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Cool Laser for Cutting Diamonds

Laser MicroJet combines the advantage of both laser cutting and water cooling in one operation. Raw diamonds can contain inclusions in the form of non-diamond hybrid materials or air bubbles, making them susceptible to damage from intense heat during laser cutting. 

By Nitin Shankar

Diamond cutters have been looking for a laser cutting tool that can slice through a diamond without causing any thermal damage. Raw diamonds can contain inclusions in the form of non-diamond hybrid materials or air bubbles, making them susceptible to damage from intense heat during laser cutting. The heat of a conventional laser beam can cause the inherent material tension in such inclusions to explode the stone. Thus, a rough diamond worth several thousands of dollars can literally be reduced to worthless bits in a matter of seconds without any warning. 

Unlike conventional laser cutting where thermal heating poses risks, the Laser MicroJet, between laser pulses, cools the surface of the stone with a water jet. This is effectively “cold laser cutting” and significantly reduces the risk of diamonds bursting due to laser heat (Fig. 1). In the Laser MicroJet system [1, 2], a laser beam, passing through a pressurized water chamber, is focused into a nozzle (Fig. 2). The low-pressure water jet emitted from the nozzle guides the laser beam by means of total internal reflection at the water/air interface. The water jet-guided laser beam is parallel and its diameter, depending on the nozzle, can be 40 or 50 microns. The required laser power is less than 20 watts. While the principle looks simple, years of experimentation were required to fine tune the process. 

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