Laser displacement interferometers with subnanometer resolution in absolute ballistic gravimeters

This is a description of the overall structure of an absolute ballistic gravimeter in which a test object moves freely in a vacuum in the gravitational field. This system is intended for determining the acceleration of gravity using measurements of length and time intervals in the equation of motion of the test object. These intervals are measured by a laser displacement interferometer and a system for precise measurement of time intervals, which are incorporated in the gravimeter. Uncertainties in the measured acceleration of gravity and metrological support of absolute ballistic gravimeters for length and time measurements are discussed.