In order to detect drunk drivers on the road, police officers first observe for signs of erratic driving behavior, such as failing to stop, swerving, speeding, or even driving too slowly. Once the vehicle is stopped, an officer then conducts a series of tests that help determine the driver’s blood alcohol level. Currently, the most widely used device for testing a person’s BAC is the Breathalyzer (Datamaster DMT in Minnesota).
According to a recent article at smithsonianmag.com, sometime in the future, however, a new method may be available to help local authorities detect drunk drivers remotely – lasers.
Earlier this year, a team of Polish researchers at Warsaw’s Military University of Technology announced that a new laser detector was being developed to detect high BAC levels from up to 20 meters away, measuring a laser beam’s reflection through a car window.
How exactly does this laser work?
The researchers shared that a laser emitter and receiver sit by one roadside, while a mirror sits on the other side. When a vehicle passes, a laser beam is sent through the car’s window via the emitter, enabling it to bounce off the mirror. The laser beam sent is at a wavelength that can be absorbed easily by any type of alcohol vapor. This means that any loss of power means that there is a presence of alcohol in the vehicle.
Since the alcohol absorbs the beam, the lower the power that is measured equates to the higher the concentration of alcohol in the vehicle. If there is no absorption, then there is no alcohol.
This method, known as standoff detection, is similar to what the military uses to detect hazardous materials, improvised explosive devices, and chemical weapons. Even speed guns make use of a laser signal reflection, although the light is bounced off passing cars and not stationary mirrors.
If alcohol vapors are indeed detected in the vehicle, a message with a photo of the vehicle and its license plate is immediately forwarded to a police officer that is waiting further down the road. The officer may then stop the car and use conventional field sobriety tests to check for signs of intoxication.
Of course, the system is far from perfect and still needs to be refined to increase its accuracy and the overall distance in which it can measure BAC levels. While researchers were able to detect alcohol vapors at concentrations as low as .01 percent, they must still be able to figure out issues such as how to maintain reading accuracy with open car windows and solar screens on side windows.
At the moment, the laser is also able to identify vehicles where the passengers are intoxicated and not the driver, as well a when there is spilled alcohol in the car. It also must first be discussed whether or not this new method will be an infringement of an individual’s privacy.
Once finalized and finally ready for use, however, the powerful laser could drastically change how our officers monitor the roads for cases of drunk driving by greatly reducing the total number of cars that need to be checked. Of course, police will still need to have reasonable suspicion to believe that a driver may be intoxicated in order to pull a driver over – even with the laser.
Source: “Lasers Could Detect Drunk Drivers on the Road”, published on www.smithsonianmag.com