Non-stop drunk driving detection system and method

Abstract

The embodiment of the invention provides a non-stop drunk driving detection system and method, relates to the technical field of spectroscopy and gas sensing, and can realize non-stop drunk driving detection. The non-stop drunk driving detection system comprises a laser emitting unit arranged on one side of a road, a signal receiving and processing unit arranged on the other side of the road, and a light transmission unit, wherein the light transmission unit comprises a first light assembly arranged on one side of the road and a second light assembly arranged on the other side of the road; the laser emitting unit comprises a signal generator, a laser driver and a laser; and the signal receiving and processing unit comprises a photoelectric detector, a lock-in amplifier and a gas concentration calculation unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spectroscopy and gas sensing technology, and in particular to a non-stop drunk driving detection system and method. BACKGROUND

[0002] In the drunk driving detection scenario, the traditional technology is that the traffic police uses a handheld alcohol detector at the intersection, and requires the driver to stop the car and blow into the handheld alcohol detector for more than 3 seconds. The handheld alcohol detector is installed with an alcohol gas sensor, which will change the current or voltage in the circuit with the change of the alcohol concentration in the exhaled gas, so as to detect the alcohol gas concentration of the driver. This method will obviously interfere with traffic and increase the traffic pressure. Therefore, a technical solution for non-stop drunk driving detection is urgently needed. SUMMARY

[0003] Therefore, the embodiments of the present application provide a non-stop drunk driving detection system and method, which can realize non-stop drunk driving detection.

[0004] To achieve the above-mentioned purpose, according to one aspect of the present application, a non-stop drunk driving detection system is provided.

[0005] The non-stop drunk driving detection system of the embodiments of the present application comprises a laser emitting unit arranged on one side of a road, a signal receiving and processing unit arranged on the other side of the road, and an optical transmission unit; wherein the optical transmission unit comprises a first optical assembly arranged on the one side of the road and a second optical assembly arranged on the other side of the road; the laser emitting unit comprises a signal generator, a laser driver and a laser; the signal generator generates a modulated signal superimposed by a sawtooth wave and a sine wave, the laser driver drives the laser based on the modulated signal, and the laser outputs a modulated laser signal based on the modulated signal; the modulated laser signal output by the laser enters the first optical assembly to form parallel light rays, the parallel light rays pass through the cabin of a vehicle to be detected and then enter the second optical assembly for convergence, and the converged optical signal enters the signal receiving and processing unit; the signal receiving and processing unit comprises a photodetector, a lock-in amplifier and a gas concentration calculation unit; the photodetector converts the converged optical signal into an electrical signal, the lock-in amplifier demodulates the electrical signal to form a harmonic signal with the sine wave as a reference signal, and the gas concentration calculation unit calculates the alcohol gas concentration in the cabin of the vehicle to be detected from the harmonic signal.

[0006] Optionally, the harmonic signal includes a first harmonic signal and a second harmonic signal; the gas concentration calculation unit obtains an amplitude of the first harmonic signal and an amplitude of the second harmonic signal, determines a first value as a product of the amplitude of the first harmonic signal and a preset calibration coefficient, determines a second value as a quotient of the amplitude of the second harmonic signal and the first value, determines a third value as a sum of the second value and 1, and determines a fourth value as a natural logarithm of the third value; the gas concentration calculation unit determines a fifth value as a product of a preset absorption coefficient and an optical path, and determines the alcohol gas concentration in the vehicle cabin to be detected as a quotient of the fourth value and the fifth value.

[0007] Optionally, the laser driver controls the center wavelength of the modulated laser signal output by the laser to align with the center of the alcohol gas absorption peak and to be outside the wavelength range blocked by the sunshade film of the vehicle.

[0008] Optionally, the laser driver further controls the output power of the laser to be in a preset power range and controls the operating temperature of the laser to be in a preset temperature range.

[0009] Optionally, the signal generator generates a digital signal and converts the digital signal into the modulated signal as an analog voltage signal by using an internal digital-to-analog converter; the center wavelength of the modulated laser signal is 3345 nanometers; the power range is 10 milliwatts to 40 milliwatts; and the temperature range is 24.9℃ to 25.1℃.

[0010] To achieve the above object, according to another aspect of the present application, a non-stop drunk driving detection method is provided.

[0011] The non-stop drunk driving detection method of the embodiment of the present application includes: a signal generator generates a modulated signal superimposed by a sawtooth wave and a sine wave, and transmits the modulated signal to a laser driver; the laser driver drives a laser based on the modulated signal, so that the laser outputs a modulated laser signal based on the modulated signal; a first optical assembly converts the modulated laser signal output by the laser into parallel light rays; the signal generator, the laser driver, the laser and the first optical assembly are arranged on one side of a road; the parallel light rays enter a second optical assembly for converging after passing through a vehicle cabin to be detected, and the converged light signal enters a photodetector; the photodetector converts the converged light signal into an electric signal, and transmits the electric signal to a phase-locked amplifier; the phase-locked amplifier demodulates the electric signal by taking the sine wave as a reference signal to form a harmonic signal; a gas concentration calculation unit calculates an alcohol gas concentration in the vehicle cabin to be detected from the harmonic signal; the second optical assembly, the photodetector, the phase-locked amplifier and the gas concentration calculation unit are arranged on the other side of the road.

[0012] Optionally, the harmonic signal includes a first harmonic signal and a second harmonic signal; and the method further comprises: the gas concentration calculation unit acquires an amplitude of the first harmonic signal and an amplitude of the second harmonic signal, determines a first value as a product of the amplitude of the first harmonic signal and a preset calibration coefficient, determines a second value as a quotient of the amplitude of the second harmonic signal and the first value, determines a third value as a sum of the second value and 1, and determines a fourth value as a natural logarithm of the third value; the gas concentration calculation unit determines a fifth value as a product of a preset absorption coefficient and an optical path, and determines the alcohol gas concentration in the vehicle cabin to be detected as a quotient of the fourth value and the fifth value.

[0013] Optionally, the method further comprises: the laser driver controls the center wavelength of the modulated laser signal output by the laser to align with the alcohol gas absorption peak center and to be outside the wavelength range blocked by the vehicle sunshade film.

[0014] Optionally, the method further comprises: the laser driver further controls the output power of the laser to be in a preset power range and controls the working temperature of the laser to be in a preset temperature range.

[0015] Optionally, the method further comprises: the signal generator generates a digital signal and converts the digital signal into the modulated signal as an analog voltage signal by using an internal digital-to-analog converter; the center wavelength of the modulated laser signal is 3345 nanometers, the power range is 10 milliwatts to 40 milliwatts, and the temperature range is 24.9 DEG C to 25.1 DEG C.

[0016] According to the technical solution of the present application, one embodiment of the above application has the following advantages or beneficial effects:

[0017] The laser emission unit including the signal generator, the laser driver and the laser is arranged on one side of the road to emit the modulated laser signal to pass through the vehicle cabin to be detected, and the signal receiving and processing unit including the photodetector, the lock-in amplifier and the gas concentration calculation unit is arranged on the other side of the road to receive the light passing through the vehicle cabin to be detected and calculate the alcohol gas concentration in the vehicle cabin to be detected, thereby realizing efficient non-contact drunk driving detection by combining the laser absorption spectrum technology, the harmonic detection technology and the weak light signal data processing technology, without the need of stopping the vehicle and without the interference to the traffic order. In one embodiment, the laser signal with the center wavelength of 3345 nanometers is used to detect the alcohol gas concentration, the alcohol molecule absorption intensity is large, the capture accuracy of the alcohol characteristic absorption peak is high, and the influence of other background gases on the alcohol gas detection can be avoided to the greatest extent, and the alcohol gas concentration detection sensitivity is improved. In addition, the laser signal with the above wavelength is used in the embodiment of the present application to prevent the vehicle sunshade film from blocking the light, which is beneficial to improve the detection precision of the alcohol gas concentration.

[0018] Further effects of the above-described non-conventional optional mode will be explained in the following in connection with the detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. Among the drawings:

[0020] Figure 1 is a schematic diagram of the non-stop drunk driving detection system in the embodiment of the present application;

[0021] Figure 2 is a schematic diagram of the execution steps of the non-stop drunk driving detection method in the embodiment of the present application. DETAILED DESCRIPTION

[0022] The exemplary embodiments of this application are described herein with reference to the accompanying drawings, in which various details are set forth by way of illustration. However, it will be understood that the intent of this application is to cover all modifications and alternatives that fall within the spirit and scope of the application. Thus, it should be understood that various changes and modifications can be made to the embodiments described herein, without departing from the scope and spirit of the application. Similarly, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the application, are given by way of illustration only, since various changes and modifications within the scope of the application will become apparent to those skilled in the art from this detailed description.

[0023] Figure 1 is a schematic diagram of the non-stop drunk driving detection system in the embodiment of the present application, see Figure 1 .

[0024] The non-stop drunk driving detection system of the present application comprises a laser emitting unit arranged on one side of the road, a signal receiving and processing unit arranged on the other side of the road, and a light transmission unit. The above drunk driving refers to driving after drinking, including drinking driving and drunk driving.

[0025] Among them, the light transmission unit comprises a first light assembly arranged on one side of the road and a second light assembly arranged on the other side of the road. The first light assembly is used to convert the received light signal into parallel light to be incident on the vehicle, and the second light assembly is used to converge the light emitted from the vehicle. Exemplarily, the first light assembly and the second light assembly can be composed of converging lenses, mirrors, etc.

[0026] The laser emission unit comprises a signal generator, a laser driver and a laser. Specifically, the signal generator generates a modulated signal superimposed by a sawtooth wave and a sine wave, the laser driver drives the laser based on the modulated signal, and the laser outputs a modulated laser signal based on the modulated signal. The above modulated laser signal can contain the frequency band of the alcohol molecule absorption peak. In one embodiment, the above signal generator can first generate a digital signal superimposed by a sawtooth wave and a sine wave, and convert the digital signal into a modulated signal as an analog voltage signal by using an internal digital-to-analog converter, which helps to improve the final alcohol gas concentration detection accuracy. The above laser driver can be implemented by using an ARM chip, and the above laser can be a near-infrared VCSEL (Vertical-Cavity Surface-Emitting Laser) laser. Exemplarily, the frequency range of the above sawtooth wave can be 0.1 Hz to 1 Hz, the frequency range of the above sine wave can be 30 kHz to 80 kHz, and the modulation expression of the modulated signal v(t) can be as follows:

[0027] v(t) = v0 + A * sawtooth(f1t) + B * sin(2p f2t)

[0028] wherein t represents time, v0 represents the center frequency of the alcohol gas absorption peak, sawtooth represents the sawtooth wave, A is the sawtooth wave amplitude, f1 is the sawtooth wave frequency, B is the sine wave amplitude, and f2 is the sine wave frequency.

[0029] The modulated laser signal output by the laser enters the first optical assembly to form parallel light rays, the parallel light rays pass through the cabin of the vehicle to be detected and then enter the second optical assembly for convergence, and the converged optical signal enters the signal receiving and processing unit. It can be understood that if the driver of the vehicle to be detected drinks, alcohol gas exists in the cabin of the vehicle to be detected, and the light intensity of the parallel light rays passing through the cabin of the vehicle to be detected will be affected by the alcohol gas, and then the signal receiving and processing unit can calculate the alcohol gas concentration in the cabin of the vehicle to be detected by detecting such influence.

[0030] The signal receiving and processing unit includes a photodetector, a lock-in amplifier, and a gas concentration calculation unit. Specifically, the photodetector converts the converged optical signal into an electrical signal, the lock-in amplifier demodulates the electrical signal using a sine wave as a reference signal to generate a harmonic signal, and the gas concentration calculation unit calculates the alcohol gas concentration in the vehicle cabin from the harmonic signal. In this invention, the signal generator generates a modulation signal by superimposing a sawtooth wave signal and a sine wave signal to modulate the laser signal, while the lock-in amplifier demodulates the same sine wave signal as a reference signal to generate a harmonic signal. This effectively removes background interference signals and improves the detection accuracy and sensitivity of alcohol gas concentration. In practical applications, the lock-in amplifier may also include an amplification circuit and a filtering circuit.

[0031] Preferably, in this embodiment of the invention, the harmonic signals include a first harmonic signal and a second harmonic signal, and the gas concentration calculation unit can calculate the alcohol gas concentration C using the following formula:

[0032]

[0033] Among them, I 1f I represents the amplitude of the first harmonic signal. 2f The amplitude of the second harmonic signal is represented by α(v), the calibration coefficient is represented by k, the absorption coefficient is represented by α(v), and the optical path length is represented by L.

[0034] In other words, the gas concentration calculation unit obtains the amplitude I of the first harmonic signal. 1f The amplitude I of the second harmonic signal 2f The amplitude I of the first harmonic signal 1f The product of k and the preset calibration coefficient k is determined as the first value kI. 1f The amplitude I of the second harmonic signal 2f The quotient of the first value is determined as the second value. The second value The sum of 1 and 1 is determined as the third value. The third value The natural logarithm of is determined to be the fourth value. The gas concentration calculation unit determines the product of the preset absorption coefficient α(v) and optical path L as the fifth value α(v)*L, and uses the fourth value... The quotient of the fifth value α(v)*L is determined as the concentration of alcohol gas in the cabin of the vehicle to be tested.

[0035] In the above calculation process, the embodiments of the present invention eliminate the influence of light intensity fluctuations by combining the first harmonic amplitude and the second harmonic amplitude, while avoiding the analysis of the spectrum before and after absorbing alcohol gas, thereby achieving high-precision calculation of alcohol gas concentration.

[0036] As a preferred solution, the laser driver controls the center wavelength of the modulated laser signal outputted by the laser to align with the center of the alcohol gas absorption peak and to be outside the wavelength range blocked by the vehicle sunshade film. Specifically, the center wavelength of the modulated laser signal is 3345 nm, and the wavelength range blocked by the vehicle sunshade film can be from 780 nm to 2500 nm, so as to avoid the influence of the vehicle sunshade film on the detection accuracy of the alcohol gas concentration. In an exemplary embodiment, the laser driver also controls the output power of the laser to be in a preset power range, and controls the working temperature of the laser to be in a preset temperature range. Exemplarily, the above power range is 10 mW to 40 mW, and the above temperature range is 24.9℃ to 25.1℃.

[0037] In this way, the present application realizes efficient non-contact drunk driving detection by combining the laser absorption spectrum technology, the harmonic detection technology and the weak light signal data processing technology, without the need of stopping the vehicle and without the interference to the traffic order. In addition, the embodiment of the present application uses the laser signal with the center wavelength of 3345 nm to detect the alcohol gas concentration, the absorption intensity of alcohol molecules is large, the capture accuracy of the alcohol characteristic absorption peak is high, and the influence of other background gases on the alcohol gas detection can be avoided to the greatest extent, so as to improve the detection sensitivity of the alcohol gas concentration.

[0038] In a specific application, the signal generator in the technical solution of the present application generates a modulated signal superimposed by a sawtooth wave and a sine wave. The sawtooth wave realizes spectral scanning, covering the frequency range near the alcohol absorption peak and ensuring that the laser frequency completely scans the absorption peak. The sine wave slightly modulates the laser frequency, so that the transmitted light intensity oscillates at a frequency of 2f (f represents the fundamental frequency), providing a basis for the second harmonic detection. After transmission, the laser forms a parallel light beam with a divergence angle ≤0.5 mrad by the converging mirror, and is incident to the vehicle cabin. The diffuse reflection light after the absorption of the ethanol gas in the cabin is collected by the combination of the converging lens and the plane mirror (the second optical assembly), and the light collection efficiency is improved, and the spot diameter at the focal point is controlled to be within 2 mm.

[0039] It can be understood that the application of the technical solution of the present application can screen a large range of possible drunk driving behaviors (including drinking driving and drunk driving) on the road, and subsequently determine whether there is drunk driving by using a handheld alcohol detector for the screened drivers.

[0040] Figure 2 is the execution step schematic diagram of the non-stop drunk driving detection method in the embodiment of the present application, referring to Figure 2 The non-stop drunk driving detection method provided by the embodiment of the present application comprises the following steps:

[0041] Step S201: The signal generator generates a modulated signal superimposed by a sawtooth wave and a sine wave, and transmits the modulated signal to the laser driver.

[0042] Step S202: The laser driver drives the laser based on the modulation signal, so that the laser outputs a modulated laser signal based on the modulation signal.

[0043] Step S203: The first optical assembly converts the modulated laser signal output by the laser into parallel light rays; wherein the signal generator, the laser driver, the laser, and the first optical assembly are disposed on one side of the road.

[0044] Step S204: The parallel light rays pass through the cabin of the vehicle to be detected and enter the second optical assembly for converging, and the converged light signal enters the photodetector.

[0045] Step S205: The photodetector converts the converged light signal into an electrical signal and transmits the electrical signal to the lock-in amplifier.

[0046] Step S206: The lock-in amplifier demodulates the electrical signal with the sinusoidal wave as a reference signal to form a harmonic signal.

[0047] Step S207: The gas concentration calculation unit calculates the alcohol gas concentration in the cabin of the vehicle to be detected from the harmonic signal; wherein the second optical assembly, the photodetector, the lock-in amplifier, and the gas concentration calculation unit are disposed on the other side of the road.

[0048] In a preferred embodiment, the harmonic signal includes a first harmonic signal and a second harmonic signal; and the method further includes: the gas concentration calculation unit obtains an amplitude of the first harmonic signal and an amplitude of the second harmonic signal, determines a first value as a product of the amplitude of the first harmonic signal and a preset calibration coefficient, determines a second value as a quotient of the amplitude of the second harmonic signal and the first value, determines a third value as a sum of the second value and 1, and determines a fourth value as a natural logarithm of the third value; the gas concentration calculation unit determines a fifth value as a product of a preset absorption coefficient and an optical path, and determines the alcohol gas concentration in the cabin of the vehicle to be detected as a quotient of the fourth value and the fifth value.

[0049] Preferably, the method further includes: the laser driver controls the center wavelength of the modulated laser signal output by the laser to align with the center of the absorption peak of alcohol gas and to be outside the wavelength range blocked by the sunshade film of the vehicle.

[0050] As a preferred solution, the method further includes: the laser driver further controls the output power of the laser to be within a preset power range and controls the operating temperature of the laser to be within a preset temperature range.

[0051] In one example embodiment, the method further comprises: the signal generator generates a digital signal, and converts the digital signal into the modulated signal as an analog voltage signal by using an internal digital-to-analog converter; the center wavelength of the modulated laser signal is 3345nm, the power range is 10-40mW, and the temperature range is 24.9-25.1℃.

[0052] In the technical solution of the present application, a laser emission unit including a signal generator, a laser driver and a laser is arranged on one side of the road to emit a modulated laser signal to pass through the cabin of a vehicle to be detected, and a signal receiving and processing unit including a photodetector, a lock-in amplifier and a gas concentration calculation unit is arranged on the other side of the road to receive the light passing through the cabin of the vehicle to be detected and calculate the alcohol gas concentration in the cabin of the vehicle to be detected, thereby realizing efficient non-contact drunk driving detection by combining the laser absorption spectroscopy technology, the harmonic detection technology and the weak light signal data processing technology, without the need of stopping the vehicle and without interfering with the traffic order. In one embodiment, the embodiment of the present application uses a laser signal with a center wavelength of 3345nm to detect the alcohol gas concentration, the alcohol molecule has a large absorption intensity, the capture accuracy of the alcohol characteristic absorption peak is high, and the influence of other background gases on the alcohol gas detection can be avoided to the greatest extent, thereby improving the detection sensitivity of the alcohol gas concentration. In addition, the laser signal with the above wavelength used in the embodiment of the present application can prevent the sunshade film of the vehicle from blocking the light, which is beneficial to improve the detection accuracy of the alcohol gas concentration.

[0053] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made depending on design requirements and other factors. Any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A non-stop drunk driving detection system characterized by, The application relates to a laser alcohol detection system for detecting alcohol concentration in a vehicle cabin. The system comprises a laser emission unit arranged on one side of a road, a signal receiving and processing unit arranged on the other side of the road, and a light transmission unit. The light transmission unit comprises a first light assembly arranged on the one side of the road and a second light assembly arranged on the other side of the road. The laser emission unit comprises a signal generator, a laser driver and a laser. The signal generator generates a modulation signal formed by superimposing a sawtooth wave and a sine wave. The laser driver drives the laser based on the modulation signal.

2. The stop- car drunk driving detection system according to claim 1, characterized by The laser outputs a modulation laser signal based on the modulation signal. The modulation laser signal output by the laser enters the first light assembly to form parallel light rays. The parallel light rays pass through the vehicle cabin to be detected and then enter the second light assembly for convergence.

3. The stop-ock drunk driving detection system of claim 1, wherein The converged light signal enters the signal receiving and processing unit.

4. The stop-ock drunk driving detection system of claim 3, wherein The signal receiving and processing unit comprises a photodetector, a lock-in amplifier and a gas concentration calculation unit.

5. The stop-ock drunk driving detection system of claim 4, wherein The photodetector converts the converged light signal into an electrical signal. The lock-in amplifier demodulates the electrical signal to form a harmonic signal with the sine wave as a reference signal. The gas concentration calculation unit calculates the alcohol gas concentration in the vehicle cabin to be detected from the harmonic signal. The harmonic signal comprises a first harmonic signal and a second harmonic signal.

6. A method of stop- and- go drunk driving detection, the method comprising: The gas concentration calculation unit obtains the amplitude of the first harmonic signal and the amplitude of the second harmonic signal. The gas concentration calculation unit determines a first value as the product of the amplitude of the first harmonic signal and a preset calibration coefficient. The gas concentration calculation unit determines a second value as the quotient of the amplitude of the second harmonic signal and the first value. The gas concentration calculation unit determines a third value as the sum of the second value and 1. The gas concentration calculation unit determines a fourth value as the natural logarithm of the third value. The gas concentration calculation unit determines a fifth value as the product of a preset absorption coefficient and an optical path. The gas concentration calculation unit determines the alcohol gas concentration in the vehicle cabin to be detected as the quotient of the fourth value and the fifth value. The laser driver controls the center wavelength of the modulation laser signal output by the laser to align with the alcohol gas absorption peak center and to be outside the wavelength range blocked by the sunshade film of the vehicle. The laser driver also controls the output power of the laser to be within a preset power range and controls the working temperature of the laser to be within a preset temperature range. The signal generator generates a digital signal and converts the digital signal into the modulation signal as an analog voltage signal by using an internal digital-to-analog converter. The center wavelength of the modulation laser signal is 3345 nanometers. The power range is 10 milliwatts to 40 milliwatts. The temperature range is 24.9 DEG C to 25.1 DEG C. The signal generator generates a modulation signal formed by superimposing a sawtooth wave and a sine wave and transmits the modulation signal to a laser driver. The laser driver drives a laser based on the modulation signal so that the laser outputs a modulation laser signal based on the modulation signal. A first light assembly converts the modulation laser signal output by the laser into parallel light rays. The signal generator, the laser driver, the laser and the first light assembly are arranged on one side of a road. The parallel light passes through the vehicle cabin to be detected and enters a second light assembly to be converged, and the converged light signal enters a photoelectric detector; The photoelectric detector converts the converged light signal into an electric signal and transmits the electric signal to a lock-in amplifier; The lock-in amplifier demodulates the electric signal to form a harmonic signal with the sinusoidal wave as a reference signal; A gas concentration calculation unit calculates the alcohol gas concentration in the vehicle cabin to be detected from the harmonic signal; the second light assembly, the photoelectric detector, the lock-in amplifier and the gas concentration calculation unit are arranged on the other side of the road.

7. The stop- car drunk driving detection method according to claim 6, characterized by, The harmonic signal includes a first harmonic signal and a second harmonic signal; and the method further comprises: The gas concentration calculation unit obtains the amplitude of the first harmonic signal and the amplitude of the second harmonic signal, determines a first value as the product of the amplitude of the first harmonic signal and a preset calibration coefficient, determines a second value as the quotient of the amplitude of the second harmonic signal and the first value, determines a third value as the sum of the second value and 1, and determines a fourth value as the natural logarithm of the third value; The gas concentration calculation unit determines a fifth value as the product of a preset absorption coefficient and an optical path, and determines the alcohol gas concentration in the vehicle cabin to be detected as the quotient of the fourth value and the fifth value.

8. The method of claim 6, wherein, The method further comprises: The laser driver controls the center wavelength of the modulated laser signal output by the laser to align with the alcohol gas absorption peak center and to be outside the wavelength range blocked by the sunshade film of the vehicle.

9. The method of claim 8, wherein, The method further comprises: The laser driver further controls the output power of the laser to be in a preset power range and controls the working temperature of the laser to be in a preset temperature range.

10. The method of claim 9, wherein, The method further comprises: The signal generator generates a digital signal and converts the digital signal into the modulated signal as an analog voltage signal by using an internal digital-to-analog converter; The center wavelength of the modulated laser signal is 3345 nanometers, the power range is 10 milliwatts to 40 milliwatts, and the temperature range is 24.9℃ to 25.1℃.

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