Depending on the state and property of the workpiece, the laser processing involves various conditions, such as wavelength, pulse width, repetition frequency, polarization state, focus spot, and focal position.
The conditions are divided into two: one relying on the laser oscillator and the other related to the processing of the oscillated laser light. The unit that affects the outcome of the laser light processing is the optical engine.
What is optical design?
The role of the optical engine is to transmit the light from the laser to the workpiece and, simultaneously, to convert the light into the beam shape suitable for processing. Optical design is the engineering work that is performed to define the shapes of various optical elements, materials, and positions based on the simulation in order to enable the optical engine to function correctly.
Polarization means the oscillation direction of the light wave. Many outputted laser lights have linear polarization with a wave oscillation that remains in one plane.
In this case, as seen in the figure, they rely on the incident angle and polarization direction, which causes difference in the processing speeds.
We contrive ways to prevent this problem, which include temporal rotation of the wave oscillation plane using optical elements for polarization control and changes in the oscillation direction within the beam cross-section surface depending on the position.
In addition, beams can be divided by utilizing polarization. The figure shows an example of the use of Wollaston prism, which divides one single beam into two. By focusing the beam with a lens, the two parts can be processed simultaneously.
Special beams (Bessel / top hat)
Requirements for beams used for laser processing vary.
The Bessel beam shown below does not change its beam shape in a wide range of beam progress directions, which makes it possible to process thick workpieces by using one operation.
In addition, the top hat converged beam, shown in the example, contributes to the realization of processing with reduced damage by evening out the peak area.