Product · Gravimeters
Micro-g LaCoste FG5 Absolute Gravimeter
The original free-fall laser-interferometer absolute gravimeter that became the international reference standard for absolute gravity measurement, superseded by the improved FG5-X but still active in gravity networks and calibration labs worldwide.
This model has been discontinued by the manufacturer (superseded by the FG5-X). PartnerGeometrics sources it through the used and refurbished market — available as Refurbished, Absolute Certified, or Surplus only.
Refurbished Absolute Certified Surplus
About the Micro-g LaCoste FG5 Absolute Gravimeter
The FG5 measures the true value of gravitational acceleration by timing a reflector in free fall inside a vacuum chamber against a laser interferometer — the same measurement principle carried forward in the current FG5-X. For over two decades the FG5 was the internationally recognized reference-grade instrument used to establish absolute gravity control networks, calibrate relative and superconducting gravimeters, and support high-precision geodesy, including international gravimeter comparison campaigns.
Note: 'absolute gravimeter' is a genuine instrument-type term describing this free-fall measurement principle — distinct from PartnerGeometrics' 'Absolute Certified' condition tier described elsewhere on this site, which refers to our used-equipment certification level, not instrument physics. Many FG5 units in the field have already been through one or more factory refurbishment/upgrade cycles, and remain in daily use at national metrology institutes and universities.
| Specification | Value |
|---|---|
| Measurement principle | Free-fall laser interferometry |
| Precision class | Sub-microGal (predecessor to FG5-X) |
| Status | Discontinued — superseded by FG5-X |
| Application | Reference gravity networks, geodesy, calibration |
As a discontinued instrument, the FG5 is available from PartnerGeometrics as Refurbished, Absolute Certified, or Surplus only — see our condition tier guide for what each tier includes.