| || Inherent Optical Properties of Natural Seawater
Author : Sathyendranath, Shubha
Source : Defence Science Journal ; Vol:34(1) ; 1984 ; pp 5-18
Subject : 551.46 Oceanography
Keywords : Cnderwater applications;Optical properties;Sea water;Oceanography;Optical devices
Abstract : The inherent optical properties of pure seawater and of optically active substances generally present in seawater are briefly reviewed. Interrelationship between inherent properties and some of the important apparent properties are also presented, so that apparent properties can be calculated quite simply, if the inherent properties are known, or vice versa.
| || Error Analysis of Aerosol Extinction Cross Section Measurement due to Forward Scattering and Diffraction
Author : Zhongcai Yuan;Jiaming Shi;Jiachun Wang;Bo Xu
Source : Defence Science Journal ; Vol:59(5) ; 2009 ; pp 545-548
Subject : 53 Applied Physics
Keywords : Optical devices
Abstract : Aerosol is a useful mean in electro-optical defence. The optical transmissivity is usually used to evaluate the performance of the aerosol. However in transmissivity measurement, forward-scattered or diffracted light might reach the detector and would be incorrectly recorded as unscattered and transmitted one, which results in the final optical density rise and experimental extinction cross-section becoming erroneously low. Based on forward scattering and diffraction analysis, the beam efficiency and effective extinction efficiency are introduced to examine the error. The results indicate that large particles and detector increase the error. To minimise the error, the distance between the aerosol and the detector must be large enough, and the detector of small area and small view angle is favourable.