Mikrometer

Mikrometer typically refers to the micrometer, a unit of length in the metric system. It is equal to one millionth of a meter, symbolized by μm. As a derived SI unit, the micrometer is used to express dimensions on the microscopic scale. The British spelling micrometre is common in some regions, while micrometer is used in American English. Since 1960 the SI prefix micro- denotes 10^-6, making 1 μm = 1×10^-6 m; equivalently, 1 μm = 1,000 nanometers, and 1 meter contains 1,000,000 μm.

Micrometre-scale measurements appear across science and industry. Typical examples include wavelengths in the near-infrared region, the thickness of thin films and coatings, and the sizes of cells and bacteria (for instance, many bacteria range from about 0.5 to 5 μm in diameter). The unit helps compare microscopic objects and characterize materials at submillimeter scales.

The term mikrometer also designates a measuring instrument known as a micrometer or micrometer screw gauge. This device uses a calibrated sleeve and a rotating thimble with a threaded spindle to measure small distances with high precision. Readings are commonly given to 0.01 millimeter (10 μm) or, in high-precision instruments, to 0.001 millimeter (1 μm). Digital versions provide direct μm or sub-μm resolution and are widely used in manufacturing and metrology.

Notes: The spelling mikrometer reflects regional variations; the instrument and the unit are distinct but share the same root. The unit is a SI-derived unit; the instrument is a tool for measurement.