Principle of operation
- The helical drilling optics consists of a beam rotator, optical components for beam tilt and parallel shift. The laser beam is rotated around the optical axis by the beam rotator – a Dove prism mounted in a high-speed hollow shaft motor, and the emitted laser beam spins in a circular path with respect to the workpiece surface. If the outgoing laser beam is offset or tilted from the optical axis, a micro-hole with a certain taper or diameter is fabricated. With the control software, the diameter and taper of the micro-hole can be changed precisely. The use of Dove prisms as image rotators has the fundamental advantage that the drilling quality does not depend on the laser beam cross-sectional characteristics. Also, due to the prism imaging characteristics, the outgoing laser beam rotates at twice the motor operating rate, increasing drilling efficiency.