New Technique

1.  What is LIDAR ?
• Light Detection And Ranging
• Remote sensing technology
• Similar to RADAR
• Uses shorter wavelength of EM-spectrum
• Measures properties of scattered light
• System based on a Laser Sensor
INTRODUCTION

2.  LASER
• Light Amplification by Stimulated Emission
of Radiation.
• Laser + Receiver System=LIDAR
• Monochromatic,Directional,Coherent
• Use of Lasers
• Measure objects that are the same size or larger than its own
wavelength.
• The Scattering Process –Rayleigh,RAMAN,Fluorescence
General Description

4. •Different Performance: on solid surface,water, on
vegetation
• pinpoint targeting
• Lidar operates in U.V,visible and infrared region
Regions of Electromagnetic Spectrum:
• Wavelengths in a range from about 10 m.m to the UV

5. LIDAR RADAR
Uses optical signals(Near
IR,visible).wavelengths~1um
Uses microwave
signals.Wavelengths~1cm(Approx 100,000
times longer than Near IR)
Shorter wavelengths allow detection of
smaller objects(cloud
particles,aerosols).
Target size limited by longer wavelength
Focussed beam and high frequency
permit high spatial resolution.(<1m
horizontal).
Beam width and antenna length limit
spatial resolution(10s of meters)
Downward looking sensor Side looking sensor
Limited to clear atmospheric
conditions,daytime or nighttime
coverage.
Can operate in presence of clouds.Daytime
or Nighttime coverage.
LIDAR Vs RADAR

6. HISTORY OF LIDAR
• Christian Huelsmeyer’s, “Telemobiloscope”-1904
• LASER - theorized by Albert Einstein
1917, designed by Gordon Gould in 1957,
developed by American physicist,Theodore Maiman in 1960
• Global Positioning Systems (GPS) -1980
• First commercial airborne Lidar systems -1995

7. TECHNOLOGIES USED
• 3 Technologies in LIDAR:-
 Lasers – Laser sensor
 Global Positioning System(GPS) – sensor position
 Inertial Navigation System(INS) – exact sensor measurment

8. LIDAR TYPES
 Based on the physical process(range finders,DIAL,doppler lidar)
 Based on scattering process(Mie, Rayleigh, Raman, Fluorescence Lidar)
 Based on the platform(Groundbased, Airborne, Spaceborne)

9. Terrestrial Airborne

10. What can we measure with LIDAR?
• Clouds
• Aerosol
• Water Vapour
• Minor constituents (eg:ozone,hydro carbons)
• Temperature

12. BASIC ARCHITECTURE OF LIDAR
Transmitter Receiver
Data Acquisition $
Control System

13.  Function of Transmitter
• provide laser pulses
• consist of lasers,wavelength control system,diagnostic equipment
• determines the performance of Lidar system
 Function of Receiver
• collect $ detect returned photon signals
• consist of telescopes,filters,photon detectors,discriminators etc
• distinguishes the returned photons

14. Function of Data Acquisition & Control System
• record returned data and time-of-flight
• provide system control and coordination
• consists of multi-channel scalar,discriminator,computer and software
• enabling various data acquisition modes

15. COMPONENTS
• Terrestrial Lidar
• Laser-Nd:YAG Laser
• Optical Telescope
• Mirror Shutter
• Photo multiplier tubes
• Detector- spectrometer

16. WORKING OF LIDAR

17. • Laser-generates an optical pulse
• Return pulse
• High speed counter
• Calculate Distance :-
* Distance=(Speed of Light * Time of flight) / 2
* Speed of light : 3 x 108 m/s
dist=t2way / 2 * c

19. • LidarTransmitter, Scanner, and Receiver
• Aircraft Positioning –Differential GPS (with post-processing)
• Aircraft Attitude –Pitch, Roll, Yaw –Inertial Navigation System

20. APPLICATIONS
 AGRICULTURE
 ARCHAEOLOGY
 BIOLOGY & CONSERVATION
 HYDROLOGY
 MILITARY & LAW ENFORCEMENT
 PHYSICS & ASTRONOMY
 METEROLOGY
 GEOLOGY

21. • Create a topological map of the fields
Agriculture

22. • Provide an overview of hidden sites
• Use airborne lidars
Archaeology
OLD maps LIDAR DEM

23. Biology & Conservation
• Used to retrieve forest canopy structural information
• Use airborne lidars

24. Hydrology
• Used for Under water investigation:flood risk mapping
• Use Bathymetric Lidar

25. Military & Law enforcement
Police officer using a hand-held LIDAR speed gun
• Lidar speed gun-measure speed of vehicles
• Identifying one vehicle from the traffic stream

26. Physics & astronomy
• Measure the distance to reflectors placed on the moon
• Used in Mars-Orbiting Satellite
• Used to detect snow in Mars atmosphere
• Used to measure molecular density
• calculate temperature
Astronomical Lidar

27. Meterology
• Used for studies of atmospherics conditions , clouds and aerosols.
• Used for measurement of atm. Gases
• Measures wind speed
• Use Mie scattering ,DIAL and space-based Doppler wind Lidar(DWL)

28. Robotics
• Allowing it to map the surrounding area and avoid obstacles.
• Use Mobile Lidar
LIDAR-equipped mobile robot

29. Geology
• Detect fault and measure uplift
• Monitors glaciers
• Use Terrestrial & airborne lidars
Terrestrial Lidar

30. SHOALS-SPECIFICAPPLICATIONS
• Undersea cable routing
• Wreck detection
• Charting and safety issues

31. ADVANTAGES
• Higher accuracy
• Minimum human dependence
• Weather or Light independence
• Canopy penetration
• Higher data density

32. DIS-ADVANTAGES
Most lidar data are collected at night, but unlike radar,lidar
cannot penetrate clouds, rain, or dense haze and must be flown
during fair weather.