This method is used to obtain the information about the moving object. It combines certain features of A-scan and B-scan. In T-M scan the transducer is held stationary as in A-scan and echoes appear as dots as in the B-scan.
Here, the X-axis indicates the dots at relevant location (or) position of the defect depending on the depth of the reflection. The Y- axis indicates the movement of the object. Therefore when the object moves, the dots also move at a low speed. Thus an object with oscillatory movement will appear as a trace as shown in above fig.Thus it gives the three dimensional image of the specimen.