The process for aligning two axes requires, first, that the axes be made parallel to each other using the angular adjustments and then collinear using the translation adjustments. This focus positioner, a translation stage, should be oriented parallel to the optical axis. The preceding examples indicate the minimum number and type of adjustments needed to align a specific type of system. Many cases, however, require additional positioners, particularly when a single positioner cannot meet all of the performance requirements of a specific degree of freedom. Although the meaning of range and load capacity are self-evident, the meaning of resolution and error need clarification.
Resolution is defined as the smallest move that can be made by a positioner.
For manual positioners, resolution is heavily dependent upon the skill of the operator. Some people with extreme manual dexterity may be able to operate a positioner with significantly more resolution than others. For automated positioners like those incorporating stepping motors, the resolution is defined mechanically by motor-step size. In this case, each movement of a positioner is an integer multiple N of the resolution. Clearly, the components selected for a system must have resolution to match or exceed the system requirements.