What Sensor Calibration Is and Why Readings Drift
Calibration maps sensor error against traceable standards, while drift stems from physical aging, mechanical strain, and environmental stress over time.
Primary Calibration Standard
Reference Artifact
High precision instrument or material that provides the foundation for a measurement hierarchy. A primary calibration standard is characterized by its direct link to the international system of units through fundamental physical constants. This device represents the highest level of accuracy within a specific metrological domain.
Uncertainty Level
Errors in these instruments are quantified through rigorous mathematical analysis and peer review. A primary calibration standard must have an uncertainty that is significantly lower than the secondary standards it is used to verify. National metrology institutes maintain these devices in strictly controlled environments to prevent environmental interference.
Metrological Chain
Traceability is established through a series of comparisons that link the factory floor to the national laboratory. Every time a primary calibration standard is used to calibrate another device, a certificate is issued to document the results. This chain ensures that a measurement made in one part of the world is equivalent to a measurement made elsewhere.
Verification Interval
Periodic checks against other high-level standards are required to ensure that the instrument has not drifted over time. The primary calibration standard is subject to international audits where different laboratories compare their results to confirm consistency. If a discrepancy is found, the laboratory must investigate the cause and correct the calibration values.
This global cooperation maintains the integrity of the worldwide measurement system.