A free-fall absolute gravimeter based on laser-cooled atoms
The Absolute Quantum Gravimeter (AQG) is the first commercially available gravimeter based on laser-cooled atoms. This unique solution is the result of more than 15 years of research conducted by (LP2N and LNE-SYRTE). This ground-breaking instrument is based on the cold atom gravimeter developed at SYRTE that has successfully participated to several international key comparisons of absolute gravimeters since 2009.
The AQG measures the acceleration of a free-falling test mass in vacuum: the ballistic free-fall of an ensemble of laser-cooled atoms is accurately monitored, and the acceleration of gravity is then inferred. This technique is one of the ballistic free-fall methods proclaimed by the BIPM (Bureau International des Poids et Mesures) as an official primary method for the measurement of gravity.Based on this approach, the AQG offers very attractive features for high-precision gravity measurements both on operational and scientific levels:
- absolute gravity measurement at the µGal level in terms of stability and accuracy
- continuous data acquisition from a few seconds to several months
- simple and fast operation: automated data acquisition system and user-friendly interface, no optical alignment, no primary pumping
- very low maintenance constraints and high reliability: no moving part is used
- excellent robustness to ground vibration (without any spring-based mechanical isolation device).
This makes the AQG highly suitable for a wide range of applications in geophysics, geodesy, metrology and sub-surface imaging for civil engineering, natural resources exploration and production.
AQG Specifications:
Cycling frequency: 2 Hz
Stability: ≤ 1 µGal
Repeatability: ≤ 2 µGal
Accuracy: few µGal
Sensitivity (at quiet site): 50 µGal/√Hz 5 µGal in 1.5 min; 2 µGal in 10 min; 1 µGal in 40min
Continuous absolute measurements from a few seconds to several months. Data averaging time can be changed at will by the user depending on the application and sub-µGal stability can be achieved with longer averaging time.
