Outer cover module of optical system

Abstract

The invention relates to an outer cover module of an optical system. The outer cover module comprises first glass, a heating unit and second glass, the heating unit is arranged on the outer side of the first glass. The second glass is arranged on the outer side of the heating unit. Wherein the difference between the penetration rate of a main wave band and the penetration rate of an auxiliary wave band of the outer cover module is less than 2%, and the wavelength of the auxiliary wave band is calculated according to the following formula: the wavelength of the main wave band + [deltaT + (Tfog-T0)] * alpha, wherein T0 is the initial temperature of the light source unit, Tfog is the dew point temperature, delta T is the demisting temperature difference, and alpha is the temperature drift coefficient of the light source unit. Therefore, under the condition that the wavelength of the light source drifts due to the temperature of the system, the outer cover module has high penetration rate in the auxiliary wave band, so that the light source can still perform sensing operation through the outer cover module during heating demisting.

Description

Technical Field

[0001] The invention relates to a lidar system, in particular to an outer cover module of the lidar system. Background Art

[0002] Lidar (Light Detection And Ranging, LIDAR) is a technology that can be used to measure the distance to a remote target. It has begun to be applied to port automation, traffic management systems, etc. Lidar usually includes a light source and a receiver. The light source can be a laser that emits light with a specific wavelength, for example, the infrared, visible light, or ultraviolet part of the electromagnetic spectrum. One of the mechanisms by which the lidar system calculates the distance of an object is that the light source emits light to the target, and then the target scatters / reflects the light. The scattered / reflected light is sensed by the receiver to calculate the distance between the object and the lidar system in the direct path of the light. For example, the system can calculate the distance between the lidar system and the target object based on the flight time of the light sensed by the lidar system's receiver.

[0003] At present, the international classification of self-driving cars is mainly based on the classification of the Society of Automotive Engineers (SAE International). Levels 1-3 are called Advanced Driver Assistance Systems (ADAS), while levels 4-5 are called Automated Driving (AD) systems. Lidar can provide detailed 3D images to identify cars, motorcycles, bicycles, pedestrians, and even the hand signals of traffic police. Therefore, lidar is an indispensable key system in the autonomous driving system.

[0004] The cover module (e.g., glass) of the lidar system must have high transmittance in a specific wavelength range to improve the signal-to-noise ratio. That is to say, the cover module shields the light of unnecessary wavelengths as much as possible, so that the receiver can directly sense the light of the preset wavelength without the need for additional signal separation processing. For example, the current lidar light source uses 905nm light, so the cover module will try to have high transmittance for 905nm light, while light other than this wavelength will be shielded by the cover module. Under the above signal operation requirements, the cover module will exclude certain glasses with high transmittance in a wide range of wavelengths. For example, patent case WO2023116886 proposes a glass with high transmittance (at least 91%) in 800-1580nm, or patent case CN113906318 proposes a glass with high transmittance (greater than 92%) in 920-1000nm. The above glasses cannot be used in lidar systems because the system will receive too much noise, making the lidar system operation complicated, thereby affecting the reliability of the autonomous driving system.

[0005] On the other hand, since the outer cover module serves as the channel for the emission / incidence of optical signals, a more comprehensive consideration must be given to the light of the lidar system, rather than just considering the single factor of the preset wavelength of the emitting light source. It is necessary to think more comprehensively about the specifications of the outer cover module. Summary of the invention

[0006] The main purpose of the present invention is to provide an outer cover module of a lidar system, and when heating and defogging are performed, a signal can pass through the outer cover module.

[0007] In order to achieve the above-mentioned purpose, the present invention provides an outer cover module of a lidar system, the lidar system includes a light source unit, the outer cover module includes a first glass, a heating unit and a second glass. The heating unit is arranged on the first glass. The second glass is arranged on the heating unit. The difference between the transmittance of a main band and the transmittance of a sub-band of the outer cover module is less than 2%, and the wavelength of the sub-band is calculated by the following formula: wavelength of the main band + [ΔT + (T fog -T 0 )]×α; where T 0 is the initial temperature of the light source unit, T fog is the dew point temperature, ΔT is the defog temperature difference, and α is the temperature drift coefficient of the light source unit.

[0008] In some embodiments, the penetration rate of the main band is greater than the penetration rate of the sub-band.

[0009] In some embodiments, the transmittance of the main band and the transmittance of the sub-band are both greater than 90%.

[0010] In some embodiments, the wavelength of the main band is 890-910 nm, and the wavelength of the sub-band is 910-930 nm; or, the wavelength of the main band is 1545-1550 nm, and the wavelength of the sub-band is 1565-1575 nm.

[0011] In order to achieve the aforementioned object, the present invention provides an outer cover module of a lidar system, comprising a first glass, a heating unit and a second glass. The heating unit is disposed on the first glass. The second glass is disposed on the heating unit. The difference between the transmittance of a main band and the transmittance of a sub-band of the outer cover module is less than 2%, the wavelength of the main band is 900-910 nm, and the wavelength of the sub-band is 920-930 nm.

[0012] In some embodiments, the penetration rate of the main band is greater than the penetration rate of the sub-band.

[0013] In some embodiments, the transmittance of the main band and the transmittance of the sub-band are both greater than 90%.

[0014] In order to achieve the aforementioned purpose, the present invention provides an outer cover module of a lidar system, comprising a first glass, a heating unit and a second glass. The heating unit is disposed on the first glass. The second glass is disposed on the heating unit. The difference between the transmittance of a main band and the transmittance of a sub-band of the outer cover module is less than 2%, the wavelength of the main band is 1545-1555 nm, and the wavelength of the sub-band is 1565-1575 nm.

[0015] In some embodiments, the penetration rate of the main band is greater than the penetration rate of the sub-band.

[0016] In some embodiments, the transmittance of the main band and the transmittance of the sub-band are both greater than 90%.

[0017] In some embodiments, the first glass is a filter.

[0018] The effectiveness of the present invention lies in that, in consideration of the wavelength drift of the light source caused by the system temperature, the present invention requires the optical properties of the outer cover module to have high transmittance in the sub-band outside the main working wavelength range, so as to meet the requirement that when the system has heating requirements, the light emitted by the light source or the light returned by the object can still pass through the outer cover module for sensing operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of a lidar system of the present invention;

[0020] Figure 2 Schematic diagram of the outer cover module of the present invention.

[0021] Description of Figure Numbers

[0022] 1: Cover module

[0023] 2: Shell

[0024] 10: Anti-reflective coating

[0025] 20: First Glass

[0026] 30: Optical adhesive layer

[0027] 40: Protective layer

[0028] 50: Circuit board

[0029] 60: first optical matching layer

[0030] 70: Heating unit

[0031] 80: second optical matching layer

[0032] 90: Second Glass

[0033] 100: Light shielding layer

[0034] 110: Bus

[0035] 200: Light source unit

[0036] 210: Target

[0037] 220: receiving unit

[0038] 230: Control unit

[0039] 240: Temperature control unit

[0040] 250: Temperature sensing unit DETAILED DESCRIPTION

[0041] The following is a more detailed description of the embodiments of the present invention with reference to the accompanying drawings and element symbols, so that those skilled in the art can implement the embodiments according to the embodiments after reading the specification.

[0042] Figure 1 is a schematic diagram of a lidar system according to an embodiment of the present invention. In this embodiment, the lidar system may include an outer cover module 1 and a housing 2, which form a housing space for arranging various components of the lidar system. The outer cover module 1 and the housing 2 are assembled in a suitable manner, including but not limited to snap-fitting, bonding, integral molding, etc. The lidar system according to this embodiment may include: a light source unit 200, a control unit 230, and a receiving unit 220. In one embodiment, the light source unit 200 may emit a near-infrared semiconductor laser unit with a pulsed laser having a target wavelength of 905nm, and the laser pulse is about 5 to 10ns; or a near-infrared semiconductor laser unit with a continuous wave laser having a target wavelength of 905nm. The receiving unit 220 receives the echo signal reflected by the target corresponding to the light source unit 200, such as a light sensor, and specifically, a photodiode (PD) or an avalanche photodiode (APD) may be used.

[0043] In one embodiment, 32 silicon-based semiconductor lasers and 32 photodiodes can be arranged into an array, and 32 sets of distance information can be received each time. The array can be rotated by a motor, measuring once every 0.1 degrees, and measuring 3600 times in a circle of 360 degrees. The rotation speed of the lidar system of this embodiment is 5 revolutions per second, so 32×3600×5=576,000 pieces of data can be obtained per second.

[0044] Please cooperate Figure 2 , Figure 2 Schematic diagram of the cover module 1 according to an embodiment of the present invention. Figure 2As shown, the outer cover module 1 may include a first glass 20, a heating unit 70 and a second glass 90. In this embodiment, the light source unit 200 may emit a pulsed laser with a target wavelength of 905 nm, and the outer cover module 1 preferably has a high transmittance to the light with a wavelength of 905 nm, for example, greater than 90%, greater than 91% or greater than 92%. Preferably, the outer cover module 1 has a low transmittance to the light with a visible wavelength such as 300-700 nm, for example, less than 5%, less than 1% or less than 0.1%.

[0045] LiDAR systems are more susceptible to adverse weather conditions, among which frost and fog are more serious factors. In an environment with frost and fog, the target signal will be greatly attenuated, and the object in front may not be detected. In addition, frost and fog may cause echo signals and cause false alarms. In view of this, the outer cover module 1 of the embodiment of the present invention has a heating unit 70, which can increase the temperature of the outer cover module 1 to be greater than the dew point temperature to remove frost generated on the outer cover module 1 or fog adhering to the outer cover module 1. In general, the dew point temperature refers to the temperature at which the gaseous water contained in the air reaches saturation and condenses into liquid water under a fixed air pressure, and the condensed water floating in the air can be called fog, and when it is attached to a solid surface, it is called dew; for the convenience of explanation, the fog, dew, frost, etc. referred to herein are only the names of different phases of water. No matter which name is used, it represents the water molecules attached to the outer cover module 1 of the embodiment of the present invention, and one of the functions of the heating unit 70 of the outer cover module 1 is to heat the system temperature to eliminate the so-called adhesion phenomenon.

[0046] The heating unit 70 of this embodiment is disposed between the first glass 20 and the second glass 90. Specifically, the first glass 20 of this embodiment is a filter glass (glass thickness of 3-4 mm, supplier: Gao Yi), which may contain a variety of oxides, such as SiO 2 , ZnO, K 2 O、TeO 2 、SO 3, 6A group compounds of cadmium / zinc, such as CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, etc. The first glass 20 has a low light transmittance in the visible region of the spectrum (such as a wavelength range of 400nm to 700nm), such as less than 5%, less than 2%, and has a high light transmittance in the near-infrared region of the spectrum (such as a wavelength range of 780nm to 1000nm), such as greater than 85%; the heating unit 70 is disposed on the transparent conductive film (such as ITO film) and printed silver paste line outside the first glass 20. The second glass 90 is glass (n=1.50~1.52, glass thickness of 0.7~1.1mm, supplier: Token), which is disposed on the outside of the heating unit 70. The second glass 90 has an outer surface facing the environment, and the aforementioned frost and fog may form on the outer surface. In another embodiment, the first glass 20 and the second glass 90 may each have an anti-reflection coating (AR coating) 10. Specifically, the anti-reflection coating 10 is a layer of a high refractive index layer (e.g., Nb with n=2.30-2.40). 2 O 5 ) and a low refractive index layer (such as SiO with n=1.48 to 1.52) 2 )Multilayer films stacked in an alternating manner.

[0047] As mentioned above, when the temperature of the lidar system of the embodiment of the present invention (especially the temperature of the outer cover module 1) is less than or equal to the dew point temperature, the air humidity near the surface of the outer cover module 1 is saturated or oversaturated, and fog / dew / frost will begin to form. In one embodiment, a temperature sensor (not shown) is provided on the outer cover module 1. When the temperature sensing unit 250 in the control unit 230 senses that the temperature of the outer cover module 1 is less than or equal to the dew point temperature through the temperature sensor, the temperature control unit 240 in the control unit 230 will drive the heating unit 70 to start heating the outer cover module 1 to avoid fog / dew / frost on the outer cover module 1. According to general theory, such as the "Handbook of Thermophysical Properties of Common Engineering Materials", the dew point temperature is related to the air moisture content. For example, when the air moisture content is about 85g / kg, the dew point temperature is about 55°C, and when the air moisture content is about 65g / kg, the dew point temperature is about 45°C. Furthermore, considering the efficiency of demisting, in one embodiment, the temperature of the heating unit 70 is set to be about 15-20° C. higher than the dew point temperature (i.e., the demisting temperature difference ΔT=15-20° C.), that is, in an environment with a dew point temperature of 55° C., the heating temperature of the heating unit 70 is set to be 70-75° C. In one embodiment, the demisting temperature difference ΔT can be 0-10° C., for example, 0° C., 2° C., 5° C., 7° C., 10° C., etc.

[0048] However, the light source unit 200 of the lidar system of the embodiment of the present invention is a temperature-sensitive component, such as Chinese patents such as CN115265816, that is, the wavelength of the light emitted by the light source unit 200 will drift due to temperature changes, which is also called the temperature drift effect (wavelength shift with temperature effect). In general theory, the temperature drift coefficient (wavelength shift with temperature coefficient) of the light source unit 200 is a relatively stable value, so in a warming environment, the emission wave of the light source unit 200 will move to a higher wavelength. In this embodiment, the preset light wavelength of the light source unit 200 is 905nm, but in the above-mentioned heating and defogging process, the light emission wavelength of the light source unit 200 moves to: 905+[ΔT+(T fog -T 0 )]×α(in nm); where T 0 is the initial temperature of the light source unit 200 (such as room temperature), T fog is the dew point temperature, ΔT is the defog temperature difference, and α is the temperature drift coefficient.

[0049] In one embodiment, the light source unit 200 is an edge emitting laser (EEL) semiconductor chip, and its temperature drift coefficient is about 0.2-0.3nm / ℃ or less. If the following situation is adopted (for example, not for limiting the present invention): the automatic driving system of the present invention is used in cold regions, the outdoor temperature in winter is about -10℃, the air humidity is about 85g / kg, and the defog temperature difference ΔT=20℃, the above temperature drift formula is inserted, and it can be calculated that the light wavelength of the light source unit 200 drifts to between 922 and 930nm. Therefore, due to the temperature drift effect, the outer cover module 1 needs to have a high transmittance for the wavelength of the main light source (i.e. 905nm), and a high transmittance for the wavelength of a sub-band range (i.e. drifting from 905nm to 922-930nm) so that the sub-band light caused by the temperature rise of defog can pass. On the other hand, although the cover module 1 has high transmittance in the sub-band range, under normal circumstances (i.e., without heating and defogger), the entire lidar system will not cause excessive noise interference due to the high transmittance in the sub-band range.

[0050] In summary, an embodiment of the present invention proposes an outer cover module 1 that can allow the main light source wavelength range and the sub-band wavelength range to pass through at the same time (but the main light source and the sub-band are lights emitted under different temperature conditions), wherein the difference between the transmittance of the main band and the transmittance of the sub-band is less than 2% or less than 1%, and the wavelength of the main band is 900-910nm (covering the predetermined main light source wavelength of 905nm), and the half-width control of the laser output by the light source unit 200 is considered here, and the calculation method can be 905nm±5%, so the wavelength range of the main light source output by the light source unit 200 is approximately 900-910nm, and the wavelength of the sub-band is 920-930nm. It is worth noting that, since the optical requirement of the outer cover module 1 is to have high transmittance in the main band wavelength (900-910nm, covering the main light source wavelength of 905nm), the embodiment of the present invention uses the transmittance of the main band as a benchmark, and additionally sets the difference between the transmittance of the sub-band and the aforementioned benchmark, hoping to achieve the control of the outer cover module 1 to have a high transmittance in the sub-band. In other words, the present invention considers the situation where the wavelength of the light source drifts due to the system temperature, and pre-controls the outer cover module 1 to have a high transmittance in the sub-band, so as to meet the requirement that the light source can still perform sensing operations through the outer cover module 1 during heating and defogging.

[0051] Preferably, the main band transmittance of the outer cover module 1 of the embodiment of the present invention will be greater than the transmittance of the sub-band. Preferably, the transmittance of the outer cover module 1 of the embodiment of the present invention in the main band wavelength (900-910nm, covering the main light source wavelength of 905nm) is greater than 91%, and the transmittance of the sub-band wavelength (920-930nm, covering the wavelength range after temperature drift) is greater than 90%, and the difference between the two is 1%. After simulation, in the general temperature environment and the defogging and heating environment, the lidar system of the embodiment of the present invention can meet the application of the aforementioned advanced automobile assisted driving system or automatic driving system.

[0052] like Figure 2 As shown, in a preferred embodiment, the outer cover module 1 further includes an anti-reflection coating 10, an optical adhesive layer 30, a protective layer 40, a circuit board 50, a first optical matching layer 60, a second optical matching layer 80 and two light shielding layers 100. The anti-reflection coating 10 is located at the innermost side of the outer cover module 1 and is composed of a high refractive index layer (e.g., Nb with n=2.35) 2 O 5 ) and a low refractive index layer (such as SiO with n=1.49) 2) are six layers of films stacked in an alternating manner. The first glass 20 is disposed on the anti-reflection coating 10. The optical adhesive layer 30 is disposed on the surface of the first glass 20, which is an optical clear adhesive (OCA, supplier: 3M). The protective layer 40 (Passivation) is disposed on the outer surface of the optical adhesive layer 30 to protect the first glass 20. The first optical matching layer 60 (index match layer) is disposed on the outer surface of the protective layer 40, which is SiNx (n=1.67) with a thickness of 500nm. The heating unit 70 is disposed on the outer surface of the first optical matching layer 60, which is an indium tin oxide (Indium Tin Oxide, ITO) thin film, and is electrically connected to the circuit board 50 through the busbar 110. The second optical matching layer 80 (second index match layer) is disposed on the outer surface of the heating unit 70, and is SiO 2 (n=1.49) and SiNx (n=2.02) with a thickness of 200nm. The light shielding layer 100 (Black Matrix, BM) is set on both sides of the outer cover module 1 to block the busbar 110 from being viewed by the user. This embodiment uses an edge-type laser semiconductor chip with a temperature drift coefficient of about 0.15nm / ℃ as the light source unit 200.

[0053] As described above, the first embodiment of the present invention is to use the first process condition to make a 50±10Ω ITO film as the heating unit 70. The lower limit of the operating temperature of the light source unit 200 (-40°C) is calculated (ie, the above formula T 0 The wavelength of the emitted light of the light source unit 200 after heating and defog is 921.5nm, that is, the sub-band wavelength is set to 920-930nm in this embodiment to cover the maximum temperature drift wavelength range. After optical measurement, the transmittance of the main band wavelength (900-910nm, covering the main light source wavelength of 905nm) is about 92.54%, while the transmittance of the sub-band wavelength (920-930nm, covering the wavelength range after temperature drift) is 91.69%, and the difference between the two is 0.85%.

[0054] The second embodiment of the present invention is the same as the first embodiment, except that the heating unit 70 is a 25±9Ω ITO film made under the second process condition as the heating unit 70. After optical measurement, the transmittance of the main band wavelength (900-910nm, covering the main light source wavelength of 905nm) is about 94.91%, and the transmittance of the sub-band wavelength (920-930nm, covering the wavelength range after temperature drift) is 94.41%, and the difference between the two is 0.5%.

[0055] The first comparative example of the present invention is the same as the first embodiment, except that the heating unit 70 is a 25±9Ω ITO film made under the first process condition as the heating unit 70. After optical measurement, the transmittance of the main band wavelength (900-910nm, covering the main light source wavelength of 905nm) is about 89.75%, and the transmittance of the sub-band wavelength (920-930nm, covering the wavelength range after temperature drift) is 86.78%, and the difference between the two is 2.97%.

[0056] After simulation, in a normal temperature environment and a defog heating environment, the detection light emitted by the light source unit 200 and the light scattered / reflected by the target 210 can complete the operation of sensing objects and measuring distances by the outer cover module 1 of the first and second embodiments. That is to say, in the above two environments, the outer cover module 1 of the present invention can allow sufficient light signals to pass through without significantly improving the signal-to-noise ratio of the system and causing the overall system's operating efficiency to decrease. In contrast, the first comparative example has a lower transmittance at the sub-band wavelength (compared to the main band transmittance). In the defog heating stage, it can be observed that the detection light emitted by the light source unit 200 cannot effectively pass through the outer cover module 1. Even if a small amount passes through, the light scattered / reflected by the target 210 is even more difficult to be received by the receiving unit 220 (that is, it is shielded by the outer cover module 1), so the control unit 230 cannot accurately calculate the object / distance in front of the vehicle. According to the formula of the photocurrent signal measured by the infrared system, the size of the photocurrent signal is directly related to the light transmittance. Therefore, when the system is heated up, the light source unit 200 will experience temperature drift. The high transmittance of the outer cover module 1 at the sub-band wavelength allows the self-driving system to obtain external information.

[0057] The present invention provides a defogging method for the outer cover module 1 of the automatic driving system of the above embodiment, comprising the following steps: a light source unit 200 emits a detection signal, the wavelength of the detection signal may be 905nm or light in the range of 900-910nm; the detection signal passes through the outer cover module 1 and is emitted into the environment; the detection signal is reflected or scattered by the target 210; the reflected signal reflected by the target 210 passes through the outer cover module 1 and returns to the system; and a receiving unit 220 receives the reflected signal, and the control unit 230 calculates the position / distance of the target 210. In the above steps, since the heating unit 70 does not start heating, it is a preset environment for the light source unit 200 (i.e., there is no temperature drift phenomenon), and both the detection signal and the return signal can effectively pass through the outer cover module 1 with high penetration rate in the main band. On the other hand, although in this case without temperature drift, the light in the sub-band can also enter the system through the outer cover module 1 to form noise, since the wavelength range of the sub-band is small (for example, below 10nm), the signal-to-noise ratio of the overall system will not be greatly affected. This can also explain why the lidar system mentioned above will not choose glass with high transmittance in a large wavelength range (such as the aforementioned 920-1000nm, covering a range of tens or even hundreds of nm), because too much noise light will cause a burden on the system operation.

[0058] The above steps also include: the temperature sensing unit 250 senses the presence of fog / dew / frost on the outer cover module 1; and the temperature control unit 240 starts the heating unit 70, so that the heating unit 70 heats the outer cover module 1. In the aforementioned steps, since the heating unit 70 has started heating, it is a high temperature environment for the light source unit 200 and produces a temperature drift phenomenon of the wavelength (that is, the wavelength drifts from the main band to the sub-band), and the outer cover module 1 of the embodiment of the present invention still has a high transmittance for the light after the wavelength temperature drift, so the detection signal and the return signal can also pass through the outer cover module 1 with high transmittance for the sub-band. In this case of temperature rise, the light signal of the sub-band becomes the main signal, and the signal of the main band becomes noise; it has been verified that the outer cover module 1 of the present invention can also meet the needs of the self-driving system to detect the external environment in this case.

[0059] In another embodiment, the wavelength of the light emitted by the light source unit 200 using the EEL chip is 1550 nm. According to the temperature drift theory, during the above heating and defogging process, the wavelength of the light emitted by the light source unit 200 shifts to: 1550+[ΔT+(T fog -T 0 )]×α; where T 0 is the initial temperature of the light source unit 200, T fogis the dew point temperature, ΔT is the defog temperature difference, and α is the temperature drift coefficient. In one embodiment, the temperature drift coefficient is about 0.2-0.3 nm / °C or less; the following scenario is used for trial calculation: the automatic driving system of the embodiment of the present invention is used in cold regions, where the outdoor temperature in winter is about -10°C, the air humidity is about 85g / kg, and the defog temperature difference ΔT=20°C. By inserting the above temperature drift formula, it can be calculated that the light emission wavelength of the light source unit 200 drifts to between 1565 and 1575 nm. In other words, the difference between the transmittance of the outer cover module 1 of the embodiment of the present invention at the main band wavelength (1545-1555 nm, covering the main light source wavelength of 1550 nm) and the transmittance of the sub-band wavelength (1565-1575 nm, covering the wavelength range after temperature drift) is less than 2% or less than 1%. In a variant embodiment, the lower limit of the operating temperature of the light source unit 200 (-40°C) can be used for calculation (i.e., the above formula T 0 The wavelength drift caused by temperature rise is -40℃.

[0060] In another embodiment, the wavelength of the light emitted by the light source unit 200 using the EEL chip is 1350nm. According to the temperature drift theory, during the above heating and defogging process, the wavelength of the light emitted by the light source unit 200 shifts to: 1350+[ΔT+(T fog -T 0 )]×α; where T 0 is the initial temperature of the light source unit 200, T fog is the dew point temperature, ΔT is the defog temperature difference, and α is the temperature drift coefficient. In one embodiment, the temperature drift coefficient is about 0.2-0.3nm / ℃ or less; the following scenario is used for trial calculation: the automatic driving system of the embodiment of the present invention is used in cold regions, where the outdoor temperature in winter is about -10℃, the air humidity is about 85g / kg, and the defog temperature difference ΔT=20℃. By inserting the above temperature drift formula, it can be calculated that the light emission wavelength of the light source unit 200 drifts to between 1365 and 1375nm. In other words, the difference between the transmittance of the outer cover module 1 of the embodiment of the present invention at the main band wavelength (1345-1355nm, covering the main light source wavelength of 1350nm) and the transmittance of the sub-band wavelength (1365-1375nm, covering the wavelength range after temperature drift) is less than 2% or less than 1%.

[0061] In a preferred embodiment, the penetration rate of the main band is greater than the penetration rate of the sub-band. Therefore, when the temperature is the preset working temperature of the light source unit 200, the detection signal and the reflected signal have a better effect of passing through the outer cover module 1 to maintain good detection accuracy.

[0062] In a preferred embodiment, the transmittance of the main band and the transmittance of the sub-band are both greater than 85%, or greater than 90%.

[0063] In a preferred embodiment, the embodiment of the present invention can select an appropriate light source unit 200 by using the condition that the main band transmittance and the sub-band transmittance of the outer cover module 1 differ by 1%. For example, the main band wavelength of the outer cover module 1 of the embodiment of the present invention is set to 905nm (transmittance is 91%), and the sub-band wavelength is set to 920-925nm (transmittance is 90%), that is, the temperature drift of the outer cover module 1 of the embodiment of the present invention is 20-25nm. In the following scenario: the automatic driving system is used in temperate areas, the outdoor temperature in winter is about 10℃, the air humidity is about 85g / kg, and the defogging temperature difference ΔT=20℃, and the temperature drift coefficient of the light source unit 200 is 0.3-0.38 by inserting the above temperature drift formula. In other words, the present invention proposes a condition for matching the outer cover module 1 and the light source unit 200, and by controlling the outer cover module 1 to maintain a high transmittance for the light emitted by the light source unit 200 after temperature drift, so as to meet the reliability of the lidar system.

[0064] The above description is only used to explain the preferred embodiments of the present invention, and is not intended to limit the present invention in any form. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included in the scope of protection intended by the present invention.

Claims

1. A cover module of a lidar system, the lidar system comprising a light source unit, the cover module include: First Glass; A heating unit, disposed on the first glass; as well as A second glass is disposed in the heating unit; The difference between the transmittance of the main band and the transmittance of the sub-band of the outer cover module is less than 2%, and the wavelength of the sub-band is calculated by the following formula: wavelength of the main band + [ΔT + (T fog -T 0 )]×α; where T 0 is the initial temperature of the light source unit, T fog is the dew point temperature, ΔT is the defog temperature difference, and α is the temperature drift coefficient of the light source unit.

2. The cover module of the lidar system according to claim 1, in, The penetration rate of the main band is greater than the penetration rate of the sub-band.

3. The cover module of the lidar system according to claim 1, in, The penetration rate of the main band and the penetration rate of the sub-band are both greater than 90%.

4. The cover module of the lidar system according to claim 1, in, The wavelength of the main band is 890-910 nm, and the wavelength of the sub-band is 910-930 nm; or, the wavelength of the main band is 1545-1550 nm, and the wavelength of the sub-band is 1565-1575 nm.

5. An outer cover module of a lidar system, include: First Glass; A heating unit, disposed on the first glass; as well as A second glass is disposed in the heating unit; The difference between the transmittance of the main band and the transmittance of the sub-band of the outer cover module is less than 2%, wherein the wavelength of the main band is 900-910nm, and the wavelength of the sub-band is 920-930nm.

6. The cover module of the lidar system according to claim 5, in, The penetration rate of the main band is greater than the penetration rate of the sub-band.

7. The cover module of the lidar system according to claim 5, in, The penetration rate of the main band and the penetration rate of the sub-band are both greater than 90%.

8. An outer cover module of a lidar system, include: First Glass; A heating unit, disposed on the first glass; as well as A second glass is disposed in the heating unit; The difference between the transmittance of the main band and the transmittance of the sub-band of the outer cover module is less than 2%, wherein the wavelength of the main band is 1545-1555 nm, and the wavelength of the sub-band is 1565-1575 nm.

9. The cover module of the lidar system according to claim 8, in, The penetration rate of the main band is greater than the penetration rate of the sub-band.

10. The cover module of the lidar system according to claim 8, in, The penetration rate of the main band and the penetration rate of the sub-band are both greater than 90%.

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