Basic Principles of Metrology
Donald A. Kelley
Professor Emil Hazarian
QAS-347: Dimensional Metrology
29 November 2012
Basic Principles of Metrology
Imagine a world with no regard for accuracy. What would happen if no one could agree on terms of time, length, weight, or the amount of electrical energy in a volt?
Advances in electricity and electronics during the past century have made accurate measurement of many different properties essential. We wake up to electrical alarm clocks, cook in microwave ovens, and regulate the heat in our homes with thermostats. These devices depend on accurate voltages, currents and resistances to function properly.
Metrology [1] is the science of measurement, providing accuracy we need to succeed in business and our personal lives. It is within metrology, that definitions for measurements are agreed upon.
Calibration is the action of metrology. Through calibration, accuracy is measured and integrity established. Calibration is the process that provides confidence our measurement results are accurate.
SI Units
An instrument often creates a measurement as a physical means of determining a quantity or variable. Measurement correlates numbers to quantities such as: a pounds, gallons, volts or miles. A quantity is a number and a unit of measure people understand and agree with.
So, how are the number and units assigned? Someone had to say, “This is what is meant when I say kilogram/meter/liter/volt/ampere.” This is where definitions come into play. A standard unit (SI) is merely the agreed upon definition of a unit of measure. A unit might be mass (kilogram), length (meter), time (second), electric current (ampere), volt and so on. The “caretaker” for these internationally agreed upon defined units is the International Committee of Weights and Measures (Bureau International des Poids et Mesures (BIPM)) [2], located in France. Units are agreed upon between countries via treaty.
The abbreviation SI is taken from its French name, Système International
Professor Emil Hazarian
QAS-347: Dimensional Metrology
29 November 2012
Basic Principles of Metrology
Imagine a world with no regard for accuracy. What would happen if no one could agree on terms of time, length, weight, or the amount of electrical energy in a volt?
Advances in electricity and electronics during the past century have made accurate measurement of many different properties essential. We wake up to electrical alarm clocks, cook in microwave ovens, and regulate the heat in our homes with thermostats. These devices depend on accurate voltages, currents and resistances to function properly.
Metrology [1] is the science of measurement, providing accuracy we need to succeed in business and our personal lives. It is within metrology, that definitions for measurements are agreed upon.
Calibration is the action of metrology. Through calibration, accuracy is measured and integrity established. Calibration is the process that provides confidence our measurement results are accurate.
SI Units
An instrument often creates a measurement as a physical means of determining a quantity or variable. Measurement correlates numbers to quantities such as: a pounds, gallons, volts or miles. A quantity is a number and a unit of measure people understand and agree with.
So, how are the number and units assigned? Someone had to say, “This is what is meant when I say kilogram/meter/liter/volt/ampere.” This is where definitions come into play. A standard unit (SI) is merely the agreed upon definition of a unit of measure. A unit might be mass (kilogram), length (meter), time (second), electric current (ampere), volt and so on. The “caretaker” for these internationally agreed upon defined units is the International Committee of Weights and Measures (Bureau International des Poids et Mesures (BIPM)) [2], located in France. Units are agreed upon between countries via treaty.
The abbreviation SI is taken from its French name, Système International