Fig. 1. Experimental set-up of picosecond laser seal welding

Fig. 2. Schematic diagrams of the two-step scanning welding strategy. (a) Laser pulse sequences for the first scanning welding; (b) laser pulse sequences for the second scanning welding; (c) small welding pool achieved by the first scanning; (d) large welding pool achieved by the second scanning

Fig. 3. Transmission optical microscopy images of the welding cross sections obtained with different welding methods. (a) Single-step scanning welding (SSSW); (b) two-step scanning welding (TSSW)

Fig. 4. Shear strength test results of welded samples by SSSW and TSSW

Fig. 5. SEM measurement result of the glass gap and variation of shear strengths of TSSW samples with gap width. (a) SEM measurement result of the glass gap; (b) variation of shear strength with gap width

Fig. 6. Water seal test for SSSW and TSSW samples. (a) An SSSW sample using the concentric-circle scan path; (b) a TSSW sample using the concentric-circle scan path; (c) SSSW samples after immersing in water for one week; (d) TSSW samples after immersing in water for one week

Fig. 7. Schematic diagram of microchannel preparation. (a) Drilling through-holes in the glass using laser; (b) machining a microgroove between through-holes; (c) seal welding along the microgroove edge

Fig. 8. A microchannel sample sealed by TSSW