Research Scanning Polarimeter (RSP)

Status

Operated By: 
PI

In order to demonstrate the capabilities of polarimetry an instrument that can make either ground-based, or aircraft measurements, the Research Scanning Polarimeter (RSP) has been developed by SpecTIR Corporation. This instrument has similar functional capabilities to the proposed EOSP satellite instrument. The picture above shows the assembled RSP instrument with its liquid nitrogen dewar on the left side and scanner assembly on the right. Currently data acquisition is performed on a laptop, which is shown here and gives an indication of the size of the instrument. The scientific requirements for the polarimetric measurements are satisfied by the RSP through its high measurement accuracy, the wide range of viewing angles measured and by sampling of the spectrum of reflected solar radiation over most of the radiatively significant range. The RSP instrument uses a polarization compensated scan mirror assembly to scan the fields of view of six boresighted, refractive telescopes through ±60° from the normal with respect to the instrument baseplate. The refractive telescopes are paired, with each pair making measurements in three spectral bands. One telescope in each pair makes simultaneous measurements of the linear polarization components of the intensity in orthogonal planes at 0° and 90° to the meridional plane of the instrument, while the other telescope simultaneously measures equivalent intensities in orthogonal planes at 45° and 135°. This approach ensures that the polarization signal is not contaminated by uncorrelated spatial or temporal scene intensity variations during the course of the polarization measurements, which could create false polarization. These measurements in each instantaneous field of view in a scan provide the simultaneous determination of the intensity, and the degree and azimuth of linear polarization in all nine spectral bands.

Instrument Type: 
Measurements: 
Aircraft: 
ER-2, P-3 Orion, NASA P-3