A novel monitoring method of nanosecond laser scribing float glass with acoustic emission

The interaction between nanosecond laser and glass is complicated, and defects such as micro-cracks and fractures are prone to be generated during laser scribing. Acoustic emission (AE) technique is applied in this paper to monitor laser scribing of float glass. Strong consistency between AE signals and width of laser ablation area is found. With laser power increasing from 11.2 to 26.9 W, root mean square (RMS) values increase from 0.160 to 0.634 V, and width of heat affected zone (HAZ) increase from 12.396 to 53.711 $${\upmu }\text{m}$$ μ m . Correlation between AE signals and laser scribing quality is investigated by characteristic analysis. When scanning speed is kept constant (200 mm/s) and laser power is gradually increasing from 11.2 to 24.2 W, RMS values and MARSE are increasing (0.3–1.2 V, 600–1500 correspondingly), and scribing quality is declining continuously ( $$\frac{{W}_{C}}{{W}_{G}}$$ W C W G increase from 0 to 0.343). Time-frequency spectrum analysis by CWT could be applied in defects diagnosis. Three prominent frequency bands contents (150 ~ 180 kHz, 200 ~ 250 kHz, and 280 ~ 320 kHz) were generated during laser scribing process. Higher frequency bands contents (200 ~ 250 kHz, and 280 ~ 320 kHz) are demonstrated to reflect defects by analyzing distribution characteristic of frequency contents. Intensity of higher frequency compositions is vigorous (≥ 0.5) when there are defects, while less than 0.5 with no defects.