Length Metrology
Length Metrology is the science of using physical measurement equipment to quantify the physical size of, or distance from, an object. Various physical scales can be used to determine linear dimensions, angles, physical distances, and other linear characteristics.
About Length Metrology
Length metrology refers to the many ways in which length, distance, or range can be measured. The most commonly used approaches are rulers, followed by transit-time methods and interferometric methods based upon the speed of light.
A ruler the simplest kind of length measurement tool: lengths are defined by printed marks or engravings on a stick. The metre was initially defined using a ruler before more accurate methods became available.
Gauge blocks are a common method for precise measurement or calibration of measurement tools.
For small or microscopic objects, microphotography, where the length is calibrated using a graticule, can be used. A graticule is a piece that has lines for precise lengths etched into it. Graticules may be fitted into the eyepiece or they may be used on the measurement plane.