1, mechanical measuring instruments: usually use mechanical principles to measure physical quantities. For example, tape measure, vernier calipers, pressure gauges, thermocouples and so on.
2, electronic measuring instruments: the use of electronic technology to measure measuring instruments. For example, electronic balance, electronic scales, electronic thermometers.
3, optical measuring instruments: the use of optical principles of measurement measuring instruments. For example, optical microscopes, optical telescopes, optical rangefinders.
4, chemical measuring instruments: the use of chemical reactions to measure the measuring instruments. For example, chemical buret, chemical analyzer, gas analyzer.