[Choice of the shape of the edge zone of a square field diaphragm in flexible endoscopes].

The choice of the adequate relation K = R/a is discussed, where R is a corner radius of the field diaphragm used in flexible endoscopes with a square cross-section of the light zone in output faces of the regular bundle, and a is a distance from the diaphragm axis to the internal edge of its sides. When defining the above relation the design of the distal endoscopic head and its built-in components should be taken into consideration.