In this example, it can be seen that the retroreflective return will easily be visible above the returns from the backscattered laser signal, the backscatter from the sun, the dark current, and the shot noise. The SNR of 47 dB is limited by the photodiode shot noise.

Chapter Contents:

• 6.1 Imaging Techniques
• 6.2 Range-Gate limited 2D Image Construction
• 6.3 Beamwidth Limited 3D Image Construction
• 6.3.1 Push-Broom Scanning
• 6.3.2 Mechanical Scanning
• 6.4 The Lidar Range Equation
• 6.5 Lidar System Performance
• 6.5.1 Direct Detection
• 6.5.1.1 Direct Detection Photodiodes
• 6.5.2 Heterodyne Detection
• 6.5.3 Signal to Noise Ratio and Detection Probability
• 6.5.4 Worked Example: Laser Radar Reflection from the Moon
• 6.6 Digital Terrain Models
• 6.6.1 Surface Models
• 6.6.2 Digital Landscapes
• 6.6.3 Thematic Visualization
• 6.6.3.1 Geographic Information Systems
• 6.6.3.2 3D City Models
• 6.7 Airborne Lidar Hydrography
• 6.8 3D Imaging
• 6.8.1 Radar Systems
• 6.8.2 Focused Beam Radar Imaging
• 6.8.3 Lidar Imaging
• 6.8.4 Jigsaw-Foliage Penetrating Lidar
• 6.9 Acoustic Imaging
• 6.9.1 Scanning Acoustic Microscopes
• 6.10 Worked Example: Lidar Locust Tracker
• 6.10.1 Requirement
• 6.10.2 Specifications
• 6.10.3 System Hardware
• 6.10.4 Determining the Required Aircraft Speed
• 6.10.5 Laser Power Density on the Ground
• 6.10.6 The power density of the reflected signals back at the laser
• 6.10.7 The Effect of the Sun
• 6.10.8 The Receiver
• 6.10.9 Conclusions
• 6.11 References

Inspec keywords: photodetectors; photodiodes; shot noise; retroreflectors; image sensors

Other keywords: photodiode shot noise; noise figure 47 dB; dark current; retroreflective return; laser signal backscattering; active imaging sensor

Subjects: Image sensors; Other topics in statistics; Photoelectric devices; Photodetectors