## 5 LiDAR 3D Point-Cloud Acquisition Techniques
### Laser Scanning
#### 5.1.2 Solid-State LiDAR Scanners  
A solid-state LiDAR has the properties of a solid-state camera and line scanners. The FoV 3D data are scanned by an oriented LiDAR beam. More recent examples of solid-state LiDAR sensors incorporate technologies such as MEMS or beam steering that can manipulate the laser beam to scan a much wider FoV than a typical ToF sensor. In similar cases, these LiDAR sensors can capture up to a 270\({}^{\circ}\) horizontal FoV. These solid-state sensors have no or fewer moving parts, which makes them less expensive and more reliable than a typical mechanical scanning LiDAR sensor (Table 2). The scan light is oriented by a micro-dimensional mirror, in the MEMS scanner. The mirrors can be oriented in two axes as perpendicular with pre-programmed electronic signals. The tilt angle of the mirror varies when applying a signal, so the emitted light beam is modified to measure a specific point in the scene. In this way, the beam is directed so that \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Brand/Model**} & **LW** & **FoV** & **Range** & \multirow{2}{*}{**Max. Range**} & **Measuring Speed** & **Range Accur.** \\  & **(nm)** & **(H\({}^{\circ}\)\(\times\) V\({}^{\circ}\))** & & & & \\ \hline Leica/BLK360 & 830 & 360 \(\times\) 270 & Phase-shift & 45 m & 680,000 pts/s & 7 mm@20 m \\ Leica/RTC360 & 1550 & 360 \(\times\) 300 & Phase-shift & 130 m & 2 M pts/s & 0.5 mm@20 m \\ Leica/ScanStatiP40 & 1550 & 360 \(\times\) 290 & Phase-shift & 270 m & 1 M pts/s & 0.5 mm@50 m \\ Z + F/IMAGER 5016 & 1500 & 360 \(\times\) 320 & Phase-shift & 365 m & 1.1 M pts/sec & 1 mm + 10 ppm \\ RIEGL/VZ-6000 & N.Inf. & 360 \(\times\) 60 & Pulsed & 6000 m & 222,000 pts/s & 15 mm@150 m \\ RIEGL/VZ-4000 & N.Inf. & 360 \(\times\) 60 & Pulsed & 4000 m & 222,000 pts/s & 15 mm@150 m \\ RIEGL/VZ-400i & N.Inf. & 360 \(\times\) 100 & Pulsed & 800 m & 500,000 pts/s & 5 mm@100 m \\ FARO/Focus Pre 350 & 1553.5 & 360 \(\times\) 300 & Phase-shift & 350 m & 2 M pts/s & 1 mm@25 m \\ OPTECH/ Polaris & 1550 & 360 \(\times\) 120 & Pulsed & 2000 m & 2 M\(\mathrm{m}\)ze & 5 mm@100 m \\ Topcom/GLS-2200 & 1064 & 360 \(\times\) 270 & Pulsed & 500 m & 120,000 pts/s & 3.1 mm@150 m \\ Trimble/TX8 & 1500 & 360 \(\times\) 317 & Pulsed & 340 m & 1 M pts/s & \(<\)2 mm \\ PENTAX/S-3180V & Na & 360 \(\times\) 320 & Pulsed & 187.3 m & 1.016 M pts/s & \(<\)1 mm \\ Maptek XR3 & N.Inf. & 360 \(\times\) 90 & Pulsed & 2400 m & 400,000 pts/s & 5 mm@65 m \\ GVI/LiPod & 903 & 360 \(\times\) 30 & Pulsed & 100 m & 600,000 pts/s & \(<\)3 cm \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical specifications of mechanical LiDAR (LW: Laser Wavelength). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Brand/Model**} & **LW** & \multirow{2}{*}{**LO**} & **FoV** & **Max.** & \multirow{2}{*}{**RR**} & **Measuring Speed** & **Range Accur.** & \multirow{2}{*}{**PC**} \\  & **(nm)** & & **(H\({}^{\circ}\)\(\times\) V\({}^{\circ}\))** & & & & & \\ \hline Velodyne/Velabit & 903 & MEMS & 90 \(\times\) 70 & 100 m & na & na & na & 3 W \\ Hesai/PandarGT-L60 & 1550 & MEMS & 60 \(\times\) 20 & 300 m\%10 & 20 Hz & 945,000 pts/s & 2 cm & 30 W \\ Livox/Mid-40 & 905 & OPA & 38.4\({}^{\circ}\) & 260 m & na & 100,000 pts/s & 2 cm & 10 W \\ Livox/Avia & 905 & OPA & 70.4 \(\times\) 77.2 & 450 m & na & 240,000 pts/s & 2 cm & 9 W \\ Intel R.Sense/L515 & 860 & MEMS & 70 \(\times\) 55 & 9 m & 30 fps & 23 M pts/s & 14 mm & 3.5 W \\ Quanergy/S-2 NSI-S00 & 905 & OPA & 50 \(\times\) 4 & 10 m\#0\%80 & 10 Hz & na & 5 cm & 6 W \\ Leishen/LS21F & 1550 & MEMS & 60 \(\times\) 25 & 250 m@\%5 & 30 Hz & 4 M pts/s & 5 cm & 35 W \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Technical specifications of solid-state LiDAR instruments. (LW: Laser wavelength, LO: Light orientation, RR: Repetition rate, PC: Power consumption). the image area is scanned. Due to the structure of the system, these mirrors may be subject to deformation in static or working conditions.