As part of the HST repair mission it is necessary to verify the performance of the correction optics before their installation in the telescope. To accomplish this precision testing a Hartmann style wavefront sensor and pupil parameter measurement tool has been designed and built. This instrument, termed the Aberrated Beam Analyzer (ABA), will be used to measure the wavefront of both aberrated HST simulators and the unaberrated output of the correction optics. In addition, the ABA measures the location, size, and obscuration ratio of the exit pupil of the system under test. Parameters such as the chief ray angle, PSF, MTF, encircled energy, and Strehl ratio are calculated from the measured data. Operation of the ABA is fully automated and is controlled via a high level scripting language. All data is permanently archived on optical disks for later analysis. The design and theory of operation of the ABA will be discussed. Particular emphasis will be given to the error budget and the measurement performance of the ABA. Some preliminary data will be presented.