Coherent laser radar efficiency and power variance with Gaussian pointing errors

摘要

In this paper we present analytic models of the CNR loss or efficiency due to Gaussian line-of-sight pointing errors with bias, as a function of the correlation coefficient between the transmit and back-propagated local oscillator beams of a coherent laser radar. We also present theoretical expressions for the normalized signal power variance (a.k.a., the scintillation index) including speckle noise. This theory is developed for Gaussian targets, which converges to the point and extended target solutions, under the appropriate small and large diameter target limits. Including correlation between the transmit and back propagated local oscillator (BPLO) beams allows one to predict performance as a function of target range for a monostatic ladar, since at zero range the two beam positions are fully correlated, whereas at infinite range they are fully uncorrelated. Numerical experiments were developed and the resulting measurements are shown to agree with the analytic theory. The validated simulation tool is then exercised against other targets (e.g., a disk), for which closed form solutions are elusive. Analysis of the best-fit Gaussian target to represent the efficiency of a uniform disk target is also explored