The Michelson/Fabry-Perot Interferometer base consists of a substantial casting that supports a machined and ground lathe bed at a convenient height for observation. The lathe bed has a precise 1mm pitch geared lead screw to adjust the movable mirror carriage. The large coarse adjustment knob sets the mirror position to within 0.01mm, read on a 205mm divided steel scale and a numbered dial for fractions of a millimeter. A further graduated fine adjustment knob reads to 0.0001mm, and is an excellent control for precise displacements and ring counting. The interferometer optics fixed parts are mounted on vertical steel plates.