Abstract: An alignment system for determining the alignment of a plurality of components has a plurality of targets (2), one target being associated with each component. An optical arrangement (4, 1) is associated with each target, for selectively providing an image of the associated target within the field of view of an optical viewing device. This arrangement enables the image of a single target to be in the line of sight of a viewing device (for example telescope), so that the depth can be determined unambiguously.