Optical monitoring system for monitoring operating conditions in a tuyere zone of a blast furnace, said optical monitoring system comprising: a light deflecting device configured for connection to a rear portion of a blowpipe such that the tuyere, the blowpipe and the light deflecting device are positioned along a common axis; a peep sight arranged in a first face of said light deflecting device for allowing an operator to monitor the operating conditions in the tuyere zone with the naked eye; an optical sensor arranged in a second face of said light deflecting device for electronic monitoring of the operating conditions in the tuyere zone; a light deflector arranged within said light deflecting device for directing incident light from the tuyere zone towards said peep sight and towards said optical sensor characterized in that, said light deflecting device comprises a housing with a spherical body rotatably arranged therein, said spherical body comprises, a first passage which is, when said light deflecting device is connected to the rear portion of the blowpipe, facing the tuyere for allowing incident light from the tuyere zone to enter the spherical body; a second passage facing said peep sight; a third passage facing said optical sensor; wherein said first, second and third passages (62, 68, 72) are configured so as to meet each other within said spherical body; said light deflector is arranged within said spherical body at the intersection of said first, second and third passages (62, 68, 72); said light deflecting device further comprises an opening in a third face thereof for accessing the spherical body and allowing rotation of the spherical body within said housing; said spherical body comprises a socket facing said opening in said third face of said light deflecting device allowing the insertion of an adjustment tool for rotating the spherical body within said housing; said opening in said third face of said light deflecting device is a guiding slot whose width is substantially the same as a diameter of said socket; wherein a linear movement of said socket along the guiding slot causes said spherical body to rotate about a first rotation axis, and wherein a rotational movement of said socket causes said spherical body to rotate about a second rotation axis. a light deflecting device configured for connection to a rear portion of a blowpipe such that the tuyere, the blowpipe and the light deflecting device are positioned along a common axis; a peep sight arranged in a first face of said light deflecting device for allowing an operator to monitor the operating conditions in the tuyere zone with the naked eye; an optical sensor arranged in a second face of said light deflecting device for electronic monitoring of the operating conditions in the tuyere zone; a light deflector arranged within said light deflecting device for directing incident light from the tuyere zone towards said peep sight and towards said optical sensor characterized in that, said light deflecting device comprises a housing with a spherical body rotatably arranged therein, said spherical body comprises, a first passage which is, when said light deflecting device is connected to the rear portion of the blowpipe, facing the tuyere for allowing incident light from the tuyere zone to enter the spherical body; a second passage facing said peep sight; a third passage facing said optical sensor; wherein said first, second and third passages (62, 68, 72) are configured so as to meet each other within said spherical body; a first passage which is, when said light deflecting device is connected to the rear portion of the blowpipe, facing the tuyere for allowing incident light from the tuyere zone to enter the spherical body; a second passage facing said peep sight; a third passage facing said optical sensor; wherein said first, second and third passages (62, 68, 72) are configured so as to meet each other within said spherical body; said light deflector is arranged within said spherical body at the intersection of said first, second and third passages (62, 68, 72); said light deflecting device further comprises an opening in a third face thereof for accessing the spherical body and allowing rotation of the spherical body within said housing; said spherical body comprises a socket facing said opening in said third face of said light deflecting device allowing the insertion of an adjustment tool for rotating the spherical body within said housing; said opening in said third face of said light deflecting device is a guiding slot whose width is substantially the same as a diameter of said socket; wherein a linear movement of said socket along the guiding slot causes said spherical body to rotate about a first rotation axis, and wherein a rotational movement of said socket causes said spherical body to rotate about a second rotation axis. wherein a linear movement of said socket along the guiding slot causes said spherical body to rotate about a first rotation axis, and wherein a rotational movement of said socket causes said spherical body to rotate about a second rotation axis.