Abstract
An experimental study of the effect that the target transmitter apertures and receiver apertures have on the performance of a laser doppler radar is presented in this thesis. Empirical design equations are presented and methods of using these equations to predict system performance for a particular target material are described. Two important parameters are defined and have been measured together with their statistical properties, They are: beta, the 'scattering loss factor' which accounts for the power lost due to scatter at the radar target, and gamma, the 'detector loss factor' which accounts for signal loss at the detector due to inefficient mixing of the scattered light. Knowledge of these two parameters for a given target enables one to determine the signal level at the output of the detector. beta is shown to be a function of the surface material and a method of obtaining its value is described. The statistics of gamma are shown to be a function of the speckle diameter/receiver diameter ratio, but appears to contradict theoretical predictions. It is found that gamma is a function of the ratio of the speckle size to the receiver size and has been determined for ratios from 01 to 12. The statistics of gamma are presented and agree with the theoretical description. Doppler broadening, which limits the sensitivity of a Doppler system, has been measured for rotational and translational velocities. From these results the optimum optical configuration can be predicted. A general design problem is discussed to show how the parameters described can be used to predict the system performance and to determine the operational parameters.