Application of a polarization array waveguide sheet and its coating process

Abstract

The application discloses a kind of application in polarized array waveguide sheet's light splitting film coating piece and its coating process, by improving coating material structure and coating process to meet the role of light splitting and low absorption of film layer when reflecting.The application is applied in polarized array waveguide sheet's light splitting film coating piece and its coating process in wavelength range 380~780nm, light splitting film coating piece has low absorption, reflection in certain range and transmission in required range, and preparation cost is lower, reliability is good, the reflectivity of light of wavelength 448-657nm is between 9% and 15%, light transmittance is greater than or equal to 82%, and absorption is less than or equal to 4%.

Description

Technical Field

[0001] This invention relates to the field of AR glasses, and more particularly to a beam splitting film coating with an application wavelength range of 380~780nm for use on polarization array waveguide sheets and its coating process. Background Technology

[0002] Optical waveguide technology is considered the best optical solution for consumer-grade AR glasses due to its slim design and high light transmittance. Optical waveguide technology can be divided into two types: arrayed waveguides and diffractive waveguides. Arrayed waveguides are also known as geometric waveguides. Diffractive waveguides mainly utilize diffractive optical devices with periodic structures to couple light in and out of the waveguide. Arrayed waveguides achieve image output and enlarged eye movement frames through stacked array mirrors.

[0003] Waveguide lenses typically use a semi-transparent, semi-reflective film to achieve image output. Currently, we often use the following two methods in beam splitter design: (1) Dielectric film: This product design has the advantage of low absorption, but it has the problems of thicker film, high stress, and high cost; (2) Cr / Al / Ti + dielectric film combination system: This film system has the advantages of thin film and relatively low film stress, but it still has the problem of high absorption, which leads to insufficient reflected light and abnormal overall brightness of the product.

[0004] In polarization array waveguide technology, waveguide lenses typically employ multiple equally spaced, parallel, semi-transparent and semi-reflective coating layers with a specific beam splitting ratio to achieve image output and exit pupil expansion. These semi-transparent and semi-reflective coating layers are angularly selective and arranged in an array. Since a waveguide can have multiple semi-transparent and semi-reflective surfaces, each forming an exit pupil, exit pupil expansion can be achieved even with a very thin substrate, enabling displays with a large field of view and a wide eye-tracking range. After multiple reflections, the emitted light can be "adjusted" to be more uniform. Therefore, low-absorption beam-splitting coatings are increasingly becoming the preferred choice for polarization array waveguides. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention designs a beam-splitting coating for use in polarization array waveguides and its coating process. By improving the coating material structure and coating process, the invention satisfies the requirements of the lens for the coating layer to perform beam splitting and low absorption during reflection.

[0006] The present invention adopts the following technical solution:

[0007] A beam-splitting film coating for use in polarization array waveguide sheets includes a substrate. The beam-splitting film coating has a reflectivity of 9%-15% for light with wavelengths of 448-657 nm, a transmittance ≥82%, and an absorptivity ≤4%. A functional film is deposited on the surface of the substrate. The functional film includes multiple layers of interleaved dielectric and metal films. The metal film is an Ag layer. The dielectric film includes one or more layers selected from silicon dioxide, titanium dioxide, tantalum pentoxide, or niobium pentoxide. The layer adjacent to the Ag layer is a niobium pentoxide layer. The innermost layer closest to the substrate is the dielectric film deposited on the inner surface of the substrate, and the outermost layer furthest from the substrate is a silicon dioxide dielectric film. The thickness of the dielectric film is 5-200 nm; the thickness of the Ag layer is 5-100 nm.

[0008] Preferably, the metal Ag layer is less than or equal to 3 layers.

[0009] Preferably, the substrate is a transparent substrate with a refractive index of 1.55-1.58.

[0010] Preferably, the transparent substrate is a crystal substrate, a glass substrate, or a sapphire substrate.

[0011] Preferably, the thickness of the substrate is 0.21 mm to 2.0 mm.

[0012] A coating process for a beam splitter coating used in a polarization array waveguide sheet, comprising the following steps:

[0013] S1. Place the substrate onto the coating fixture in the coating chamber of the vapor deposition equipment, and evacuate the coating chamber to a vacuum level of 5.0*10-4~1.0*10-3 Pa or higher at 70°C.

[0014] S2. The dielectric film material and the metal Ag layer film material are respectively placed into the corresponding evaporation source. The corresponding evaporation source deposits the dielectric film source material and the metal film source material onto the substrate through an evaporation process at a rate of 1 Å / s-10 Å / s. A multilayered dielectric film (2) and a metal film are formed on the substrate (1) to obtain the finished coated sheet. The dielectric film source material is one or more of silicon dioxide, titanium dioxide, aluminum oxide, and niobium pentoxide. The metal film source material is silver.

[0015] S3: Take out the finished spectrophotometer coating film.

[0016] Preferably, in step S2, the evaporation time of the evaporation process is determined according to the thickness of the required vapor-deposited film.

[0017] A coating process for a beam splitter coating used in a polarization array waveguide sheet, comprising the following steps:

[0018] X1. Mount the metal target and the dielectric target on their respective target platforms;

[0019] X2. Place the substrate onto the substrate turntable of the sputtering equipment and evacuate the sputtering chamber to a vacuum level of 5.0*10-4 Pa to 1.0*10-3 Pa.

[0020] X3. Pre-sputtering of each target material;

[0021] X4. Sequentially turn on the target power supply of the required sputtering target, adjust the substrate turntable, and sputter and deposit the required target on the substrate to form a multilayered dielectric film and metal film on the substrate, thus obtaining the finished coated sheet. When sputtering the dielectric target, oxygen and argon must be introduced into the sputtering chamber at the same time to ensure that the excited dielectric target is completely oxidized during the sputtering process. Before sputtering the metal target, the oxygen in the sputtering chamber is evacuated to prevent the excited metal target from being oxidized during the sputtering process.

[0022] X5. Take out the finished spectrophotometer coating film.

[0023] Preferably, in step X3, the dielectric target is sputtered at a power of 5-10 kW and a voltage of 370-510 V at a sputtering rate of 1.5 nm / s-4 nm / s, and the sputtering time is determined according to the thickness of the sputtered film; the metal target is sputtered at a power of 1-5 kW and a voltage of 500-600 V at a sputtering rate of 20 nm / s-30 nm / s, and the sputtering time is determined according to the thickness of the sputtered film.

[0024] Preferably, the pre-sputtering time for dielectric targets is 2–10 min; the pre-sputtering time for metal targets is 0–60 s.

[0025] The beneficial effects of this invention are as follows: This invention designs a beam-splitting film coating with an application wavelength range of 380~780nm for use in polarization array waveguides and its coating process. The beam-splitting film coating has low absorption, reflection within a certain range and transmittance within the required range, and has low manufacturing cost and good reliability. For light with a wavelength of 448-657nm, the reflectivity is between 9% and 15%, the transmittance is ≥82%, and the absorption rate is ≤4%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a structure of the coating sheet of the present invention;

[0027] Figure 2 This is a reflection spectrum curve of the coated sheet of the present invention;

[0028] Figure 3 This is a transmission spectrum curve of the coated sheet of the present invention;

[0029] Figure 4 This is the absorption spectrum curve of the coating sheet of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0031] Example: Figure 1 As shown, a beam-splitting film coating for use in polarization array waveguides includes a substrate. The beam-splitting film coating has a reflectivity of 9%-15% for light with wavelengths of 448-657 nm, a transmittance ≥82%, and an absorptivity ≤4%. A functional film is deposited on the surface of the substrate. The functional film includes multiple layers of interleaved dielectric and metal films. The metal film is an Ag layer. The dielectric film includes one or more layers selected from silicon dioxide, titanium dioxide, tantalum pentoxide, or niobium pentoxide. The layer adjacent to the Ag layer is a niobium pentoxide layer. The innermost layer closest to the substrate is the dielectric film deposited on the inner surface of the substrate, and the outermost layer furthest from the substrate is a silicon dioxide dielectric film. The thickness of the dielectric film is 5-200 nm; the thickness of the Ag layer is 5-100 nm.

[0032] The number of Ag metal layers is less than or equal to 3.

[0033] The substrate is a transparent substrate with a refractive index of 1.56.

[0034] The transparent substrate is a crystal substrate, a glass substrate, or a sapphire substrate.

[0035] The thickness of the substrate is 0.21mm-2.0mm.

[0036] A coating process for a beam splitter coating used in a polarization array waveguide sheet, comprising the following steps:

[0037] S1. Place the substrate onto the coating fixture in the coating chamber of the vapor deposition equipment, and evacuate the coating chamber to a vacuum level of 5.0*10-4~1.0*10-3 Pa or higher at 70°C.

[0038] S2. The dielectric film material and the metal Ag layer film material are respectively placed into the corresponding evaporation source. The corresponding evaporation source deposits the dielectric film source material and the metal film source material onto the substrate through an evaporation process at a rate of 1 Å / s-10 Å / s. A multilayered dielectric film (2) and a metal film are formed on the substrate (1) to obtain the finished coated sheet. The dielectric film source material is one or more of silicon dioxide, titanium dioxide, aluminum oxide, and niobium pentoxide. The metal film source material is silver.

[0039] S3: Take out the finished spectrophotometer coating film.

[0040] In step S2, the evaporation time of the evaporation process is determined according to the thickness of the required vapor-deposited film.

[0041] A coating process for a beam splitter coating used in a polarization array waveguide sheet, comprising the following steps:

[0042] X1. Mount the metal target and the dielectric target on their respective target platforms;

[0043] X2. Place the substrate onto the substrate turntable of the sputtering equipment and evacuate the sputtering chamber to a vacuum level of 5.0*10-4 Pa to 1.0*10-3 Pa.

[0044] X3. Pre-sputtering of each target material;

[0045] X4. Sequentially turn on the target power supply of the required sputtering target, adjust the substrate turntable, and sputter and deposit the required target on the substrate to form a multilayered dielectric film and metal film on the substrate, thus obtaining the finished coated sheet. When sputtering the dielectric target, oxygen and argon must be introduced into the sputtering chamber at the same time to ensure that the excited dielectric target is completely oxidized during the sputtering process. Before sputtering the metal target, the oxygen in the sputtering chamber is evacuated to prevent the excited metal target from being oxidized during the sputtering process.

[0046] X5. Take out the finished spectrophotometer coating film.

[0047] In step X3, dielectric targets are sputtered at a power of 5-10 kW and a voltage of 370-510 V at a sputtering rate of 1.5 nm / s-4 nm / s, with the sputtering duration determined by the required thickness of the sputtered film; metal targets are sputtered at a power of 1-5 kW and a voltage of 500-600 V at a sputtering rate of 20 nm / s-30 nm / s, with the sputtering duration determined by the required thickness of the sputtered film.

[0048] The pre-sputtering time for dielectric targets is 2–10 min; the pre-sputtering time for metal targets is 0–60 s.

[0049] like Figure 2 The figure shows the reflectance spectrum curve of the coating of the present invention. As can be seen from the figure, the average reflectance of the coating of the present invention in the wavelength range of 448-657nm and the incident angles of 48°, 57° and 66.5° is between 9% and 15%.

[0050] like Figure 3 The figure shows the transmission spectrum curve of the coating of the present invention. As can be seen from the figure, the average transmittance of the coating of the present invention in the wavelength range of 448-657nm and the incident angles of 48°, 57° and 66.5° is above 82%.

[0051] like Figure 4 The figure shows the absorption spectrum curve of the coating of the present invention. As can be seen from the figure, the average absorption value of the coating of the present invention in the wavelength range of 448-657nm and the incident angles of 48°, 57° and 66.5° is less than 4%.

[0052] It is evident that the spectrophotometer coating of the present invention has low absorption, reflection within a certain range and transmittance within the required range, and has low manufacturing cost and good reliability.

[0053] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A beam-splitting coating for use in polarization array waveguides, comprising a substrate, characterized in that, The beam-splitting film has a reflectivity of 9%-15% for light with wavelengths of 448-657nm, a transmittance of ≥82%, and an absorptivity of ≤4%. The substrate surface is coated with a functional film, which includes multiple layers of interleaved dielectric and metal films. The metal film is an Ag layer. The dielectric film includes one or more layers of silicon dioxide, titanium dioxide, tantalum pentoxide, or niobium pentoxide. The layer adjacent to the Ag layer is a niobium pentoxide layer. The innermost layer closest to the substrate is the dielectric film deposited on the inner surface of the substrate, and the outermost layer furthest from the substrate is a silicon dioxide dielectric film. The thickness of the dielectric film is 5-200nm; the thickness of the Ag layer is 5-100nm.

2. The beam-splitting coating used in polarization array waveguides according to claim 1, characterized in that, The number of Ag metal layers is less than or equal to 3.

3. The beam-splitting coating used in polarization array waveguides according to claim 1, characterized in that, The substrate is a transparent substrate with a refractive index of 1.55-1.

58.

4. The beam-splitting coating for a polarization array waveguide as described in claim 3, characterized in that, The transparent substrate is a crystal substrate, a glass substrate, or a sapphire substrate.

5. The beam-splitting coating for a polarization array waveguide as described in claim 1, characterized in that, The thickness of the substrate is 0.21mm-2.0mm.

6. A coating process for a beam-splitting film coating sheet applied to a polarization array waveguide sheet according to any one of claims 1-5, characterized in that, The process steps are as follows: S1. Place the substrate onto the coating fixture in the coating chamber of the vapor deposition equipment, and evacuate the coating chamber to a vacuum level of 5.0*10-4~1.0*10-3 Pa or higher at 70°C. S2. The dielectric film material and the metal Ag layer film material are respectively placed into the corresponding evaporation source. The corresponding evaporation source deposits the dielectric film source material and the metal film source material onto the substrate through an evaporation process at a rate of 1 Å / s-10 Å / s. A multilayered dielectric film (2) and a metal film are formed on the substrate (1) to obtain the finished coated sheet. The dielectric film source material is one or more of silicon dioxide, titanium dioxide, aluminum oxide, and niobium pentoxide. The metal film source material is silver. S3: Take out the finished spectrophotometer coating film.

7. The coating process for a beam-splitting film coating sheet applied to a polarization array waveguide sheet according to claim 6, characterized in that, In step S2, the evaporation time of the evaporation process is determined according to the thickness of the required vapor-deposited film.

8. A coating process for a beam-splitting film coating sheet applied to a polarization array waveguide sheet according to any one of claims 1-5, characterized in that, The process steps are as follows: X1. Mount the metal target and the dielectric target on their respective target platforms; X2. Place the substrate onto the substrate turntable of the sputtering equipment and evacuate the sputtering chamber to a vacuum level of 5.0*10-4 Pa to 1.0*10-3 Pa. X3. Pre-sputtering of each target material; X4. Sequentially turn on the target power supply of the required sputtering target, adjust the substrate turntable, and sputter and deposit the required target on the substrate to form a multilayered dielectric film and metal film on the substrate, thus obtaining the finished coated sheet. When sputtering the dielectric target, oxygen and argon must be introduced into the sputtering chamber at the same time to ensure that the excited dielectric target is completely oxidized during the sputtering process. Before sputtering the metal target, the oxygen in the sputtering chamber is evacuated to prevent the excited metal target from being oxidized during the sputtering process. X5. Take out the finished spectrophotometer coating film.

9. The coating process for a beam-splitting film coating in a polarization array waveguide as described in claim 8, characterized in that, In step X3, dielectric targets are sputtered at a power of 5-10 kW and a voltage of 370-510 V at a sputtering rate of 1.5 nm / s-4 nm / s, with the sputtering duration determined by the required thickness of the sputtered film; metal targets are sputtered at a power of 1-5 kW and a voltage of 500-600 V at a sputtering rate of 20 nm / s-30 nm / s, with the sputtering duration determined by the required thickness of the sputtered film.

10. The coating process for a beam-splitting film coating sheet applied to a polarization array waveguide sheet according to claim 9, characterized in that, The pre-sputtering time for dielectric targets is 2–10 min; the pre-sputtering time for metal targets is 0–60 s.

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