Novel optical sight glass

The utility model relates to a novel optical sight glass, and in particular to a novel optical sight glass which is wide in observation range, adjustable in observation distance, and unlimited in observation angle. The novel optical sight glass comprises an optical guide fibre (1), and transparent glass cones (2) arranged at the both ends of the optical guide fibre (1) respectively; the bottom surfaces of the transparent glass cones (2) are projected outwards to form convex lenses, the top ends of the transparent glass cones (2) are superposed with the focuses of the convex lenses and in seamless connection with the end head of the optical guide fibre (1), and reflecting layers (3) are arranged outside the sidewalls of the transparent glass cones (2); and a protecting layer is arranged outside the optical guide fibre (1). The light rays of an object are conducted by virtue of the total-reflection optical guide property of the optical guide fibre (1), thus realizing a random adjustment for the observation rang