Telescopes in polarization lidar often modify the input polarization of the return signal, such that the telescope may significantly impact the depolarization estimates of aerosol and introduce error to the polarization lidar measurements. The error cannot be corrected by a traditional calibration constant. We present a method to correct the polarization effect of the telescope. We analyze the polarization effect of a telescope on the basis of the Mueller formalism, and introduce an algorithm for correcting the depolarization parameter of aerosol. A Newton telescope and a Cassegrain telescope are often chosen as the receiver in lidar. Their polarization models are established, and the Mueller matrices are calculated. The components of these matrices are dependent on wavelength, incident angle of the incoming light, and surface properties. The polarization impact of the telescope in lidar can be calibrated by a parameter, and the effects of different telescopes are discussed. The polarization crosstalk induced by the Newton telescope is obvious. The depolarization parameters change greatly with coating and wavelength, and they are calculated and presented. Whereas the crosstalk of a Cassegrain telescope is much smaller, the error can reach the level of 10 −3 and can be negligible. The method presented in this paper could also be upgraded by taking into account all of the optical devices instead of only the telescope.
A multi-wavelength Mie-scattering lidar is designed and established for detecting the aerosol profiles under different weather conditions. And inversion algorithm about multi-wavelength lidar signal is studied. The atmosphere observations are carried out in Xi'an city in the winter of 2013 by using the multi - wavelength lidar. The mixed-layer depth, aerosol particle size characteristics, and atmosphere extinction are studied and analyzed on haze, cloudy and sunny days. The mixed layer depth is lower on haze day and is just about 0.4 km, while it can reach 0.5-0.8 km on sunny day. The aerosol particle characteristics are discussed under different weather conditions by using two Ångström exponents, one for the short - wavelength range (355 nm/532 nm) and other for long-wavelength range (532 nm/1064 nm). The long-wavelength Ångström exponent is less than the short-wavelength Ångström exponent on haze day, and it is contrary on sunny day. The results show that there are more coase particles on pollution day. The Ångström exponents significantly decrease, and even become negative in the clouds, showing that cloud particles are relatively large.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.