The Michelson/Fabry-Pérot 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.