DPSS Lasers Overcome Glass Process Challenges 2
Besides CO2 and USP lasers, a third option for glass processing is the nanosecond-pulse, Q-switched diode-pumped solid state (DPSS) laser, which falls near the middle of the spectrum in terms of complexity and dollars per watt. Glass processing with such lasers inherits qualities of both the fast, crude CO2 tool and the slow, fine USP scalpel. Although the speed is lower than that of the straight-line CO2 laser cuts, the quality can be better �C and what's more, contoured shapes can be cut. Likewise, compared with USP laser processing, the edge chipping formed with nanosecond-time-scale pulses is larger �C often several tens of microns �C but the throughput can be significantly higher and at a much lower cost.
Markets for glass processing
Various markets and industries currently benefit from laser glass processing. For example, in the fabrication of biomedical lab-on-chip devices, lasers are used to machine microgrooves, titration vias and even embedded waveguides for optical sensing. For such devices, short nanosecond-pulse Q-switched DPSS lasers can be used for high-quality, cost-efficient glass processing. One example application is fast subsurface micromarking of glass parts with a short nanosecond-pulse laser at the 355-nm wavelength. Figure 1 shows a variety of subsurface glass marks machined with just such a laser.
Figure 1. Nanosecond-pulse Q-switched DPSS lasers can produce high quality in glass processing. Here, various subsurface micromarkings in glass are made with a 355-nm, nanosecond-pulse Q-switched laser (Spectra-Physics Tristar series 355-nm 2- to 3-W lasers). Single-character marking times are as low as 10 ms.
These lasers offer good marking power of 2 W or more at a very reasonable cost; and with fast pulse trains at 50 to 100 kHz or more, typical write times of a few tens of milliseconds per character are achieved, translating to a marking capability of several tens of characters per second. Although the biomedical lab-on-chip market is relatively small, it likely will grow as medical-related industries continue to see large capital investments. Industrial-grade, high-throughput and high-quality lasers such as this can offer cost-effective solutions for the demands of high-volume production tasks.