Interferometer light source and alignment aid using single-mode optical fibres

A system has been developed using optical fibres to allow accurate positioning of a light source in the collimator of an interferometer. The design reduces the obliquity effect of the source by using single-mode fibres as the light source. Alignment of the interferometer is achieved using an autocollimation technique where one fibre detects the return spot. Up to three lasers can be launched into the collimator with no speckle in the image field.