Roughness sensing by contract of speckle in THz ISAR image

Speckle pattern is always observed in sub-millimeter or terahertz (THz) wave ISAR image. Statistics distribution of speckle pattern is related to roughness of rough surface. In this paper, the certain relationship between root-mean-square height of rough surface and contrast of speckle pattern is built. 2D randomly rough surface is generated and imaged by single frequency ISAR. Contrast of speckle indicates how roughness varies which can be used in roughness sensing of 0.02λ to 0.15λ.