2kL method of the optical-path difference
additional optical path difference
angle multi-path optical system
automatic optical-path switching protection
coaxial symmetric optical path
difference in optical path
double optical path-replacement method
electron optical imaging system
electron optical imaging systems
Electro-Optical Imaging
electro-optical imaging guidance
Electro-optical Imaging Guided Systems
Electro-optical imaging system
electrooptical imaging system
endoscopic optical path