Processing of natural diamond using nanosecond and picosecond lasers: relative merits and demerits

Lasers are able to saw complex diamond crystals with improved yields and provide better accuracy, greater speed, and lower breakage rates even for sensitive diamonds and lower weight loss for difficult stones. In the present investigation, four different types of nanosecond Q-switched Nd:YAG lasers namely an arc lamp pumped Nd:YAG laser operating at 1064 nm, arc lamp pumped Nd:YAG laser operating at second harmonically generated 532 nm, diode pumped Nd:YVO 4 laser operating at 1064 nm, a diode pumped Nd:YAG laser operating at 1064 nm, 532nm picosecond Diode pumped Nd:YAG laser and 510 nm Cu vapor laser have been employed for the processing of single crystal gem quality natural diamond to study the effects of pulse width and wavelength on various aspects of processing and the relative merits and demerits. The overall weight loss of the diamond and formation of micro cracking during processing have been studied for the above four cases. The characteristics of graphite formed during processing, elemental analysis, surface morphology of cut face and process dynamics have been studied using Micro Raman spectroscopic technique and Scanning Electron Microscopy (SEM). The Micro Raman and SEM analysis show that the surface quality is obtained superior by using diode pumped Nd:YVO 4 laser due to its extremely high peak power. The maximum graphite content is observed while processing using lamp pumped Nd:YAG laser at 532 nm. Shorter laser pulses result in higher cutting rate of natural diamonds due to better localization of absorbed laser energy.