A 266 nanometer high-power laser antireflection film and preparation method thereof
By designing and preparing a 266-nanometer high-power laser urgency film with high refractive index and low refractive index film layer, the problems of low transmittance and insufficient threshold for resisting light damage in the prior art are solved, and high transmissibility is achieved The over-rate and high anti-light damage threshold extend the product life and improve the use effect, meeting the needs of high-end applications in the near-ultraviolet field.
Patent Information
- Application Number
- CN202110142035.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-02-02
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2041-02-02
AI Technical Summary
The existing ultraviolet laser products have low transmittance, low threshold for resisting light damage, poor use effect and short life, which cannot meet the needs of high-end applications in the near-ultraviolet field.
Design a 266-nanometer high-power laser induced propagation film with the film structure of A/cL/bH/aL/SUB/aL/bH/cL/A, using HfO2 or AL2O3 as the high refractive index film layer, and SIO2 or MgF2 as the low The refractive index film layer is coated in a high vacuum state by ultrasonic cleaning and electron beam or resistive thermal evaporation. The physical thickness and preparation conditions of each film layer are controlled to reduce the absorption and defect density of the film.
The reflectivity in the 266nm band is less than 0.05%, and the transmittance can reach more than 99.9%. The threshold for anti-light damage is increased to 6J/cm2 (266nm, 7ns), which extends the service life of the product and improves the use effect, satisfying high-end applications. need.
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Figure CN112782791B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a 266-nanometer high-power laser anti-reflection film and a preparation method thereof, belonging to the technical field of anti-reflection films. Background Art
[0002] Ultraviolet lasers are widely used in material processing, lithography, medical treatment, scientific research and other fields due to their short wavelength, high molecular energy and small diffraction effect.
[0003] In optical components, light energy is lost due to reflection from the component surface. In order to reduce the reflection loss on the component surface, a transparent dielectric film is often coated on the surface of the optical component. This film is called an anti-reflection film.
[0004] The anti-reflection films for UV laser products currently on the market have problems such as low transmittance, low threshold for resisting light damage, poor performance, and short life. Summary of the invention
[0005] The present invention provides a 266nm high-power laser anti-reflection film and a preparation method thereof. The obtained anti-reflection film has a reflectivity of less than 0.05% and a transmittance of more than 99.9% at a 266nm band, thereby improving the light damage resistance threshold, which can reach 6J / cm 2 (266nm, 7ns); improve the use effect and service life of the product; can meet some high-end applications in the current near-ultraviolet field.
[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:
[0007] A 266-nanometer high-power laser anti-reflection film, the film layer structure is: A / cL / bH / aL / SUB / aL / bH / cL / A, wherein SUB represents a glass substrate; A represents air; H represents a high-refractive-index film layer; L represents a low-refractive-index film layer; a, b, and c are respectively theoretical values of coefficients of optical thickness of one-quarter reference wavelength of each film layer, a is 1.6±0.2, b is 0.53±0.2, and c is 1.13±0.2.
[0008] The above reference wavelength is 266nm.
[0009] The design and preparation method of the laser film with high laser damage resistance threshold in the ultraviolet band is as follows: the transmittance of the anti-reflection film can reach more than 99.9% in the 266nm band. The anti-light damage threshold reaches 6J / cm 2 (266nm, 7ns); can meet some high-end applications in the near-ultraviolet field.
[0010] In order to further reduce the absorption of the anti-reflection film, the material used for the high refractive index film layer is HfO2 or Al2O3; the material used for the low refractive index film layer is SIO2 or MgF2.
[0011] The material used for the substrate is preferably fused quartz, sapphire or calcium fluoride.
[0012] The preferred physical thickness of each film layer is: aL is 75.44±7.5 nm, bH is 20±2 nm, and cL is 52.36±5.2 nm.
[0013] The method for preparing the above 266 nm high power laser anti-reflection film comprises the following steps:
[0014] (1) Ultrasonic cleaning: Ultrasonic cleaning removes microscopic particles attached to the surface of the glass substrate, making the film layer more adherent;
[0015] (2) Thin film preparation: Use electron beam or resistance thermal evaporation method to evaporate on the glass substrate, and introduce high-purity oxygen into the vacuum chamber at the same time, so that the deposited material can be fully oxidized under high vacuum conditions, wherein the purity of high-purity oxygen is ≥99.99%, so as to reduce the absorption of the film, thereby improving the anti-laser damage threshold; this method not only retains the unique favorable properties of laser thin film preparation by thermal evaporation method, but also improves the intrinsic absorption and defect density of the film, and has the characteristics of strong targeting, high quality, and simple and easy operation. During evaporation, the glass substrate is plated on one side, and then step (2) is repeated to plate the other side. The process of double-sided coating is the same.
[0016] The above-mentioned percentages of high-purity oxygen purity are volume percentages.
[0017] The control of the conditions during film preparation is also very critical. The preparation conditions of each film layer not only affect the compactness and other properties of the single film layer, but also affect the bonding strength with the adjacent film layer and the optical properties of the entire film layer. Preferably, in step (2), before film formation, the substrate temperature is first kept at 250-350°C for more than 40 minutes, and the substrate temperature is maintained at 250-350°C during the film formation process; when plating Al2O3, the gas injection volume of high-purity oxygen is 10-180sccm, and the Al2O3 The evaporation rate is 0.15-0.5nm / s; when AL2O3 or HFO2 is plated, the filling amount of high-purity oxygen is 10-180sccm, and the evaporation rate of AL2O3 or HFO2 is 0.15-0.5nm / s; when MGF2 is plated, high-purity oxygen is not filled, and the evaporation rate of MgF2 is 0.3-1.5nm / s; when SIO2 is plated, the filling amount of high-purity oxygen is 10-150sccm, and the evaporation rate of SIO2 is 0.5-1.5nm / s.
[0018] In order to improve the quality of the anti-reflection film, in step (2), during evaporation, an isolation baffle is added between the evaporation source and the glass substrate. The isolation baffle is located below the glass substrate and above the evaporation source, blocking and adsorbing invalid evaporation materials, reducing contamination near the glass substrate and reducing the probability of film defect formation.
[0019] The key factors that cause damage in laser thin films are absorption and defects in the films. The above method can effectively reduce film defects.
[0020] The technologies not mentioned in the present invention are all referred to the prior art.
[0021] The 266nm high-power laser anti-reflection film of the present invention has a high laser damage resistance threshold in the ultraviolet band. The transmittance of the anti-reflection film in the 266nm band can reach more than 99.9%, which improves the anti-light damage threshold and can reach 6J / cm 2 (266nm, 7ns), it has both good spectral performance and good mechanical stability, which improves the use effect of the product and prolongs its service life, and can meet some high-end applications in the current near-ultraviolet field. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a schematic diagram of the structure of a 266 nm high-power laser anti-reflection film in Example 1 of the present invention;
[0023] Figure 2 This is a design curve diagram of the 266 nm high power laser anti-reflection film in Example 1 of the present invention;
[0024] Figure 3 This is a detection spectrum curve of the 266 nm high-power laser anti-reflection film in Example 1 of the present invention, where a is single-side R% and b is double-side T%;
[0025] In the figure, 1 is a fused quartz substrate, 2 is a MgF2 film layer, 3 is an AL2O3 film layer, and 4 is air. DETAILED DESCRIPTION
[0026] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.
[0027] Example 1
[0028] like Figure 1 As shown, the 266nm high-power laser anti-reflection film has a film structure of A / cL / bH / aL / SUB / aL / bH / cL / A, where SUB represents a fused quartz substrate; A represents air; H represents an AL2O3 film layer; L represents a MgF2 film layer; a, b, and c are coefficients of a quarter reference wavelength optical thickness of each film layer, a is 1.6, b is 0.53, and c is 1.13, and the physical thickness of each film layer is A / 52.36nm / 20nm / 75.44nm / SUB / 75.44nm / 20nm / 52.36nm / A.
[0029] The preparation of the above 266 nm high power laser anti-reflection film comprises the following steps:
[0030] (1) Maintaining the evaporation environment: adding an isolation baffle between the evaporation source and the glass substrate to block and absorb ineffective evaporation materials, reduce contamination near the glass substrate, and reduce the probability of film defect formation;
[0031] (2) Ultrasonic cleaning: removes microscopic particles attached to the surface of the glass substrate to make the film layer more adherent;
[0032] (3) Thin film preparation: In step (2), before film formation, the substrate temperature is kept constant at 260-270°C for more than 40 minutes. During the film formation process, the substrate temperature is maintained at 260-270°C. Electron beam (or resistance) thermal evaporation is used to evaporate on the glass substrate. When MgF2 is plated, high-purity oxygen (≥99.99%) is not introduced, and the evaporation rate of MgF2 is 0.6nm / s. When Al2O3 is plated, the gas volume of high-purity oxygen is 100sccm, and the evaporation rate of Al2O3 is 0.2nm / s.
[0033] Optical performance test: The single-side reflectivity and double-side transmittance of the film were tested using the Belarusian PHOTO RT spectrophotometer. Figure 2-3 As shown in the figure, the obtained spectral curve meets the design requirements, and the light damage resistance threshold reaches 6J / cm 2 (266nm, 7ns). Repeat the above steps 3 times, and the product performance remains unchanged.
[0034] Film environmental performance test:
[0035] In order to ensure the reliability of optical components, the broadband anti-reflection film samples were subjected to the following environmental tests in accordance with the requirements of GJB2485-95 General Specifications for Optical Coatings:
[0036] a. Abrasion resistance test: Wrap 2 layers of dry absorbent gauze on the rubber friction head, rub the film layer along the same track under a pressure of 4.9N, and repeat 25 times. There is no scratch or other damage to the film layer.
[0037] b. Adhesion test: Use a 2cm wide tape with a peel strength of I>2.94N / cm to stick it firmly on the surface of the film layer. Quickly pull the tape up from the edge of the part in the direction perpendicular to the surface, and pull it repeatedly 25 times. The film layer does not fall off or get damaged.
[0038] c. Immersion test: The sample is completely immersed in distilled water or deionized water. After 96 hours, the film layer will not show new defects such as peeling, peeling, cracking, blistering, etc.
Claims
1. A 266 nm high power laser anti-reflection film, characterized in that: The film structure is: A / cL / bH / aL / SUB / aL / bH / cL / A, where SUB represents the glass substrate; A represents air; H represents the high refractive index film layer; L represents the low refractive index film layer; a, b, and c are the theoretical values of the coefficients of the optical thickness of one quarter of the reference wavelength of each film layer, a is 1.6±0.2, b is 0.53±0.2, and c is 1.13±0.2; The material used for the high refractive index film layer is AL2O3; The material used for the low refractive index film layer is MgF2; When MgF2 is plated, high-purity oxygen is not introduced, and the evaporation rate of MgF2 is 0.3-1.5nm / s; When plating AL2O3, the filling amount of high-purity oxygen is 10-180sccm, and the evaporation rate of AL2O3 is 0.15-0.5nm / s.
2. The 266 nm high power laser anti-reflection film according to claim 1, characterized in that: The substrate materials used are fused quartz, sapphire or calcium fluoride.
3. The 266 nm high power laser anti-reflection film according to claim 1 or 2, characterized in that: The physical thickness of the film layer is: aL is 75.44±7.5nm, bH is 20±2nm, and cL is 52.36±5.2nm.
4. The method for preparing a 266 nm high power laser anti-reflection film according to any one of claims 1 to 3, characterized in that: The film structure of the 266nm high-power laser anti-reflection film is: A / cL / bH / aL / SUB / aL / bH / cL / A, where SUB represents the glass substrate; A represents air; H represents the high-refractive-index film layer; L represents the low-refractive-index film layer; a, b, and c are the coefficient theoretical values of the optical thickness of one-quarter of the reference wavelength of each film layer, a is 1.6±0.2, b is 0.53±0.2, and c is 1.13±0.2; The material used for the high refractive index film layer is AL2O3; The material used for the low refractive index film layer is MgF2; A method for preparing a 266 nm high power laser anti-reflection film comprises the following steps: (1) Ultrasonic cleaning: Ultrasonic cleaning removes microscopic particles attached to the surface of the glass substrate; (2) Thin film preparation: Use electron beam or resistance thermal evaporation method to evaporate on the glass substrate, and introduce high-purity oxygen into the vacuum chamber at the same time, so that the deposited material can be fully oxidized under high vacuum conditions, and the purity of the high-purity oxygen is ≥99.99%; In step (2), when coating AL2O3, the filling amount of high-purity oxygen is 10-180sccm, and the evaporation rate of AL2O3 is 0.15-0.5nm / s; In step (2), when plating MgF2, high-purity oxygen is not introduced, and the evaporation rate of MgF2 is 0.3-1.5nm / s.
5. The preparation method according to claim 4, characterized in that: In step (2), before film formation, the substrate temperature is kept at 250-350°C for more than 40 minutes, and the substrate temperature is maintained at 250-350°C during the film formation process.
6. The preparation method according to claim 4 or 5, characterized in that: In step (2), during evaporation, an isolation baffle is added between the evaporation source and the glass substrate. The isolation baffle is located below the glass substrate and above the evaporation source to block and absorb ineffective evaporation materials.