This standard specifies the use of Si (111) crystal surface atomic step height z atomic force microscope sample calibration to standard measurement method. This standard applies to work under atmospheric or vacuum atomic force microscope, and the z order to achieve maximum magnification, ie z displacement in the nanometer and sub-nanometer range, which is the atomic force microscope is used to detect the semiconductor surface, optical devices surfaces and other high-tech component surface frequently used detection range. This standard does not indicate that all possible security problems in the application of this standard, the user has the responsibility to take appropriate safety and health practices and to ensure compliance with the relevant regulations of the condition.