| 摘要 |
FIELD: auxiliary optical devices allowing to watch persons or objects placed within vision field but on the outside. SUBSTANCE: optical system of door inspection hole builds bright and clear image of visitor on lusterless screen viewed both from close and far distance, up to two meters away from door. For installation of inspection hole there is needed comparably small hole in door. Inspection hole has inverting unit composed of two rectangular prisms mated with reflecting faces and three positive lenses installed in sequence and forming erect image on display which presents flat lusterless surface of collective lens facing viewer. Similar radii of curvature of spherical surfaces of biconvex intermediate and flat-convex collective lenses provides for adaptability to manufacture and reduced cost of inspection hole. EFFECT: adaptability to manufacture and reduced cost of door inspection hole. 5 cl, 2 dwg |
