When a micromachine works inside a narrow space, visually-equipped microdevices are indispensable. To monitor minute shapes that are impossible to observe, fiberscope-type environmental recognition devices have been developed.
O. Tohyama, O. Tohyama,
"Fiberscope-type environmental recognition devices", Proc. SPIE 3746, 13th International Conference on Optical Fiber Sensors, 37461V (1 September 1999); doi: 10.1117/12.2302057; https://doi.org/10.1117/12.2302057