WIDE-ANGLE OPTICAL SYSTEM FOR CLOSED OBSERVATION Russian patent published in 1995 - IPC

FIELD: optical instrument engineering. SUBSTANCE: system has objective, erecting system and eye-piece. The objective has three identical flat-convex lenses, two of which are turned with their flat surface to the object; the third lens is concave. Two identical lenses of erecting system are identical to lenses of the objective and disposed with their flat surfaces one to the other. Distance between the last lens of the objective and the first lens the erecting system, as well as distance between the lenses of the erecting system is chosen in a specific manner. EFFECT: improved reliability of operation; improved efficiency. 2 cl, 2 dwg