A method for preparing coated glass for optical sensors and the coated glass itself.

Abstract

This application relates to the field of optical coating technology, specifically disclosing a method for preparing coated glass for optical sensors and the coated glass itself. The method for preparing coated glass for optical sensors includes the following steps: S1, an optical glass substrate is pretreated to obtain pretreated glass; S2, a silicon dioxide layer is magnetron sputtered onto the surface of the pretreated glass, followed by a magnesium fluoride layer, arranged alternately for a total of 5-6 layers, to obtain a semi-finished product; S3, the surface of the semi-finished product is ion-beam polished to obtain coated glass. The coated glass prepared using this method for preparing coated glass for optical sensors has the advantage of reducing interference from ambient light on PPG signals over a wide wavelength range.

Description

Technical Field

[0001] This application relates to the field of optical coating technology, and more specifically, to a method for preparing coated glass for optical sensors and the coated glass itself. Background Technology

[0002] In an era of continuous development in modern healthcare and smart wearable devices, heart rate monitoring technology is becoming increasingly important. It is not only widely used in professional medical diagnostic scenarios to help doctors understand patients' heart health status in a timely manner, but it has also been integrated into everyday wearable devices such as smartwatches and wristbands, allowing people to monitor their heart rate changes in real time and conduct exercise monitoring and health management.

[0003] Currently, in the field of optical heart rate monitoring, optical sensors detect changes in blood's absorption of light to monitor heart rate. The coated glass used in these sensors needs to resist ambient light interference. Common approaches include physical shielding, which involves designing special structures or adding light shields to block external light from entering the monitoring area, thereby reducing the impact of ambient light on the monitoring signal; and filtering algorithm compensation, which uses software algorithms to process the acquired signal and filter out noise signals that may be introduced by ambient light, thus improving the accuracy of the monitoring results. Additionally, multi-wavelength light sources are used in conjunction with detection, comprehensively judging heart rate by analyzing the reflection of different wavelengths of light, which to some extent reduces the error caused by interference from a single wavelength of ambient light.

[0004] However, existing methods for dealing with ambient light interference have significant shortcomings. While physical blocking can block ambient light to some extent, it cannot adapt to complex and changing environments. For example, its effectiveness is greatly reduced when light shines from different angles or when light intensity changes drastically. Filtering algorithm compensation methods rely on pre-set algorithm models, which struggle to effectively identify and handle certain special ambient light interference patterns, leading to misjudgments. Using multiple wavelength light sources for detection increases the cost and complexity of the equipment, and its ability to counteract ambient light interference over a wide wavelength range is limited, failing to adequately meet the needs of high-precision heart rate monitoring in complex environments.

[0005] Therefore, there is an urgent need to develop a new type of coated glass for optical sensors to reduce the interference of ambient light on PPG signals over a wide wavelength range. Summary of the Invention

[0006] In order to effectively reduce the interference of ambient light on PPG signals over a wide wavelength range, this application provides a method for preparing coated glass for optical sensors and the coated glass itself.

[0007] In a first aspect, this application provides a method for preparing coated glass for optical sensors, employing the following technical solution:

[0008] A method for preparing coated glass for optical sensors includes the following steps:

[0009] S1. The optical glass substrate is pretreated to obtain pretreated glass;

[0010] S2. Pre-treat the glass surface by magnetron sputtering a silicon dioxide layer, then magnetron sputtering a magnesium fluoride layer, alternating between 5-6 layers to obtain a semi-finished product;

[0011] S3. The surface of the semi-finished product is polished by ion beam to obtain coated glass.

[0012] By employing the above technical solution, silicon dioxide and magnesium fluoride are alternately stacked on the surface of optical glass to form a nano-layered array network structure. The refractive index of silicon dioxide is approximately 1.46, and that of magnesium fluoride is approximately 1.38. Utilizing the refractive index gradient of the alternately stacked films, the destructive effect of optical interference is enhanced, significantly reducing reflectivity in a wide wavelength range of 400-1000nm. High transmittance and low reflectivity can be achieved for commonly used light sources in PPG sensors (such as green light at 530nm and red light at 940nm), while suppressing transmission in other ambient light bands, thereby reducing interference from ambient light on PPG signals in a wide wavelength range. Combined with ion beam polishing, the height of the protrusions on the surface of the micro / nano array network structure is further controlled, adjusting the difference between the highest and lowest points of the micro / nano array network structure, reducing refractive index fluctuations, and thus reducing noise caused by interface loss, further reducing interference from ambient light on PPG signals in a wide wavelength range.

[0013] Preferably, the pre-treated glass includes the following steps:

[0014] Ultrasonic cleaning, deionized water rinsing, ethanol dehydration, and nitrogen drying.

[0015] By adopting the above technical solutions, ultrasonic cleaning removes grease, particulate contaminants, and nanoscale organic residues from the surface of optical glass. Deionized water cleaning removes residual chemical reagents and metal ions after ultrasonic cleaning. Ethanol dehydration can break the water molecule adsorption layer through hydrogen bonding, reducing film defects. After ethanol evaporates, it increases the surface energy of the glass and enhances the adhesion of the film. Nitrogen drying prevents the glass surface from re-adsorbing contaminants in the air, thereby ensuring the loading effect of the film.

[0016] Preferably, the target material for magnetron sputtering of the silicon dioxide layer is a microporous silicon dioxide target material.

[0017] By adopting the above technical solution, the porous structure of the microporous silica target further improves the uniformity and distribution density of the sputtered micro-nano array network structure, thereby reducing the effective refractive index of the film and selectively transmitting the wavelength required for the PPG signal; and the setting of the multilayer structure further promotes the formation of overlapping micro-nano network structures, further suppresses light reflection, and can also reduce signal noise caused by light scattering, thereby reducing the interference of ambient light on the PPG signal in a wide band.

[0018] Preferably, the microporous silica target is prepared from mesoporous silica microspheres, yttrium oxide, titanium oxide and polyethylene glycol solution in a mass ratio of 1:0.1-0.15:0.02-0.05:0.1-0.2.

[0019] By adopting the above technical solution, mesoporous silica microspheres, yttrium oxide, titanium oxide and polyethylene glycol solution are combined, and the viscosity of polyethylene glycol solution is used to bond the mesoporous silica microspheres, yttrium oxide and titanium oxide, so as to prepare a dense target material.

[0020] During magnetron sputtering, mesoporous silica microspheres can optimize gas diffusion and improve film density. Furthermore, the mesoporous structure of the microspheres acts as a template during sputtering, guiding the film to form an ordered array of nanopores. Yttrium oxide doping refines the film grains, increasing the density of the nanostructure and reducing interference from ambient light on PPG signals over a wide wavelength range. Combined with titanium dioxide-induced lattice changes and the pyrolysis of polyethylene glycol, micron-scale structures are formed, creating a multi-level micro / nano network that further reduces interference from ambient light on PPG signals over a wide wavelength range.

[0021] Preferably, the sputtering target of the magnesium fluoride layer is a magnesium fluoride target, which is prepared from a solution of magnesium fluoride, silicon carbide and polyethylene glycol in a mass ratio of 1:0.02-0.05:0.05-0.08.

[0022] By adopting the above technical solution, using magnesium fluoride as a substrate and utilizing the viscosity of polyethylene glycol solution, it is easy to stably bond silicon carbide and magnesium fluoride to prepare the target material. The magnesium fluoride target material is sputtered onto the surface of the silicon dioxide film. By utilizing the connection effect between silicon and silicon dioxide layers in silicon carbide, the mechanical interlocking effect between the magnesium fluoride layer and silicon dioxide layer can be improved. Furthermore, the high melting point of silicon carbide can compensate for the difference in thermal expansion coefficient of magnesium fluoride at high temperatures, reduce interfacial stress, improve film stability, and promote the formation of micro-nano network structures. Combined with the pyrolysis of polyethylene glycol, the distribution of micro-nano network structures is further improved, thereby reducing the interference of ambient light on PPG signals in a wide wavelength range.

[0023] Preferably, the sputtering frequency of the silicon dioxide layer magnetron sputtering deposition is 140-160W, and the sputtering pressure is 0.4-0.6Pa.

[0024] By adopting the above technical solution and limiting the sputtering frequency, the thickness of the silicon dioxide film can be controlled. With the limitation of gas pressure, a dense and uniform film can be formed, constructing a micro-nano network structure, reducing surface scattering and internal defects, thereby suppressing diffuse reflection interference from ambient light, reducing surface scattering and internal defects, and reducing interference of ambient light on PPG signals in a wide band.

[0025] Preferably, the magnetron sputtering deposition of the magnesium fluoride layer has a sputtering frequency of 150-180W and a sputtering pressure of 0.4-0.6Pa.

[0026] By adopting the above technical solution, this power range can ensure stable sputtering of magnesium fluoride target material, forming a dense and low-defect thin film structure. Too high a power may lead to increased film stress, while too low a power will affect the deposition rate. This pressure range optimizes the ionization efficiency of argon plasma, giving sputtered particles higher kinetic energy, improving the uniformity and density of the film, and reducing the interference of ambient light on PPG signals over a wide band.

[0027] Preferably, the average deposition thickness of each silicon dioxide layer is 80-100 nm, and the average deposition thickness of each magnesium fluoride layer is 50-70 nm.

[0028] By adopting the above technical solution and limiting the thickness of the alternately deposited film layers, the prepared coated glass surface can form a gradient stacked micro-nano network structure, thereby reducing the interference of ambient light on PPG signals over a wide wavelength range.

[0029] Preferably, the beam current density of the ion beam polishing treatment is 0.2-0.4 mA / cm², the working gas pressure is 0.2-0.4 Pa, and the incident angle is 4-5°.

[0030] By adopting the above technical solution, it is possible not only to control surface protrusions and micro-defects and reduce light scattering rate, but also to avoid excessive etching, effectively suppress stray light, and ensure etching stability, thereby reducing the interference of ambient light on PPG signals in a wide band.

[0031] Secondly, this application provides a coated glass, which adopts the following technical solution:

[0032] A coated glass, prepared using a method for preparing coated glass for optical sensors.

[0033] By adopting the above technical solution, the prepared coated glass can reduce the interference of ambient light on PPG signals over a wide wavelength range.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. Alternating stacking of silicon dioxide and magnesium fluoride on the surface of optical glass forms a nano-layered array network structure. The refractive index of silicon dioxide is approximately 1.46, and that of magnesium fluoride is approximately 1.38. Utilizing the refractive index gradient of the alternating stacked layers enhances the destructive effect of optical interference, significantly reducing reflectivity in a wide wavelength range of 400-1000nm. This achieves high transmittance and low reflectivity for commonly used light sources in PPG sensors, while suppressing transmission in other ambient light bands, thereby reducing interference from ambient light on PPG signals across a wide wavelength range. Combined with ion beam polishing, the height of the protrusions on the surface of the micro / nano array network structure is further controlled, managing the difference between the highest and lowest points of the network structure, reducing refractive index fluctuations, and thus reducing noise caused by interface loss, further minimizing interference from ambient light on PPG signals across a wide wavelength range.

[0036] 2. During magnetron sputtering, mesoporous silica microspheres can optimize gas diffusion and improve film density. Furthermore, the mesoporous structure of the microspheres acts as a template during sputtering, guiding the film to form an ordered array of nanopores. Yttrium oxide doping refines the film grains, increasing the density of the nanostructure and reducing interference from ambient light on PPG signals over a wide wavelength range. Combined with titanium dioxide-induced lattice changes and the pyrolysis of polyethylene glycol, micron-scale structures are formed, creating a multi-level micro / nano network that further reduces interference from ambient light on PPG signals over a wide wavelength range.

[0037] 3. When magnesium fluoride target material is sputtered onto the surface of silicon dioxide film, the bonding effect between silicon and silicon dioxide layers in silicon carbide can be utilized to improve the mechanical interlocking effect between magnesium fluoride and silicon dioxide layers. Furthermore, the high melting point of silicon carbide can compensate for the difference in thermal expansion coefficient of magnesium fluoride at high temperatures, reduce interfacial stress, improve film stability, and promote the formation of micro-nano network structures. Combined with the pyrolysis of polyethylene glycol, the distribution of micro-nano network structures is further improved, thereby reducing the interference of ambient light on PPG signals over a wide wavelength range. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the embodiments.

[0039] All of the following ingredients are commercially available.

[0040] Example of silica target preparation

[0041] Preparation Example 1: Silica sputtering targets were prepared using the following method:

[0042] 1 kg of mesoporous silica microspheres, 0.12 kg of yttrium oxide, and 0.04 kg of titanium oxide were mixed and stirred until homogeneous. Then, 0.15 kg of polyethylene glycol solution was added and ball-milled for 5 hours to mix evenly. After drying, the mixture was vacuum hot-pressed and sintered at 1400℃ for 1.5 hours at a pressure of 20 MPa to obtain a silica target material. The average particle size of the mesoporous silica microspheres was 500 nm, the average particle size of yttrium oxide and titanium oxide was 200 nm, the purity of yttrium oxide and titanium oxide was 99.99%, and the polyethylene glycol solution was a 2% (w / w) aqueous solution of polyethylene glycol, and the polyethylene glycol was polyethylene glycol 8000.

[0043] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that:

[0044] 1 kg of mesoporous silica microspheres, 0.1 kg of yttrium oxide, and 0.02 kg of titanium oxide were mixed and stirred until homogeneous. Then, 0.1 kg of polyethylene glycol solution was added and ball-milled for 5 hours until homogeneous. After drying, the mixture was vacuum hot-pressed and sintered at 1400℃ for 1.5 hours at a pressure of 20 MPa to obtain a silica target material. The average particle size of the mesoporous silica microspheres was 500 nm, and the average particle size of the yttrium oxide and titanium oxide was 200 nm. The polyethylene glycol solution was a 2% (w / w) aqueous solution of polyethylene glycol, and the polyethylene glycol was polyethylene glycol 8000.

[0045] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that:

[0046] 1 kg of mesoporous silica microspheres, 0.15 kg of yttrium oxide, and 0.05 kg of titanium oxide were mixed and stirred evenly. Then, 0.2 kg of polyethylene glycol solution was added and ball-milled for 5 hours to mix evenly. After drying, the mixture was vacuum hot-pressed and sintered at 1400℃ for 1.5 hours at a pressure of 20 MPa to obtain a silica target material. The average particle size of the mesoporous silica microspheres was 500 nm, and the average particle size of the yttrium oxide and titanium oxide was 200 nm. The polyethylene glycol solution was a 2% (w / w) polyethylene glycol aqueous solution, and the polyethylene glycol was polyethylene glycol 8000.

[0047] Example of magnesium fluoride sputtering target preparation

[0048] Preparation Example 4: Magnesium fluoride target material was prepared using the following method:

[0049] 1 kg of magnesium fluoride and 0.04 kg of silicon carbide were mixed and stirred evenly. Then, 0.06 kg of polyethylene glycol solution was added and ball-milled for 5 hours to mix evenly. After drying, the mixture was vacuum hot-pressed and sintered at 700℃ for 5 hours at a pressure of 50 MPa to obtain a silicon dioxide target material. The purity of magnesium fluoride and silicon carbide was 99.99%, and the polyethylene glycol solution was a 2% (w / w) aqueous solution of polyethylene glycol, which was polyethylene glycol 8000.

[0050] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0051] 1 kg of magnesium fluoride and 0.02 kg of silicon carbide were mixed and stirred evenly. Then, 0.08 kg of polyethylene glycol solution was added and ball-milled for 5 hours to mix evenly. After drying, the mixture was vacuum hot-pressed and sintered at 700℃ for 5 hours at a pressure of 50 MPa to obtain a silicon dioxide target material. The purity of magnesium fluoride and silicon carbide was 99.99%, and the polyethylene glycol solution was a 2% (w / w) aqueous solution of polyethylene glycol, which was polyethylene glycol 8000.

[0052] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that:

[0053] 1 kg of magnesium fluoride and 0.05 kg of silicon carbide were mixed and stirred evenly. Then, 0.05 kg of polyethylene glycol solution was added and ball-milled for 5 hours to mix evenly. After drying, the mixture was vacuum hot-pressed and sintered at 700℃ for 5 hours at a pressure of 50 MPa to obtain a silicon dioxide target material. The purity of magnesium fluoride and silicon carbide was 99.99%, and the polyethylene glycol solution was a 2% (w / w) aqueous solution of polyethylene glycol, which was polyethylene glycol 8000.

[0054] Example 1: A method for preparing coated glass for optical sensors:

[0055] S1. Select 1mm thick optical glass as the substrate. The optical glass is ultrasonically cleaned at 20kHz, then rinsed with deionized water, then dehydrated with 95% ethanol, and finally dried with nitrogen to complete the pretreatment and obtain the pretreated glass.

[0056] S2. Pre-treatment of glass surface: A silica layer was prepared using the silica target prepared in Example 1 by magnetron sputtering. The sputtering frequency was 150 W, the sputtering pressure was 0.5 Pa, and the vacuum degree during magnetron sputtering was 5 × 10⁻⁶. -4 The sputtering gas was argon, and the average deposition thickness of the silicon dioxide layer was 90 nm. Then, the magnesium fluoride layer was prepared using the magnesium fluoride target prepared in Example 4 by magnetron sputtering. The sputtering frequency was 160 W, the sputtering gas pressure was 0.5 Pa, and the average deposition thickness of the magnesium fluoride layer was 60 nm. The vacuum level during magnetron sputtering was 5 × 10⁻⁶ Pa. -4 Pa, sputtering gas is argon; five layers of silicon dioxide and magnesium fluoride are deposited alternately on the pretreated glass surface to obtain a semi-finished product;

[0057] S3. The surface of the semi-finished product is polished by ion beam with a beam current density of 0.3 mA / cm², a working gas pressure of 0.3 Pa, and an incident angle of 5° to obtain coated glass.

[0058] Example 2: The difference between this example and Example 1 is that:

[0059] S1. Select 1mm thick optical glass as the substrate. The optical glass is ultrasonically cleaned at 20kHz, then rinsed with deionized water, then dehydrated with 95% ethanol, and finally dried with nitrogen to complete the pretreatment and obtain the pretreated glass.

[0060] S2. Pre-treatment of glass surface: A silica layer was prepared using the silica target prepared in Example 2 by magnetron sputtering. The sputtering frequency was 140 W, the sputtering pressure was 0.6 Pa, and the vacuum degree during magnetron sputtering was 5 × 10⁻⁶. -4 The sputtering gas was argon, and the average deposition thickness of the silicon dioxide layer was 80 nm. Then, the magnesium fluoride layer was prepared using the magnesium fluoride target prepared in Example 5 by magnetron sputtering. The sputtering frequency was 150 W, the sputtering gas pressure was 0.6 Pa, and the average deposition thickness of the magnesium fluoride layer was 70 nm. The vacuum level during magnetron sputtering was 5 × 10⁻⁶ Pa. -4 Pa, sputtering gas is argon; five layers of silicon dioxide and magnesium fluoride are deposited alternately on the pretreated glass surface to obtain a semi-finished product;

[0061] S3. The surface of the semi-finished product is polished by ion beam with a beam current density of 0.2 mA / cm², a working gas pressure of 0.2 Pa, and an incident angle of 4° to obtain coated glass.

[0062] Example 3: The difference between this example and Example 1 is that:

[0063] S1. Select 1mm thick optical glass as the substrate. The optical glass is ultrasonically cleaned at 20kHz, then rinsed with deionized water, then dehydrated with 95% ethanol, and finally dried with nitrogen to complete the pretreatment and obtain the pretreated glass.

[0064] S2. Pre-treatment of glass surface: A silica layer was prepared from the silica target material prepared in Example 3 by magnetron sputtering. The sputtering frequency was 160 W, the sputtering pressure was 0.4 Pa, and the vacuum degree during magnetron sputtering was 5 × 10⁻⁶. -4 The sputtering gas was argon, and the average deposition thickness of the silicon dioxide layer was 100 nm. Then, a magnesium fluoride layer was prepared using the magnesium fluoride target prepared in Example 6 by magnetron sputtering. The sputtering frequency was 180 W, the sputtering gas pressure was 0.4 Pa, and the average deposition thickness of the magnesium fluoride layer was 50 nm. The vacuum level during magnetron sputtering was 5 × 10⁻⁶ Pa. -4 Pa, sputtering gas is argon; five layers of silicon dioxide and magnesium fluoride are deposited alternately on the pretreated glass surface to obtain a semi-finished product;

[0065] S3. The surface of the semi-finished product is polished by ion beam with a beam current density of 0.4 mA / cm², a working gas pressure of 0.4 Pa, and an incident angle of 5° to obtain coated glass.

[0066] Example 4: The difference between this example and Example 1 is that:

[0067] No yttrium oxide was added during the preparation of the microporous silica target.

[0068] Example 5: The difference between this example and Example 1 is that:

[0069] No titanium dioxide was added during the preparation of the microporous silica target.

[0070] Example 6: The difference between this example and Example 1 is that:

[0071] In S2, the microporous silica target is replaced with a silica target of equal mass.

[0072] Example 7: The difference between this example and Example 1 is that:

[0073] No silicon carbide was added during the preparation of the magnesium fluoride target.

[0074] Example 8: The difference between this example and Example 1 is that:

[0075] The semi-finished product was not subjected to ion beam polishing.

[0076] Comparative Example

[0077] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0078] In S2, the magnesium fluoride layer is replaced by a silicon dioxide layer.

[0079] Performance testing

[0080] 1. Transmittance testing

[0081] Coated glasses were prepared using the methods of Examples 1-8 and Comparative Example 1, respectively, and the transmittance under green light at 530 nm was measured.

[0082] 2. Reflection detection

[0083] Coated glass was prepared using the methods of Examples 1-8 and Comparative Example 1, and the reflectivity under red light at 940 nm was measured.

[0084] 3. Signal-to-noise ratio detection

[0085] Coated glass was prepared using the methods of Examples 1-8 and Comparative Example 1, respectively. The coated glass was irradiated with a 530nm green LED, and the transmitted / reflected light signal was received by a photodiode (PD) as the signal power. The dark current (noise substrate under no light conditions) was measured to separate the noise component as the noise power. The signal-to-noise ratio was calculated as 10·log10(signal power / noise power).

[0086] Table 1 Performance Test Table

[0087]

[0088] As can be seen from Examples 1-3 and Table 1, the coated glass has high transmittance, low reflectance, and high signal-to-noise ratio, indicating that the alternating magnetron sputtered silicon dioxide and magnesium fluoride layers can reduce the interference of ambient light on PPG signals in the wide wavelength range.

[0089] Combining Examples 1 and 4-8 with Table 1, it can be seen that no yttrium oxide was added during the preparation of the microporous silica target in Example 4. Compared with Example 1, the transmittance of Example 4 is lower than that of Example 1, the reflectance is higher than that of Example 1, and the signal-to-noise ratio is lower than that of Example 1. This indicates that the silica layer uses mesoporous silica microspheres as the substrate, and the doping of yttrium oxide refines the thin film grains, improves the nanostructure density of the nanonetwork structure, and reduces the interference of ambient light on the PPG signal in a wide band.

[0090] In Example 5, no titanium dioxide was added during the preparation of the microporous silica target. Compared with Example 1, the transmittance of Example 5 was lower than that of Example 1, the reflectance was higher than that of Example 1, and the signal-to-noise ratio was lower than that of Example 1. This indicates that titanium dioxide induces lattice changes, which, together with the pyrolysis of polyethylene glycol, promotes the formation of micron-scale structures and forms a multi-level micro-nano network with the nanostructure, further reducing the interference of ambient light on PPG signals in a wide wavelength range.

[0091] In Example 6, the microporous silica target was replaced with a silica target of equal mass. Compared with Example 1, the transmittance of Example 6 was lower than that of Example 1, the reflectance was higher than that of Example 1, and the signal-to-noise ratio was lower than that of Example 1. This shows that the mesoporous structure of the mesoporous silica microspheres acts as a template during sputtering, guiding the formation of an ordered nanopore array in the thin film. The silica target without gaps affects the formation of the micro-nano array structure. Therefore, the silica target prepared by the mesoporous silica microspheres can reduce the interference of ambient light on the PPG signal in a wide wavelength range.

[0092] In Example 7, no silicon carbide was added during the preparation of the magnesium fluoride target. Compared with Example 1, the transmittance of Example 7 was lower than that of Example 1, the reflectance was higher than that of Example 1, and the signal-to-noise ratio was lower than that of Example 1. This indicates that by utilizing the connection effect between silicon and silicon dioxide layers in silicon carbide, the mechanical interlocking effect between the magnesium fluoride layer and the silicon dioxide layer can be improved. Furthermore, the high melting point of silicon carbide can compensate for the difference in the coefficient of thermal expansion of magnesium fluoride at high temperatures, reduce interfacial stress, improve film stability, and promote the formation of micro-nano network structures. Combined with the pyrolysis of polyethylene glycol, the distribution of micro-nano network structures is further improved, thereby reducing the interference of ambient light on PPG signals in a wide wavelength range.

[0093] The semi-finished product of Example 8 was not subjected to ion beam polishing. Compared with Example 1, the transmittance of Example 8 was lower than that of Example 1, the reflectance was higher than that of Example 1, and the signal-to-noise ratio was lower than that of Example 1. This shows that ion beam polishing can control surface protrusions and micro-defects, reduce light scattering rate, avoid over-etching, effectively suppress stray light, and ensure etching stability, thereby reducing the interference of ambient light on PPG signals in a wide band.

[0094] Combining Example 1 and Comparative Example 1 with Table 1, it can be seen that in Comparative Example 1, replacing the magnesium fluoride layer with a silicon dioxide layer results in lower transmittance, higher reflectance, and lower signal-to-noise ratio compared to Example 1. This indicates that the alternating stacking of silicon dioxide and magnesium fluoride on the optical glass surface forms a nano-stacked array network structure. The refractive index of silicon dioxide is approximately 1.46, and the refractive index of magnesium fluoride is approximately 1.38. By utilizing the refractive index gradient of the alternating stacked layers, the destructive effect of optical interference is enhanced, reducing the interference of ambient light on the PPG signal over a wide wavelength range.

[0095] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing coated glass for optical sensors, characterized in that, Includes the following steps: S1. The optical glass substrate is pretreated to obtain pretreated glass; S2. Pre-treat the glass surface by magnetron sputtering a silicon dioxide layer, followed by magnetron sputtering a magnesium fluoride layer, alternating 5-6 layers to obtain a semi-finished product. The target material for magnetron sputtering of the silicon dioxide layer is a microporous silicon dioxide target. The microporous silicon dioxide target is prepared by a mesoporous silicon dioxide microsphere, yttrium oxide, titanium oxide, and polyethylene glycol solution in a mass ratio of 1:0.1-0.15:0.02-0.05:0.1-0.

2. The sputtering target material for the magnesium fluoride layer is a magnesium fluoride target, prepared by a magnesium fluoride, silicon carbide, and polyethylene glycol solution in a mass ratio of 1:0.02-0.05:0.05-0.

08. The average deposition thickness of each silicon dioxide layer is 80-100 nm, and the average deposition thickness of each magnesium fluoride layer is 50-70 nm. S3. The surface of the semi-finished product is polished by ion beam to obtain coated glass.

2. The method for preparing coated glass for optical sensors according to claim 1, characterized in that: The pre-processing of the glass includes the following steps: Ultrasonic cleaning, deionized water rinsing, ethanol dehydration, and nitrogen drying.

3. The method for preparing coated glass for optical sensors according to claim 1, characterized in that, The beam current density of the ion beam polishing treatment is 0.2-0.4 mA / cm², the working gas pressure is 0.2-0.4 Pa, and the incident angle is 4-5°.

4. A coated glass, characterized in that, The coated glass is prepared by the method for preparing coated glass for optical sensors according to any one of claims 1-3.

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