Waterjet-guided laser processing (WGLP) is a sophisticated hybrid technology that delivers a high-power laser beam through a micro-waterjet acting as an optical waveguide. By utilizing total internal reflection at the water-air interface, WGLP offers an extended working distance and effective thermal management during laser processing, distinguishing it from conventional laser methods. Due to these unique characteristics, WGLP has been increasingly adopted since the 1990s for machining high-hardness and high-strength materials, such as semiconductors and advanced ceramics.

The performance of WGLP depends heavily on generating a long, stable laminar waterjet that functions as a consistent optical waveguide to the workpiece. Therefore, characterizing laminar waterjet formation is critical for achieving high precision and superior machining quality. In this study, we systematically observed the formation and behavioral transitions of the waterjet under various operational conditions. We evaluated the effects of key parameters, including nozzle orifice diameter, hydraulic pressure, and the presence of a coaxial air-jet, on the waterjet and the WGLP performance.

In addition, our investigation focused on the power-handling capacity in relation to processing parameters such as water pressure and orifice diameter. These experimental findings provide practical guidelines for the implementation of waterjet-guided laser systems, ensuring stable laminar waterjet formation in precision microprocessing applications.