Introduction to Metrology

• Metrology is derived from the Greek words "metron" (measurement) and "logos" (tratado).
• The objective of metrology is the study of measurement systems in any field of science.
• It studies measurement instruments and the proper way to perform measurements.
• Two characteristics of metrology are the measurement result and the measurement uncertainty.

What is Measurement?

• Measurement is a process in which a pattern or standardized element is compared to another object.
• This comparison allows assigning a numerical value.
• A measurement process aims to distinguish objects or phenomena for classification.

What is a Measurement Instrument?

• A measurement instrument is an apparatus used to measure physical magnitudes of different phenomena.
• These instruments are not ideal systems but real, and they have a series of limitations to consider.

Instrument Characteristics

• Accuracy and precision
• Error
• Resolution
• Sensitivity
• Range and scale
• Linearity

Accuracy and Precision

• Accuracy relates to how closely an instrument's indication approximates the true value of the measured quantity.
• The true or exact value is obtained through a method agreed upon by experts to be sufficiently accurate for reference.
• Precision refers to the number of significant figures representing a quantity.

Error

• Error is defined as the difference between the measured value and the true value.

Resolution

• Resolution is the smallest increment of the variable under measurement that can be reliably detected by the instrument.

Sensitivity

• Sensitivity is the smallest magnitude that the instrument can measure.

Range and Scale

• Range is defined as the difference between the maximum and minimum measurable values that the instrument can offer.
• The range can be divided into various scales or consist of a single scale.

Linearity

• Linearity expresses how constant the sensitivity of the sensor or measurement apparatus is.

Classification of Measurement Instruments

• Lengths
• Masses
• Time
• Angles
• Temperatures
• Pressure
• Flow
• Electrical

Examples of instruments and their classifications

• Lengths include flexometers, verniers, micrometers, and comparators.
• Masses include scales, balances, and catarometers.
• Time includes chronometers and clocks.
• Angles include sextants, protractors, and goniometers.
• Temperature includes thermometers and pyrometers.
• Pressure includes barometers and manometers.
• Flow includes flowmeters.
• Electrical include electrometers, ammeters, voltmeters, multimeters, and oscilloscopes.