Polarimetric Imaging in the Environment Containing Medium and Object

Polarimetric imaging has been studied and applied to the problem of visibility restoration in various scenarios such as haze, mist and underwater. Although studies have shown that under certain conditions, circular polarimetric imaging has certain advantages over linear polarimetric imaging, however, for a complex environment containing both scattering medium and object, the performance of linear and circular polarimetric imaging is affected by many factors. In this paper, the propagation of linear and circular polarized light in the scattering medium is theoretically analyzed, then the simulation experiments under different experimental conditions are carried out and the conclusions are summarized. In order to validate the simulation results, the measurement experiments are carried out in dynamic smoke scenarios with different smoke concentrations. The results show that, the propagation of the polarized light, especially the circular polarized light, is determined by medium conditions. Generally, both the linear and circular polarimetric imaging had an ability to reduce the image degradation caused by smoke, however, under some certain environment conditions, unlike the linear polarized channels, the difference between the orthogonal circular polarized channels may be approached or even reversed, which may limit the circular polarization-based difference imaging and visibility restoration performance.

Optical anticounterfeiting photonic bilayer film based on handedness of solid-state helicoidal structure

Anticounterfeiting photonic bilayer DH-CLCsolid films were fabricated by sandwiching two CLCsolid films having different handedness. The encrypted information is only disclosed under right-handed circular polarized light.

Measurement of ellipsometric data and surface orientations by modulated circular polarized light / Messung von ellipsometrischen Daten und Oberflächenorientierungen durch moduliertes zirkular polarisiertes Licht

Ellipsometry is a widely used optical method for the characterization of materials and thin films. However, only flat or nearly flat surfaces can be measured since small deviations of the angle of incidence might lead to significant experimental errors. In order to overcome the geometrical limitations of ellipsometry, the retroreflex ellipsometry developed at Fraunhofer IOSB is used. Based on this configuration, a new illumination method is proposed. When the sample is illuminated by modulated circular polarized light (LCP and RCP), the ellipsometric parameters (Ψ, Δ) and the tilted angle (Φ) can be determined directly. Combined with reflectance measurement or prior knowledge of optical properties of samples, the surface orientation can be obtained.