Method and device for measuring a light flux backscattered by a dispersed medium, unperturbed by interface reflections

Device for measuring a light flux backscattered by a dispersed medium located on a first side of a wall, by interaction with a plurality of light rays emitted from the second side of said wall which is opposite the first side, said plurality of light rays being able to traverse said wall and being backscattered at least partially by said dispersed medium in the direction of receiving means located on the second side of the wall, said wall being able to be traversed by said emitted and backscattered light rays, and to be in contact with said dispersed medium, wherein said device comprises:

• means for emitting, towards said wall, a light radiation which is able to traverse the wall and to reach said dispersed medium, so that the latter can emit in turn, through said wall, a plurality of backscattered light rays with the aim of forming a backscattering spot in which at least one central zone in the form of a disc is defined, the centre of which corresponds to the luminous barycentre of the backscattering spot and the radius of which is equal to four times the maximum free transport length (1*max) of said dispersed medium, said backscattering spot being able to be imaged at least in part on said receiving means,
• means for receiving light radiation backscattered by said dispersed medium through said wall and intended to form said backscattering spot, said receiving means covering at least one direction extending from the luminous barycentre of said spot,
• means for suppressing, from light rays backscattered by said dispersed medium, light rays which have emanated from said central zone and have undergone a total reflection on the surface forming the interface of said wall with said second side,
• means for measuring a spatial sample of the profile of the light flux received by one part at least of said receiving means.