Longitudinally Excited CO2 Laser with Short Laser Pulse like TEA CO2 Laser

Abstract

We have developed a longitudinally excited CO 2 laser with a short laser pulse similar to that of TEA and Q-switched CO 2 lasers. A capacitor transfer circuit with a low shunt resistance provided rapid discharge and a sharp spike pulse with a short pulse tail. Specifically, a circuit with a resistance of 10 M Ω provided a spike pulse width of 103.3 ns and a pulse tail length of 61.9 μs, whereas a circuit with a shunt resistance of 100 Ω provided a laser pulse with a spike pulse width of 96.3 ns and a pulse tail length of 17.2 μs. The laser pulses from this longitudinally excited CO 2 laser were used for processing a human tooth without carbonization and for glass marking without cracks.

Longitudinally Excited CO2 Laser

“…On the other hand, when the pre-ionization is required in the highpressure operation (> 1 atm), the discharge tube is covered with Al foil (Fig. 5, 6) (El-Osealy et al, 2002b;Uno et al, 2009;Uno et al, 2012a). A corona discharge occurs along the tube wall before the main discharge to serve as pre-ionization.…”

“…In recent years, especially, new gas lasers, for example, a longitudinally excited CO2 laser with short laser pulse like TEA and Qswitched CO2 laser (Uno et al, 2009), a longitudinally excited N2 laser with the same excitation system as an excimer lamp (Uno et al, 2006), and a longitudinally excited F2 laser at low-pressure (total pressure of 40 Torr) (El-Osealy et al, 2002b) have been developed. …”

“…For example, in our study (Uno et al, 2009), the discharge tube was a ceramic pipe made of alumina, with an inner diameter of 13 mm, an outer diameter of 17 mm, and a length of 45 cm. The discharge tube was covered with an Al sheet.…”

“…Fig. 13 and 14 shows the laser pulse in the discharge formation time of 32.8 µs and 0.97 µs, respectively, at the same discharge tube with the inner diameter of 13 mm and the length of 45 cm and the same gas pressure of 2.9 kPa (CO2: N2: He= 1: 1: 2) (Uno et al, 2009). Fig.…”

“…Therefore, a circuit without a buffer capacitance, called a direct-drive circuit like Fig. 15, has been developed (Uno et al, 2012a). Fig.…”