Accurate laser interferometer system for displacement measurements with 1 pm resolution

The laser interferometer technique with noise level up to 10
^-12
m is described. It is based on a precise interference fringe measuring servo-system with wide range displacement linearity. The r.m.s. deviation of displacement-to-voltage transform factor is below 1% in the range of plusmn10
⁵
periods of the interference pattern shifts. The dynamic range of available displacement amplitude is near of 210 dB. The system characteristics have been accurately tested and investigated. The examples of precise interferometer applications to geophysics and technological measurements are shown.