Fig. 1. Schematic diagram of TSOM detection system

Fig. 2. Femtosecond laser processing device

Fig. 3. Internal damage diagram of K9 glass processed by femtosecond laser

Fig. 4. Schematic of sample processing

Fig. 5. TSOM scanning image of subsurface defects of femtosecond laser processing sample. (a) Data cube of TSOM scanning; (b) partial magnification of data cube; (c) TSOM data cubic cross section

Fig. 6. TSOM scanning image of subsurface defects of 3D micromachined sample. (a) Data cube of TSOM scanning; (b) TSOM data cubic cross section

Fig. 7. Schematic diagram of refraction and reflection of light acting on materials with different refractive indices

Fig. 8. Surface test diagram of 3D micromachined sample

Fig. 9. Results of distance between surface defects and edges of 3D micromachined samples tested by National Institute of Metrology, China

Fig. 10. FDTD simulated light intensities at different location heights from subsurface defect center. (a) Simulated light intensity distributions at location heights of 35, 33, 0, and -33 μm; (b) simulated light intensity change trend at different location heights

Fig. 11. Schematic diagram of maximum position of light intensity of TSOM scanning defect