Scientific and Technical Report

Abstract

Advanced Materials Corporation has designed and constructed a spectro-polarimetric imaging system under contract with the Department of the Army (DAAL01-98-C-0080). The unit, which we will hereafter refer to as Spectroimager II, is a versatile spectro-polarimetric video imaging system that operates in the short wave infrared region between 900 nm and 1700 nm. It is an integrated imaging system with complete electronic control and interfaced with a standard PC. The software is user-friendly and allows easy access to the basic control parameters (filter wavelength, acoustic power level, sensitivity, retardance, etc.). In addition, it provides various data acquisition modes such as spectral data, spectrally filtered images, and real time image processing. In this Final Report, we will review the design and performance of the system and give an outline of steps for further improvement. The basic configuration of Spectroimager II is shown schematically in Fig. 1.1. At the heart of the system is the acousto-optic tunable filter (AOTF) that provides efficient, polarization-specific light filtering. The range and resolution of the AOTF depend on the crystal and transducer design. In Spectroimager II, it is optimized for 800 ^ 1800 nm to cover the range of the InGaAs imaging array (900 ^ 1700 nm). The FWHM spectral resolution is 61 /cm.