The precision of a beam splitter not only depends on its material and design but also on the accuracy of the angle at which the light beam is split. Most of the current quality inspection methods rely on inefficient and inaccurate manual observation. Historically these measurements have been limited to normal incidence transmission (T). With the large variety of beamsplitters available, the designer needs to take many factors into consideration. This article and its illustrations will go a long way toward making the correct choice less of a risk. All curves show typical performance.