By Christoph Ruettimann, Noémie Dury and Markus Danner

With almost 40 years of experience in precision processing of synthetic crystalline materials, Swiss laser manufacturer ROFIN-LASAG AG has developed a process for cutting sapphire glass, which is now increasingly used in mobile electronic devices and high-quality mechanical watches. Synthetic sapphire is a mono-crystalline aluminum oxide with outstanding technical properties, such as a high thermal conductivity, very high light transmission and complete acid resistance. In addition, it is an outstanding electric insulator and extremely scratch-resistant: With a Mohs’ hardness of 9 sapphire is beaten only by diamond.

Sapphire can be cut with a variety of laser technologies. Ultrashort pulse lasers, such as picosecond lasers, cut the material using very short pulses. The energy of these pulses is transferred so quickly to the electrons that the chemical bonds of the atoms are destroyed. In contrast to that, pulsed fiber lasers with a pulse length in the range of microseconds to milliseconds work with another cutting process, so-called fusion cutting. Continue reading →