micrometer• And you had to sign a chit to use things like the heightgauge, the big micrometers, calipers.• Single-mode fibres also operate at 1.3 micrometres, but they have cores only a few micrometers across.• The heights of accumulation at known time intervals are measured by opticalmicrometer and the particle sizes calculated from these figures.• She appeared to be searching for dust, fussing over squaremicrometers where maybe some of it had landed.• They have a diameter of about three micrometers.