Huawei's optical pulse clipper provides safety for human eyes

According to Jiwei.com, the news about Huawei making cars has recently reached a climax in public opinion, but "Huawei does not make cars, but will help car companies make good cars!" Huawei's Wuhan Optoelectronics Technology Research Center specializes in LiDAR technology. While developing and researching, it is also considering the safety risks that LiDAR brings to the human eye.

LiDAR systems generate pulses and use reflected light for imaging, detection, and ranging. To avoid eye damage, some jurisdictions have eye safety regulations for LiDAR systems that limit the power level of continuous wave lasers or the energy allowed per pulse of pulsed lasers. To obtain high-resolution distance measurements, short laser pulses on the order of 100 picoseconds are required. However, it is difficult and expensive to make lasers produce pulses short enough to meet the distance requirements of some LiDAR applications while staying within eye safety regulations.

To this end, Huawei applied for an invention patent entitled "Optical Pulse Clipper for LiDAR" (application number: 201780088566.6) on April 20, 2017, and the applicant was Huawei Technologies Co., Ltd.

Figure 1 LiDAR system block diagram

FIG1 is a block diagram of a laser radar system, which mainly includes a transmitter 100 and a receiver 200. The transmitter 100 sends light pulses toward the object to be measured, and the receiver 200 is used to receive (detect) and process the pulses reflected from the object. The transmitter 100 also includes a laser 130 and a pulse clipper 110, and the laser 130 can generate infrared or visible laser pulses. The pulse clipper 110 receives the output laser pulses from the laser and generates a chopped pulse. The calibration device 150 is mainly composed of a beam steering device that steers the chopped pulses toward the object to be measured, and scans the object by illuminating different parts of the object with the steered beam, which is received by the receiver 200 at the same time. In the flash laser radar, the beam transmission component of the beam transmission device 150 can illuminate the entire object with a single pulse by spatially spreading the chopped pulses.

The laser 130 can generate a light pulse having a first power for a first duration. The pulse clipper 110 receives the output pulse of light from the laser and is capable of generating a chopped pulse having a second duration, wherein the second duration is less than the first duration. The pulse clipper 110 is similar to a shutter, allowing the output laser beam from the laser 130 to pass through for the second duration and blocking the remainder of the pulse. Moreover, the pulse clipper 110 is not completely lossless, which results in the output of the pulse clipper 110 being less than the output of the laser 130 (the first power). However, if the loss is small, the pulse clipper 110 will generate a chopped pulse having a power level close to the first power for the second duration and significantly dropping from the first power after the second duration.

In short, Huawei's optical pulse clipper patent allows lasers to generate pulses short enough to meet the distance requirements of certain lidar applications, making it more suitable for time-of-flight lidar applications than existing methods while not exceeding the safety limits of the human eye.

Huawei does not manufacture cars, but it will make plans in the automotive field. As time goes by, Huawei's automotive chip layout has begun to take shape, and Huawei's automotive business has made important progress in three aspects: intelligent driving, intelligent electric, and intelligent networking. At present, the technological development and market education of new energy vehicles are accelerating towards maturity. Looking forward to the future, can Huawei become a giant in the automotive industry? Let us wait and see.