WELCOME

LIDAR

DEEPTHI

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CONTENTS

• Introduction

• Lidar - What???

Why???

How(operating principle)???

• General Description -

Lidar Vs Radar

Technologies used in Lidar

Types of Lidar

• History of Lidar

• Basic Architecture of Lidar

• Components

• Working of Lidar

• Applications

• Advantages

• Dis-advantages

• Future Scope

• Conclusion

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

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

Regions of Electromagnetic Spectrum:

• Different Performance: on solid surface,water, on

vegetation

• pinpoint targeting

• Lidar operates in U.V,visible and infrared region

• Wavelengths in a range from about 10 m.m to the UV

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

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

TECHNOLOGIES USED

• 3 Technologies in LIDAR:-

Lasers – Laser sensor

Global Positioning System(GPS) – sensor position

Inertial Navigation System(INS) – exact sensor measurment

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)

Terrestrial Airborne

What can we measure with LIDAR?

• Clouds

• Aerosol

• Water Vapour

• Minor constituents (eg:ozone,hydro carbons)

• Temperature

BASIC ARCHITECTURE OF LIDAR

Transmitter Receiver

Data Acquisition $Control System

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

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

COMPONENTS

• Terrestrial Lidar

• Laser-Nd:YAG Laser

• Optical Telescope

• Mirror Shutter

• Photo multiplier tubes

• Detector- spectrometer

WORKING OF LIDAR

• 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

• LidarTransmitter, Scanner, and Receiver

• Aircraft Positioning –Differential GPS (with post-processing)

• Aircraft Attitude –Pitch, Roll, Yaw –Inertial Navigation System

APPLICATIONS

AGRICULTURE

ARCHAEOLOGY

BIOLOGY & CONSERVATION

HYDROLOGY

MILITARY & LAW ENFORCEMENT

PHYSICS & ASTRONOMY

METEROLOGY

GEOLOGY

• Create a topological map of the fields

Agriculture

• Provide an overview of hidden sites

• Use airborne lidars

Archaeology

OLD maps LIDAR DEM

Biology & Conservation

• Used to retrieve forest canopy structural information

• Use airborne lidars

Hydrology

• Used for Under water investigation:flood risk mapping

• Use Bathymetric Lidar

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

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

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)

Robotics

• Allowing it to map the surrounding area and avoid obstacles.

• Use Mobile Lidar

LIDAR-equipped mobile robot

Geology

• Detect fault and measure uplift

• Monitors glaciers

• Use Terrestrial & airborne lidars

Terrestrial Lidar

SHOALS-SPECIFIC APPLICATIONS

• Undersea cable routing

• Wreck detection

• Charting and safety issues

ADVANTAGES

• Higher accuracy

• Minimum human dependence

• Weather or Light independence

• Canopy penetration

• Higher data density

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.