System for generating at least one signal representative of the profile of an outer surface of a medium having a median plane and having a relative speed V with respect to the system in a direction U, comprising: - A first light source able to emit a first Gaussian beam of coherent and monochromatic light, the wavelength λ 1 of which is adapted to the optical absorption characteristics of the medium, along a first optical path; - A first sensor able to evaluate the effects of electromagnetic interference between a portion of the first emitted beam of light and a portion of the beam of light backscattered from the outer surface of the medium of the first beam of light, and delivering an electrical signal; - At least one optical splitter element located upstream of the first sensor, redirecting a portion of the first beam of light located on the first optical path, the other portion of the first beam of light being a second beam of light following a second optical path; - At least one focusing lens (5, 6) located upstream or downstream of the at least one optical splitter element on the first and/or the second optical path (11, 12) for focusing all or part of the beam of light at a focusing distance f and defining an upstream optical path (11', 12'), and - A means for routing the at least one second beam of light, comprising at least one mirror able to redirect at least a portion of the second optical path in the direction of the first optical path such that the length of the first optical path is different from the length of the second optical path, wherein the two optical paths (11', 12') are coplanar, the combination of the focusing distance (f1, f2) and the optical path (11', 12') for each beam of light defines two distinct geometric points d1 and d2 corresponding to the focal points of each beam of light, the distance between the geometric points d1 and d2 is greater than the greatest Rayleigh length of the first and second Gaussian beams of light and the direction vectors of the first and second optical paths (11', 12') define an angle θ greater than or equal to 3 degrees, the system being able to be placed such that: - each direction vectors of a optical path (11', 12') defines an angle of at least one degree with respect to the normal to the outer surface of the medium along the direction U, - the two geometric positions d1 and d2 surround the median plan of the outer surface of the medium - A first light source able to emit a first Gaussian beam of coherent and monochromatic light, the wavelength λ 1 of which is adapted to the optical absorption characteristics of the medium, along a first optical path; - A first sensor able to evaluate the effects of electromagnetic interference between a portion of the first emitted beam of light and a portion of the beam of light backscattered from the outer surface of the medium of the first beam of light, and delivering an electrical signal; - At least one optical splitter element located upstream of the first sensor, redirecting a portion of the first beam of light located on the first optical path, the other portion of the first beam of light being a second beam of light following a second optical path; - At least one focusing lens (5, 6) located upstream or downstream of the at least one optical splitter element on the first and/or the second optical path (11, 12) for focusing all or part of the beam of light at a focusing distance f and defining an upstream optical path (11', 12'), and - A means for routing the at least one second beam of light, comprising at least one mirror able to redirect at least a portion of the second optical path in the direction of the first optical path such that the length of the first optical path is different from the length of the second optical path, wherein the two optical paths (11', 12') are coplanar, the combination of the focusing distance (f1, f2) and the optical path (11', 12') for each beam of light defines two distinct geometric points d1 and d2 corresponding to the focal points of each beam of light, the distance between the geometric points d1 and d2 is greater than the greatest Rayleigh length of the first and second Gaussian beams of light and the direction vectors of the first and second optical paths (11', 12') define an angle θ greater than or equal to 3 degrees, the system being able to be placed such that: - each direction vectors of a optical path (11', 12') defines an angle of at least one degree with respect to the normal to the outer surface of the medium along the direction U, - the two geometric positions d1 and d2 surround the median plan of the outer surface of the medium - each direction vectors of a optical path (11', 12') defines an angle of at least one degree with respect to the normal to the outer surface of the medium along the direction U, - the two geometric positions d1 and d2 surround the median plan of the outer surface of the medium