Our objective is to disseminate the importance of sensing geometry when comparing reflectance data from different polarimeters. Results are presented from an eye-safe laser scatterometer that was used to measure the Mueller matrix of samples under a diversity of sensing geometries, thus providing a common reference for instrument comparison. Data from three other polarimeters are compared to this reference, and apparent discrepancies are explained in terms of each instrument's unique experimental sensing geometry. Results are also provided showing that the degree of sensing geometry dependence varied widely among sample types.
Herein are discussed five straightforward field tests that are appropriate for evaluation of the performance of focal plane array (FPA) based ladar systems capable of generating high-resolution 3D imagery. The tests assess system level performance using traditional imaging targets and ladar specific targets. In addition, the tests allow comparisons to be made between the predicted performance of a ladar system and the actual performance. Analysis of actual field test ladar data is included based on appropriateness and availability of data. In the first test, range resolution is examined when the target is obscured by camouflage; the intent is to provide two pulse returns within the same instantaneous field of view (IFOV) and determine the source of the range report from different pixels within the range image with the emphasis on determining performance based on the pulse detection approach that is implemented. The second series of tests evaluates the lateral and range resolution of the FPA using standard modulation transfer function (MTF) and statistical approaches. The third test (Sect. 3.4) involves a moving target to introduce a dynamic version of the previous spatial frequency dependent tests. The fourth test (Sect. 3.5) assesses the system range performance as a function of received signal, essentially determining the performance of the system as signal-to-noise ratio (SNR) is varied. The fifth test (Sect. 3.6) assesses the uniformity of the range resolution and range accuracy of the FPA.