Fig. 1. Experimental setup for testing damage.

Fig. 2. Real-time images induced by different laser energy densities for (a) 19 and (b) 23  J/cm2, respectively. (c) and (d) Corresponding morphological images taken by an optical microscope (OM) after experiment.

Fig. 3. (a)–(d) Real-time images at different times. The laser energy density is 28  J/cm2. (e) the morphological image taken by the OM after the experiment.

Fig. 4. Simulation model of a silicon wafer under laser irradiation.

Fig. 5. (Color online) (a) Temperature of spot center and (b) von Mises stresses along the X axis at 0.7, 1, 1.1, and 1.3 ms, respectively.

Fig. 6. Images just before fracture. The experiment is the same as that of Fig. 3.

Fig. 7. (Color online) (a) Concentric circle and (b) shear stresses along it at 1.5 ms. S1, S2, and S3 represent the shear stress along (111)[110], (111)[101], and (111)[011], respectively.

Fig. 8. (a) Typical ablation morphology induced by a millisecond laser and (b) a nanosecond laser.