Requirements and analysis of Multispectral Volume Scattering Meter

Abstract

The volume scattering function (VSF), which describes the angular distribution of light scattered from an incident beam, is a fundamental inherent optical property of the aquatic environment. Despite its fundamental nature, there is little known about the range of variability in the VSF in the aquatic environment. This is mainly because the measurements of the function are difficult to perform. A lot of currently used radiate transfer models are based on a very limited set of measurements, which are made over 20 years ago. For the correct calculations of the radiate transfer, it is essential to know the variations of the phase function. Instruments, which have previously been used for measuring VSF, were complicated, bulky and most importantly: they are not able to take measurements of the function in full angular range. The purpose of this document is to describe the system requirements specifications of a Multispectral Volume Scattering Meter (MVSM). Document describes a new instrument for measuring the volume scattering function of seawater and other natural waters across a hemispheric angle range. System requirements and analysis is put together following modern methodology and standards. The measurement principles implemented in the device, are based on static scatter approach. Photomultiplier tube (PMT) is used to detect scattering light at different angles. Device’s mechanistic approach involves a use of a special periscope prism and a novel light shadow method.