How big is a micron?
There are 25,4000 microns in one inch. 40 µm is visible to the naked eye. 5 µm can be felt with the fingertip. 0.5 µm is visible with a microscope.
A grain of beach sand is from 100 to 2000 µm. A mold spore is 10 to 30 µm. Tobacco smoke is from 0.01 to 1 µm.
Daetwyler R&D recently delivered a specialty machine with a raw accuracy of 2 µm over 2,200 mm.
Micron or Micrometer?
The symbol for micron is the Greek lowercase mu, the µ symbol.
The micrometre is a common unit of measurement ... . Some people ... use the old name micron and/or the solitary symbol µ (both of which were official between 1879 and 1967) to denote a micrometre. This practice persists in the face of official discouragement, perhaps to help disambiguate between the unit of measurement and the micrometer, a measuring device.
Editor. Micrometre. en.wikipedia.org/wiki/Micrometre. Last revised 16 February 2009. Accessed 18 February 2009.
In 1967 the 13th CGPM abolished the micron (Resolution 7). The approved SI term for the same length is micrometer (symbol, µm). Nonetheless, “micron” is still the term most commonly used in certain fields
Editor. Micron. www.sizes.com/units/micron.htm. Last revised 11 December 2006. Accessed 18 February 2009.