An optical unit for a projective optical metrological system, configured to receive a light signal coming from a light constellation comprising a number of light sources (4A-4C), said optical unit (7; 107) comprising: - an optoelectronic image acquisition system (10; 110); - a first and a second optical circuit (OT1, OT2) configured to receive the light signal and to be traversed by a first and a second optical beam (R 1,R 2), respectively, the first and the second optical circuits (OT1, OT2) being further configured to direct, respectively, at least a first part (R 1 ') of the first optical beam (R 1) and at least a first part (R 2 ') of the second optical beam (R 2) on said optoelectronic image acquisition system (10; 110), so as to cause the simultaneous formation of two different images (I 1, I 2) of the constellation in the optoelectronic image acquisition system (10; 110); - an electronic processing unit coupled to the optoelectronic image acquisition system (10; 110) and configured to determine a number of quantities indicative of the position and/or attitude of the light constellation with respect to the optical unit, based on said two images; characterized by the fact of further comprising: - an optical receiver; and - a derivation optical circuit (16, 26) configured to optically couple the optical receiver and at least one of the first and the second optical circuits (OT1, OT2), so that the optical receiver receives an optical information signal, which is a function of at least one of the first and the second optical beams (R 1, R 2); and wherein the optical receiver is configured to demodulate digital data from the optical information signal. - an optoelectronic image acquisition system (10; 110); - a first and a second optical circuit (OT1, OT2) configured to receive the light signal and to be traversed by a first and a second optical beam (R 1,R 2), respectively, the first and the second optical circuits (OT1, OT2) being further configured to direct, respectively, at least a first part (R 1 ') of the first optical beam (R 1) and at least a first part (R 2 ') of the second optical beam (R 2) on said optoelectronic image acquisition system (10; 110), so as to cause the simultaneous formation of two different images (I 1, I 2) of the constellation in the optoelectronic image acquisition system (10; 110); - an electronic processing unit coupled to the optoelectronic image acquisition system (10; 110) and configured to determine a number of quantities indicative of the position and/or attitude of the light constellation with respect to the optical unit, based on said two images; characterized by the fact of further comprising: - an optical receiver; and - a derivation optical circuit (16, 26) configured to optically couple the optical receiver and at least one of the first and the second optical circuits (OT1, OT2), so that the optical receiver receives an optical information signal, which is a function of at least one of the first and the second optical beams (R 1, R 2); - an optical receiver; and - a derivation optical circuit (16, 26) configured to optically couple the optical receiver and at least one of the first and the second optical circuits (OT1, OT2), so that the optical receiver receives an optical information signal, which is a function of at least one of the first and the second optical beams (R 1, R 2); and wherein the optical receiver is configured to demodulate digital data from the optical information signal.