RESUMO
Speckle is a significant challenge for laser imaging systems, as it degrades the image quality. In this study, an improved theoretical model is established to describe the speckle features in free-space optical path. The model quantitatively defines the relationship between speckle contrast and five parameters: wavelength, screen surface roughness, light-spot diameter, incidence angle, and observation angle. Subsequently, the theoretical results are experimentally verified. This study enhances the theory of speckle suppression in free-space optical path, and thus enriches the existing speckle suppression theory. The speckle features based on free-space surface-scattered fields have the potential for applications related to non-imaging optics.
RESUMO
Current static speckle suppression methods have an extremely large system size and unsatisfactory performance. This study proposes a device called beam-splitting cavity (BSC) and establishes a model of speckle suppression based on the combination of BSC and a liquid-core fiber. Subsequently, a passive static speckle suppression system is constructed and the key factors affecting the speckle contrast are studied. Consequently, the speckle contrast was reduced from 30.2% to 3.1%, which is below the human-eye speckle-discrimination limit (<4%). The scheme consists entirely of passive optical elements, which are more applicable to projectors than the traditional static and dynamic speckle-suppression methods.
