MSGID: 1:317/3 63e5c863   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Compact, non-mechanical 3D lidar system could make autonomous driving   
   safer    
    Unique, chip-based light source allows scanning lidar to be combined with   
   3D flash lidar    
      
     Date:   
         February 9, 2023   
     Source:   
         Optica   
     Summary:   
         A new system represents the first time that the capabilities of   
         conventional beam-scanning lidar systems have been combined with   
         those of a newer 3D approach known as flash lidar. The nonmechanical   
         3D lidar system is compact enough to fit in the palm of the hand and   
         solves issues of detecting and tracking poorly reflective objects.   
      
      
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   FULL STORY   
   ==========================================================================   
   Our roads might one day be safer thanks to a completely new type of system   
   that overcomes some of lidar's limitations. Lidar, which uses pulsed   
   lasers to map objects and scenes, helps autonomous robots, vehicles and   
   drones to navigate their environment. The new system represents the first   
   time that the capabilities of conventional beam-scanning lidar systems   
   have been combined with those of a newer 3D approach known as flash lidar.   
      
      
   ==========================================================================   
   In Optica, Optica Publishing Group's journal for high-impact research,   
   investigators led by Susumu Noda from Kyoto University in Japan describe   
   their new nonmechanical 3D lidar system, which fits in the palm of the   
   hand. They also show that it can be used to measure the distance of poorly   
   reflective objects and automatically track the motion of these objects.   
      
   "With our lidar system, robots and vehicles will be able to reliably   
   and safely navigate dynamic environments without losing sight of poorly   
   reflective objects such as black metallic cars," said Noda. "Incorporating   
   this technology into cars, for example, would make autonomous driving   
   safer."  The new system is possible thanks to a unique light source the   
   researchers developed called a dually modulated photonic-crystal laser   
   (DM-PCSEL). Because this light source is chip-based it could eventually   
   enable the development of an on-chip all-solid-state 3D lidar system.   
      
   "The DM-PCSEL integrates non-mechanical, electronically controlled beam   
   scanning with flash illumination used in flash lidar to acquire a full 3D   
   image with a single flash of light," said Noda. "This unique source allows   
   us to achieve both flash and scanning illumination without any moving   
   parts or bulky external optical elements, such as lenses and diffractive   
   optical elements."  Combining scanning and flash illumination Lidar   
   systems map objects within view by illuminating those objects with laser   
   beams and then calculating the distance of those objects by measuring the   
   beams' time of flight (ToF) -- the time it takes for the light to travel   
   to objects, be reflected and then return to the system. Most lidar systems   
   in use and under development rely on moving parts such as motors to scan   
   the laser beam, making these systems bulky, expensive and unreliable.   
      
   One non-mechanical approach, known as flash lidar, simultaneously   
   illuminates and evaluates the distances of all objects in the field of   
   view with a single broad, diffuse beam of light. However, flash lidar   
   systems can't be used to measure the distances of poorly reflective   
   objects like black metallic cars due to the very small amount of light   
   reflected from these objects. These systems also tend to be large   
   because of the external lenses and optical elements needed to create   
   the flash beam.   
      
   To address these critical limitations, the researchers developed the   
   DM-PCSEL light source. It has both a flash source that can illuminate a   
   wide 30DEGx30DEG field of view and a beam-scanning source that provides   
   spot illumination with 100 narrow laser beams.   
      
   They incorporated the DM-PCSEL into a 3D lidar system, which allowed them   
   to measure the distances of many objects simultaneously using wide flash   
   illumination while also selectively illuminating poorly reflective objects   
   with a more concentrated beam of light. The researchers also installed a   
   ToF camera to perform distance measurements and developed software that   
   enables automatic tracking of the motion of poorly reflective objects   
   using beam-scanning illumination.   
      
   Measuring objects with varying reflectivity "Our DM-PCSEL-based 3D lidar   
   system lets us range highly reflective and poorly reflective objects   
   simultaneously," said Noda. "The lasers, ToF camera and all associated   
   components required to operate the system were assembled in a compact   
   manner, resulting in a total system footprint that is smaller than a   
   business card."  The researchers demonstrated the new lidar system by   
   using it to measure the distances of poorly reflective objects placed   
   on a table in a lab. They also showed that the system can automatically   
   recognize poorly reflective objects and track their movement using   
   selective illumination.   
      
   The researchers are now working to demonstrate the system in practical   
   applications, such as the autonomous movement of robots and vehicles. They   
   also want to see if replacing the ToF camera with a more optically   
   sensitive single- photon avalanche photodiode array would allow the   
   measurement of objects across even longer distances.   
      
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   ==========================================================================   
   Story Source: Materials provided by Optica. Note: Content may be edited   
   for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Menaka De Zoysa, Ryoichi Sakata, Kenji Ishizaki, Takuya Inoue,   
      Masahiro   
         Yoshida, John Gelleta, Yoshiyuki Mineyama, Tomoyuki Akahori,   
         Satoshi Aoyama, Susumu Noda. Non-mechanical three-dimensional LiDAR   
         system based on flash and beam-scanning dually modulated photonic   
         crystal lasers.   
      
         Optica, 2023; 10 (2): 264 DOI: 10.1364/OPTICA.472327   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230209114747.htm   
      
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