This document provides an overview of light detection and ranging (LiDAR) technology. It discusses the need for LiDAR to enable remote sensing, automation, and object identification. The basic working principle of LiDAR is described, which involves using laser pulses to measure the time it takes for light to reflect off objects and return. Key design considerations for LiDAR systems are highlighted, such as laser wavelength and power, pulse repetition rate, and challenges like background noise. Applications of LiDAR and related technologies are presented along with examples of further research opportunities.

1. Light detection and ranging (LiDAR)
Outline
• The need for laser radar (LiDAR)
• Basic concept and simple measurements using LiDAR
• Challenges in designing and operating LiDAR
Slide No 1 LIDAR Presenter: Usman Habib
• Referenc book: "LiDAR Technologies and Systems" by Paul F. McManamon, SPIE Press, July 2019.
• Simulation: LiDAR processing toolbox (MATLAB)
• Experimental demonstration: Getting Started with LiDAR, video on youtube by DroneBot Workshop (https://www.youtube.com/watch?v=VhbFbxyOI1k)

2. What will we learn?
• The need of optical/photonics devices in state-of-the-art technologies
• Working principle of LiDAR and factors to be considered for its design and operation
Prerequisite courses:
• Electronics and Circuit analysis, Semiconductor materials and devices, Signals and systems
Related courses:
• Optical engineering (Optical beams and optical detectors.)
• Lasers and application (Laser operation, characteristics of Laser beams, Meteorological
measurement systems: alignment gauging and range finding, laser beam communications.)
• Opto Electronics (optical detection.)
• Optical communication and computing (advanced applications)
Lab work and further research:
• Laser Research Laboratory
Slide No 2 LIDAR Presenter: Usman Habib

3. Applications and associated problem:
• Remote sensing over large regions > to characterize vegetation, search operations,
landscape monitoring, agricultural advancements, etc
• Full automation for mobility > 3D representation of the surroundings
Deployed technologies and challenges:
• Radars can’t provide precise object identification at longer distances due to low resolution
• Cameras are limited by the visibility conditions and require complex AI to translate
captured data into 3D interpretation
• Ultrasound is very short range
Possible solution: Optical system + Signal processing
Slide No 3 LIDAR Presenter: Usman Habib

4. Slide No 4 LIDAR Presenter: Usman Habib
How LiDAR works?
Source: https://www.geoilenergy.com/en/servicios/geoespaciales/eagle-mapping

5. • Laser generates an optical pulse
• Pulse is reflected off an object and
returns to the system receiver
• High-speed counter measures the time
of flight from the start pulse to the
return pulse
• Time measurement is converted to a
distance (the distance to the target and
the position of the transmitter is then
used to determine the elevation and
location)
• Multiple returns can be measured for
each pulse
Slide No 5 LIDAR Presenter: Usman Habib
Principle of LiDAR measurements
Source:https://www.microcontrollertips.com/lidar-
and-time-of-flight-part-2-operation/

6. Tx
Rx
Limit the
field of
view
Processing
only
correlated
photons
Optical
Narrowband
filter
Slide No 6 LIDAR Presenter: Usman Habib
Lets start with some simple mathematical calculations

7. Wavelength of the laser (transmitter):
 1064 nm using Ytterbium-doped fiber lasers
• commercially-available, detector can be Si-based, high reflectance from vegetation
and snow
• hazardous for the eyes (Class 1 lasers?), large background noise from the sunlight
 532 nm produced by frequency-doubling a 1064 nm laser
• ideal for bathymetry applications
 1550 nm using Er-doped fiber lasers
• Eye-safe lasers
• use of InGaAs or Ge photodetectors which are more expensive and have lower
detectivity than Si detectors
• strong water absorption
Slide No 7 LIDAR Presenter: Usman Habib
Laser Parameters (1/2)

8. Pulse Repetition Rate (vertical resolution)
• High pulse repetition rates enable faster acquisition of data and/or higher point cloud
density.
• The laser pulse width determines the range or vertical target resolution
Laser Power and Beam Divergence (Range)
• laser peak power, target surface diffuse reflectance, and the amount of reflected
ambient light
• Range also depends on the type of receiver (photomultiplier) and photon budget
Spectral Width and wavelength stability
• Narrow bandpass filter is utilized
Efficiency, Footprint, and Weight
Slide No 8 LIDAR Presenter: Usman Habib
Laser Parameters (2/2)

9. Summary:
• LiDAR can provide fast acquisition and low dependence on weather conditions or
terrain
• Laser properties (linewidth, wavelength, peak power, pulse repetition rate) are
important design parameters
• Challenges like background noise (sunlight, etc) and low reflective targets need to be
considered for the LiDAR design
• Higher data density enables accurate 3D mapping but it requires storage and
advanced signal processing (cost)
• Next time we will talk about:
• How beam divergence affects the LiDAR range (mathematical model)
• Signal processing (filtering, Noise cancellation, etc) for the acquired data
• Any questions or points for discussion ?
Slide No 9 LIDAR Presenter: Usman Habib