Coated high-laser-damage-threshold high-reflectivity laser optical element and preparation method thereof

Abstract

The invention relates to a coated high-laser-damage-threshold high-reflectivity laser optical element and a preparation method thereof.The preparation method of the coated high-laser-damage-threshold high-reflectivity laser optical element comprises the following steps that (1) a substrate is subjected to ultrasonic cleaning, then Ar plasma generated by an anode ion source is adopted for cleaning the substrate, and a pre-cleaned substrate is obtained; (2) alternately carrying out high-refraction layer coating and low-refraction layer coating on the surface of the pre-cleaned substrate obtained in the step (1) to obtain a coated substrate; and coating a protective layer on the surface of the obtained coated substrate to obtain the coated high-laser-damage-threshold high-reflectivity laser optical element. According to the method, before high-refraction layer coating and low-refraction layer coating are carried out, the Ar plasma generated by the anode ion source is adopted to clean the substrate, and the laser damage threshold value of the high-reflectivity laser optical element composed of the thin film and the substrate is remarkably increased.

Description

Technical Field

[0001] The invention relates to the technical field of optical film coating, and in particular to a film-coated high laser damage threshold high-reflection laser optical element and a preparation method thereof. Background Art

[0002] With the increasingly widespread application of ultra-strong laser systems in the fields of weapon guidance, space electronic countermeasures, and laser-induced nuclear fusion, the demand for the laser damage resistance of the system's highly reflective optical components is also increasing. In laser optical systems, the laser damage resistance of optical components often determines the laser damage resistance of the entire system. For example, in the laser protection of laser infrared detectors, the optical window of the laser photodetector often needs to be coated with multiple layers of optical films to achieve total reflection of specific blinding pulse lasers, thereby improving its survivability. The higher the laser damage threshold of the optical component coated with a multilayer optical film, the higher the level of laser protection that the laser infrared detector can provide. Therefore, it is of great economic and social value to improve the laser damage resistance of highly reflective optical components through innovations such as materials or processing and molding processes.

[0003] CN111679347A discloses a high damage threshold laser thin film process technology method, which uses quartz or K9 as a coating substrate, sapphire as a substrate film material M, HfO2 as a high refractive index film material H, and SiO2 as a low refractive index film material L, and uses TFC to give the geometric thickness of each layer of the film system and the film system sequence calculation results; ultrasonic cleaning and heating baking of the coating substrate; in the optical film layer bonding and priming process and stress matching process, the three film materials are placed in the electron gun evaporation source crucible in sequence, and then the coating process is completed according to the geometric thickness of each layer of the film system and the film system sequence; before and during the evaporation coating, the coating substrate is bombarded with an ion source. However, the process steps of this method are relatively complicated, and the anti-laser damage threshold of the optical film obtained is still low.

[0004] CN101499399A discloses a substrate plasma processing device and a plasma processing method, wherein the substrate plasma processing device comprises a substrate support electrode and a counter electrode arranged in a cavity; a 50MHz or high frequency generating device to apply a DC negative pulse voltage to the substrate support electrode; a DC negative pulse generating device to apply a DC negative pulse voltage in a manner superimposed on the high frequency; and a controller, wherein the controller controls to cause the intermittent application of the high frequency and causes the intermittent application of the DC negative pulse voltage according to the timing of the high frequency being turned on or off. The process mainly uses an RF power supply to generate Ar plasma to clean the sample substrate, and this method has the defect of easily introducing contaminants. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a coated high laser damage threshold high reflectivity laser optical element and a preparation method thereof, which uses an anode ion source to generate Ar plasma to effectively clean the optical substrate before coating, thereby significantly improving the laser damage threshold of the coated high laser damage threshold high reflectivity laser optical element.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a high-laser damage threshold and high-reflectivity laser optical element with a coating, the preparation method comprising the following steps:

[0008] (1) ultrasonically cleaning the substrate, and then cleaning the substrate using Ar plasma generated by an anode ion source to obtain a pre-cleaned substrate;

[0009] (2) Alternately coating the surface of the pre-cleaned substrate obtained in step (1) with a high refractive layer and coating the surface with a low refractive layer to obtain a coated substrate; and coating the surface of the obtained coated substrate with a protective layer to obtain the coated high laser damage threshold and high reflectivity laser optical element.

[0010] The method for preparing a high-reflection laser optical element with high laser damage threshold by coating provided by the present invention is to clean the substrate by using Ar plasma generated by an anode ion source before coating the high-refractive layer and the low-refractive layer, thereby significantly improving the laser damage threshold of the high-reflective laser optical element composed of the thin film and the substrate, and the laser damage performance is improved by nearly 5 times compared with that before the treatment; in addition, the method has excellent laser optical reflectivity. The preparation method is relatively novel, the process is simple, and it is suitable for industrial-scale production.

[0011] Preferably, the substrate in step (1) comprises any one of quartz glass, sapphire, BK7 or calcium fluoride glass.

[0012] Preferably, the preparation method is carried out by a preparation device for coating high laser damage threshold and high reflectivity laser optical elements, the preparation device comprising a vacuum chamber, a rotating sample stage is provided on the top of the inner cavity of the vacuum chamber, a magnetron target gun is fixedly provided on the opposite side of the rotating sample stage, an anode ion source and an argon gas inlet pipe are provided on one side of the inner cavity of the vacuum chamber, and a molecular pump and a mechanical pump are respectively connected to the other side of the inner cavity, and the molecular pump is communicated with the mechanical pump.

[0013] The device for preparing the coated high laser damage threshold high reflectivity laser optical element is a device for preparing the optical element by high vacuum magnetron sputtering.

[0014] Preferably, a rotating rod is disposed on the top surface of the rotating sample stage, and the rotating rod is fixedly connected to a servo motor via a flange.

[0015] Preferably, the magnetron target gun is connected to a radio frequency power supply.

[0016] Preferably, the magnetron target gun comprises a first magnetron target gun, a second magnetron target gun and a third magnetron target gun which are arranged in parallel.

[0017] Preferably, the inner cavity of the vacuum chamber is also provided with an ionization gauge.

[0018] Preferably, a limiting flow valve is provided at the front end of the molecular pump.

[0019] Preferably, a front-end valve is provided at the front end of the mechanical pump.

[0020] Preferably, before the Ar plasma is used to clean the substrate in step (1), the background vacuum of the vacuum chamber is controlled to be ≤8×10 -5 Pa, for example, can be 8×10 -5 Pa, 6×10 -5 Pa, 5×10 -5 Pa, 3×10 -5 Pa or 1×10 -5 Pa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, after controlling the background vacuum degree of the vacuum chamber, argon gas is introduced, and then the opening of the limiting valve is adjusted to make the working vacuum degree 0.5-1Pa, for example, it can be 0.5Pa, 0.6Pa, 0.8Pa, 0.9Pa or 1Pa, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the purity of the argon gas is 99.999%.

[0023] Preferably, the current of the anode ion source used for cleaning the substrate with Ar plasma in step (1) is 150-500mA, for example, it can be 150mA, 200mA, 300mA, 400mA or 500mA, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, before the high refractive layer is coated in step (2), the working vacuum is adjusted to 0.5-1Pa, for example, it can be 0.5Pa, 0.6Pa, 0.8Pa, 0.9Pa or 1Pa, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the target material used for coating the high refractive layer in step (2) includes any one of yttrium oxide, hafnium oxide or tantalum oxide, or a combination of at least two of them. Typical but non-limiting combinations include a combination of yttrium oxide and hafnium oxide, a combination of hafnium oxide and tantalum oxide, or a combination of yttrium oxide, hafnium oxide and tantalum oxide.

[0026] Preferably, the purity of the target material used for coating the high refractive layer in step (2) is 99.99%.

[0027] Preferably, the target material used for coating the low-refractive layer in step (2) comprises silicon oxide and / or magnesium fluoride.

[0028] Preferably, the optical thickness of the high refractive layer coating and the low refractive layer coating in step (2) are respectively one quarter of the wavelength of 1064 nm.

[0029] Preferably, the target material used for coating the protective layer in step (2) includes any one of yttrium oxide, hafnium oxide, tantalum oxide or silicon oxide.

[0030] In a second aspect, the present invention provides a coated high laser damage threshold high reflection laser optical element, wherein the coated high laser damage threshold high reflection laser optical element is prepared by the method for preparing the coated high laser damage threshold high reflection laser optical element described in the first aspect.

[0031] The structure of the coated high laser damage threshold high reflective laser optical element provided by the present invention is composed of a substrate cleaned by Ar plasma, a high refractive layer, a low refractive layer and a protective layer. The coated high laser damage threshold high reflective laser optical element has excellent anti-laser damage performance, and the damage threshold to 1064nm high power laser can reach 40.76J / cm 2 ; In addition, it has excellent laser optical reflectivity, with a reflectivity of 99.4% for 1064nm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The invention provides a method for preparing a high-reflection laser optical element with a high laser damage threshold. Before coating the high-refractive layer and the low-refractive layer, the substrate is first cleaned with Ar plasma generated by an anode ion source, thereby significantly improving the laser damage threshold of the high-reflective laser optical element composed of the thin film and the substrate. The damage threshold to a 1064nm high-power laser can reach 40.76J / cm 2 In addition, it has excellent laser optical reflectivity, and the reflectivity at 1064nm reaches 99.4%. The preparation method is relatively novel, the process is simple, and it is suitable for industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1It is a schematic structural diagram of a device for preparing a coated high laser damage threshold high reflective laser optical element provided in Example 1 of the present invention;

[0035] Figure 2 This is a scanning electron microscope image of a coated high laser damage threshold high reflectivity laser optical element provided in Example 1 of the present invention;

[0036] Figure 3 is a graph showing changes in transmittance at different wavelengths of a coated high laser damage threshold high reflectivity laser optical element provided in Example 1 of the present invention;

[0037] Figure 4 This is a scanning electron microscope image of a coated high laser damage threshold high reflectivity laser optical element provided in Comparative Example 1 of the present invention;

[0038] Figure 5 This is a graph showing the transmittance variation of the coated high laser damage threshold and high reflectivity laser optical element at different wavelengths provided in Comparative Example 1 of the present invention.

[0039] Among them: 1, vacuum chamber; 2, rotating sample stage; 3, flange; 4, servo motor; 5, first magnetron target gun; 6, second magnetron target gun; 7, third magnetron target gun; 8, RF power supply; 9, argon gas inlet pipe; 10, anode ion source; 11, molecular pump; 12, mechanical pump; 13, current limiting valve; 14, fore valve; 15, ionization gauge. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] Example 1

[0042] This embodiment provides a film-coated high laser damage threshold high reflectivity laser optical element. The method for preparing the film-coated high laser damage threshold high reflectivity laser optical element is performed by a film-coated high laser damage threshold high reflectivity laser optical element preparation device. The structural schematic diagram of the film-coated high laser damage threshold high reflectivity laser optical element preparation device is shown in FIG. Figure 1 As shown, the preparation device includes a vacuum chamber 1, a rotating sample stage 2 is provided on the top of the inner cavity of the vacuum chamber 1, a rotating rod is provided on the top surface of the rotating sample stage 2, and the rotating rod is fixedly connected to a servo motor 4 through a flange 3; a first magnetron target gun 5, a second magnetron target gun 6 and a third magnetron target gun 7 are fixedly arranged in parallel on the opposite side of the rotating sample stage 2, and the first magnetron target gun 5, the second magnetron target gun 6 and the third magnetron target gun 7 are independently connected to a radio frequency power supply 8.

[0043] An anode ion source 10 and an argon gas inlet pipe 9 are arranged on one side of the inner cavity of the vacuum chamber 1, and a molecular pump 11 and a mechanical pump 12 are respectively connected to the other side of the inner cavity of the vacuum chamber 1, and the molecular pump 11 is connected to the mechanical pump 12; a limiting flow valve 13 is arranged at the front end of the molecular pump 11; a fore-stage valve 14 is arranged at the front end of the mechanical pump 12; and the inner cavity of the vacuum chamber 1 is also connected to an ionization gauge 15.

[0044] The method for preparing the coated high laser damage threshold high reflective laser optical element comprises the following steps:

[0045] (1) The quartz glass is ultrasonically cleaned; the background vacuum degree of the vacuum chamber 1 is controlled to be 3×10 -5 Pa, introduce argon gas, and then adjust the opening of the limiting valve to make the working vacuum degree 1Pa; use Ar plasma generated by the anode ion source to clean the substrate, set the cleaning current to 400mA, and obtain a pre-cleaned substrate;

[0046] (2) adjusting the opening of the limiting valve 14 so that the working vacuum is 0.6 Pa; then alternately coating the surface of the pre-cleaned substrate obtained in step (1) with a high refractive layer and coating the low refractive layer, the optical thickness of the high refractive layer and the low refractive layer being respectively one-quarter wavelength of 1064 nm, to obtain a coated substrate; the target material used for the high refractive layer coating comprises yttrium oxide with a purity of 99.99% and hafnium oxide with a purity of 99.99%, and the molar number of yttrium oxide in the high refractive layer accounts for 5% of the total molar number; the high refractive layer coating comprises pre-sputtering for 2 min and dual magnetron co-sputtering; the target material used for the low refractive layer coating is silicon oxide with a purity of 99.99%, and the low refractive layer coating comprises pre-sputtering for 2 min and sputtering; coating the surface of the obtained coated substrate with a protective layer, the target material used is silicon oxide with a purity of 99.99%, and the sputtering time is 30 min, to obtain the coated high laser damage threshold and high reflection laser optical element.

[0047] The SEM image of the obtained coated high laser damage threshold high reflective laser optical element is as follows: Figure 2 As shown in the figure, it can be seen that the film consists of 20 layers of high and low refractive layers. The damage threshold of the coated high laser damage threshold high reflective laser optical element was measured by a laser damage threshold test system for 1064nm high power pulse laser, and the damage threshold was 40.76J / cm 2 The transmittance of the coated high laser damage threshold and high reflectivity laser optical element was measured using a spectrophotometer. The transmittance variation of the coated high laser damage threshold and high reflectivity laser optical element at different wavelengths is shown in the figure below. Figure 3 As shown in the figure, compared with the extremely low reflectivity of the uncoated optical substrate, the reflectivity of the coated high laser damage threshold high reflectivity laser optical element at 1064nm reaches 99.4%.

[0048] Comparative Example 1

[0049] This comparative example provides a coated high-reflection laser optical element. The difference between the method for preparing the coated high-reflection laser optical element and that in Example 1 is that there is no ion source cleaning step in step (1), and the rest is the same as that in Example 1.

[0050] The SEM image of the obtained coated high-reflection laser optical element is as follows: Figure 4 As shown in the figure, it can be seen that there are nodules at the interface between the film and the substrate. The damage threshold of the coated high-reflection laser optical element was measured by 1064nm high-power pulsed laser, and the damage threshold was 8.52J / cm 2 The damage threshold is greatly reduced compared with Example 1. The transmittance variation of the coated high-reflection laser optical element at different wavelengths is shown in the figure below. Figure 5 As shown in the figure, compared with the extremely low reflectivity of the uncoated optical substrate, the reflectivity of the coated high-reflectivity laser optical element at 1064nm reaches 99.7%.

[0051] In summary, the method for preparing a high-reflection laser optical element with a high laser damage threshold provided by the present invention is to clean the substrate with Ar plasma generated by an anode ion source before coating the high-refractive layer and the low-refractive layer, thereby significantly improving the laser damage threshold of the high-reflective laser optical element composed of the thin film and the substrate, and the damage threshold to a 1064nm high-power laser can reach 40.76J / cm 2 Compared with the substrate not treated by Ar plasma, the laser damage threshold is increased by about 5 times; in addition, it has excellent laser optical reflectivity, and the reflectivity for 1064nm reaches 99.4%. The preparation method is relatively novel, the process is simple, and it is suitable for industrial-scale production.

[0052] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high-laser damage threshold and high-reflection laser optical element with a coating, characterized in that: The preparation method comprises the following steps: (1) ultrasonically cleaning the substrate, and then cleaning the substrate using Ar plasma generated by an anode ion source to obtain a pre-cleaned substrate; (2) Alternately coating the surface of the pre-cleaned substrate obtained in step (1) with a high refractive layer and coating the surface with a low refractive layer to obtain a coated substrate; and coating the surface of the obtained coated substrate with a protective layer to obtain the coated high laser damage threshold and high reflectivity laser optical element.

2. The preparation method according to claim 1, characterized in that: The substrate in step (1) comprises any one of quartz glass, sapphire, BK7 or calcium fluoride glass.

3. The preparation method according to claim 1 or 2, characterized in that: The preparation method is carried out by a preparation device for a high-laser damage threshold and high-reflection laser optical element with a coating, the preparation device comprising a vacuum chamber, a rotating sample stage is provided on the top of the inner cavity of the vacuum chamber, a magnetron target gun is fixedly provided on the opposite side of the rotating sample stage, an anode ion source and an argon gas inlet pipe are provided on one side of the inner cavity of the vacuum chamber, and a molecular pump and a mechanical pump are respectively connected on the other side of the inner cavity, and the molecular pump is communicated with the mechanical pump.

4. The preparation method according to claim 3, characterized in that: Step (1) Before the Ar plasma is used to clean the substrate, the background vacuum of the vacuum chamber is controlled to be ≤8×10 -5 Pa.

5. The preparation method according to claim 4, characterized in that: After controlling the background vacuum degree of the vacuum chamber, argon gas is introduced, and then the opening of the limiting valve is adjusted to make the working vacuum degree 0.5-1Pa.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step (1), the current of the anode ion source used for cleaning the substrate with Ar plasma is 150-500 mA.

7. The preparation method according to any one of claims 1 to 6, characterized in that: Before coating the high refractive layer in step (2), the working vacuum is adjusted to 0.5-1 Pa; Preferably, the target material used for coating the high refractive layer in step (2) comprises any one of yttrium oxide, hafnium oxide or tantalum oxide, or a combination of at least two of them.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The target material used for coating the low refractive layer in step (2) includes silicon oxide and / or magnesium fluoride; Preferably, the optical thickness of the high refractive layer coating and the low refractive layer coating in step (2) are respectively one quarter of the wavelength of 1064 nm.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The target material used for coating the protective layer in step (2) includes any one of yttrium oxide, hafnium oxide, tantalum oxide or silicon oxide.

10. A high-reflection laser optical element with high laser damage threshold and coating, characterized in that: The film-coated high laser damage threshold high reflectivity laser optical element is prepared by the method for preparing a film-coated high laser damage threshold high reflectivity laser optical element according to any one of claims 1 to 9.

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