Optomechanics

Optomechanics is the manufacture and maintenance of optical parts and devices.

This includes the design and manufacture of hardware used to hold and align elements in optical systems, such as:[1] Optomechanics also covers the methods used to design and package compact and rugged optical trains, and the manufacture and maintenance of fiber optic materials

A typical Porro prism binoculars design showing the arrangement of lenses in the optical train and the line of sight
Galilean binoculars