Manufacturing of a fiber optic Young's double pinhole interferometer for use as a 3-D profilometer

The method used to manufacture a Young's double pinhole interferometer is dis ussed. This interferometer is destined to be used in a surface profilometer using two wavelengths so that the zero order fringe can be determined. Hence stringent requirements are placed on the absolute length difference between the two output fibers of a single mode coupler. These requirements are discussed along with the manufacturing process. The interferometer is shown along with measurements showing a length difference on the order of 6microm.