Speckle noise model for optical heterodyne line-scan imagery

An imaging system that consists of a laser scanning a surface and a heterodyne receiver that measures the backscattered field is considered. The second moment statistics of the amplitude and amplitude-squared of the output signal of the optical receiver are developed, assuming the rough surface is a random process with known mean, variance, and correlation distance properties. The mean and covariance functions of each measurement are related to the scattered field correlation function, the reflection of the surface, and the key system parameters. The resulting noise models describe both the average speckle cell size and the contrast variations in the image caused by speckle noise.