Our triple-beam interferometers, which combine three interferometers in a single unit and thus allow making simultaneous, nanometer-precision, triaxial, length measurements, are intended for incorporation into customer-supplied systems. Angles may be determined with high precisions from the differences between pairs of length measurements and the respective beam separations involved. The dynamic ranges for pitch and roll measurements are approximately two minutes of arc.
 A He‑Ne‑laser emitting an ultrastable wavelength supplies all three interferometers in order that all three length measurements will be based on the same reference length. A single fiberoptic lightguide conducts its

output beam to the interferometric sensor head. Motions of the moving mirrors are converted into modulated signals that are transmitted to the electronic power-supply/ signal-processing unit.
The He‑Ne‑laser, which is frequency stabilized in cases where large displacements are to be measured, along with corrections for barometric-pressure and ambient-temperature variations, form the basis for high metric precisions. Operation of the electronic power-supply/signal-processing unit and display of measurement data employ a PC running the associated software package.