Misalignment detection

A means for detecting the incorrect orientation of a component with respect to a reference orientation is described. A laser beam is directed along a reference path towards, and along the optical axis of, a lens mounted on the component so that the beam undergoes reflection at the front and rear faces of the lens to form two reflected beams. The reflected beams may be intercepted by a screen to provide a visual indication of any divergence between the beams. In the presence of any misalignment (which may take the form of lateral offset and/or tilt), the reflected beams form non-concentric spots on the screen. (author)