# Application of Laser-Ultrasonics for Evaluating Textures and Anisotropy
## Materials and Methods
### Cold-Rolled 316
The second echo, at around 5.75 us, is sharp and continuous for the scan around the TD axis in Figure 3a, whereas in the scan around the RD axis, Figure 3b, this second echo is somewhat hidden behind other background signals. Figure 1: Pole figures of the iron face centred cubic orientations with stereographic projection of the upper hemisphere with m3m symmetry for (**a**) the 50% deformed sample (792,127 data points) and (**b**) the 70% deformed sample (70,977 data points). The four crosses in Figure 3b, as well as the smileys on the second echo at the ND and TD polar angles, are attributed to the head wave which is also visible in the TD-scan of the flat samples which is discussed later. The second approach to measuring wave velocities in the 316 stainless steel plates involved directing the generating laser beam to different positions over the plate surface using Galvano mirrors. A schematic of the setup is shown in Figure 4, where the detection laser (red arrow) is directed by the use of 2 Galvano mirrors at the back of the sample and the generation laser (green arrow) is directed to different locations on the sample front side. The lateral distance between the generation and detection lasers is referred to as GD. The generation laser point was scanned in the pattern shown in Figure 5 below, to probe the ultrasonic response in several different azimuthal and polar angles inside the material. This approach can be adapted so that the measurements are made from one side only of the material so that it would be more suitable for application in industrial environments. A typical B-scan for such a measurement is shown in Figure 6 below. There are three regions indicated in the B-scan which correspond to the scan in: the RD direction, the TD direction, and one circle. The different echoes, i.e., the pressure-(P) and the shear-wave (S), are visible in the scans. Figure 3: B-scans of the 70% deformed heat-treated 316 sample with rotation around the (**a**) TD and (**b**) RD axis. Figure 2: (**a**) Illustration of how the cuboid samples were cut from the cold-rolled samples. (**b**) Photograph of the sample after turning, where some part of the original cuboid was left untouched to keep track of the material axes. Figure 4: Schematic of the laser ultrasonic transmission measurement set-up, generating on one side and detecting on the opposite side. The Galvano mirrors can direct the generation point and the position is measured synchronously with the ultrasonic response. The detection and generating lasers are focused on opposite sides of the specimen. Figure 5: Image of the sample after the transmission measurement showing the ablation marks on the generation side. Figure 6: Typical B-scans for measurements with a cross extending \(\pm\)3 times the plate thickness together with one circle at a radius of 0.7\(\times\) thickness. The parabolas are longitudinal (P), shear (S), or mode-converted (PS) waves. The RD scan and the TD scan are similar but differ in the region close to the GD = 0, i.e., the top of the parabolas. Here, the TD scan direction shows the head wave more clearly as almost straight lines originating from the peak of the uppermost parabola. The head wave is also visible in the circle scan showing up only close to the TD directions at \(\sim\)5 \(\upmu\)s.