A method for visualising, in real time, a signal for the non-destructive testing of a mechanical part, the signal being emitted by a non-destructive testing device comprising: - an optical motion tracking system to which a reference coordinate system (R 0) is tied, - a sensor holder, - a rigid body, - a non-destructive testing sensor integral with the sensor holder connected fixedly to the rigid body, - a computer, the visualisation method being executed by an augmented reality visualisation device facing the mechanical part, to which an augmented reality coordinate system (R A) is tied, the method being characterised in that it comprises the following steps: - moving the non-destructive testing sensor over an examination area of the mechanical part; - simultaneously with the step of moving the non-destructive testing sensor, emitting the signal from a point of emission along an emission axis and receiving the signal by way of the sensor; - determining, by way of the computer, a cut-out of an occlusion inside the mechanical part, the cut-out being centred around the point of emission; - determining, by way of the computer, a signal visualisation surface constructed from the paths of the signal, this surface being located inside the cut-out; - visualising, on the augmented reality visualisation device: ▪ a real view of the mechanical part, of the sensor holder and of the non-destructive testing sensor, ▪ a holographic 3D representation of the mechanical part, of the sensor holder and of the non-destructive testing sensor, which are superimposed on the real view, ▪ a holographic representation of the cut-out of the occlusion of the part and of the signal visualisation surface, which are superimposed on the real view, - the occlusion being created at least partially by superimposing the holographic 3D representation of the mechanical part on the real view of the mechanical part, - the cut-out of the occlusion passing through the depth of the mechanical part in its holographic 3D representation until it reaches the signal visualisation surface, - the signal visualisation surface being a quadric that is determined so as to correspond to a mesh formed by the paths of said signals propagating in the mechanical part. - an optical motion tracking system to which a reference coordinate system (R 0) is tied, - a sensor holder, - a rigid body, - a non-destructive testing sensor integral with the sensor holder connected fixedly to the rigid body, - a computer, - moving the non-destructive testing sensor over an examination area of the mechanical part; - simultaneously with the step of moving the non-destructive testing sensor, emitting the signal from a point of emission along an emission axis and receiving the signal by way of the sensor; - determining, by way of the computer, a cut-out of an occlusion inside the mechanical part, the cut-out being centred around the point of emission; - determining, by way of the computer, a signal visualisation surface constructed from the paths of the signal, this surface being located inside the cut-out; - visualising, on the augmented reality visualisation device: ▪ a real view of the mechanical part, of the sensor holder and of the non-destructive testing sensor, ▪ a holographic 3D representation of the mechanical part, of the sensor holder and of the non-destructive testing sensor, which are superimposed on the real view, ▪ a holographic representation of the cut-out of the occlusion of the part and of the signal visualisation surface, which are superimposed on the real view, ▪ a real view of the mechanical part, of the sensor holder and of the non-destructive testing sensor, ▪ a holographic 3D representation of the mechanical part, of the sensor holder and of the non-destructive testing sensor, which are superimposed on the real view, ▪ a holographic representation of the cut-out of the occlusion of the part and of the signal visualisation surface, which are superimposed on the real view, - the occlusion being created at least partially by superimposing the holographic 3D representation of the mechanical part on the real view of the mechanical part, - the cut-out of the occlusion passing through the depth of the mechanical part in its holographic 3D representation until it reaches the signal visualisation surface, - the signal visualisation surface being a quadric that is determined so as to correspond to a mesh formed by the paths of said signals propagating in the mechanical part.