Optical element for head-mounted device

Abstract

The utility model provides an optical element used for a head-mounted device, the optical element comprises a base material layer and a coating film layer, the coating film layer is located on one side surface of the base material layer, the coating film layer is formed by twelve layers of films formed by alternately arranging a first material and a second material, and the coating film layer comprises a front film system, a middle film system and a rear film system which are stacked in sequence; the average reflectivity R4070 of the coating layer at the wavelength of 400 nm to 700 nm meets the following condition: R4070 is more than 48.5% and less than 50.5%; the average reflectivity R80100 of the coating layer at the wavelength of 800 nm to 1000 nm meets the condition that R80100 is larger than 2.5% and smaller than 3.0%. According to the utility model, the problem that the semi-transmission and semi-reflection of the visible light band and the low reflectivity of the infrared band of the optical film in the prior art are difficult to consider at the same time is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of optical elements, and particularly relates to an optical element for a head-mounted device. Background Art

[0002] The folded-back system can effectively reduce the thickness of the overall device by folding the optical path, thereby achieving a thinner and lighter design, so it is very popular in the technology of virtual reality head-mounted displays. Among them, optical thin films are very crucial for the folded-back system, such as semi-transmissive and semi-reflective films. The semi-transmissive and semi-reflective film has a reflectivity of 50% and a transmittance of 50% in the visible light band to ensure that the visible light of the screen can pass through and participate in the reflection of polarized light. However, as VR devices gradually develop towards AR or even MR devices, the ability to achieve interaction has gradually become the goal of the whole device. Currently, head-mounted devices usually adopt an eye movement tracking system involving infrared light. At this time, if the semi-transmissive and semi-reflective film still has a reflectivity of 50%, it will be extremely unfavorable for the signal capture of eye movement tracking.

[0003] That is to say, in the prior art, there is a problem that it is difficult to balance the semi-transmission and semi-reflection in the visible light band and the low reflectivity in the infrared band of the optical thin film. Summary of the Utility Model

[0004] The main purpose of the utility model is to provide an optical element for a head-mounted device to solve the problem that it is difficult to balance the semi-transmission and semi-reflection in the visible light band and the low reflectivity in the infrared band of the optical thin film in the prior art.

[0005] To achieve the above purpose, the utility model provides an optical element for a head-mounted device. The optical element includes a substrate layer and a coating layer. The coating layer is located on one side surface of the substrate layer. The coating layer is formed by twelve layers of films alternately arranged with a first material and a second material. The coating layer includes a front film system, a middle film system, and a rear film system stacked in sequence. The average reflectivity R4070 of the coating layer at a wavelength of 400 nm to 700 nm satisfies: 48.5% < R4070 < 50.5%; the average reflectivity R80100 of the coating layer at a wavelength of 800 nm to 1000 nm satisfies: 2.5% < R80100 < 3.0%.

[0006] Further, the front film system is connected to one side surface of the substrate layer. The front film system includes, successively stacked: a first film layer, which is connected to one side surface of the substrate layer. The first film layer is made of a first material, and the thickness T1 of the first film layer is greater than 26 nm and less than 39 nm; a second film layer, which is made of a second material, and the thickness T2 of the second film layer is greater than 28 nm and less than 67 nm; a third film layer, which is made of the first material, and the thickness T3 of the third film layer is greater than 31 nm and less than 75 nm; a fourth film layer, which is made of the second material, and the thickness T4 of the fourth film layer is greater than 45 nm and less than 82 nm; a fifth film layer, which is made of the first material, and the thickness T5 of the fifth film layer is greater than 64 nm and less than 81 nm; a sixth film layer, which is made of the second material, and the thickness T6 of the sixth film layer is greater than 81 nm and less than 117 nm.

[0007] Further, the front film system is connected to one side surface of the substrate layer. The middle film system includes, successively stacked: a seventh film layer, which is connected to the side surface of the front film system away from the substrate layer. The seventh film layer is made of the first material, and the thickness T7 of the seventh film layer is greater than 64 nm and less than 88 nm; an eighth film layer, which is made of the second material, and the thickness T8 of the eighth film layer is greater than 20 nm and less than 34 nm. The thicknesses T7 and T8 of the seventh and eighth film layers satisfy: 1.9 < T7 / T8 < 3.4; a ninth film layer, which is made of the first material, and the thickness T9 of the ninth film layer is greater than 14 nm and less than 33 nm; a tenth film layer, which is made of the second material, and the thickness T10 of the tenth film layer is greater than or equal to 15 nm and less than 76 nm.

[0008] Further, the front film system is connected to one side surface of the substrate layer. The rear film system includes, successively stacked: an eleventh film layer, which is connected to the side surface of the middle film system away from the front film system. The eleventh film layer is made of the first material, and the thickness T11 of the eleventh film layer is greater than 22 nm and less than 34 nm; a twelfth film layer, which is made of the second material, and the thickness T12 of the twelfth film layer is greater than 75 nm and less than 101 nm. The thicknesses T12 and T11 of the twelfth and eleventh film layers satisfy: 2.2 < T12 / T11 < 4.5.

[0009] Further, the first material includes titanium trioxide, and the refractive index of the first material is greater than 2.3 and less than 2.4.

[0010] Further, the second material includes one of silicon dioxide and SL-4, and the refractive index of the second material is greater than 1.4 and less than 1.5.

[0011] Further, the second material includes SL-4, and the second material is a mixture of aluminum oxide and silicon dioxide with a mass ratio of aluminum oxide to silicon dioxide being 6:4.

[0012] Further, the total thickness ∑T of the coating layer is greater than 641 nm and less than 673 nm.

[0013] Further, the reflectivity R50 of the coating layer at a wavelength of 500 nm satisfies: 48.5% < R50 < 50.2%.

[0014] Further, the reflectivity R60 of the coating layer at a wavelength of 600 nm satisfies: 49% < R60 < 49.5%.

[0015] Further, the reflectivity R90 of the coating layer at a wavelength of 900 nm satisfies: 1.1% < R90 < 1.4%.

[0016] Applying the technical solution of the present utility model, the optical element for a head-mounted device includes a substrate layer and a coating layer. The coating layer is located on one surface of the substrate layer. The coating layer is formed by twelve layers of films alternately arranged with a first material and a second material. The coating layer includes a front film system, a middle film system, and a rear film system stacked in sequence; the average reflectivity R4070 of the coating layer at wavelengths from 400 nm to 700 nm satisfies: 48.5% < R4070 < 50.5%; the average reflectivity R80100 of the coating layer at wavelengths from 800 nm to 1000 nm satisfies: 2.5% < R80100 < 3.0%.

[0017] The optical element for a head-mounted device in this application is sequentially a substrate layer and a coating layer. The coating layer is formed by twelve layers of films alternately arranged with a first material and a second material, which is beneficial to the stable reflection characteristics of the optical element and facilitates the simplification of the coating process and the control of the coating quality and consistency. The coating layer is stacked with a front film system, a middle film system, and a rear film system in sequence. Among them, the front film system is connected to one side of the substrate layer, so that the required target reflectivity range can be achieved. By restricting the average reflectivity R4070 of the optical element to light in the wavelength range of 400 nm to 700 nm, that is, the visible light band, within a certain range, the semi-transmissive and semi-reflective function of the coating layer for the screen light in the folding system of the head-mounted device can be ensured, providing a basic guarantee for the folding of the optical path in the folding system, further ensuring the visible light transmittance and polarized light reflectivity of the screen, and controlling the intensity of the light entering the eyes of the user interface to be appropriate. At the same time, by restricting the average reflectivity R80100 of the coating layer to light in the wavelength range of 800 nm to 1000 nm, that is, the infrared band, within a certain range, most of the light in the infrared band can pass through the coating layer, thus avoiding the interference of stray light at the reflection interface during the infrared capture of the built-in lens in the eye movement tracking process and affecting the recognition accuracy. Description of the Drawings

[0018] The accompanying drawings forming a part of this application are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0019] Figure 1 A schematic diagram of the overall structure of an optical element according to an alternative embodiment of the present utility model is shown;

[0020] Figure 2 A reflectance characteristic diagram of the optical element of the first embodiment of the present utility model for light of different wavelengths is shown;

[0021] Figure 3 A reflectance characteristic diagram of the optical element of the second embodiment of the present utility model for light of different wavelengths is shown;

[0022] Figure 4 A reflectance characteristic diagram of the optical element of the third embodiment of the present utility model for light of different wavelengths is shown.

[0023] Among them, the above-mentioned drawings include the following reference numerals:

[0024] 10. Substrate layer; 20. Coating layer; 21. Front film system; 211. First film layer; 212. Second film layer; 213. Third film layer; 214. Fourth film layer; 215. Fifth film layer; 216. Sixth film layer; 22. Middle film system; 221. Seventh film layer; 222. Eighth film layer; 223. Ninth film layer; 224. Tenth film layer; 23. Rear film system; 231. Eleventh film layer; 232. Twelfth film layer. Detailed implementation manners

[0025] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present utility model will be described in detail below with reference to the drawings and in combination with the embodiments.

[0026] It should be pointed out that unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0027] In the present utility model, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are usually in relation to the directions shown in the drawings, or in relation to the vertical, perpendicular or gravitational directions of the components themselves; similarly, for the convenience of understanding and description, "inner, outer" refer to the inner and outer of the contours of the respective components themselves, but the above orientation terms do not limit the present utility model.

[0028] In order to solve the problem in the prior art that it is difficult to balance the semi-transmission and semi-reflection in the visible light band and the low reflectivity in the infrared band of an optical thin film, the present utility model provides an optical element for a head-mounted device.

[0029] As Figures 1 to 4 shown, the optical element for a head-mounted device includes a substrate layer 10 and a coating layer 20. The coating layer 20 is located on one side surface of the substrate layer 10. The coating layer 20 is formed by twelve layers of films alternately arranged with a first material and a second material. The coating layer 20 includes a front film system 21, a middle film system 22, and a rear film system 23 stacked in sequence. The average reflectivity R4070 of the coating layer 20 at a wavelength of 400 nm to 700 nm satisfies 48.5% < R4070 < 50.5%. The average reflectivity R80100 of the coating layer 20 at a wavelength of 800 nm to 1000 nm satisfies 2.5% < R80100 < 3.0%.

[0030] The optical element for a head-mounted device in the present application is sequentially a substrate layer 10 and a coating layer 20. The coating layer 20 is formed by twelve layers of films alternately arranged with a first material and a second material, which is beneficial to the stable reflection characteristics of the optical element, and facilitates the simplification of the coating process and the control of the coating quality and consistency. The coating layer 20 is stacked in sequence by a front film system 21, a middle film system 22, and a rear film system 23. Among them, the front film system 21 is connected to one side of the substrate layer 10, so that the required target reflectivity range can be achieved. By restricting the average reflectivity R4070 of the optical element to the light in the visible light band of 400 nm to 700 nm within a certain range, the function of semi-transmission and semi-reflection of the screen light in the folding-back system of the head-mounted device can be ensured for the coating layer 20, providing a basic guarantee for the folding of the optical path in the folding-back system, further ensuring the visible light transmittance and polarized light reflectivity of the screen, and controlling the intensity of the light entering the eyes of the user interface to be appropriate. At the same time, by restricting the average reflectivity R80100 of the coating layer 20 to the light in the infrared band of 800 nm to 1000 nm within a certain range, most of the light in the infrared band can pass through the coating layer 20, thereby avoiding the interference of stray light at the reflection interface during the infrared capture of the built-in lens during the eye movement tracking and affecting the recognition accuracy.

[0031] As Figures 1 to 4As shown, the front film system 21 is connected to one side surface of the substrate layer 10. The front film system 21 includes a first film layer 211, a second film layer 212, a third film layer 213, a fourth film layer 214, a fifth film layer 215, and a sixth film layer 216 that are stacked in sequence. The first film layer 211 is connected to one side surface of the substrate layer 10. The first film layer 211 is made of a first material, and the thickness T1 of the first film layer 211 is greater than 26 nm and less than 39 nm; the second film layer 212 is made of a second material, and the thickness T2 of the second film layer 212 is greater than 28 nm and less than 67 nm; the third film layer 213 is made of the first material, and the thickness T3 of the third film layer 213 is greater than 31 nm and less than 75 nm; the fourth film layer 214 is made of the second material, and the thickness T4 of the fourth film layer 214 is greater than 45 nm and less than 82 nm; the fifth film layer 215 is made of the first material, and the thickness T5 of the fifth film layer 215 is greater than 64 nm and less than 81 nm; the sixth film layer 216 is made of the second material, and the thickness T6 of the sixth film layer 216 is greater than 81 nm and less than 117 nm. That is to say, the first film layer 211, the third film layer 213, and the fifth film layer 215 of the optical element are made of the same first material, while the second film layer 212, the fourth film layer 214, and the sixth film layer 216 are made of the same second material. The alternating material design method helps to stabilize the reflection characteristics and can achieve the target reflectivity range required for the optical element. By alternately forming the film layers with the first material and the second material, and the thickness of each film layer is strictly controlled within a specific range, it is beneficial to control the quality and consistency of the optical element coating.

[0032] As Figures 1 to 4As shown, the front film system 21 is connected to one side surface of the substrate layer 10. The middle film system 22 includes a seventh film layer 221, an eighth film layer 222, a ninth film layer 223, and a tenth film layer 224 stacked in sequence. The seventh film layer 221 is connected to the side surface of the front film system 21 away from the substrate layer 10. The seventh film layer 221 is made of a first material, and the thickness T7 of the seventh film layer 221 is greater than 64 nm and less than 88 nm; the eighth film layer 222 is made of a second material, and the thickness T8 of the eighth film layer 222 is greater than 20 nm and less than 34 nm. The thickness T7 of the seventh film layer 221 and the thickness T8 of the eighth film layer 222 satisfy: 1.9 < T7 / T8 < 3.4; the ninth film layer 223 is made of a first material, and the thickness T9 of the ninth film layer 223 is greater than 14 nm and less than 33 nm; the tenth film layer 224 is made of a second material, and the thickness T10 of the tenth film layer 224 is greater than or equal to 15 nm and less than 76 nm. That is to say, the thickness ratio T7 / T8 between the seventh film layer 221 and the eighth film layer 222 of the optical element is limited between 1.9 and 3.4, which helps to optimize the reflectivity and transmittance of the optical element and meets the requirements of the optical element for a specific wavelength range. By restricting T7 / T8 within an accurate range, it can ensure that the optical properties between the seventh film layer 221 and the eighth film layer 222 are more matched, which helps to improve the optical consistency of the entire coating layer 20. By optimizing the design of the seventh film layer 221 to the tenth film layer 224, the performance of the optical element in the visible light band and the near-infrared band is further improved, thereby enhancing the functionality of the optical element and the user's experience of the imaging effect of the head-mounted device.

[0033] As Figures 1 to 4 shown, the front film system 21 is connected to one side surface of the substrate layer 10. The rear film system 23 includes an eleventh film layer 231 and a twelfth film layer 232 stacked in sequence. The eleventh film layer 231 is connected to the side surface of the middle film system 22 away from the front film system 21. The eleventh film layer 231 is made of a first material, and the thickness T11 of the eleventh film layer 231 is greater than 22 nm and less than 34 nm; the twelfth film layer 232 is made of a second material, and the thickness T12 of the twelfth film layer 232 is greater than 75 nm and less than 101 nm. The thickness T12 of the twelfth film layer 232 and the thickness T11 of the eleventh film layer 231 satisfy 2.2 < T12 / T11 < 4.5. That is to say, the thickness ratio T12 / T11 between the eleventh film layer 231 and the twelfth film layer 232 of the optical element is limited between 2.2 and 4.5, which helps to precisely control the reflection characteristics. By restricting the thickness T11 of the eleventh film layer 231 and the thickness T12 of the twelfth film layer 232 within a certain range, it helps to improve the durability and endurance of the coating layer 20 of the optical element and avoid reliability problems.

[0034] Optionally, the first material includes titanium pentoxide, and the refractive index of the first material is greater than 2.3 and less than 2.4. That is to say, by using a material with a specific high refractive index range, the thickness of each film layer of the optical element can be better controlled, thereby optimizing the optical design of the entire coating layer 20 and reducing unnecessary light loss. At the same time, titanium pentoxide, as a stable material, can improve the durability and chemical stability of the coating layer 20. This helps to extend the service life of the optical element and reduce possible problems during use.

[0035] Optionally, the second material includes one of silicon dioxide and SL-4, and the refractive index of the second material is greater than 1.4 and less than 1.5. That is to say, the refractive index of the second material being between 1.4 and 1.5 belongs to a lower refractive index range, which helps to form a contrast with high refractive index materials (such as titanium pentoxide) in the coating layer 20, thereby achieving the required optical performance of the optical element.

[0036] Optionally, the second material includes SL-4, and the second material is a mixture of aluminum oxide and silicon dioxide, and the mass ratio of the mixture of aluminum oxide and silicon dioxide is 6:4. That is to say, when the second material is SL-4, it is a mixture of aluminum oxide and silicon dioxide with a ratio of 6:4. This mixture with a specific ratio can provide additional chemical stability and strength, helping to improve the overall performance of the coating layer 20.

[0037] As Figures 1 to 4 shown, the total thickness ∑T of the coating layer 20 is greater than 641 nm and less than 673 nm. That is to say, by controlling the total thickness of the coating layer 20, the strength of the basic film layer of the optical element is ensured, and problems such as reliability film cracking or appearance damage caused by the coating layer 20 being too thin are avoided. At the same time, there is enough space within the above-mentioned coating layer 20 film thickness limit for the twelve-layer film system distribution of the two materials, ensuring the performance of the coating layer 20.

[0038] As Figures 1 to 4 shown, the reflectivity R50 of the coating layer 20 at a wavelength of 500 nm satisfies 48.5% < R50 < 50.2%. That is to say, by controlling the reflectivity of the coating layer 20 at a wavelength of 500 nm to meet a certain range, the reflectivity in the core visible light band can be made to fluctuate within a very small range around 50%, which is convenient for confirming the single-layer film thickness and is conducive to process stability and mass production replication.

[0039] As Figures 1 to 4 shown, the reflectivity R60 of the coating layer 20 at a wavelength of 600 nm satisfies 49% < R60 < 49.5%. That is to say, by controlling the reflectivity of the coating layer 20 at a wavelength of 600 nm to meet a certain range, it is possible to avoid the reflectivity at the visible long wave (red) being too high when controlling the visible short wave reflectivity, resulting in the film color of the coating layer 20 turning red.

[0040] As Figures 1 to 4 shown, the reflectivity R90 of the coating layer 20 at a wavelength of 900 nm satisfies 1.1% < R90 < 1.4%. That is to say, by controlling the reflectivity of the coating layer 20 at a wavelength of 900 nm to meet a certain range, the reflectivity of the optical element in the infrared band is effectively reduced, the intensity of possible infrared stray light is weakened, and signal interference to the eye movement tracking process is avoided.

[0041] The following further describes, with reference to the accompanying drawings, examples of the specific structures and parameters of the optical element applicable to the above embodiments.

[0042] Example 1

[0043] As Figures 1 to 2 shown, the optical element of Example 1 of the present application is described. The optical element for the head-mounted device includes a substrate layer 10 and a coating layer 20. The coating layer 20 is located on one surface of the substrate layer. The coating layer 20 is formed by twelve layers of films alternately arranged with a first material and a second material. The coating layer 20 includes a front film system 21, a middle film system 22, and a rear film system 23 stacked in sequence; the average reflectivity R4070 of the coating layer 20 at wavelengths from 400 nm to 700 nm satisfies 48.5% < R4070 < 50.5%; the average reflectivity R80100 of the coating layer 20 at wavelengths from 800 nm to 1000 nm satisfies 2.5% < R80100 < 3.0%. In this embodiment, the material of the substrate layer 10 is plastic, the first material uses titanium trioxide (Ti3O5), and the second material uses SL-4.

[0044] Table 1 shows the specific structure parameter table of the optical element of Example 1, where the unit of thickness is nm.

[0045]

[0046] Table 1

[0047] Figure 2 Describes the reflectivity characteristic diagram of the optical element of Example 1 of the present application at different wavelengths, indicating the good visible light transmittance and polarized light reflectivity of the optical element at wavelengths from 400 nm to 700 nm, and the low reflectivity of light at wavelengths from 800 nm to 1000 nm.

[0048] Example 2

[0049] As Figure 3As shown in the figure, the optical element of the second embodiment of the present application is described. The difference from the first embodiment is that the thicknesses of different film layers are different. The optical element for the head-mounted device includes a substrate layer 10 and a coating layer 20. The coating layer 20 is located on one surface of the substrate layer 10. The coating layer 20 is formed by twelve layers of films alternately arranged with a first material and a second material. The coating layer 20 includes a front film system 21, a middle film system 22, and a rear film system 23 stacked in sequence; the average reflectance R4070 of the coating layer 20 at wavelengths from 400 nm to 700 nm satisfies 48.5% < R4070 < 50.5%; the average reflectance R80100 of the coating layer 20 at wavelengths from 800 nm to 1000 nm satisfies 2.5% < R80100 < 3.0%. In this embodiment, the material of the substrate layer 10 is plastic, the first material uses titanium trioxide (Ti3O5), and the second material uses SL-4.

[0050] Table 2 shows the specific structural parameter table of the optical element of the second embodiment, where the unit of thickness is nm.

[0051]

[0052]

[0053] Table 2

[0054] Figure 3 The reflectivity characteristic diagram of the optical element of the second embodiment of the present application at different wavelengths is described, indicating the good visible light transmittance and polarized light reflectance of the optical element at wavelengths from 400 nm to 700 nm, and the low reflectance of light at wavelengths from 800 nm to 1000 nm.

[0055] Embodiment 3

[0056] As Figure 4 shown in the figure, the optical element of the third embodiment of the present application is described. The difference from the first embodiment is that the materials, thicknesses, and refractive indices of different film layers are different. The optical element for the head-mounted device includes a substrate layer 10 and a coating layer 20. The coating layer 20 is located on one surface of the substrate layer. The coating layer 20 is formed by twelve layers of films alternately arranged with a first material and a second material. The coating layer 20 includes a front film system 21, a middle film system 22, and a rear film system 23 stacked in sequence; the average reflectance R4070 of the coating layer 20 at wavelengths from 400 nm to 700 nm satisfies 48.5% < R4070 < 50.5%; the average reflectance R80100 of the coating layer 20 at wavelengths from 800 nm to 1000 nm satisfies 2.5% < R80100 < 3.0%. In this embodiment, the material of the substrate layer 10 is plastic, the first material uses titanium trioxide (Ti3O5), and the second material uses silicon dioxide (SiO2).

[0057] Table 3 shows the specific structural parameter table of the optical element in the third embodiment, where the unit of thickness is nm.

[0058]

[0059]

[0060] Table 3

[0061] Figure 4 Describes the reflectivity characteristic diagram of the optical element in the third embodiment of the present application at different wavelengths, indicating the good visible light transmittance and polarized light reflectivity of the optical element for wavelengths from 400 nm to 700 nm, as well as the low reflectivity of light with wavelengths from 800 nm to 1000 nm.

[0062] In summary, some parameters of the optical elements in Embodiments 1 to 3 respectively satisfy the relationships shown in Table 4. Among them, the unit of ∑T is nm, and the units of R4070, R80100, R50, R60, and R90 are all %.

[0063] Data / Examples Example 1 Example 2 Example 3 R4070 50.41 48.60 48.73 R80100 2.65 2.85 2.75 ∑T 641.15 667.21 672.16 T12 / T11 2.27 3.04 4.48 T7 / T8 3.07 1.94 3.30 R50 50.13 48.51 48.54 R60 49.27 49.22 49.17 R90 1.19 1.33 1.21

[0064] Table 4

[0065] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0066] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0067] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above drawings are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0068] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, various modifications and variations can be made to the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. An optical element for a head-mounted device, characterized in that, The optical element includes a substrate layer (10) and a coating layer (20). The coating layer (20) is located on one side surface of the substrate layer (10). The coating layer (20) is formed by twelve layers of films arranged alternately with a first material and a second material. The coating layer (20) includes a front film system (21), a middle film system (22), and a rear film system (23) stacked in sequence; The average reflectivity R4070 of the coating layer (20) at wavelengths from 400 nm to 700 nm satisfies: 48.5% < R4070 < 50.5%; The average reflectivity R800 of the coating layer (20) at wavelengths from 800 nm to 1000 nm satisfies: 2.5% < R800 < 3.0%.

2. The optical element according to claim 1, characterized in that, The front film system (21) is connected to one side surface of the substrate layer (10). The front film system (21) includes, stacked in sequence: A first film layer (211). The first film layer (211) is connected to one side surface of the substrate layer (10). The first film layer (211) is made of the first material. The thickness T1 of the first film layer (211) is greater than 26 nm and less than 39 nm; A second film layer (212). The second film layer (212) is made of the second material. The thickness T2 of the second film layer (212) is greater than 28 nm and less than 67 nm; A third film layer (213). The third film layer (213) is made of the first material. The thickness T3 of the third film layer (213) is greater than 31 nm and less than 75 nm; A fourth film layer (214). The fourth film layer (214) is made of the second material. The thickness T4 of the fourth film layer (214) is greater than 45 nm and less than 82 nm; A fifth film layer (215). The fifth film layer (215) is made of the first material. The thickness T5 of the fifth film layer (215) is greater than 64 nm and less than 81 nm; A sixth film layer (216). The sixth film layer (216) is made of the second material. The thickness T6 of the sixth film layer (216) is greater than 81 nm and less than 117 nm.

3. The optical element according to claim 1, characterized in that, The front film system (21) is connected to one side surface of the substrate layer (10). The middle film system (22) includes, stacked in sequence: A seventh film layer (221). The seventh film layer (221) is connected to the side surface of the front film system (21) away from the substrate layer (10). The seventh film layer (221) is made of the first material. The thickness T7 of the seventh film layer (221) is greater than 64 nm and less than 88 nm; An eighth film layer (222). The eighth film layer (222) is made of the second material. The thickness T8 of the eighth film layer (222) is greater than 20 nm and less than 34 nm. The relationship between the thickness T7 of the seventh film layer (221) and the thickness T8 of the eighth film layer (222) satisfies: 1.9 < T7 / T8 < 3.4; A ninth film layer (223). The ninth film layer (223) is made of the first material. The thickness T9 of the ninth film layer (223) is greater than 14 nm and less than 33 nm; The tenth film layer (224), the tenth film layer (224) is made of the second material, and the thickness T10 of the tenth film layer (224) is greater than or equal to 15 nm and less than 76 nm.

4. The optical element according to claim 1, characterized in that, The front film system (21) is connected to one side surface of the substrate layer (10), and the rear film system (23) includes the following layers stacked in sequence: The eleventh film layer (231), the eleventh film layer (231) is connected to one side surface of the middle film system (22) away from the front film system (21), the eleventh film layer (231) is made of the first material, and the thickness T11 of the eleventh film layer (231) is greater than 22 nm and less than 34 nm; The twelfth film layer (232), the twelfth film layer (232) is made of the second material, the thickness T12 of the twelfth film layer (232) is greater than 75 nm and less than 101 nm, and the following relationship is satisfied between the thickness T12 of the twelfth film layer (232) and the thickness T11 of the eleventh film layer (231): 2.2 < T12 / T11 < 4.

5.

5. The optical element according to any one of claims 1 to 4, characterized in that, The first material includes titanium trioxide, and the refractive index of the first material is greater than 2.3 and less than 2.

4.

6. The optical element according to any one of claims 1 to 4, characterized in that The second material includes one of silicon dioxide and SL-4, and the refractive index of the second material is greater than 1.4 and less than 1.

5.

7. The optical element according to any one of claims 1 to 4, characterized in that, The total thickness ∑T of the coating layer (20) is greater than 641 nm and less than 673 nm.

8. The optical element according to any one of claims 1 to 4, characterized in that The reflectivity R50 of the coating layer (20) at a wavelength of 500 nm satisfies: 48.5% < R50 < 50.2%.

9. The optical element according to any one of claims 1 to 4, characterized in that The reflectivity R60 of the coating layer (20) at a wavelength of 600 nm satisfies: 49% < R60 < 49.5%.

10. The optical element according to any one of claims 1 to 4, characterized in that, The reflectivity R90 of the coating layer (20) at a wavelength of 900 nm satisfies: 1.1% < R90 < 1.4%.

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