Patent ID: 9110182
Filing Date: 2015-08-18
Classification: G01N,G01V

Abstract:
1. An apparatus for estimating gravitational acceleration, the apparatus comprising: a chamber configured to contain a first gas, the chamber having a longitudinal axis; a first cavity ring-down spectrometer configured to measure a density of the first gas at a first location along the longitudinal axis using a first optical cavity having a first optical axis and configured to resonate light rays that are absorbed by the first gas in the first optical cavity, wherein the first optical axis has at least a vector component perpendicular to the longitudinal axis; a second gas contained in the chamber, the second gas being lighter than the first gas, wherein the first cavity ring-down spectrometer is further configured to measure a density of the second gas at the first location; and a processor configured to receive a first density measurement from the first cavity ring-down spectrometer and to estimate the gravitational acceleration using the first density measurement, wherein the processor is further configured to calculate a change in volume of the chamber using a density measurement of the second gas.