Drilling with Lasers
When a laser beam collides with material, the laser pulse heats, melts, and vaporizes it. During the process, the vaporized material rapidly increases in volume. The pressure created quickly expels the vaporized material, leaving behind the laser-drilled hole. The greater the energy in the pulse, the larger the hole, and this can be controlled with great precision. Laser drilling allows for very exact location, and accurate hole size.
Pulsed lasers can be carefully controlled and rapidly charged. These characteristics lend it to drilling at elevated rates in a given amount of time. It is simple, clean, and fast. This is the most basic form of laser drilling. This process led to several variations of laser drilling, including percussion, trepanning, and helical.
Percussion drilling is fairly similar to single pulse. Instead of using one burst of energy, it reduces the power and uses several shorter bursts at the lower energy. Using the percussion method, holes can be deeper, more accurate, and hole diameters can be made even smaller due to less material vaporizing with each rapid pulse.
Trepanning uses the laser much like a drill bit. Instead of a single beam creating a hole through a single or multiple pulse laser bursts on one spot, trepanning first creates a starter hole and then enlarges the hole by moving the beam outward in an ever-increasing circular pattern. This method can create larger holes with smaller beams, allowing for greater precision and burr-free edges.
Helical drilling is much like trepanning, but without the starter hole. Instead, the laser begins drilling through the material immediately, starting from the center and moving outward until the desired diameter is achieved. The laser beam’s focus can be adjusted in real time through the drilling process, ensuring the hole is consistent in measurement from top to bottom.