This standard specifies the terms, definitions, types and basic parameters, technical requirements, inspection methods, signs and Encasements of Optical inspection torsion spring micrometers. The standard applies to Optical inspection torsion spring micrometers with scale intervals of 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, indication interval of +/- 100 scale indexing, and a simple diameter of 28 mm in the clamping sleeve. Optical inspection torsion spring micrometers use torsion spring elements and Optical inspection principle to convert the linear displacement of the measurement rod into the angular displacement of the index line, and read through the dial, which is widely used in high-precision dimensional measurement. Optical inspection covers the technical parameters and performance requirements of the torsion spring micrometer to ensure its measurement accuracy and Reliability.