A highly reflective lens for lidar

Abstract

The present invention discloses a highly reflective lens for lidar. A film layer is deposited on the lens, and the film layer includes a filtering layer, a metal sandwich film, at least one nano-dielectric stack film, and an oil-proof, stain-proof, and fingerprint-proof film. By depositing a film layer on the lens, and the film layer includes a filtering layer, a metal sandwich film, a nano-dielectric stack film, and an oil-proof, stain-proof, and fingerprint-proof film, the reflectivity is greater than 95% between 10 degrees and 80 degrees of the incident angle in the near-infrared band of 870nm - 950nm. In the entire spectral range, from visible light to near-infrared between 380nm - 1000nm, the absorbance OD is greater than 5. The film layer has the advantages of fewer layers, smaller lens deformation, strong oil and stain resistance and impact resistance, excellent weather resistance, being able to withstand harsh climate condition changes such as high and low temperature shocks, sunlight ultraviolet irradiation, high temperature and high humidity, long service life, and low production cost, and can be widely used in large-scale mass production applications of automotive autonomous driving lidar.

Description

Technical Field

[0001] The present invention belongs to the field of lidar optical elements, and particularly relates to a high-reflection lens for lidar. Background Art

[0002] Lidar (light detection and ranging) is a sensing technology that uses a light source and a receiver for remote object detection and ranging. The emitted light pulse is reflected after hitting an object and returns to the lidar system, and the receiver detects the returned light pulse from the system. Lidar can provide accurate 3D measurement data and can work better under relatively harsh weather and lighting conditions. Lidar can combine with sensor data such as millimeter-wave radar and cameras and be applied to the automotive industry to provide reliable identification data of static and dynamic objects in the driving environment of vehicles, which helps with obstacle detection, collision avoidance, and safe navigation. Moreover, lidar is a highly available and mass-producible solution. It can be said that lidar is a good way to achieve a higher level of autonomous driving (above level L3) and higher safety. Compared with millimeter-wave radar, lidar has higher resolution, better stability, and more reliable three-dimensional data.

[0003] The application of lidar in the automotive industry has relatively high requirements for the optical device lidar. For example, the optical device is a high-reflection lens. Generally, there are two types of high-reflection lenses. One is to deposit metal film layers such as silver, aluminum, and gold on a glass substrate. Since the metal film is relatively soft and easily damaged, a protective film is often deposited outside the metal film. However, the high-reflection lens with a metal film layer cannot meet the requirements of lidar due to the harsh weather resistance requirements of the automotive industry. The other is to deposit multi-layer dielectric films with alternating high and low refractive indices by using the material interference effect. However, if the optical density value of 5 is to be achieved in the near-infrared band for multi-layer dielectric films, the number of film layers may be as many as 120, and the thickness is about 20 micrometers. This not only greatly increases the coating time and the cost is very high, but also the film layer stress is high, resulting in film cracking and serious deformation of the lens. At the same time, cars are generally used outdoors, and the high-reflection lenses in the prior art have poor resistance to high and low temperature shocks, sunlight ultraviolet irradiation, and high humidity, which greatly affects the performance change of lidar. Summary of the Invention

[0004] The purpose of the present invention is to propose a high-reflection lens for lidar to solve the problems raised in the background art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A high-reflection lens for lidar proposed by the present invention has a film layer coated on the lens. The film layer includes a filter layer, a metal sandwich film, at least one nano-dielectric stack film, and an oil-proof, stain-proof, and fingerprint-proof film arranged in sequence, where:

[0007] The thickness of the lens is from 1 mm to 3 mm.

[0008] The thickness of the film layer is from 2.5 um to 3.5 um, and the number of layers is from 20 to 45.

[0009] The filter layer is arranged on the side wall of the lens, and its thickness is from 10 nm to 50 nm.

[0010] The metal sandwich film is arranged on one side of the filter layer, and its thickness is from 60 nm to 200 nm.

[0011] The nano dielectric stack film is arranged on one side of the metal sandwich film and includes at least one film stack.

[0012] The oil-proof, stain-resistant and fingerprint-proof film is arranged on one side of the nano dielectric stack film, and its thickness is from 30 nm to 100 nm.

[0013] Preferably, the lens is a glass substrate, a silicon wafer, an acrylic substrate, a PC plastic substrate or a stainless steel substrate.

[0014] Preferably, the filter layer is aluminum oxide, silicon monoxide, silicon dioxide or titanium pentoxide.

[0015] Preferably, the metal sandwich film includes a metal material and a non-metal material. The non-metal material is inserted into the metal material in a single layer or a double layer. The thickness of the single layer of the non-metal material is from 0 nm to 20 nm. The metal material is gold, silver, aluminum, chromium, nickel or titanium, and the non-metal material is silicon dioxide.

[0016] Preferably, the number of film stacks is from 10 to 50. Each film stack includes stacked high-refractive-index dielectric films and low-refractive-index dielectric films. The number of stacked layers of the high-refractive-index dielectric films and the low-refractive-index dielectric films is from 19 to 41. The high-refractive-index dielectric films are away from the metal sandwich film, and the low-refractive-index dielectric films are close to the metal sandwich film. The high-refractive-index dielectric films are titanium pentoxide, niobium dioxide, tantalum pentoxide or zirconium dioxide, and the low-refractive-index dielectric films are silicon dioxide.

[0017] Preferably, the oil-proof, stain-resistant and fingerprint-proof film is a fluorine compound.

[0018] Preferably, the glass substrate is a double-sided polished optical glass, and the PV value of the optical glass is from -1.0 um to -0.5 um.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: By coating a film layer on the lens, and the film layer includes a filter layer, a metal sandwich film, a nano-dielectric stack film, and an oil-proof, stain-proof, and fingerprint-proof film, the reflectance between 10 degrees and 80 degrees of incidence in the near-infrared band of 870nm - 950nm is greater than 95%, and in the entire spectral range from visible light to near-infrared of 380nm - 1000nm, the absorbance OD is greater than 5. It has the advantages of fewer film layers, smaller lens deformation, strong oil and stain resistance and impact resistance, excellent weather resistance, being able to withstand harsh climate condition changes such as high and low temperature shocks, sunlight ultraviolet irradiation, high temperature and high humidity, long service life, and low production cost, and can be widely used in the mass production applications of automotive autonomous driving lidar. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the film layer coated on the high-reflection lens for lidar of the present invention;

[0021] Figure 2 It is a spectral splitting curve diagram of 43 film layers of the present invention;

[0022] Figure 3 It is a spectral splitting curve diagram of 21 film layers of the present invention;

[0023] Figure 4 It is a transmittance spectral splitting curve diagram of 21 film layers of the present invention;

[0024] Figure 5 It is a spectral curve diagram of the lens coated with the film layer of the present invention;

[0025] Figure 6 It is a schematic diagram of the change value of the PV of the lens surface shape coated with the film layer of the present invention.

[0026] Description of the reference numerals: 1, lens; 2, filter layer; 3, metal sandwich film; 4, nano-dielectric stack film; 5, oil-proof, stain-proof, and fingerprint-proof film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0028] It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or there can also be an intermediate component. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] As Figure 1-6 shown, a highly reflective lens for lidar, a film layer is provided on the lens 1, and the film layer includes a filter layer 2, a metal sandwich film 3, at least one nano dielectric stack film 4, and an oil-proof, stain-proof and fingerprint-proof film 5 arranged in sequence, where:

[0030] The thickness of the lens 1 is 1 mm to 3 mm.

[0031] The thickness of the film layer is 2.5 um to 3.5 um, and the number of layers is 20 layers to 45 layers.

[0032] The filter layer 2 is provided on the side wall of the lens 1, and the thickness is 10 nm to 50 nm.

[0033] The metal sandwich film 3 is provided on one side of the filter layer 2, and the thickness is 60 nm to 200 nm.

[0034] The nano dielectric stack film 4 is provided on one side of the metal sandwich film 3 and includes at least one film stack.

[0035] The oil-proof, stain-proof and fingerprint-proof film 5 is provided on one side of the nano dielectric stack film 4, and the thickness is 30 nm to 100 nm.

[0036] Specifically, the film layer is plated on the light surface of the lens 1. As Figure 1 shown, the lens 1, the filter layer 2, the metal sandwich film 3, the nano dielectric stack film 4, and the oil-proof, stain-proof and fingerprint-proof film 5 are arranged in sequence from bottom to top. The filter layer 2 is connected to the light surface of the lens 1 through an ionic bond, the metal sandwich film 3 is connected above the filter layer 2 through an ionic bond, the nano dielectric stack film 4 is connected above the metal sandwich film 3 through an ionic bond, and the oil-proof, stain-proof and fingerprint-proof film 5 is connected above the nano dielectric stack film 4 through an ionic bond.

[0037] In one embodiment, the lens 1 is a glass substrate, a silicon wafer, an acrylic substrate, a PC plastic substrate or a stainless steel substrate.

[0038] Specifically, the lens 1 can also be of other types without specific limitation.

[0039] In one embodiment, the filter layer 2 is aluminum oxide, silicon monoxide, silicon dioxide or titanium pentoxide.

[0040] Specifically, aluminum oxide, silicon monoxide, silicon dioxide, and titanium pentoxide are all selected as materials with a relatively close coefficient of thermal expansion to that of lens 1. The filter layer 2 can also be other substances. The filter layer 2 can enhance the adhesion between the metal sandwich film 3 and the lens 1, reduce grain boundary defects, and lower the internal stress between the film interfaces.

[0041] In one embodiment, the metal sandwich film 3 includes a metal material and a non-metal material. The non-metal material is inserted into the metal material in a single layer or a double layer. The thickness of the single-layer non-metal material is from 0 nm to 20 nm. The metal material is gold, silver, aluminum, chromium, nickel, or titanium, and the non-metal material is silicon dioxide.

[0042] Specifically, the metal sandwich film 3 improves the reflectivity and absorbance of the overall lens through the absorption and reflection of light wave energy. The insertion of the non-metal material into the metal material reduces stress and increases the hardness of the metal sandwich film 3. The metal material and the non-metal material can also be other substances.

[0043] In one embodiment, the number of film stacks is from 10 to 50. Each film stack includes stacked high-refractive-index dielectric films and low-refractive-index dielectric films. The number of stacked layers of the high-refractive-index dielectric films and the low-refractive-index dielectric films is from 19 to 41. The high-refractive-index dielectric films are away from the metal sandwich film 3, and the low-refractive-index dielectric films are close to the metal sandwich film 3. The high-refractive-index dielectric films are titanium pentoxide, niobium dioxide, tantalum pentoxide, or zirconium dioxide, and the low-refractive-index dielectric films are silicon dioxide.

[0044] Specifically, the structure of the film stack is 1.035(HL)^101.285(HL)^10. The low-refractive-index dielectric films and the high-refractive-index dielectric films are stacked in sequence. Both the lowermost layer and the uppermost layer are low-refractive-index dielectric films. The high-refractive-index dielectric films can also be other substances, and the low-refractive-index dielectric films can also be other substances, without specific limitations. The number of the nano dielectric stacked films 4 and the number of the film stacks can be selected according to the optical reflectivity and transmittance spectrum requirements of the lens, so as to meet different requirements for reflectivity and absorbance. The more the number, the higher the absorbance, the higher the reflectivity, and the wider the spectral range.

[0045] In one embodiment, the lens anti-oil, anti-fouling, and anti-fingerprint film lens 5 is a fluorine compound.

[0046] Specifically, the oil-proof, stain-proof, and fingerprint-proof film 5 has good acid and alkali resistance and can pass the strict high and low temperature and salt spray tests in industries such as mobile phones and automobiles. The oil-proof, stain-proof, and fingerprint-proof film 5 can avoid oil stains and fingerprint marks during the installation process and can increase the wear resistance and acid, alkali, and salt spray resistance of the lens. The oil-proof, stain-proof, and fingerprint-proof film 5 can be deposited by the method of vacuum resistance evaporation or prepared by the method of electron beam evaporation vacuum coating. The deposited hydrophobic film is required to have a water contact angle greater than 110°, and the water contact angle is above 100° after 3000 times of friction with steel wool.

[0047] In one embodiment, the glass substrate is double-sided polished optical glass, and the PV value of the optical glass is -1.0um to -0.5um.

[0048] Specifically, the glass substrate is K9 optical glass or BK7 optical glass.

[0049] In one embodiment, as Figure 2 , it is the spectral curve diagram of the total number of film layers being 43 layers. The total thickness of the film layer is 3.5um. The abscissa is in the range of wavelength 850nm - 1000nm, and the ordinate is the reflectivity. The two curves in the figure represent the incident angles of 10 degrees and 80 degrees respectively.

[0050] In one embodiment, as Figure 3 , it is the spectral curve diagram of the total number of designed film layers being 21 layers. The total thickness of the film layer is 2.6um. The abscissa is the wavelength, in the range of 850nm - 1000nm, and the ordinate is the reflectivity. The two curves in the figure represent the incident angles of 10 degrees and 80 degrees respectively.

[0051] In one embodiment, as Figure 4 , it is the transmittance spectral curve diagram of the total number of designed film layers being 21 layers. The abscissa is in the range of wavelength 850nm - 1000nm, and the ordinate is the transmittance. The two curves in the figure represent the incident angles of 10 degrees and 80 degrees respectively.

[0052] In one embodiment, as Figure 5 , it is the spectral curve of the lens coated with the film layer, the reflectivity spectral curve in the wavelength range of 850nm - 1000nm. The two curves in the figure represent the incident angles of 10 degrees and 80 degrees respectively. The test instrument is a PE950 type spectrophotometer. The absorbance OD is 5, and the test instrument is a Carry6000 spectrophotometer.

[0053] In one embodiment, as Figure 6, which is the change value of the PV of the lens surface shape with a film layer before and after the test. The change value is between -0.095 and 0.221 microns. The lens can control the PV value between -0.4um and 0.6um. After a 1-hour rapid weathering aging test in a 100-degree water bath, the appearance of the lens remains unchanged after the water bath, there are no color spots, and the spectral curve remains basically unchanged.

[0054] By coating a film layer on the lens, and the film layer includes a filter layer, a metal sandwich film, a nano-dielectric multilayer film, and an oil-proof, stain-resistant, and fingerprint-proof film, the reflectivity between 10 degrees and 80 degrees of incidence in the near-infrared band of 870nm - 950nm is greater than 95%, and in the entire spectral range from visible light to near-infrared of 380nm - 1000nm, the absorbance OD is greater than 5. It has the advantages of fewer film layers, smaller lens deformation, strong oil and stain resistance, and strong impact resistance, excellent weather resistance, being able to withstand harsh climate condition changes such as high and low temperature impacts, sunlight ultraviolet irradiation, high temperature and high humidity, long service life, and low production cost, and can be widely used in the mass production applications of automotive autonomous driving lidar.

[0055] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as the combination of these technical features does not conflict, it should be considered as within the scope described in this specification.

[0056] The above-described embodiments only express the embodiments of the present application that are described more specifically and in detail, but should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A high-reflection lens for laser radar, characterized by: The lens (1) is coated with a film layer, which comprises a filter layer (2), a metal sandwich film (3), at least one nano-medium laminated film (4), and an oil-proof, stain-resistant, and fingerprint-resistant film (5) arranged in sequence, wherein: The thickness of the lens (1) is 1 mm to 3 mm; The thickness of the film layer is 2.5um to 3.5um, and the number of layers is 20 to 45; The filter layer (2) is arranged on the side wall of the lens (1) and has a thickness of 10 nm to 50 nm; The metal sandwich membrane (3) is arranged on one side of the filter layer (2) and has a thickness of 60 nm; The nano-medium stacked film (4) is arranged on one side of the metal sandwich film (3) and includes at least one film stack; The oil-proof, stain-resistant and fingerprint-resistant film (5) is arranged on one side of the nano-medium laminated film (4) and has a thickness of 30 nm to 100 nm; The metal sandwich film (3) comprises a metal material and a non-metal material, wherein a single layer or a double layer of the non-metal material is inserted into the metal material, the metal material is gold, silver, aluminum, chromium, nickel or titanium, and the non-metal material is silicon dioxide; The number of the film stacks is 10 to 50 groups, each of the film stacks comprises a stacked high-refractive index dielectric film and a low-refractive index dielectric film, and the number of layers of the high-refractive index dielectric film and the low-refractive index dielectric film stack is 19 to 41 layers, the high-refractive index dielectric film is away from the metal sandwich film (3), the low-refractive index dielectric film is close to the metal sandwich film (3), the high-refractive index dielectric film is titanium pentoxide, niobium dioxide, tantalum pentoxide or zirconium dioxide, and the low-refractive index dielectric film is silicon dioxide; The structure of the membrane stack is 1.035(HL)^101.285(HL)^10.

2. The high-reflection lens for laser radar according to claim 1, characterized in that: The lens (1) is a glass substrate, a silicon wafer, an acrylic substrate, a PC plastic substrate or a stainless steel substrate.

3. The high-reflection lens for laser radar according to claim 1, characterized in that: The filter layer (2) is made of aluminum oxide, silicon monoxide, silicon dioxide or titanium pentoxide.

4. The high-reflection lens for laser radar according to claim 1, characterized in that: The oil-proof, stain-resistant and fingerprint-resistant film (5) is a fluorine-based compound.

5. The high-reflection lens for laser radar according to claim 2, characterized in that: The glass substrate is double-sided polished optical glass, and the PV value of the optical glass is -1.0um to -0.5um.

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