GAJENDRA KUMAR EC 3rd YR. ROLL NO.- 0800131040 LIDAR GAJENDRA KUMAR EC 3rd YR. ROLL NO.- 0800131040

CONTENTS Introduction LIDAR- What??? Why??? MADE BY: MANISH KR. CONTENTS Introduction LIDAR- What??? Why??? How(operating principle)??? Traditional photography VS Lidar Components and Characteristics

LIDAR Light Detection And Ranging is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser.

General Description LIDAR uses ultraviolet, visible, or near infrared light to image objects and can be used with a wide range of targets, including non-metallic objects, rocks, rain, chemical compounds, aerosols, clouds and even single molecules.[1] A narrow laser beam can be used to map physical features with very high resolution.

HOW???? Each time the laser is pulsed: 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 airplane is then used to determine the elevation and location) Multiple returns can be measured for each pulse

COMPONENTS:: LASER SCANNER AND OPTICS PHOTODETECTOR AND RECEIVER POSITION AND NAVIGATIONAL SYS.

LASER -600–1000 nm lasers are most common for non scientific applications -Airborne topographic mapping lidars generally use 1064 nm diode pumped YAG lasers -Better target resolution is achieved with shorter pulses, provided the LIDAR receiver detectors and electronics have sufficient bandwidth[1].

SCANNER AND OPTICS How fast images can be developed is also affected by the speed at which it can be scanned into the system . There are several options to scan the azimuth and elevation, including dual oscillating plane mirrors, a combination with a polygon mirror, a dual axis scanner

PHOTODETECER Two main photodetector technologies are used in lidars: solid state photodetectors, such as silicon avalanche photodiodes, or photomultipliers The sensitivity of the receiver is another parameter that has to be balanced in a LIDAR design.

NAVIGATIONAL SYS. LIDAR sensors that are mounted on mobile platforms such as airplanes or satellites require instrumentation to determine the absolute position and orientation of the sensor. Such devices generally include a Global Positioning System receiver and an Inertial Measurement Unit (IMU).

BASIC PRINCIPLE Similar principle to RADAR – pulses of light emitted into the atmosphere and scattered back by clouds, aerosols or air molecules Light collected by a telescope Spectrometers or interference filters isolate wavelength concerned Photon-counting or analogue detection Time-of-flight gives scattering height z=2ct

TRADITIONAL PHOTOGRAPHY VS LIDAR 1.Day time collection only 2. Complicated and sometimes unreliable procedures 3. Planimetric accuracy is better than vertical* 1.Day or night data acquisition 2.Direct acquisition of 3D collection 3. Vertical accuracy is better than planimetric*

APPLICATIONS AGRICULTURE ARCHAEOLOGY BIOLOGY & CONSERVATION GEOLOGY HYDROLOGY METROLOGY