Narrowband optical filter applied to vehicle-mounted LiDAR

Abstract

The utility model discloses a narrowband optical filter applied to a vehicle-mounted LiDAR, comprising a substrate and a nanometer medium lamination layer, the substrate is a right-angle prism and is used for turning the returned light emitted by the vehicle-mounted LiDAR to a detected target so as to pass through the nanometer medium lamination layer and return to the vehicle-mounted LiDAR to complete detection, the nanometer medium lamination layer is located on the right-angle surface of the right-angle prism, and the nanometer 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. 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, and is low in process cost and suitable for batch production.

Description

Technical Field

[0001] This utility model belongs to the field of optical element technology, specifically relating to a narrowband filter for use in automotive LiDAR. Background Technology

[0002] With the technological innovation of assisted driving and autonomous driving in the automotive field, the application of optical thin films is becoming increasingly widespread. As application scenarios expand, optical quality also needs to be improved to reduce energy loss in optical systems and enhance image quality and clarity. Examples include high-reflectivity films and dichroic mirrors for head-up displays; and narrowband filters for LiDAR (Light Detection and Range). LiDAR utilizes the time-of-fight measurement method used in bat ranging to detect objects through the emission, reflection, and reception of infrared beams. The wavelengths used are mainly 905nm, 940nm, and 1550nm. 905nm exhibits strong scattering and absorption capabilities in the atmosphere, 940nm has high tissue penetration and excellent blood vessel visualization, and 1550nm can operate at higher luminous power while ensuring eye safety, enabling longer detection distances.

[0003] Because narrowband filters used in LiDAR need to collect as much signal as possible and have a high signal-to-noise ratio over a wide viewing angle, a common requirement for these narrowband filters is that the offset between the center wavelength and the transmission band should be as small as possible under large-angle incident conditions. Common optical film structures for designing wide-band cutoff narrowband filters for LiDAR require more than 80 layers, with film thicknesses as high as 8-10 micrometers or even thicker. This is not conducive to mass production, has a long processing time, and is also not conducive to changing the light propagation path to achieve overall miniaturization when integrating into automotive systems. Furthermore, the offset at large-angle incident angles, typically greater than 15nm, can also lead to a decrease in LiDAR recognition accuracy. Utility Model Content

[0004] The purpose of this invention is to address the above-mentioned problems by proposing a narrowband filter for automotive LiDAR, which features wide band cutoff, high transmittance, and advantages such as fewer film layers and simple fabrication. It can be directly combined with prism deposition, reducing process costs and is suitable for mass production.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] This invention proposes a narrowband filter for automotive LiDAR, comprising a substrate and a nano-dielectric stack. The substrate is a right-angle prism used to deflect the light rays incident on the target from the automotive LiDAR, allowing them to pass through the nano-dielectric stack and return to the automotive LiDAR for detection.

[0007] The nanomaterial stack is located on the right-angled face of a right-angled prism and includes several first films and several second films stacked in sequence. The outermost layer of the nanomaterial stack is always the first film, which is a low-refractive-index material, while the second film is a high-refractive-index material with a higher refractive index than the first film.

[0008] Preferably, the nanomaterial stack 2 adopts (aLbH) ^m (xLyH) ^n The membrane stack structure is L, where L represents the first membrane layer with a thickness of λ0 / 4, H represents the second membrane layer with a thickness of λ0 / 4, λ0 is the center wavelength of the corresponding membrane layer, a and x are the bandwidth matching coefficients of the first membrane layer, b and y are the bandwidth matching coefficients of the second membrane layer, and the values ​​of a, x, b, and y are all in the range of 0 to 2. m and n represent the number of cycles, and the values ​​of m and n are both in the range of 0 to 15.

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

[0010] Preferably, the thickness of the first film layer on the outermost layer of the nanomaterial stack, which is farthest from the right-angle prism, is 20 nm to 150 nm, and the thickness of the first film layer on the outermost layer, which is closest to the right-angle prism, is 20 nm to 100 nm.

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

[0012] Preferably, the narrowband filter used in vehicle-mounted LiDAR allows wavelengths with a center wavelength of 905±40nm or 1550±10nm and a half-width of ≤40nm to pass through in the 350nm to 1600nm band, while all other bands are blocked.

[0013] Preferably, 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.

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

[0015] Preferably, the right-angle prism is a beam splitter prism, which is composed of the inclined surfaces of two right-angle triangular prisms glued together, and a beam splitter film for visible light transmission and infrared light reflection is provided between the adjacent surfaces of the two right-angle triangular prisms.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] This invention relates to a narrowband filter for automotive LiDAR, comprising a right-angle prism and a nano-dielectric stack, in (aLbH) ^m (xLyH) ^n Based on the L-film stack structure, an optimized design was implemented. By adjusting the bandwidth through parameter matching, a cutoff band of less than 0.1% and an average passband transmittance of over 92% with a center wavelength shift of less than 7 nm were achieved, both at incident angles of 0° and 18°, extending from the visible to near-infrared range. Furthermore, this nanomaterial stack exhibits excellent weather resistance, withstanding harsh climatic conditions such as high and low temperature shocks, ultraviolet radiation from sunlight, and high temperature and humidity. Its spectroscopic optical properties showed no significant change after being boiled in water at 100°C for 2 hours. It can be prepared using physical vapor deposition and possesses advantages such as a cutoff bandwidth of 350-1200nm (center wavelength range 905±40nm) or 350-1600nm (center wavelength range 1550±40nm) in the visible to near-infrared band, and high transmittance. This design effectively reduces the number of film layers and thickness to achieve the desired optical properties, lowering manufacturing costs and time. Combined with right-angle prisms, it can be widely used for the large-scale mass production of narrowband filters for miniaturized LiDAR. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the narrowband filter of this utility model applied to vehicle-mounted LiDAR;

[0019] Figure 2 This is a spectrophotometer of the transmittance (at an incident angle of 0 degrees) of Embodiment 1 of the present invention in the wavelength range of 350m-1200nm.

[0020] Figure 3 This is a spectrophotometer of the transmittance (at an incident angle of 18 degrees) of Embodiment 1 of this utility model in the wavelength range of 350nm-1200nm.

[0021] Figure 4 This is a measured spectral curve of the transmittance (at incident angles of 0 degrees and 18 degrees) of Embodiment 1 of this utility model in the wavelength range of 350nm-1200nm.

[0022] Figure 5 This is a spectrophotometer of the transmittance (at an incident angle of 0 degrees) in the wavelength range of 350nm-1200nm for Embodiment 2 of this utility model.

[0023] Figure 6 This is a spectrophotometer of the transmittance (at an incident angle of 18 degrees) between wavelengths of 350nm and 1200nm in Embodiment 2 of this utility model.

[0024] Figure 7 This is a spectroscopic curve of transmittance (at an incident angle of 0 degrees) in the wavelength range of 350nm-1600nm for Embodiment 3 of this utility model.

[0025] Figure 8 This is a spectrophotometer of the transmittance (at an incident angle of 18 degrees) of Embodiment 3 of this utility model in the wavelength range of 350nm-1600nm.

[0026] Figure labeling: 1. Substrate; 2. Nanomaterial stack. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application.

[0029] like Figures 1-8 As shown, a narrowband filter for automotive LiDAR includes a substrate 1 and a nano-dielectric stack 2. The substrate 1 is a right-angle prism used to deflect the light rays incident on the target from the automotive LiDAR, allowing them to pass through the nano-dielectric stack 2 and return to the automotive LiDAR for detection.

[0030] The nano-dielectric stack 2 is located on the right-angled face of the right-angled prism and includes several first film layers and several second film layers stacked in sequence. The outermost layer of the nano-dielectric stack 2 is always the first film layer, and the first film layer is a low refractive index material, while the second film layer is a high refractive index material. The refractive index of the second film layer is greater than that of the first film layer.

[0031] like Figure 1As shown, the narrowband filter for automotive LiDAR includes a right-angle prism 1 and a nano-dielectric stack 2. The nano-dielectric stack 2 is deposited on the right-angle face of the right-angle prism and includes several first films and several second films, with the first and second films stacked sequentially. The outermost layer of the nano-dielectric stack 2 is always the first film, which is a low-refractive-index material that can effectively improve the delamination phenomenon and the double 85 environment test.

[0032] Among them, the nano-medium stack 2 is deposited on the right-angled surface of the substrate 1. The number of nano-medium stack 2 can be selected according to the optical reflectance and transmittance spectral requirements, so as to achieve different reflectance and transmittance requirements. The more layers there are, the higher the transmittance, the wider the spectral range, and the greater the cutoff depth.

[0033] At incident angles of 0° and 18°, the cutoff band extends from the visible to near-infrared range, with a cutoff band transmittance of less than 0.1% and an average passband transmittance exceeding 92%, while the center wavelength shift is less than 7 nm. Furthermore, the nanomaterial stack exhibits excellent weather resistance, withstanding harsh climatic conditions such as high and low temperature shocks, ultraviolet radiation from sunlight, and high temperature and humidity. After being boiled in water at 100°C for 2 hours, its spectroscopic optical properties show no significant change. It can be prepared using physical vapor deposition (PVD) and possesses advantages such as a cutoff bandwidth of 350-1200 nm or 350-1600 nm in the visible to near-infrared band, and high transmittance. This effectively reduces the number of film layers and thickness to achieve the desired optical properties, lowering manufacturing costs and time. Combined with right-angle prisms, it can be widely used for the large-scale mass production of narrowband filters for miniaturized LiDAR.

[0034] Specifically, the nano-dielectric stack 2 can be deposited on the right-angled surface of a right-angled prism using vacuum deposition at a temperature of 100℃ to 170℃. The vacuum deposition method can be one of ion beam sputtering, magnetron sputtering, or ion-assisted deposition / electron beam evaporation. Integrating the nano-dielectric stack 2 on the right-angled prism via bonding presents challenges related to size and bonding risks, as well as increased costs. Direct deposition on the prism surface reduces the number of processes, lowers costs, and ensures a reliable and stable film. The preparation temperature for the nano-dielectric stack 2 is 100℃ to 170℃. A low-temperature preparation method is recommended, with 100℃ to 170℃ being preferred, and a preparation time of 3 to 4 hours to reduce film stress. If ion-assisted deposition / electron beam evaporation is used, a high-energy radio frequency ion source (e.g., voltage greater than 600V, current greater than 600mA) is recommended.

[0035] In one embodiment, the nanomaterial stack 2 employs (aLbH) ^m (xL yH) ^nThe membrane stack structure is L, where L represents the first membrane layer with a thickness of λ0 / 4, H represents the second membrane layer with a thickness of λ0 / 4, λ0 is the center wavelength of the corresponding membrane layer, a and x are the bandwidth matching coefficients of the first membrane layer, b and y are the bandwidth matching coefficients of the second membrane layer, and the values ​​of a, x, b, and y are all in the range of 0 to 2. m and n represent the number of cycles, and the values ​​of m and n are both in the range of 0 to 15.

[0036] This invention relates to a narrowband filter for automotive LiDAR, comprising a right-angle prism and a nano-dielectric stack, in (aLbH) ^m (xLyH) ^n Based on the L-film stack structure, an optimized design is carried out. The bandwidth is adjusted by matching parameters (where a, x, b, and y can be decimals or integers, and m and n are integers. The matching of a, b, x, y, m, and n together achieves the adjustment of the bandwidth). It can achieve a cutoff band ranging from visible light to near-infrared light with an average transmittance of less than 0.1% and an average transmittance of over 92% in the passband, and a center wavelength shift of less than 7 nm, under incident angles of 0° and 18°. Furthermore, this nanomaterial stack exhibits excellent weather resistance, capable of withstanding harsh climatic conditions such as high and low temperature shocks, sunlight ultraviolet radiation, and high temperature and humidity. After being boiled in water at 100℃ for 2 hours, its spectroscopic optical properties showed no significant change. It can be prepared using the physical vapor deposition principle and has advantages such as a cutoff bandwidth of 350-1200nm (center wavelength range 905±40nm) or 350-1600nm (center wavelength range 1550±40nm) in the visible to near-infrared band and high transmittance. It can effectively reduce the number of film layers and thickness to achieve optical properties, reduce manufacturing costs and time, and, combined with right-angle prisms, can be widely used to realize the large-scale mass production application of narrowband filters for miniaturized LiDAR.

[0037] As optical systems in the automotive industry become increasingly miniaturized, the narrowband filter combined with the prism system in this application can achieve optical deviation and polarization changes of different wavelengths. More importantly, prisms with different functions are cemented together to refract or reflect light, thereby deflecting the light path to adapt to narrow or complex spaces. This enables more complex optical systems, such as those that can achieve visible light transmission and infrared light reflection, thus realizing the functions of a narrowband filter and an infrared cutoff filter on a single right-angle prism. It can also split the light beam into two or more beams for multiple sensors to share a light source or for synchronous imaging, achieving smaller and lighter components, which is especially suitable for the needs of miniaturized and integrated optical devices. When installed on an automotive system, the laser beam emitted by the LiDAR in the vehicle system is incident on the target being measured, and then reflected by the target. The reflected light passes through the narrow-band filter applied to the automotive LiDAR to eliminate or filter out stray light, ensuring that the chip or sensor receives a high-precision optical signal. That is, through the deflection effect of the right-angle prism, visible light and infrared light are separated. Visible light can enter the chip or sensor for imaging, while infrared light passes through the nano-dielectric stack 2 and returns to the LiDAR to complete the detection.

[0038] In one embodiment, the thickness of the first film layer is 10 nm to 300 nm and the refractive index is 1.4 to 2.0, and the thickness of the second film layer is 10 nm to 200 nm and the refractive index is greater than 2.0.

[0039] In one embodiment, the thickness of the first film layer on the outermost layer of the nanomaterial stack 2, which is away from the right-angle prism, is 20 nm to 150 nm, and the thickness of the first film layer on the outermost layer of the nanomaterial stack 2, which is close to the right-angle prism, is 20 nm to 100 nm. The first film layer on the outermost layer, which is away from the right-angle prism, is a protective film layer and helps to avoid poor appearance, while the first film layer on the outermost layer, which is close to the right-angle prism, can effectively improve the phenomenon of film delamination.

[0040] In one embodiment, the total number of layers in which the first and second films are stacked sequentially is 19 to 43. If an adjacent first film and a second film are grouped together, the nanomaterial stack 2 includes 9 to 21 groups of first and second films, with an additional first film layer to ensure that the outermost layer is entirely composed of first films. Preferably, the total number of layers in which the first and second films are stacked sequentially is 27 to 35.

[0041] In one embodiment, the narrowband filter used in automotive LiDAR allows wavelengths with a center wavelength of 905±40nm or 1550±10nm and a half-width of ≤40nm to pass through in the 350nm to 1600nm band, while all other bands are blocked.

[0042] In one embodiment, 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. The first film layer is a low-refractive-index material, and the second film layer is a high-refractive-index material. For example, a suitable metal target can be used. The corresponding metal film layer is first deposited on the surface of the substrate 1 using magnetron sputtering. Then, a plasma containing active oxygen, active hydrogen, or active nitrogen reacts with the corresponding metal film layer to undergo oxidation, hydrogenation, or nitridation reactions to obtain the corresponding material. The flow rate is preferably limited to 10-300 sccm. Separating sputtering and reaction processes reduces the risk of target contamination by reaction gases during sputtering, effectively avoiding target poisoning.

[0043] In one embodiment, substrate 1 is one of K9 optical glass substrate, BK7 optical glass substrate, PMMA substrate, and PC plastic substrate. PMMA substrate is acrylic substrate. It is easy to understand that substrate 1 can be made of glass substrate and plastic substrate, and the specific materials of glass substrate and plastic substrate can be adjusted according to actual needs, such as other materials commonly used by those skilled in the art.

[0044] In one embodiment, the right-angle prism is a beam splitter prism, which is composed of the inclined surfaces of two right-angle triangular prisms glued together, and a beam splitter film for visible light transmission and infrared light reflection is provided between the adjacent surfaces of the two right-angle triangular prisms.

[0045] For ease of understanding, the following detailed description is provided through specific embodiments.

[0046] Example 1:

[0047] In this embodiment, the preferred membrane stack structure is 0.75 (LH)^ 8 1.3(LH)^ 6 L, center wavelength 910nm, full width at half maximum (FWHM) 16nm, first film layer is silicon dioxide, second film layer is silicon hydride, vacuum deposition method is magnetron sputtering vacuum deposition, firstly, silicon is deposited on substrate 1 by magnetron sputtering on silicon target, then silicon hydride is obtained by hydrogenation reaction of silicon with plasma containing active hydrogen, and silicon dioxide is obtained by oxidation reaction of silicon with plasma containing active oxygen. Substrate 1 is a right-angle prism. If the right-angle prism is a right-angle triangular prism with two inclined planes cemented together, it can be combined with its... First, a right-angled prism is deposited, and then two right-angled prisms are bonded together. The nano-dielectric stack 2 is deposited on the right-angled faces of the prisms. The number of nano-dielectric stack 2 layers is 14 groups (first film layer + second film layer) plus an additional first film layer, totaling 29 layers. This ensures that the outermost layer of the nano-dielectric stack 2 is always the first film layer. Table 1 shows the specific film structure of the 29-layer nano-dielectric stack 2, with each layer thickness in nm. A film stack structure of 0.75 (LH)^ is used. 8 1.3(LH)^ 6L is obtained through optimization using the simplex method or conjugate gradient method in the MatrixOd software. Here, A represents air, S represents BK7 substrate material (substrate 1), the reference wavelength is 910nm, and the refractive index is 1.52. H indicates that it is in the second film layer with a refractive index of 3.03505, and L indicates that it is in the first film layer with a refractive index of 1.46323. The total thickness is about 3.3 micrometers, the deposition time is relatively short, and it is suitable for mass production.

[0048] Table 1

[0049] 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

[0050] Figure 2 The transmittance spectrometry curves of the narrowband filter used in this embodiment for automotive LiDAR are shown in the wavelength range of 350nm-1200nm (at an incident angle of 0 degrees). The spectrometry requirements are: 350nm-885nm, 935-1100nm, Tave (average transmittance) ≤0.1%; 906nm-914nm, Tave ≥92%, and half-width at half-maximum 16nm.

[0051] Figure 3 The transmittance spectrometry curves of the narrowband filter used in this embodiment for automotive LiDAR are shown in the wavelength range of 350nm-1200nm (at an incident angle of 18 degrees). The spectrometry requirements are: 350nm-880nm, 930nm-1100nm, Tave (average transmittance) ≤0.1%; 899nm-907nm, Tave ≥92%, and half-width at half-maximum 16nm.

[0052] Figure 4 The measured spectral curves of the narrowband filter applied to automotive LiDAR in this embodiment are shown, with transmittance spectrophotometers in the wavelength range of 350nm-1200nm (at incident angles of 0° and 18°). The test instrument is an Agilent Cary 6000iUV-VIS spectrometer.

[0053] Example 2:

[0054] In this embodiment, the preferred membrane stack structure is 0.7(LH)^ 8 1.35(LH)^ 10L, center wavelength 920nm, half-width at half-maximum 40nm, the first film layer is silicon dioxide, the second film layer is silicon hydride, the vacuum deposition method is magnetron sputtering vacuum deposition, firstly, silicon is deposited on substrate 1 by magnetron sputtering on a silicon target, then silicon hydride is obtained by hydrogenation reaction of silicon with plasma containing active hydrogen, and silicon dioxide is obtained by oxidation reaction of silicon with plasma containing active oxygen. Substrate 1 is a right-angle prism. If the right-angle prism is a right-angle triangular prism with two inclined planes bonded together, it can be combined with... One right-angled prism is deposited first, and then the two right-angled prisms are bonded together. The nano-dielectric stack 2 is deposited on the right-angled faces of the right-angled prism. The number of layers in the nano-dielectric stack 2 is 18 groups (first film layer + second film layer) plus an additional first film layer, totaling 37 layers. This ensures that the outermost layer of the nano-dielectric stack 2 is always the first film layer. Table 2 shows the specific film structure of the 37-layer nano-dielectric stack 2, with each layer thickness in nm. A film stack structure of 0.7 (LH)^ is used. 8 1.35(LH)^ 10 L is obtained through optimization using the simplex method or conjugate gradient method in the MatrixOd software. Here, A represents air, S represents BK7 substrate material (substrate 1), the reference wavelength is 910nm, and the refractive index is 1.52. H indicates that it is in the second film layer with a refractive index of 3.03505, and LL indicates that it is in the first film layer with a refractive index of 1.46323. The total thickness is about 3.3 micrometers, the deposition time is relatively short, and it is suitable for mass production.

[0055] Table 2

[0056]

[0057]

[0058] Figure 5 The transmittance spectrometry curves of the narrowband filter used in this embodiment for automotive LiDAR are shown in the wavelength range of 350nm-1200nm (at an incident angle of 0 degrees). The spectrometry requirements are: 350nm-875nm, 965nm-1200nm, Tave (average transmittance) ≤0.1%; 910nm-930nm, Tave ≥95%, and half-width at half-maximum 40nm.

[0059] Figure 6 The transmittance spectrometry curves of the narrowband filter used in this embodiment for automotive LiDAR are shown in the wavelength range of 350nm-1200nm (incident angle 18 degrees). The spectrometry requirements are: 350nm-865nm, 955-1100nm, Tave (average transmittance) ≤0.1%; 900-920nm, Tave ≥92%, half-width at half-maximum 40nm.

[0060] Example 3:

[0061] In this embodiment, the preferred membrane stack structure is 1.45 (LH)^ 11 1.6(LH)^ 10 L, center wavelength 1550nm, half-width at half-maximum 15nm, the first film layer is silicon dioxide, the second film layer is silicon hydride, the vacuum deposition method is magnetron sputtering vacuum deposition, firstly, silicon is deposited on substrate 1 by magnetron sputtering on silicon target, then silicon hydride is obtained by hydrogenation reaction of silicon with plasma containing active hydrogen, and silicon oxide is obtained by oxidation reaction of silicon with plasma containing active oxygen. Substrate 1 is a right-angle prism. If the right-angle prism is a right-angle triangular prism with two inclined planes cemented together, it can be combined with its... First, a right-angled prism is deposited, and then two right-angled prisms are bonded together. The nano-dielectric stack 2 is deposited on the right-angled faces of the prisms. The number of nano-dielectric stack 2 layers is 21 groups (first film layer + second film layer) plus an additional first film layer, totaling 43 layers. This ensures that the outermost layer of the nano-dielectric stack 2 is always the first film layer. Table 3 shows the specific film structure of the 43-layer nano-dielectric stack 2, with each layer thickness in nm. A film stack structure of 1.45 (LH)^ is used. 11 1.6(LH)^ 10 L is obtained through optimization using the simplex method or conjugate gradient method in the MatrixOd software. Here, A represents air, S represents BK7 substrate material (substrate 1), the reference wavelength is 910nm, and the refractive index is 1.52. H indicates that it is in the second film layer with a refractive index of 3.03505, and L indicates that it is in the first film layer with a refractive index of 1.46323. The total thickness is about 5.7 micrometers, the deposition time is relatively short, and it is suitable for mass production.

[0062] Table 3

[0063]

[0064]

[0065] Figure 7 The spectral curves of the narrowband filter used in this embodiment for automotive LiDAR are shown, with transmittance spectrometry curves (incident angle 0 degrees) in the wavelength range of 350nm-1600nm. Spectrometry requirements: 350-1510nm, 1580-1600nm, Tave (average transmittance) ≤0.1%; 1545-1555nm, Tave ≥95%, half-width at half-maximum 15nm.

[0066] Figure 8The spectral curves of the narrowband filter used in this embodiment for automotive LiDAR are shown, with transmittance spectrometry curves in the wavelength range of 350nm-1600nm (incident angle 18 degrees). Spectrometry requirements: 350-1505nm, 1575-1600nm, Tave (average transmittance) ≤0.1%; 1540-1550nm, Tave ≥95%, half-width at half-maximum 15nm.

[0067] The narrowband filter prepared using this invention for use in LiDAR can control the center wavelength shift to less than 7nm under large-angle incident light. After a rapid weathering test at 100℃ for 2 hours, the appearance of the lens remains unchanged, with no color spots and the spectral curve remains basically unchanged.

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0069] The embodiments described above are merely specific and detailed examples of the embodiments described in this application, and should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A narrowband optical filter for use in a vehicular LiDAR, the narrowband optical filter comprising: The narrow-band filter applied to the vehicle-mounted LiDAR comprises a substrate (1) and a nanometer medium stack (2), the substrate (1) is a right-angle prism and is used for turning the light returned by the vehicle-mounted LiDAR to the measured target to return to the vehicle-mounted LiDAR through the nanometer medium stack (2) to complete detection, wherein: The nanometer medium stack (2) is located on the right-angle face of the right-angle prism and comprises a plurality of first film layers and a plurality of second film layers which are stacked in sequence, the outermost layer of the nanometer medium stack (2) is the first film layer, the first film layer is a low-refractive-index material, 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.

2. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The nanomedia stack (2) adopts (aLbH) ^m (xLyH) ^n The film stack structure of L, 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 center 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 0-2, m and n respectively represent the number of cycles, and the value ranges of m and n are both 0-15.

3. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The thickness of the first film layer is 10-300 nm, and the refractive index is 1.4-2.0; the thickness of the second film layer is 10-200 nm, and the refractive index is greater than 2.

0.

4. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The thickness of the first film layer far from the outermost layer of the right-angle prism is 20-150 nm, and the thickness of the first film layer close to the outermost layer of the right-angle prism is 20-100 nm.

5. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The total number of layers of the first film layer and the second film layer stacked in sequence is 19-43.

6. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The narrow-band filter applied to the vehicle-mounted LiDAR allows the wavelength with a center wavelength of 905±40 nm or 1550±40 nm and a half-peak width of ≤40 nm to pass in the wavelength range of 350-1600 nm, and all the other wavelength bands are cut off.

7. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The first film layer is a silicon dioxide layer, and the second film layer is one of a silicon layer, a hydrogenated silicon layer, a tantalum pentoxide layer, a zirconium dioxide layer, a hafnium dioxide layer, a titanium pentoxide layer, and a niobium pentoxide layer.

8. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The substrate (1) is one of a K9 optical glass substrate, a BK7 optical glass substrate, a PMMA substrate, and a PC plastic substrate.

9. The narrowband optical filter for vehicular LiDAR of claim 1, wherein: The right-angle prism is a light-splitting prism which is composed of the inclined faces of two right-angle prisms and is provided with a light-splitting film between the adjacent faces of the two right-angle prisms for transmitting visible light and reflecting infrared light.

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