Popular Science | Will LiDAR damage your eyes?

In the era of intelligent driving, safety comes first.

Are vehicles equipped with lidar really safer to drive? International insurance giant Swiss Re has given a positive answer using a test data report.

The report shows that vehicles equipped with LiDAR systems are expected to avoid up to 25% more collisions than vehicles of the same type without LiDAR, and their ability to mitigate the impact of accidents will be improved by 29%. The "effective support" for safety is also the reason why more and more smart cars, Robotaxi, and robots have chosen to be equipped with LiDAR on the road in recent years.

However, as LiDAR becomes more and more popular, people are beginning to worry: How safe is this laser-emitting device for human eyes?

Before understanding this issue, we first need to know what lidar and the laser it emits are.

LiDAR is one of the core sensors of current autonomous driving systems. It scans and detects the surrounding environment by emitting and receiving lasers. It can accurately obtain key data such as the distance, position, speed and shape of the target object in three-dimensional space. With its advantages of pixel-level imaging resolution, centimeter-level ranging accuracy, and no influence from ambient light, it provides sufficient safety redundancy for the safety of autonomous driving.

The laser of LiDAR is actually infrared light. Infrared light is everywhere in our lives, and it interacts with the human body and eyes mainly through thermal effects. To make LiDAR safe, the most important effort is to focus on infrared light.

Rigorous LiDAR product design

When the energy is low, infrared light has little effect on the temperature of materials and is very safe. Therefore, low-energy infrared light is widely used in daily life, such as electric heaters, remote control sensors, automatic faucets, and face recognition cameras.

对激光雷达而言，为确保激光不会在人眼内引起显著温度升高，必须将激光的能量控制在足够低的水平。根据公式Q=P×t（激光能量密度=功率密度×照射时间），只需要让激光照射的时间（t）足够短，或者在相同时间内功率密度（P）足够小，即可确保人眼安全。

Therefore, the most direct way for LiDAR companies to ensure product safety is to reduce laser power and ensure that the laser energy is far below the threshold of harming the human eye. In actual operation, companies will also flexibly use a variety of methods to adjust the laser energy in response to the performance requirements of different products to keep it within a safe range, such as:

Adjust the laser emission timing. By controlling the time interval of laser emission, the number of laser pulses entering the human eye in the same period of time is reduced, and the continuous absorption time of energy is reduced, thereby reducing the laser energy received by the eye. In addition, the scanning speed of each laser beam is very fast, only in microseconds, and the position of laser irradiation is constantly changing, so that the weak laser energy transmitted to the human eye will also dissipate in an instant.

Change the spot size. According to the formula P=Q/A (laser energy density = laser energy/spot irradiation area), when the energy is the same, the larger the spot, the smaller the energy density, that is, the more dispersed the laser energy. Therefore, laser radar companies will also adjust the laser energy by enlarging the spot of each laser beam.

This also explains why ordinary toy laser pens can cause harm to human eyes, but laser radars will not: on the one hand, the laser power emitted by laser radars that enters the human eye is about 10% of that of laser pens, and in the most extreme cases, it is less than half of its power entering the eye; on the other hand, laser pens emit a continuous, energy-intensive beam of light, while laser radars emit intervals of light with dispersed energy and constantly changing positions. Therefore, automotive-grade laser radar products that have undergone rigorous product design are not comparable to laser pens.

Strict international standards for laser products

Since laser energy needs to be adjusted, what standards should be used to ensure absolute safety? And how can we ensure that all laser radars on the market meet safety standards?

In fact, before LiDAR was mass-produced, strict laser product safety standards had already been promulgated internationally.

The International Electrotechnical Commission (IEC) is the world's oldest international electrotechnical standardization organization. It promulgated the IEC 60825-1 laser product safety standard as early as 1993, and has been continuously optimized with the development of the industry. This standard judges the safety of lasers from the perspectives of human eye safety and skin safety, and sets strict testing conditions for laser products to ensure that human eyes are protected from the hazards of laser radiation.

IEC 60825-1 tests lasers based on the most extreme conditions that humans may encounter:

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• The test aperture is based on the maximum pupil size in a person's lifetime - 7mm aperture.

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• The test distance is close to the shortest distance that the human eye can focus on, 100mm

In actual use, the human eye will hardly ever be exposed to lasers under such extreme conditions. IEC 60825-1 uses this extreme condition as the standard test, which fully reflects the strictness and safety of the standard.

Following the IEC 60825-1 standard, the Standardization Administration of China has also formulated the national standard for optical and radiation protection safety GB 7247.1: 2012. Based on the test results of laser products, the IEC 60825-1 standard divides laser safety into 7 levels, and the smaller the number, the higher the safety.

According to this standard, lidars used in cars and robots can reach the highest safety level of Class 1.

Rigorous LiDAR product verification

So, how can we reasonably adjust the laser energy so that LiDAR can achieve the best intelligent driving perception effect while ensuring safety? This requires LiDAR companies to have the ability to design a product development system that fully considers laser safety.

RoboSense has established a laser safety laboratory and safety testing platform for this purpose, and through a product forward design system that fully considers laser safety, it has achieved full-process laser safety verification from product pre-research, R&D to production.

Every LiDAR from RoboSense will go through dozens of rounds of simulation and real machine testing from the beginning of the R&D phase. The test items include multiple pulse energy, number of pulses, and spot size, to ensure that the performance and safety of the product can be fully balanced from the early stage of design. At the prototype stage, the LiDAR will be sent to SGS, Goebel and other international authoritative organizations for testing, and will only start formal mass production after obtaining the highest level of Class 1 certification.

As of September 2024, automotive LiDAR has already been applied in millions of products in the global market, and more than 720,000 of them are RoboSense LiDARs, providing solid safety protection for hundreds of thousands of users. So far, there has been no case of LiDAR products causing any discomfort to users' eyes.

Optimizing cutting-edge standards to make safety safer

LiDAR is a new type of sensor that has only been put into mass production in recent years. As the application fields of LiDAR are accelerating and the complexity of application scenarios is constantly increasing, the iteration speed of products is also getting faster and faster. The international community has also put forward more and higher standards for the safety regulations of LiDAR.

Since its establishment, RoboSense has been committed to improving the safety level of the LiDAR industry and actively ensuring the safety of users after the widespread use of LiDAR. In the field of laser safety, from deeply participating in the revision of standards of relevant international committees to taking the lead in the introduction and upgrading of relevant international and domestic standard systems, RoboSense has always been striving to make LiDAR a more mature general sensor.

Internationally, RoboSense is one of the first Chinese companies to join IEC TC76 (International Electrotechnical Commission Technical Committee on Optical Radiation Safety and Laser Equipment), and is deeply involved in the work of international standards such as IEC 60825-1. Domestically, RoboSense is a member of SAC TC284 (National Technical Committee for Standardization of Optical Radiation Safety and Laser Equipment) and its subordinate organization TC284/SC1 (Sub-Technical Committee on Laser Material Processing and Laser Equipment), and actively promotes the revision of the GB 7247 series of standards.

At the same time, RoboSense also took the lead in participating in standard pilot projects such as automotive photobiological safety, and joined hands with dozens of leading companies in the autonomous driving industry to jointly formulate forward-looking and leading laser safety standard systems such as "Vehicle LiDAR Test Methods" for the complex applications of LiDAR in the second half of automotive intelligence, further promoting the standardization and implementation of laser safety.

Based on the strict specifications of the continuously updated international standards and the systematic control of product safety by responsible LiDAR manufacturers, the LiDARs installed on cars and robots on the road are now "certified" and meet the highest Class 1 human eye safety level. In daily life, people can rest assured to enjoy the safe travel experience brought by LiDAR.

Since its inception, LiDAR has shouldered the natural mission of protecting safety with its perception ability that "surpasses human eyes". With the advent of the wave of changes in the intelligent driving industry, RoboSense, as an industry leader, has always believed that safety is the "greatest luxury" and the "bottom line of intelligence". Adhering to the corporate mission of "making the world safer and life smarter", RoboSense will continue to work with the entire industry to continuously create higher-quality laser safety products and standard systems, and "making safety safer" is its firm commitment.