 min, and the flow rate of the reaction gas is 30-100 sccm.

9. The preparation method according to claim 6, characterized in that: Before depositing the light absorbing layer, the method further includes: plasma cleaning the endoscope lens, wherein the gas used for the plasma cleaning includes an inert gas, wherein the inert gas includes argon and / or helium, and the purity of the argon and helium is greater than 99.99%; and the flow rate of the inert gas is 10 to 90 sccm; After the insulating layer is deposited, the method further includes: cooling the deposited sample to obtain the lens shading film; the cooling time is 10 to 60 minutes.

10. Use of the lens shading film according to any one of claims 1 to 5 or the lens shading film prepared by the preparation method according to any one of claims 6 to 9 in an endoscope lens shading film.

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