Research To Improve Precision Velocimetry Of Doppler Lidar

The Doppler lidar(LD) is an active remote sensing instrument that provides rangeand time-resolved measurements of radial velocite and attenuated backscatter. The principle of operation is similar to radar in that pulsesof energy are transmitted into the atmosfere. The enegy scattered back to the transceiver is collected and measured as a time-resolved signal.A Laser Doppler Velocimeter is an optical measurement device used for estimating particle velocities, by means of specific signal processing of the light scattered by seeding particles. The velocimeter set-up we used has been adapted in order to measure acoustic particle velocities in gases. Specific signal processing methods have been developed for harmonic acoustic fields in ducts without flow. The aim of this study is to measure the velocities of harmonic acoustic fields in free space with flow. Signal processing methods, estimating both flow and acoustic velocities, are presented, and their limits are discussed.Laser Doppler Velocimetry(LDV) is widely used for flow measurements but it may also be used for measuring the acoustic particle velocity. LDV is widely used in the science research and industry. LDV system is fielded a lot of technological advances, for example, as non-contact dimension, linearity lengthy permission and velocity dynamic response. But the Doppler signal is the performance of grave noise interference, wide variation of frequency and intermittent signal. These assay and manipulation immediately influences, if the whole system is superiorly or not. Thereby, removing the noise efficiently and improving the dimensional accuracy be come a considerable question for the system of LDV.