This part of GB/T 2 2057.2 - 2008 focuses on the imagery distance relative to the mechanical reference plane in the Microscope infinity correction Optical inspection system. The imagery distance plays a key role in the Microscope imagery mass. Under the infinity correction Optical inspection system, the standard specifies the relevant parameters and technical requirements of the imagery distance in detail. This provides a basis for Microscope manufacturers to ensure the accuracy of the imagery distance during design and production, helping users in scientific research, medical and other fields to obtain stable and clear imagery effects, and promoting the standard application of Microscope in the infinity correction Optical inspection system.