Non-stop drunk driving detection system and method integrating laser absorption spectrum and laser Raman spectrum

Abstract

The invention provides a non-stop drunk driving detection system and method fusing a laser absorption spectrum and a laser Raman spectrum. Comprising a dual-mode laser emitting unit, a light transmission unit and a signal receiving and processing unit. In the transmitting unit, a signal generator generates a superposition modulation signal of sawtooth waves and sine waves to drive a first laser to output modulation laser for absorption spectrum analysis; the second laser outputs laser for exciting Raman scattering; and the mode switching controller supports synchronous work of an absorption mode, a Raman mode or dual modes. The optical transmission unit emits the laser light to a vehicle cabin and collects a return optical signal. The receiving and processing unit demodulates an absorption signal through a lock-in amplifier to obtain a harmonic wave, analyzes a Raman scattering signal through a spectrograph to obtain a characteristic peak, and further calculates the alcohol concentration, so that rapid and reliable non-contact detection is realized.

Description

Technical Field

[0001] This invention relates to the field of information technology, and in particular to a non-stop drunk driving detection system and method that integrates laser absorption spectroscopy and laser Raman spectroscopy. Background Technology

[0002] Traditional drunk driving detection relies on traffic police intercepting drivers on-site and using breathalyzers, requiring drivers to stop and cooperate, which easily causes traffic congestion and reduced traffic efficiency. In recent years, non-stop detection technology based on laser absorption spectroscopy has gradually developed. It inverts the concentration by detecting the degree of absorption of alcohol gas in the vehicle cabin by a specific wavelength of laser light. Although it achieves non-stop detection, it still has problems such as interference from window tint, ambient light, and cross-sensitivity to water vapor. Laser Raman spectroscopy is based on molecular vibrational scattering and has advantages such as no sample pretreatment required, resistance to matrix interference, and qualitative identification, making it particularly suitable for complex gas mixtures. However, its equipment cost is high, fluorescence interference is significant, and sensitivity at low concentrations is limited.

[0003] To overcome the limitations of single technologies and improve the reliability, adaptability, and accuracy of drunk driving detection, there is an urgent need for a fusion system that integrates multiple optical detection principles to achieve rapid, dual-verification detection of alcohol gas. Summary of the Invention

[0004] This invention aims to provide a non-stop drunk driving detection system and method that integrates laser absorption spectroscopy and laser Raman spectroscopy. By combining the high-sensitivity detection of laser absorption spectroscopy with the qualitative identification capability of laser Raman spectroscopy, it achieves rapid, reliable, and non-contact detection of alcohol gas inside moving vehicles, improving screening accuracy and environmental adaptability.

[0005] This invention provides a non-stop drunk driving detection system that integrates laser absorption spectroscopy and laser Raman spectroscopy, mainly comprising: A dual-mode laser emitting unit is installed on one side of the road, a signal receiving and processing unit is installed on the other side of the road, and an optical transmission unit is installed on both sides of the road. The dual-mode laser emitting unit includes: a signal generator, a laser driver, a first laser, a second laser, and a mode switching controller; the signal generator generates a modulation signal, which includes a superposition signal of a sawtooth wave and a sine wave; the laser driver drives the first laser to output a modulated laser signal based on the modulation signal; the second laser outputs continuous or pulsed laser light for exciting Raman scattering; the mode switching controller is used to select the first laser mode, the second laser mode, or the dual-laser synchronous mode; The optical transmission unit includes a first optical component disposed on one side of the road and a second optical component disposed on the other side of the road; the first optical component is used to convert the laser output from the first laser or the second laser into parallel light and direct it toward the vehicle cabin; the second optical component is used to collect the light signals passing through or scattered from the vehicle cabin and converge them to the signal receiving and processing unit. The signal receiving and processing unit includes: a first photodetector, a lock-in amplifier, a second photodetector, a spectrometer, and a gas concentration calculation unit; the first photodetector is used to receive the transmitted / absorbed light signal collected by the second optical component and convert it into a first electrical signal; the lock-in amplifier demodulates the first electrical signal with the sine wave as a reference signal to obtain a harmonic signal; the second photodetector is used to receive the Raman scattered light signal collected by the second optical component and convert it into a second electrical signal; the spectrometer is used to analyze the Raman shift characteristic peak of the second electrical signal; the gas concentration calculation unit is used to calculate the alcohol gas concentration in the vehicle cabin based on the harmonic signal and / or the Raman shift characteristic peak.

[0006] Furthermore, the center wavelength of the modulated laser signal output by the first laser is 3345 nanometers, which is located at the center of the alcohol gas absorption peak and avoids the wavelength range blocked by the vehicle's sunshade film; the laser wavelength output by the second laser is in the visible light or near-infrared band, which is suitable for exciting the Raman characteristic shift of ethanol molecules.

[0007] Furthermore, the gas concentration calculation unit calculates the alcohol gas concentration based on the harmonic signal in the first laser mode, and the calculation method is as follows:

[0008] in, The amplitude of the first harmonic. The value represents the second harmonic amplitude, and k is the calibration coefficient. Where L is the absorption coefficient and L is the optical path length. In the second laser mode, the alcohol gas concentration is calculated based on the Raman characteristic peak intensity and the preset calibration curve.

[0009] Furthermore, the mode switching controller can automatically switch detection modes based on ambient light intensity, vehicle sunshade film transmittance detection results, or preliminary screening concentration thresholds, or can manually switch modes upon receiving external commands.

[0010] Furthermore, the system also includes an environmental parameter sensor and a signal fusion processing module; the environmental parameter sensor is used to detect ambient temperature and humidity, light intensity and vehicle speed; the signal fusion processing module is used to combine the environmental parameters to perform weighted fusion of harmonic signals and Raman signals, and output the final alcohol concentration determination result.

[0011] Furthermore, the non-stop drunk driving detection method that integrates laser absorption spectroscopy and laser Raman spectroscopy includes the following steps: Step S1: Select the working mode according to the detection conditions and control the dual-mode laser emitting unit to emit the corresponding laser; Step S2: The first optical component converts the laser into parallel light and directs it toward the cabin of the moving vehicle; Step S3: The second optical component collects the light signals that pass through or are scattered from the vehicle cabin and converges them to the signal receiving and processing unit; Step S4: The signal receiving and processing unit performs separation processing on the optical signal: If it is an absorption spectral mode, the harmonic signal is obtained by processing the first photodetector and the lock-in amplifier; If it is in Raman spectroscopy mode, the Raman shift spectrum is obtained by processing with the second photodetector and spectrometer; Step S5: The gas concentration calculation unit calculates the alcohol gas concentration based on harmonic signals or Raman spectroscopy; Step S6: Output the detection results and perform dual-mode result comparison or fusion judgment as needed.

[0012] Furthermore, in dual-laser synchronous mode, absorption spectral signals and Raman scattering signals are acquired simultaneously, and the data is fused through a signal fusion processing module to improve the detection confidence.

[0013] Furthermore, it also includes the step of dynamically adjusting the laser power and integration time according to the vehicle speed to adapt to the signal acquisition requirements at different vehicle speeds.

[0014] Furthermore, if the absorption spectroscopy mode detects that the alcohol concentration exceeds a preset threshold, the Raman spectroscopy mode is automatically triggered for secondary verification to eliminate false alarms.

[0015] Furthermore, the test results are uploaded to the traffic management platform in real time and linked to vehicle information, supporting the tracing and statistics of drunk driving behavior.

[0016] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: This invention discloses a non-stop drunk driving detection technology, addressing the need for rapid, non-contact alcohol concentration detection in scenarios such as urban main roads, highway entrances and exits, and key nighttime road sections where vehicles do not need to slow down or stop. It innovatively integrates high-throughput screening with complex environmental interference to meet the high-specificity verification requirements of high-traffic environments. This invention utilizes a dual-mode laser emission unit, combining mid-infrared absorption spectroscopy and Raman scattering spectroscopy, to achieve a dual detection mechanism of rapid initial screening and accurate confirmation. Supplemented by environmental parameter compensation and mode switching control, it effectively addresses challenges such as sunshade films, moisture interference, and vehicle speed fluctuations, enabling real-time detection of alcohol gas concentration. This invention significantly improves the efficiency of traffic management departments in detecting and intercepting suspected drunk driving vehicles, providing strong technical support for road safety. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the composition of the non-stop drunk driving detection system in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the execution steps of the non-stop drunk driving detection method in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and thoroughly described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of the present invention.

[0019] like Figures 1-2 This invention provides a non-stop drunk driving detection system and method that integrates laser absorption spectroscopy and laser Raman spectroscopy. The embodiments of this invention are described in detail below with reference to the accompanying drawings.

[0020] The non-stop drunk driving detection system of this invention is mainly used in scenarios where vehicles do not need to slow down or stop, such as urban main roads, highway entrances and exits, and night patrol points on key road sections. It can complete the non-contact rapid detection of alcohol gas concentration when the vehicle passes through the detection area at normal driving speed, thereby assisting traffic management departments in timely detection and interception of suspected drunk driving vehicles.

[0021] The system includes a dual-mode laser emitting unit located on one side of the road, a signal receiving and processing unit located on the other side of the road, and an optical transmission unit that spans the road and connects the two sides. The dual-mode laser emitting unit and the signal receiving and processing unit are located on opposite sides of the road, while the optical transmission unit is responsible for directing the laser to the vehicle passage area and collecting the return optical signal, forming an effective optical path that crosses the lane.

[0022] Specifically, the dual-mode laser emitting unit is mounted on a roadside pillar or cantilever beam, typically at a height between 1.1 and 1.4 meters, corresponding to the exhalation range of most passenger car drivers. The signal receiving and processing unit is installed at the same height on the opposite side of the road, with the distance between them determined according to the actual road width, usually covering 2 to 4 lanes in one direction. The first and second optical components of the optical transmission unit are respectively located at the transmitting and receiving ends, achieving collimated emission and efficient collection of the laser beam through optical mirror groups.

[0023] In one embodiment, the dual-mode laser emitting unit includes a signal generator, a laser driver, a first laser, a second laser, and a mode switching controller. The signal generator is responsible for generating a composite waveform for modulating the laser, which is composed of a low-frequency sawtooth wave and a high-frequency sine wave linearly superimposed. The sawtooth wave is used to achieve wavelength scanning, causing the laser frequency to change periodically within a certain range; the sine wave serves as a reference signal for subsequent phase-locked demodulation processing.

[0024] After receiving the composite modulation signal, the laser driver modulates the current of the first laser, thereby causing the first laser to output modulated laser with a center wavelength in the mid-infrared band. Preferably, the center wavelength of the first laser is set to around 3345 nanometers, which corresponds precisely to the absorption peak of the strong CH bond stretching vibration of ethanol molecules, while avoiding the high absorption region of most vehicle windshields and sunshades in this band, thus ensuring that the laser can pass through the vehicle interior with high transmittance.

[0025] The second laser operates in the visible or near-infrared band, such as 532 nm or 785 nm. These wavelengths are relatively safe for the human eye and can effectively excite Raman scattering signals from ethanol molecules. The mode switching controller determines whether the system operates in the first laser mode, the second laser mode, or the dual-laser synchronous mode based on the current detection requirements or external commands.

[0026] In one implementation, when the ambient light is strong or vehicles generally use light-colored sunshade films, the system tends to prioritize the first laser mode and use mid-infrared absorption spectroscopy for rapid screening. When the preliminary screening results are close to the threshold or there is a lot of water vapor interference in the environment, the system can switch to the second laser mode or enable dual-mode synchronous verification to improve the detection specificity.

[0027] After receiving the laser output from the first or second laser, the first optical component of the optical transmission unit expands it into a parallel beam with a diameter of approximately 30 to 60 centimeters through a collimating lens group, and directs it in a near-horizontal manner toward the oncoming lane. This parallel beam covers the main area from the driver's seat to the passenger seat, ensuring that the path of the breath exhaled by the vast majority of passenger vehicle drivers can fully interact with the beam.

[0028] The second optical assembly, located on the opposite side of the road, includes a main collecting lens, a light trap, and an optical fiber coupler. The main collecting lens is typically designed with an aperture of 80 mm to 150 mm to collect as much transmitted light as possible through the cockpit, as well as backscattered Raman signals. The collected light signal is split into two paths by a beam splitter: one path leads to a first photodetector for absorption spectroscopy measurement, and the other path leads to a second photodetector for Raman spectroscopy analysis.

[0029] The signal receiving and processing unit is the core analytical component of the system. It contains a first photodetector, a lock-in amplifier, a second photodetector, a spectrometer, and a gas concentration calculation unit.

[0030] The first photodetector employs a mid-infrared detector with high responsivity around 3345 nm, such as an MCT detector or an InAsSb detector. Its output electrical signal reflects the intensity attenuation of the laser beam due to absorption by alcohol molecules after passing through the cabin. A lock-in amplifier uses a sine wave generated by a signal generator as a reference signal to perform phase-sensitive demodulation on the first electrical signal, extracting the first and second harmonic components. These harmonic signals are extremely sensitive to concentration changes caused by absorption and can effectively suppress interference from background light, scattered light, and electronic noise.

[0031] The second photodetector is typically a silicon-based or InGaAs detector sensitive to visible or near-infrared light, used to receive Raman scattered light. The spectrometer disperses this signal, obtaining an intensity distribution spectrum with the Raman shift as the horizontal axis. The characteristic Raman peak of ethanol molecules mainly appears at approximately 880 cm⁻¹. -1 1050cm -1 1450cm -1 Locations such as 880cm -1 The nearby CC skeleton vibration peaks are relatively strong and specific, which are important evidence for alcohol quantification.

[0032] The gas concentration calculation unit selects to use harmonic signals, Raman characteristic peak intensity, or a combination of both to invert the alcohol vapor concentration in the cabin, depending on the current operating mode.

[0033] In one implementation, when the system operates in the first laser mode, the gas concentration calculation unit primarily relies on the harmonic signals output by the lock-in amplifier for concentration inversion. The specific process is as follows: First, the amplitude of the first harmonic is obtained. and second harmonic amplitude Then, using the pre-calibrated coefficient k and absorption coefficient The concentration value C is calculated using a specific formula based on the optical path length L. This calculation process takes into account the effects of laser intensity fluctuations, background absorption, and optical path length variations, and can complete the concentration estimation within a single measurement time.

[0034] In another implementation, when the system is operating in the second laser mode, the gas concentration calculation unit first locates the position of the characteristic peak of ethanol in the Raman spectrum output by the spectrometer, then extracts the peak height or peak area as the signal intensity, and then maps the measured peak intensity to the corresponding concentration value through a calibration curve established in the laboratory using alcohol vapor of known concentration.

[0035] In dual-laser synchronous mode, two measurement results can be obtained simultaneously. The gas concentration calculation unit calculates the concentration values ​​of the two channels separately, and then determines the final reported value through a preset weighting strategy or consistency check. For example, when the difference between the two concentrations is less than a certain range, the weighted average value is taken as the final result; when the difference is large, the Raman mode result is taken as the standard, while indicating that the absorption mode may be affected by the shading film or water vapor.

[0036] The non-stop drunk driving detection system and method integrating laser absorption spectroscopy and laser Raman spectroscopy of this application are as follows: Step S1: Select the working mode according to the detection conditions and control the dual-mode laser emitting unit to emit the corresponding laser.

[0037] In actual deployment, the mode selection logic is handled by the system's central controller, which receives data from environmental parameter sensors and trigger signals from the vehicle proximity detection unit in real time. When the system is in standby mode, it defaults to using the low-power first laser mode for continuous scanning; once a vehicle enters the detection area, the system immediately decides whether to maintain the current mode or switch modes based on the overall conditions at that time.

[0038] For example, under strong sunlight at midday on a sunny day, the system preferentially selects the first laser mode because the mid-infrared absorption signal is not sensitive to ambient light interference, and the 3345 nm wavelength laser has a strong ability to penetrate most sunshade films, thus obtaining a more stable harmonic signal. At night or in cloudy or rainy weather, if the initial detection finds a suspected positive result, it automatically switches to the second laser mode to use Raman scattering signals for more specific verification.

[0039] In another implementation, when the system detects that the vehicle is using a thicker metallized sunshade film, resulting in a significant decrease in the transmittance of the 3345 nm laser, the mode switching controller will prioritize activating the second laser mode. The switching command can be issued automatically by the system's internal algorithm or triggered remotely by the traffic management center.

[0040] In step S2, the first optical component converts the laser into parallel light and directs it toward the cabin of the moving vehicle.

[0041] When a vehicle passes through the detection area at a speed of 30 km / h to 120 km / h, the first optical component needs to effectively illuminate the vehicle's cabin within a very short time window. To this end, the width of the parallel beam is typically designed to be 1.2 to 1.5 times the width of the vehicle, and its height covers the area from the driver's head to their chest. The beam's propagation direction is perpendicular to the vehicle's direction of travel or at a small angle to prolong the interaction path between the light and exhaled air.

[0042] In one embodiment, when a large bus or truck is detected passing by, the system can dynamically adjust the pitch angle of the light beam, causing the light path to pass more through the driver's cab area rather than the cargo compartment or passenger area, thereby improving detection targeting. The adjustment process is completed collaboratively by the mode switching controller and the beam pointing unit, typically pre-aiming 50 to 100 meters before the vehicle enters the detection area.

[0043] In step S3, the second optical component collects the light signals that pass through or are scattered from the vehicle cabin and converges them to the signal receiving and processing unit.

[0044] The collection efficiency of the second optical component directly affects the system's sensitivity and detection distance. The collection lens group adopts a large-aperture aspherical lens design to achieve high light collection capability within a limited space. The collected light signal first passes through an optical trap to filter out some stray light, and then is split into a transmission path and a scattering path by a beam splitter.

[0045] The light in the transmission path mainly carries absorption information and is coupled to the first photodetector after being focused; the light in the scattering path mainly carries Raman information and is also sent to the second photodetector after being focused. To reduce crosstalk, a cutoff filter is placed between the two optical paths to ensure that mid-infrared light does not enter the Raman detection channel and visible / near-infrared light does not enter the absorption detection channel.

[0046] In real-world road environments, the curvature, dirt, coating, and driving posture of vehicle glass all affect collection efficiency. Therefore, the second optical component is typically equipped with an automatic alignment assist mechanism. When a vehicle approaches, the system fine-tunes the pointing angle of the collection lens based on the vehicle's front profile recognition results, ensuring that the light spot falls as close as possible to the detector's effective surface.

[0047] Step S4: The signal receiving and processing unit performs separation processing on the optical signal: if it is an absorption spectrum mode, the first photodetector and lock-in amplifier process the signal to obtain the harmonic signal; if it is a Raman spectrum mode, the second photodetector and spectrometer process the signal to obtain the Raman shift spectrum.

[0048] In actual operation, the optical signal collected by the second optical component enters the signal receiving and processing unit, and first undergoes path separation through a beam splitting module. The beam splitting module is equipped with high-efficiency beam splitters for different wavelengths. Transmitted light in the mid-infrared band is primarily guided to the first photodetector, while scattered light in the visible to near-infrared band is reflected or transmitted to the second photodetector. This separation design ensures that optical signals generated by two different physical mechanisms can enter the subsequent processing channels without interference.

[0049] When the system operates in the first laser mode or dual laser synchronization mode and requires absorption spectral data, the first photodetector converts the received mid-infrared light into a first electrical signal. This electrical signal contains all the information about the laser intensity changing with time and wavelength, where the absorption characteristics caused by alcohol molecules manifest as periodic attenuation at a specific frequency. After receiving this first electrical signal, the lock-in amplifier uses the sinusoidal wave component generated by the signal generator as a reference signal for phase-sensitive detection. In this way, the system can accurately extract the first harmonic component with the same frequency as the sine wave and the second harmonic component with its harmonic multiple.

[0050] Specifically, the first harmonic component mainly reflects the linear part of the absorbed signal, while the second harmonic component is particularly sensitive to changes in symmetry at the center of the absorption line. In dynamic scenarios where vehicles pass by at high speeds, this harmonic extraction method can significantly suppress low-frequency noise caused by road vibrations, vehicle posture changes, and ambient light fluctuations, thus allowing the weak alcohol absorption signal to be clearly presented.

[0051] In one implementation, the integration time constant of the lock-in amplifier is dynamically adjusted according to the real-time speed of the vehicle. When the vehicle speed is low, for example, in the range of 30 km / h to 50 km / h, the integration time can be appropriately extended to 20 to 50 milliseconds to obtain a higher signal-to-noise ratio; when the vehicle speed reaches 100 km / h or above, the integration time is compressed to the range of 5 to 10 milliseconds to ensure that a single measurement can be completed during the vehicle's passage through the optical path, avoiding signal distortion.

[0052] When the system is in the second laser mode or dual-laser synchronous mode and requires Raman data, the second photodetector converts the collected scattered light into a second electrical signal. This electrical signal is typically several orders of magnitude weaker than the transmitted light, but it contains characteristic information about molecular vibrational energy level transitions. After receiving the second electrical signal, the spectrometer spatially disperses the scattered light at different wavelengths using internal gratings or prisms. Subsequently, the array detector records the intensity distribution at each wavelength, thus forming a complete Raman shift spectrum.

[0053] In Raman shift spectra, the horizontal axis is usually represented by wavenumber difference, with units of cm. -1The vertical axis represents relative light intensity. The characteristic peaks of the fingerprint region of ethanol molecules are relatively concentrated, mainly at 700 cm⁻¹. -1 Up to 1500cm -1 The range, including 880cm -1 The nearby peak corresponds to the CC skeleton vibration, 1050 cm⁻¹ -1 The corresponding CO stretching vibration is located nearby, at 1450 cm. -1 The nearby peaks correspond to the antisymmetric deformation vibrations of CH3. The positions of these peaks are relatively fixed, while the peak intensities are approximately proportional to the number density of ethanol molecules in the cabin.

[0054] In one implementation, the spectrometer's spectral resolution is set to 4 cm⁻¹. -1 Up to 8cm -1 This approach allows for clear differentiation of ethanol characteristic peaks while avoiding the signal-to-noise ratio drop and data processing burden caused by excessively high resolution. In low-light conditions at night, the system can appropriately increase the output power of the second laser or extend the single integration time to enhance the Raman signal intensity, thereby improving the reliability of characteristic peak detection. It should be noted that in dual-laser synchronous mode, data acquisition from the absorption channel and the Raman channel is performed simultaneously. The two channels are processed independently, but ultimately undergo joint analysis in the gas concentration calculation unit. This parallel acquisition method fully utilizes the opportunity of a single vehicle passing by to acquire complementary spectral information, thus achieving higher detection reliability in complex environments.

[0055] Step S5: The gas concentration calculation unit calculates the alcohol gas concentration based on harmonic signals or Raman spectra.

[0056] After receiving the harmonic signals and / or Raman shift spectra obtained from the aforementioned processing, the gas concentration calculation unit selects the appropriate concentration inversion path according to the current operating mode. In single absorption spectroscopy mode, the calculation is mainly performed using the harmonic amplitudes output by the lock-in amplifier; in single Raman spectroscopy mode, the quantification is mainly based on the intensity of characteristic peaks; and in dual mode, the results from both paths are combined.

[0057] In the absorption spectroscopy mode, the computing unit first extracts the first harmonic amplitude. and second harmonic amplitude These two amplitudes correspond to the odd and even components of the absorbed signal, respectively. Then, using the coefficient k, absorption coefficient α, and actual optical path L obtained beforehand through standard gas calibration, the concentration value C is determined according to a specific mathematical relationship. This process fully considers the effects of laser power fluctuations, optical path variations, and background gas absorption.

[0058] For example, in practical applications on urban main roads, the optical path typically fluctuates between 12 and 25 meters, with the specific value calculated in real time using the road width and beam tilt angle. The absorption coefficient α is then determined by looking up a table or making an approximate correction based on the current laser wavelength and ambient temperature. When the ambient temperature rises from 15°C to 35°C, the absorption linewidth of ethanol molecules will broaden slightly, causing the peak absorption coefficient to decrease by approximately 8% to 12%. The calculation unit will adjust the α value accordingly based on temperature sensor data to maintain consistency in concentration calculations.

[0059] In Raman spectroscopy mode, the computational unit first locates a preset characteristic peak window in the Raman shift spectrum, for example, 860 cm⁻¹. -1 Up to 900cm -1 The maximum peak value within the interval is defined as 880cm. -1 The peak intensity is representative. This intensity value is then substituted into a calibration curve established in the laboratory for concentration mapping. The calibration curve typically employs polynomial fitting or piecewise linear methods, exhibiting good linear response in the concentration range of 0 ppm to 500 ppm.

[0060] In one implementation, when the relative humidity of the environment is high, the Raman signal may be slightly interfered with by the Raman peaks of water molecules, especially at 3100 cm⁻¹. -1 Up to 3700cm -1 The characteristic peak is wide. To reduce this effect, the computing unit automatically subtracts the baseline before extracting the characteristic peak. Specifically, a linear or quadratic baseline is fitted to a flat region with no obvious ethanol signal on both sides of the characteristic peak, and then the baseline is subtracted from the original spectrum to restore the true ethanol peak shape.

[0061] When both modes are operating simultaneously, the computing unit will obtain the absorption mode concentration value C separately. abs Raman mode concentration value C raman Then, fusion is performed according to preset confidence weights. For example, when C... abs With C raman When the relative deviation is less than 15%, the weighted average of the two is taken as the final concentration; when the deviation exceeds 25%, the Raman mode result is used first, while the absorption mode result is marked as a reference value for subsequent mode switching decisions.

[0062] Preferably, the weighting coefficients are determined by comprehensively considering the current environmental parameters and the light transmittance test results of the vehicle's sunshade film. In scenarios with strong sunlight and light-colored sunshade films, the absorption mode weight can be set to 0.65 to 0.75; in scenarios at night or with a large number of vehicles using dark metallic films, the Raman mode weight can be increased to over 0.70. This adaptive weighting strategy can dynamically optimize the final output results based on actual road conditions.

[0063] Step S6: Output the detection results and perform dual-mode result comparison or fusion judgment as needed. After the gas concentration calculation unit completes the concentration inversion, the result data, along with information such as vehicle passage time, lane number, detection mode, and environmental parameters, forms a complete detection record. This record is first cached in the local storage unit and then uploaded to the traffic management platform in real time via wired or wireless communication modules.

[0064] In practical applications, the detection results are based on a three-level alarm mechanism. When the calculated alcohol concentration is below 20 ppm, it is considered negative and no intervention is required. When the concentration is between 20 ppm and 80 ppm, it is marked as a suspected positive, and the system will alert the driver on the roadside display screen or voice broadcast and notify the interception point ahead to strengthen its observation. When the concentration exceeds 80 ppm, a strong positive alarm is triggered, and the system immediately pushes vehicle characteristic information, including license plate, vehicle type, color, and time of passage, to the traffic management platform and the nearest on-duty personnel.

[0065] In one implementation, when the absorption mode first detects a concentration exceeding the initial threshold of 50 ppm, the system automatically triggers the Raman mode for secondary verification. Even if initially in single absorption mode, the laser's operating state is rapidly switched within tens of milliseconds to acquire Raman data and confirm the result. This rapid secondary verification mechanism effectively eliminates false alarms caused by sunshade absorption, interference from in-car perfume volatiles, or transient breath cloud concentration peaks.

[0066] For example, in a real-world test at a highway entrance / exit, a small car passed through the detection zone at 85 km / h. The initial concentration measured in absorption mode was approximately 92 ppm, triggering a strong positive alarm. The system then completed mode switching and acquired Raman spectra within 0.4 seconds, confirming the concentration at 880 cm⁻¹. -1 The peak intensity corresponded to a concentration of approximately 87 ppm, and the deviation between the two was within an acceptable range. The result was ultimately determined to be a true positive, and the vehicle was successfully intercepted. Subsequent breathalyzer testing confirmed a result of 89 ppm, indicating that the system has high accuracy in dynamic scenarios.

[0067] In another implementation, when multiple vehicles pass by rapidly, causing signal overlap, the system performs temporal windowing on the effective signal segments of each vehicle based on the segmentation information provided by the vehicle contour recognition unit. Subsequently, independent concentration calculations and pattern determinations are performed on each windowed segment, thereby achieving multi-target parallel detection capabilities. This processing method is particularly important during morning and evening rush hours, maintaining high single-vehicle resolution even when traffic flow reaches 15 to 25 vehicles per minute.

[0068] According to the various dependent features described in the claims, environmental parameter sensors and signal fusion processing modules can also be integrated in practical deployments. Environmental parameter sensors include temperature and humidity sensors, light sensors, and vehicle speed radar or laser speedometers. Data from these sensors, along with spectral signals, are fed into the signal fusion processing module.

[0069] The signal fusion processing module first synchronizes the data from each sensor in time, and then applies environmental compensation to the harmonic and Raman signals according to preset rules. For example, when the relative humidity exceeds 85%, the overall intensity of the Raman signal will increase due to enhanced atmospheric scattering, and the fusion module will apply a negative correction coefficient to the original peak intensity based on the humidity value; when the ambient temperature is below 5°C, the saturated vapor pressure of ethanol decreases significantly, and the fusion module will adjust the absorption coefficient and calibration curve for temperature compensation.

[0070] In one embodiment, the fusion module employs a hierarchical decision tree structure. The first layer determines whether the absorption mode result exceeds a low threshold; if not, it directly outputs a negative result. If it exceeds the low threshold, it proceeds to the second layer, which combines Raman results and environmental parameters for a comprehensive score. If the score is higher than the confidence threshold, a positive alarm is output; otherwise, it is marked as pending confirmation. This hierarchical structure effectively controls the false alarm rate while ensuring detection sensitivity. Furthermore, when the system operates in dual-laser synchronous mode, the fusion module also performs a consistency check on the two concentration values. If the deviation between the two results is less than a preset range, the detection result is considered reliable, and the fused concentration is directly output. If the deviation is large, a mode retest is triggered, or the vehicle is added to a list of vehicles requiring close monitoring, awaiting subsequent manual review or intervention from higher-level verification equipment.

[0071] In applications on key urban roads at night, the system typically operates in a dual-laser synchronous mode. The absorption channel provides rapid, high-throughput screening capabilities, while the Raman channel offers high-specificity confirmation. The combination of these two technologies enables a complete detection and reliable result output within 0.5 to 1.2 seconds of a single vehicle passing through. Actual operational data shows that, under conditions of an average vehicle speed of 75 km / h and a traffic flow of 12 vehicles per minute, the system achieves a sensitivity of over 92% for detecting alcohol vapor concentrations above 50 ppm, with a false positive rate controlled below 3%.

[0072] In another implementation, the system supports dynamic adjustment of laser power and integration time based on vehicle speed. When the vehicle speed is below 40 km / h, the laser power can be appropriately reduced to extend device life, while the integration time is extended to improve single measurement accuracy. When the speed is above 100 km / h, the laser power is increased to the safe upper limit, and the integration time is compressed to the shortest feasible value to ensure that the signal acquisition window can completely cover the vehicle cabin area.

[0073] For example, at highway tollbooth exits, vehicle speeds typically fluctuate between 20 km / h and 60 km / h. The system updates the laser drive parameters and detector integration constant every 50 milliseconds based on real-time speed radar data. When a vehicle suddenly decelerates to 25 km / h, the system immediately increases the integration time to 40 milliseconds, improving the signal-to-noise ratio of the harmonic signal by approximately 6 dB, thus more accurately capturing the weaker exhalation signals that drivers may exhibit at low speeds.

[0074] When the absorption spectroscopy mode detects an alcohol concentration exceeding a preset threshold, such as 60 ppm, the system automatically triggers the Raman spectroscopy mode for secondary verification. Even if the current mode is single absorption, the mode switching controller will complete laser switching and optical path reconfiguration within tens of milliseconds, activating the second laser and acquiring Raman scattering signals. If the secondary verification result matches the initial screening, an alarm is triggered; if there is a significant deviation, the initial screening result is marked as pending confirmation, and the vehicle image and preliminary concentration data are uploaded to the backend for manual review.

[0075] In actual road tests, this secondary verification mechanism successfully reduced the false alarm rate caused by absorption signal attenuation due to dark metallized sunshade film by about 70%. For example, a test vehicle was equipped with a metallized film with a transmittance of only 15%. The concentration measured in absorption mode was abnormally low at only 18 ppm, but after triggering the threshold, it switched to Raman mode and successfully detected the true concentration of 92 ppm, ultimately avoiding false alarms.

[0076] After the test results are uploaded to the traffic management platform in real time, they are linked to vehicle information. The uploaded information includes fields such as test time, test location, lane number, vehicle license plate number, vehicle type, vehicle color, speed, test mode, alcohol concentration value, and alarm level. This information, once entered into the platform's database, supports subsequent tracking of drunk driving behavior, statistical analysis, and management of blacklists for key vehicles.

[0077] In one implementation, when the same vehicle passes through the same checkpoint multiple times within a short period and repeatedly shows suspected positive results, the system automatically generates a high-risk warning on the platform, notifying nearby personnel to prepare for interception. This spatiotemporal correlation-based tracing mechanism can effectively identify vehicles with recurring anomalies in urban expressway networks, improving investigation efficiency.

[0078] Preferably, the upload link uses an encrypted transmission protocol to ensure the integrity and confidentiality of the detection data during transmission over the public network. Simultaneously, the platform implements multi-level access control, allowing only authorized law enforcement personnel to query and retrieve raw spectral data and intermediate concentration calculation results, supporting post-event verification and evidence preservation.

[0079] If the technical solution of this application involves personal information, the product using this solution has clearly informed the user of the personal information processing rules and obtained the user's voluntary consent before processing the personal information. If sensitive personal information is involved, the user's separate consent has been obtained before processing, and the "express consent" requirement is met. For example, a clear sign is placed at the collection device such as a camera to inform the user that they have entered the collection area, and the user's voluntary entry is considered as consent; or the processing device clearly indicates the processing rules and obtains authorization through pop-up windows or by asking the user to upload information themselves. The personal information processing rules include the processor, the purpose of processing, the processing method, and the types of personal information.

[0080] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the concept of this application. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A non-stop drunk driving detection system integrating laser absorption spectroscopy and laser Raman spectroscopy, characterized in that, include: A dual-mode laser emitting unit is installed on one side of the road, a signal receiving and processing unit is installed on the other side of the road, and an optical transmission unit is installed on both sides of the road. The dual-mode laser emitting unit includes: a signal generator, a laser driver, a first laser, a second laser, and a mode switching controller; the signal generator generates a modulation signal, which includes a superposition signal of a sawtooth wave and a sine wave; the laser driver drives the first laser to output a modulated laser signal based on the modulation signal; the second laser outputs continuous or pulsed laser light for exciting Raman scattering; the mode switching controller is used to select the first laser mode, the second laser mode, or the dual-laser synchronous mode; The optical transmission unit includes a first optical component disposed on one side of the road and a second optical component disposed on the other side of the road; the first optical component is used to convert the laser output from the first laser or the second laser into parallel light and direct it toward the vehicle cabin; the second optical component is used to collect the light signals passing through or scattered from the vehicle cabin and converge them to the signal receiving and processing unit. The signal receiving and processing unit includes: a first photodetector, a lock-in amplifier, a second photodetector, a spectrometer, and a gas concentration calculation unit; the first photodetector is used to receive the transmitted / absorbed light signal collected by the second optical component and convert it into a first electrical signal; the lock-in amplifier demodulates the first electrical signal with the sine wave as a reference signal to obtain a harmonic signal; the second photodetector is used to receive the Raman scattered light signal collected by the second optical component and convert it into a second electrical signal; the spectrometer is used to analyze the Raman shift characteristic peak of the second electrical signal; the gas concentration calculation unit is used to calculate the alcohol gas concentration in the vehicle cabin based on the harmonic signal and / or the Raman shift characteristic peak.

2. The non-stop drunk driving detection system according to claim 1, characterized in that, The modulated laser signal output by the first laser has a center wavelength of 3345 nanometers, which is located at the center of the alcohol gas absorption peak and avoids the wavelength range blocked by the vehicle's sunshade film; the laser wavelength output by the second laser is in the visible or near-infrared band, which is suitable for exciting the Raman characteristic shift of ethanol molecules.

3. The non-stop drunk driving detection system according to claim 1, characterized in that, The gas concentration calculation unit calculates the alcohol gas concentration based on the harmonic signal in the first laser mode, and the calculation method is as follows: ； in, The amplitude of the first harmonic. The value represents the second harmonic amplitude, and k is the calibration coefficient. Where L is the absorption coefficient and L is the optical path length. In the second laser mode, the alcohol gas concentration is calculated based on the Raman characteristic peak intensity and the preset calibration curve.

4. The non-stop drunk driving detection system according to claim 1, characterized in that, The mode switching controller automatically switches the detection mode based on ambient light intensity, vehicle sunshade film transmittance detection results, or preliminary screening concentration threshold, or can be manually switched upon receiving external commands.

5. The non-stop drunk driving detection system according to claim 1, characterized in that, The system also includes an environmental parameter sensor and a signal fusion processing module; the environmental parameter sensor is used to detect ambient temperature and humidity, light intensity and vehicle speed; the signal fusion processing module is used to combine the environmental parameters to perform weighted fusion of harmonic signals and Raman signals, and output the final alcohol concentration determination result.

6. A non-stop method for detecting drunk driving by integrating laser absorption spectroscopy and laser Raman spectroscopy, based on the system described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Select the working mode according to the detection conditions and control the dual-mode laser emitting unit to emit the corresponding laser; Step S2: The first optical component converts the laser into parallel light and directs it toward the cabin of the moving vehicle; Step S3: The second optical component collects the light signals that pass through or are scattered from the vehicle cabin and converges them to the signal receiving and processing unit; Step S4: The signal receiving and processing unit performs separation processing on the optical signal: If it is an absorption spectral mode, the harmonic signal is obtained by processing the first photodetector and the lock-in amplifier; If it is in Raman spectroscopy mode, the Raman shift spectrum is obtained by processing with the second photodetector and spectrometer; Step S5: The gas concentration calculation unit calculates the alcohol gas concentration based on harmonic signals or Raman spectroscopy; Step S6: Output the detection results and perform dual-mode result comparison or fusion judgment as needed.

7. The method according to claim 6, characterized in that, In dual-laser synchronous mode, absorption spectrum signals and Raman scattering signals are acquired simultaneously, and the data are fused through the signal fusion processing module to improve the detection confidence.

8. The method according to claim 6, characterized in that, It also includes steps to dynamically adjust the laser power and integration time according to the vehicle speed to adapt to the signal acquisition requirements at different vehicle speeds.

9. The method according to claim 6, characterized in that, If the absorption spectroscopy mode detects that the alcohol concentration exceeds the preset threshold, the Raman spectroscopy mode will be automatically triggered for secondary verification to eliminate false alarms.

10. The method according to claim 6, characterized in that, The test results are uploaded to the traffic management platform in real time and linked to vehicle information, supporting the tracing and statistics of drunk driving behavior.

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