Laser displacement interferometers with subnanometer resolution in absolute ballistic gravimeters

Abstract

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

Absolute Gravity Measurements

“…The reflector in the reference arm of the interferometer is fixed by means of the passive (usually a long-period seismometer) or active vibro-isolation system. A suspended reference mirror forms a quasi-inertial reference system (see, e.g., Vitushkin et al, 2012). …”

Features of an acousto-optical two-channel laser displacement interferometer with multi-frequency photodetectors with subpycometer resolution

“…Currently, laser displacement interferometers (LDI) are actively used for high-precision control of product displacements [1][2][3][4][5][6][7][8][9][10]. The current trend of their improvement is to increase the resolution to the level of subpicometric values, less than 1 ρm [7][8][9].…”