Narrowband optical filter applied to vehicle-mounted LiDAR

Abstract

The invention discloses a narrowband optical filter applied to a vehicle-mounted LiDAR, the narrowband optical filter comprises a substrate and a nano-medium lamination layer, the substrate is a right-angle prism and is used for turning light rays emitted by the vehicle-mounted LiDAR to a detected target and returning the light rays to the vehicle-mounted LiDAR through the nano-medium lamination layer to complete detection, the nano-medium lamination layer is located on the right-angle surface of the right-angle prism, and the nano-medium lamination layer is located on the right-angle surface of the right-angle prism. Comprising a plurality of first film layers and a plurality of second film layers which are stacked in sequence, the outermost layers of the nano-medium stacked layers are the first film layers, the first film layers are made of low-refractive-index materials, the second film layers are made of high-refractive-index materials, and the refractive index of the second film layers is larger than that of the first film layers; and the nanometer medium lamination layer adopts a film stack structure of (aLbH) m (xLyH) n L. The device has the characteristics of broadband cut-off, high transmittance and the like, has the advantages of small number of film layers, simple preparation and the like, can be directly combined with prism deposition, reduces the process cost, and is suitable for batch production.

Description

Technical Field

[0001] The invention belongs to the technical field of optical elements, and in particular relates to a narrow-band filter applied to a vehicle-mounted LiDAR. Background Art

[0002] With the technological innovation of assisted driving and autonomous driving in the automotive field, the application of optical films has become increasingly widespread. With the expansion of application scenarios, the optical quality also needs to be improved to improve the energy loss of the optical system, improve the imaging quality and clarity, such as the high-reflection film and dichroic mirror of the Head-up-Display; the narrow-band filter used for LiDAR (Light Detection and Ranging). LiDAR uses the echo time (Time of Fight) measurement method used by bats to detect objects through infrared light beam emission, reflection and reception. The wavelengths used are mainly 905nm, 940nm and 1550nm. Among them, 905nm mainly shows strong scattering and absorption capabilities in the atmosphere, 940nm has high tissue penetration and excellent blood vessel visualization, and 1550nm can work at a higher luminous power while ensuring the safety of human eyes, which can achieve a longer detection distance.

[0003] Since the narrowband filter used in LiDAR needs to collect as many signals as possible with a high signal-to-noise ratio under a wide viewing angle, the common requirement for this narrowband filter is that the offset of the center wavelength and the transmission band needs to be as small as possible under large-angle incidence conditions. Common optical film structures require more than 80 layers in the design of narrowband filters for LiDAR with wide-band cutoff, and the film thickness is as high as 8-10 microns, or even thicker, which is not conducive to mass production, has a long processing time, and is not conducive to changing the light propagation path when integrated into the vehicle system to achieve overall miniaturization. At the same time, the offset of large-angle incidence is usually greater than 15nm, which will also reduce the recognition accuracy of LiDAR. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned problems and propose a narrow-band filter for use in vehicle-mounted LiDAR, which has the characteristics of wide-band cutoff and high transmittance, as well as the advantages of few film layers and simple preparation. It can be directly combined with prism deposition, reduce process costs, and is suitable for mass production.

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

[0006] The invention proposes a narrow-band filter for vehicle-mounted LiDAR, comprising a substrate and a nano-medium stack, wherein the substrate is a right-angle prism and is used to redirect the light incident on the vehicle-mounted LiDAR to the target to be detected and return to the vehicle-mounted LiDAR through the nano-medium stack to complete detection, wherein:

[0007] The nano-medium stack is located on the right-angle surface of the right-angle prism, and includes a plurality of first film layers and a plurality of second film layers stacked in sequence, wherein the outermost layer of the nano-medium stack is the first film layer, and the first film layer is a low-refractive index material, and the second film layer is a high-refractive index material, and the refractive index of the second film layer is greater than that of the first film layer;

[0008] And the nano dielectric stack 2 adopts (aL bH) ^m (xL yH) ^n L's film stack structure, L means it is in the first film layer and the thickness unit is λ0 / 4, H means it is in the second film layer and the thickness unit is λ0 / 4, λ0 is the central wavelength of the corresponding film layer, a and x are the bandwidth matching coefficients of the first film layer, b and y are the bandwidth matching coefficients of the second film layer, and the value ranges of a, x, b and y are all 0 to 2, m and n respectively represent the number of cycles, and the value ranges of m and n are all 0 to 15.

[0009] Preferably, the first film layer has a thickness of 10 nm to 300 nm, and a refractive index of 1.4 to 2.0; the second film layer has a thickness of 10 nm to 200 nm, and a refractive index greater than 2.0.

[0010] Preferably, the thickness of the outermost first film layer on the nano-medium stack away from the right-angle prism is 20nm-150nm, and the thickness of the outermost first film layer close to the right-angle prism is 20nm-100nm.

[0011] Preferably, the total number of layers of the first film layer and the second film layer stacked in sequence is 19 to 43 layers.

[0012] Preferably, the narrow-band filter used for vehicle-mounted LiDAR allows wavelengths with a central wavelength of 905±40nm or 1550±10nm and a half-peak width ≤40nm to pass within the band range of 350nm to 1600nm, and cuts off all other bands.

[0013] Preferably, the first film layer is a silicon dioxide layer, and the second film layer is one of a silicon layer, a silicon hydrogenation layer, a tantalum pentoxide layer, a zirconium dioxide layer, a hafnium dioxide layer, a titanium pentoxide layer, and a niobium pentoxide layer.

[0014] Preferably, the substrate is one of a K9 optical glass substrate, a BK7 optical glass substrate, a PMMA substrate, and a PC plastic substrate.

[0015] Preferably, the right-angle prism is a beam splitter prism, which is formed by gluing the inclined surfaces of two right-angle triangular prisms, and a beam splitter film for transmitting visible light and reflecting infrared light is provided between adjacent surfaces of the two right-angle triangular prisms.

[0016] Preferably, the nano-medium stack is deposited on the right-angle surface of the right-angle prism by vacuum coating, and the vacuum coating method is one of ion beam sputtering vacuum coating, magnetron sputtering vacuum coating and ion-assisted deposition electron beam evaporation vacuum coating.

[0017] Preferably, the preparation temperature of the nano-medium stack is 100°C to 170°C.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The narrow-band filter applied to the vehicle-mounted LiDAR of the present invention comprises a right-angle prism and a nano-medium stack, wherein (aL bH) ^m (xLyH) ^n The optimized design is based on the L film stack structure, and the bandwidth is adjusted by parameter matching. It can achieve a cut-off band from visible light to near-infrared range under the incident angle of 0° and 18°, with a cut-off band transmittance of less than 0.1%, a passband average transmittance of more than 92%, and a center wavelength offset of less than 7nm. In addition, the nano-medium stack has excellent weather resistance and can withstand high and low temperature impact, sunlight ultraviolet radiation, high temperature and high humidity and other adverse climatic conditions. After boiling in water at 100°C for 2 hours, its spectroscopic optical properties have no obvious changes. It can be prepared by physical vapor deposition principle, with visible light to near-infrared band 350-1200nm (center wavelength range 905±40nm) or 350-1600nm (center wavelength range 1550±40nm) cut-off bandwidth, high transmittance and other advantages, which can effectively reduce the film layer and thickness to achieve optical characteristics, reduce manufacturing costs and time, and combine with right-angle prisms to be widely used in large-scale mass production of narrow-band filters for miniaturized LiDAR. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a narrow-band filter applied to a vehicle-mounted LiDAR according to the present invention;

[0021] Figure 2 Spectral curve diagram of transmittance (at an incident angle of 0 degree) of Example 1 of the present invention between wavelengths of 350 nm and 1200 nm;

[0022] Figure 3 Spectral curve diagram of transmittance (at an incident angle of 18 degrees) of Example 1 of the present invention between wavelengths of 350nm-1200nm;

[0023] Figure 4 This is a measured spectrum curve diagram of the transmittance of Example 1 of the present invention at wavelengths between 350nm and 1200nm (at incident angles of 0 degrees and 18 degrees).

[0024] Figure 5Spectral curve diagram of transmittance (at an incident angle of 0 degree) of Example 2 of the present invention between wavelengths of 350nm-1200nm;

[0025] Figure 6 Spectral curve diagram of transmittance (at an incident angle of 18 degrees) of Example 2 of the present invention between wavelengths of 350nm-1200nm;

[0026] Figure 7 Spectral curve diagram of transmittance (at an incident angle of 0 degree) of Example 3 of the present invention between wavelengths of 350nm-1600nm;

[0027] Figure 8 This is a spectral curve diagram of the transmittance (at an incident angle of 18 degrees) of Example 3 of the present invention between wavelengths of 350nm-1600nm.

[0028] Explanation of the reference numerals: 1. substrate; 2. nano-medium stack. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of this application. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] like Figure 1-Figure 8 As shown, a narrow-band filter for vehicle-mounted LiDAR includes a substrate 1 and a nano-medium stack 2, wherein the substrate 1 is a right-angle prism and is used to redirect the light incident on the vehicle-mounted LiDAR to the target to be detected so as to pass through the nano-medium stack 2 and return to the vehicle-mounted LiDAR to complete detection, wherein:

[0032] The nano-medium stack 2 is located on the right-angle surface of the right-angle prism, and includes a plurality of first film layers and a plurality of second film layers stacked in sequence, wherein the outermost layers of the nano-medium stack 2 are all first film layers, and the first film layers are made of low-refractive index materials, and the second film layers are made of high-refractive index materials, and the refractive index of the second film layers is greater than that of the first film layers;

[0033] And the nano dielectric stack 2 adopts (aL bH) ^m (xL yH) ^nL's film stack structure, L means it is in the first film layer and the thickness unit is λ0 / 4, H means it is in the second film layer and the thickness unit is λ0 / 4, λ0 is the central wavelength of the corresponding film layer, a and x are the bandwidth matching coefficients of the first film layer, b and y are the bandwidth matching coefficients of the second film layer, and the value ranges of a, x, b and y are all 0 to 2, m and n respectively represent the number of cycles, and the value ranges of m and n are all 0 to 15.

[0034] like Figure 1 As shown, the narrow-band filter applied to the vehicle-mounted LiDAR includes a right-angle prism 1 and a nano-medium stack 2. The nano-medium stack 2 is deposited on the right-angle surface of the right-angle prism, including a plurality of first film layers and a plurality of second film layers, and the first film layers and the second film layers are stacked in sequence. The outermost layer of the nano-medium stack 2 is the first film layer, and the first film layer is a low refractive index material, which can effectively improve the film stripping phenomenon and double 85 environmental testing.

[0035] Among them, the nano-medium stack 2 is deposited on the right-angle surface of the substrate 1. The nano-medium stack 2 can select different numbers of film layers according to the optical reflectivity and transmittance spectrum requirements, so as to achieve different reflectivity and transmittance requirements. The more the number, the higher the transmittance, the wider the spectral range, and the greater the cut-off depth.

[0036] Under the conditions of incident angles of 0° and 18°, the cutoff band is from visible light to near infrared, the cutoff band transmittance is less than 0.1%, the passband average transmittance can reach more than 92%, and the center wavelength offset is less than 7nm. The nano-medium stack has excellent weather resistance and can withstand high and low temperature impact, sunlight ultraviolet radiation, high temperature and high humidity and other adverse climatic conditions. After boiling in water at 100°C for 2 hours, its spectroscopic optical properties have no obvious changes. It can be prepared by physical vapor deposition principle, with the advantages of 350-1200nm or 350-1600nm cutoff bandwidth from visible light to near infrared band, high transmittance, etc. It can effectively reduce the film layer and thickness to achieve optical characteristics, reduce manufacturing costs and time, and is widely used in combination with right-angle prisms to realize large-scale mass production of narrow-band filters for miniaturized LiDAR.

[0037] The narrow-band filter applied to the vehicle-mounted LiDAR of the present invention comprises a right-angle prism and a nano-medium stack, wherein (aL bH) ^m (xLyH) ^nThe optimized design is based on the L-film stack structure, and the bandwidth is adjusted through parameter matching (where a, x, b, y can be decimals or integers, m and n are integers, and the matching of a, b, x, y, m and n can jointly achieve the adjustment of the bandwidth). It can achieve a cutoff band from visible light to near-infrared range under incident angles of 0° and 18°, with a cutoff band transmittance less than 0.1%, a passband average transmittance of more than 92%, and a center wavelength offset of less than 7nm. Moreover, the nano-medium stack has excellent weather resistance and can withstand high and low temperature impact, sunlight ultraviolet radiation, high temperature and high humidity and other adverse climatic conditions. After being boiled in water at 100°C for 2 hours, its spectral optical properties showed no obvious change. It can be prepared by the principle of physical vapor deposition, and has the advantages of cut-off bandwidth of 350-1200nm (central wavelength range 905±40nm) or 350-1600nm (central wavelength range 1550±40nm) in the visible to near-infrared band, high transmittance, etc. It can effectively reduce the film layer and thickness to achieve optical properties, reduce manufacturing cost and time, and is widely used in combination with right-angle prisms to realize large-scale mass production of narrow-band filters for miniaturized LiDAR.

[0038] As the optical systems in the automotive industry are gradually becoming miniaturized, the narrow-band filter of the present application combined with the prism system can achieve optical deviation and polarization change of different wavelengths. More importantly, prisms with different functions are glued together to refract or reflect the light path, thereby achieving deflection of the light path to adapt to narrow or complex spaces. More complex optical systems can be realized, such as visible light transmission and infrared light reflection, thereby realizing the functions of narrow-band filter and infrared cut-off filter on a right-angle prism; the light beam can also be divided into two or more beams for multi-sensor light source sharing or synchronous imaging, achieving smaller and lighter components, which is particularly suitable for the needs of miniaturized and integrated optical equipment. If installed on a vehicle-mounted system, the laser beam emitted by the laser radar (LiDAR) on the vehicle-mounted system is incident on the target to be measured and then reflected by the target to be measured. The reflected light passes through the narrow-band filter applied to the vehicle-mounted LiDAR to eliminate or filter out stray light, ensuring that the chip or sensor receives high-precision optical signals, that is, through the steering effect of the right-angle prism, the splitting of visible light and infrared light is achieved, the visible light can enter the chip or sensor for imaging, and the infrared light passes through the nano-medium stack 2 and returns to the laser radar to complete detection.

[0039] In one embodiment, the first film layer has a thickness of 10 nm to 300 nm and a refractive index of 1.4 to 2.0, and the second film layer has a thickness of 10 nm to 200 nm and a refractive index greater than 2.0.

[0040] In one embodiment, the thickness of the outermost first film layer away from the right-angle prism on the nano-medium stack 2 is 20nm-150nm, and the thickness of the outermost first film layer close to the right-angle prism is 20nm-100nm. The outermost first film layer away from the right-angle prism is a protective film layer, which is helpful to avoid poor appearance, and the outermost first film layer close to the right-angle prism can effectively improve the film peeling phenomenon.

[0041] In one embodiment, the total number of layers of the first film layer and the second film layer stacked in sequence is 19 to 43 layers. If an adjacent first film layer and a second film layer form a group, the nano-medium stack 2 includes 9 to 21 groups of first film layers and second film layers, and an additional first film layer is provided to achieve that the outermost side is the first film layer. Preferably, the total number of layers of the first film layer and the second film layer stacked in sequence is 27 to 35 layers.

[0042] In one embodiment, a narrowband filter applied to an on-vehicle LiDAR allows wavelengths with a center wavelength of 905±40nm or 1550±10nm and a half-peak width ≤40nm to pass within the wavelength range of 350nm to 1600nm, and cuts off all other wavelengths.

[0043] In one embodiment, the first film layer is a silicon dioxide layer, and the second film layer is a silicon layer, a silicon hydride layer, a tantalum pentoxide layer, a zirconium dioxide layer, a hafnium dioxide layer, a titanium pentoxide layer, or a niobium pentoxide layer. The first film layer is a low refractive index material, and the second film layer is a high refractive index material. For example, a corresponding metal target material can be used. By magnetron sputtering, a corresponding metal film layer is first deposited on the surface of the substrate 1, and a plasma containing active oxygen, active hydrogen, or active nitrogen undergoes oxidation, hydrogenation, or nitridation reaction with the corresponding metal film layer to obtain the corresponding material. The flow rate is preferably limited to 10-300 sccm. Sputtering and reaction are carried out separately, and the target material is not easily contaminated by the reaction gas during the sputtering process, which effectively avoids the problem of target material poisoning.

[0044] In one embodiment, the substrate 1 is one of a K9 optical glass substrate, a BK7 optical glass substrate, a PMMA substrate, and a PC plastic substrate. The PMMA substrate is an acrylic substrate. It is easy to understand that the substrate 1 can be a glass substrate and a plastic substrate, and the specific materials of the glass substrate and the plastic substrate can also be adjusted according to actual needs, such as other materials commonly used by those skilled in the art.

[0045] In one embodiment, the right-angle prism is a beam splitter prism, which is formed by gluing the inclined surfaces of two right-angle triangular prisms together, and a beam splitter film for transmitting visible light and reflecting infrared light is provided between adjacent surfaces of the two right-angle triangular prisms.

[0046] In one embodiment, the nano-medium stack 2 is deposited on the right angle surface of the right angle prism by vacuum coating, the preparation temperature is 100°C to 170°C, and the vacuum coating method is one of ion beam sputtering vacuum coating, magnetron sputtering vacuum coating and ion assisted deposition electron beam evaporation vacuum coating. If the nano-medium stack 2 is integrated on the right angle prism by gluing, there will be size and gluing risks and cost increase; in addition, direct deposition on the surface of the right angle prism can reduce the process flow, reduce costs, and the film layer is reliable and stable.

[0047] In one embodiment, the preparation temperature of the nano-medium stack 2 is 100°C to 170°C. During the implementation process, the film forming temperature is recommended to be prepared by low temperature, preferably 100°C to 170°C, and the preparation time is 3h to 4h to reduce the stress of the film layer. If ion-assisted deposition electron beam evaporation vacuum coating is used, it is recommended to use a radio frequency ion source with high ion energy (such as voltage greater than 600V, current greater than 600mA).

[0048] For ease of understanding, a detailed description is given below through specific embodiments.

[0049] Embodiment 1:

[0050] In this embodiment, the preferred membrane stack structure is 0.75 (LH)^ 8 1.3(LH)^ 6 L, central wavelength 910nm, half peak width 16nm, the first film layer is silicon dioxide, the second film layer is silicon hydride, the vacuum coating method is magnetron sputtering vacuum coating, firstly, silicon is deposited on substrate 1 by magnetron silicon target sputtering, then silicon hydride is obtained by hydrogenation reaction of plasma containing active hydrogen with silicon, silicon dioxide is obtained by oxidation reaction of plasma containing active oxygen with silicon, substrate 1 is a right-angle prism, for example, when the right-angle prism is a right-angle triangular prism with two bevels glued together, it can be A right-angle prism is first deposited, and then the two right-angle prisms are glued together, and the nano-medium stack 2 is deposited on the right-angle surface of the right-angle prism. The number of stacked layers of the nano-medium stack 2 is 14 groups (first film layer + second film layer) plus an additional first film layer, that is, a total of 29 layers, so that the outermost layer of the nano-medium stack 2 is the first film layer. Table 1 is the specific film layer structure of the 29-layer nano-medium stack 2, the thickness of each layer is nm, and the film stack structure is 0.75 (LH)^ 8 1.3(LH)^ 6L is obtained by optimizing the simplex method or conjugate gradient method of the macleod software, wherein A is air (Air), S is the BK7 substrate material (substrate 1), the reference wavelength is 910nm, the refractive index is 1.52, H represents the second film layer, the refractive index is 3.03505, L represents the first film layer, the refractive index is 1.46323, the total thickness is about 3.3 microns, the deposition time is relatively short, and it is suitable for mass production.

[0051] Table 1

[0052] S L H L H L H L H L H L BK7 149.65 65.30 126.05 45.37 108.77 40.27 131.01 56.84 139.41 71.69 127.18 H L H L H L H L H L H L 85.68 125.44 161.55 254.33 158.38 146.39 84.09 159.04 83.38 158.12 80.38 137.78 H L H L H L A 149.50 98.53 130.97 125.07 80.08 30.00 Air

[0053] Figure 2 The transmittance spectral curve of the narrow-band filter applied to the vehicle-mounted LiDAR in this embodiment in the wavelength range of 350nm-1200nm is shown (at an incident angle of 0 degree), and the spectral requirements are: 350nm-885nm, 935-1100nm, Tave (average transmittance) ≤0.1%; 906nm-914nm, Tave ≥92%, half-peak width 16nm.

[0054] Figure 3 The transmittance spectral curve of the narrow-band filter used in the vehicle-mounted LiDAR in this embodiment in the wavelength range of 350nm-1200nm is shown (at an incident angle of 18 degrees). The spectral requirements are: 350nm-880nm, 930nm-1100nm, Tave (average transmittance) ≤0.1%; 899nm-907nm, Tave ≥92%, half-peak width 16nm.

[0055] Figure 4 The measured spectral curve of the narrow-band filter used in the vehicle-mounted LiDAR of this embodiment is shown, as well as the transmittance spectroscopic curve in the wavelength range of 350nm-1200nm (at incident angles of 0 and 18 degrees). The testing instrument is Agilent's Cary 6000i UV-VIS spectrometer.

[0056] Embodiment 2:

[0057] In this embodiment, the preferred membrane stack structure is 0.7 (LH)^ 8 1.35(LH)^ 10L, central wavelength 920nm, half peak width 40nm, the first film layer is silicon dioxide, the second film layer is silicon hydride, the vacuum coating method is magnetron sputtering vacuum coating, firstly, silicon is deposited on substrate 1 by magnetron silicon target sputtering, then silicon hydride is obtained by hydrogenation reaction of plasma containing active hydrogen with silicon, and silicon dioxide is obtained by oxidation reaction of plasma containing active oxygen with silicon, substrate 1 is a right-angle prism, for example, when the right-angle prism is a right-angle triangular prism with two bevels glued together, it can be One of the right-angle prisms is deposited first, and then the two right-angle prisms are glued together, and the nano-medium stack 2 is deposited on the right-angle surface of the right-angle prism. The number of stacks of the nano-medium stack 2 is 18 groups (first film layer + second film layer) plus an additional first film layer, that is, a total of 37 layers, so that the outermost layer of the nano-medium stack 2 is the first film layer. Table 2 is the specific film layer structure of the 37-layer nano-medium stack 2, the thickness of each layer is nm, and the film stack structure is 0.7 (LH)^ 8 1.35(LH)^ 10 L is obtained by optimizing the simplex method or conjugate gradient method of the macleod software, wherein A is air (Air), S is the BK7 substrate material (substrate 1), the reference wavelength is 910nm, the refractive index is 1.52, H represents the second film layer, the refractive index is 3.03505, LL represents the first film layer, the refractive index is 1.46323, the total thickness is about 3.3 microns, the deposition time is relatively short, and it is suitable for mass production.

[0058] Table 2

[0059] S L H L H L H L H L H L BK7 148.71 115.41 49.99 101.88 217.60 114.25 17.39 119.20 108.33 120.71 156.21 H L H L H L H L H L H L 117.50 164.91 69.51 122.36 168.55 120.72 81.69 127.95 106.15 138.97 70.63 96.46 H L H L H L H L H L H L 52.20 45.13 72.23 110.79 136.3 110.79 93.3 149.59 90.58 49.36 188.6 126.81 H L A 43.05 99.60 Air

[0060] Figure 5 The transmittance spectral curve of the narrow-band filter applied to the vehicle-mounted LiDAR in this embodiment within the wavelength range of 350nm-1200nm is shown (at an incident angle of 0 degree). The spectral requirements are: 350nm-875nm, 965nm-1200nm, Tave (average transmittance) ≤0.1%; 910nm-930nm, Tave ≥95%, half-peak width 40nm.

[0061] Figure 6 The transmittance spectral curve of the narrow-band filter applied to the vehicle-mounted LiDAR in this embodiment in the wavelength range of 350nm-1200nm is shown (incident angle 18 degrees), and the spectral requirements are: 350nm-865nm, 955-1100nm, Tave (average transmittance) ≤0.1%; 900-920nm, Tave ≥92%, half-peak width 40nm.

[0062] Embodiment 3:

[0063] In this embodiment, the preferred membrane stack structure is 1.45 (LH)^ 11 1.6(LH)^ 10 L, central wavelength 1550nm, half peak width 15nm, the first film layer is silicon dioxide, the second film layer is silicon hydride, the vacuum coating method is magnetron sputtering vacuum coating, firstly, silicon is deposited on substrate 1 by magnetron silicon target sputtering, then silicon is hydrogenated by plasma containing active hydrogen to obtain silicon hydride, and silicon is oxidized by plasma containing active oxygen to obtain silicon oxide, substrate 1 is a right-angle prism, such as when the right-angle prism is a right-angle triangular prism with two bevels glued together, it can be The deposition is first performed on one of the right-angle prisms, and then the two right-angle prisms are glued together, and the nano-medium stack 2 is deposited on the right-angle surface of the right-angle prism. The number of stacks of the nano-medium stack 2 is 21 groups (first film layer + second film layer) plus an additional first film layer, that is, a total of 43 layers, so that the outermost layer of the nano-medium stack 2 is the first film layer. Table 3 is the specific film layer structure of the 43-layer nano-medium stack 2, the thickness of each layer is in nm, and the film stack structure is 1.45 (LH)^ 11 1.6(LH)^ 10 L is obtained by optimizing the simplex method or conjugate gradient method of the macleod software, wherein A is air (Air), S is the BK7 substrate material (substrate 1), the reference wavelength is 910nm, the refractive index is 1.52, H represents the second film layer, the refractive index is 3.03505, L represents the first film layer, the refractive index is 1.46323, the total thickness is about 5.7 microns, the deposition time is relatively short, and it is suitable for mass production.

[0064] Table 3

[0065]

[0066]

[0067] Figure 7 The spectral curve of the narrow-band filter applied to the vehicle-mounted LiDAR in this embodiment is a transmittance spectroscopic curve in the wavelength range of 350nm-1600nm (incident angle 0 degree), and the spectroscopic requirements are: 350-1510nm, 1580-1600nm, Tave (average transmittance) ≤0.1%; 1545-1555nm, Tave ≥95%, half-peak width 15nm.

[0068] Figure 8The spectral curve of the narrow-band filter used for vehicle-mounted LiDAR in this embodiment is shown as a transmittance spectroscopic curve in the wavelength range of 350nm-1600nm (incident angle 18 degrees), and the spectroscopic requirements are: 350-1505nm, 1575-1600nm, Tave (average transmittance) ≤0.1%; 1540-1550nm, Tave ≥95%, half-peak width 15nm.

[0069] The narrow-band filter used for LiDAR prepared by the present invention can control the central wavelength deviation to be less than 7nm under large-angle incidence. In a rapid weathering test in a 100°C water bath for 2 hours, the appearance of the lens does not change after the water bath, there is no color spot, and the spectral curve remains basically unchanged.

[0070] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The above-described embodiments only express the more specific and detailed embodiments described in this application, but they cannot be understood as limiting the scope of the application. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of this application, which all belong to the protection scope of this application. Therefore, the protection scope of this application shall be based on the attached claims.

Claims

1. A narrow-band filter for vehicle-mounted LiDAR, characterized in that: The narrow-band filter applied to the vehicle-mounted LiDAR comprises a substrate (1) and a nano-medium stack (2), wherein the substrate (1) is a right-angle prism and is used to deflect the light incident on the vehicle-mounted LiDAR and returned to the target to be detected so as to pass through the nano-medium stack (2) and return to the vehicle-mounted LiDAR to complete detection, wherein: The nano-medium stack (2) is located on the right-angle surface of the right-angle prism, and comprises a plurality of first film layers and a plurality of second film layers stacked in sequence, the outermost layers of the nano-medium stack (2) are all the first film layers, the first film layers are made of low-refractive index materials, the second film layers are made of high-refractive index materials, and the refractive index of the second film layers is greater than that of the first film layers; The nano-medium stack (2) adopts (aLbH) ^m (xLyH) ^n L's film stack structure, L represents the first film layer and the thickness unit is λ0 / 4, H represents the second film layer and the thickness unit is λ0 / 4, λ0 is the central wavelength of the corresponding film layer, a and x are the bandwidth matching coefficients of the first film layer, b and y are the bandwidth matching coefficients of the second film layer, and the value ranges of a, x, b and y are all 0 to 2, m and n respectively represent the number of cycles, and the value ranges of m and n are all 0 to 15.

2. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The thickness of the first film layer is 10 nm to 300 nm, and the refractive index is 1.4 to 2.0; the thickness of the second film layer is 10 nm to 200 nm, and the refractive index is greater than 2.

0.

3. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The thickness of the outermost first film layer on the nano-medium stack (2) far from the right-angle prism is 20nm-150nm, and the thickness of the outermost first film layer close to the right-angle prism is 20nm-100nm.

4. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The total number of layers of the first film layer and the second film layer stacked in sequence is 19 to 43 layers.

5. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The narrow-band filter applied to the vehicle-mounted LiDAR allows wavelengths with a central wavelength of 905±40nm or 1550±40nm and a half-peak width of ≤40nm to pass within the wavelength band of 350nm to 1600nm, and cuts off all other wavelength bands.

6. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The first film layer is a silicon dioxide layer, and the second film layer is one of a silicon layer, a silicon hydride layer, a tantalum pentoxide layer, a zirconium dioxide layer, a hafnium dioxide layer, a titanium pentoxide layer, and a niobium pentoxide layer.

7. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The substrate (1) is one of a K9 optical glass substrate, a BK7 optical glass substrate, a PMMA substrate, and a PC plastic substrate.

8. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The right-angle prism is a beam splitter prism, which is formed by gluing the inclined surfaces of two right-angle triangular prisms, and a beam splitter film for transmitting visible light and reflecting infrared light is provided between adjacent surfaces of the two right-angle triangular prisms.

9. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The nano-medium stack (2) is deposited on the right-angle surface of the right-angle prism by vacuum coating, and the vacuum coating method is one of ion beam sputtering vacuum coating, magnetron sputtering vacuum coating and ion-assisted deposition electron beam evaporation vacuum coating.

10. The narrow-band filter for vehicle-mounted LiDAR according to claim 1, characterized in that: The preparation temperature of the nano-medium stack (2) is 100°C to 170°C.

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