SBIR-STTR Award

Optical target acquisition and identification meets with some severe problems under difficult lighting conditions. For example, the target object may be obscured by smoke or fog. In addition, the ability to distinguish the appropriate target may depend upon its material composition. Spectral-polarization imaging provides means of removing the effects of obscuring aerosols and means of distinguishing the material composition of the target object. This ability will be in high demand in the military sector. Its utility in aiding the scope of machine vision for industrial applications should lead to an even greater demand in the private sector. Conventional methods for detecting and identifying objects revolve around the sensing of reflected and emitted light intensity. Conventional imaging records intensity, which is the square of the electric field associated with the electromagnetic radiation field. This works well when an object to be detected has high contrast relative to its background or foreground. However, when the object exhibits low contrast against the background or foreground, identification is often blurred by the 'noise' light, which is produced by surrounding non-vital objects. The spectral and polarization signatures of the target can enhance the contrast of the target with respect to the background.

This proposal outlines a program to develop complete wavelength agile, Stokes polarization imaging systems. The effort is based on the spectacular success of the Phrase I effort of demonstrating the concept at a single pixel level, which will form the basis of the two-dimensional imaging systems. Spectral-polarimetric imaging utilizes all three characteristics of light, intensity, wavelength, and polarization to add a new dimension to imaging by providing complete information about the image. The proposed polarization based imaging systems is expected to significantly enhance the capabilities of object identification and differentiation, which will be very useful in target acquisition and identification particularly in difficult environments. For example, certain polarization states of light have been shown to be impervious to the effects of scattering by aerosols (smoke, fog, etc.). In addition, the light transmitted or reflected from an object has a polarization signature that offers means for identification of the material characteristics of the target object (e.g., ice on a wing surface). The first year milestone is to develop a fast compact spectral polarimeter operating in the IR range, followed by a milestone of delivering a imaging spectral polarimetric system in the 3Q of the second year.

Keywords:
Ellipsometry, Polarization Imaging, Spectral=Polarimetric Imaging, Wavelength Agile, Birefringent, Fabry-Perot