To reduce the use of fossil fuels, the adoption of battery electric vehicles (BEVs) using lithium-ion batteries has been increasing in internal combustion engine alternatives. Accordingly, significant efforts have been made to improve the manufacturing process of lithium-ion batteries within electric vehicles. In particular, the cutting process of lithium-ion batteries has been actively discussed as it is closely related to battery performance. Laser-based cutting enables a more precise and sustainable manufacturing process. The laser ablation threshold has been investigated in many studies to achieve high-precision laser processing. While laser parameters and ambient conditions have been examined to determine the laser ablation threshold, studies focusing on the effect of relative humidity remain insufficient. Thus, this study investigated the laser ablation threshold of aluminum foil under varying relative humidity conditions. First, a laser interaction chamber was fabricated to control the relative humidity during experiments. A scanning electron microscope (SEM) was then used to observe laser ablation craters and analyze the threshold. The variation of the laser ablation threshold with relative humidity revealed changes in the interaction between the laser and aluminum foil depending on the humidity level.

Diffractive Optical Element (DOE) composed of repetitive patterns is necessary for 3D measurement, or for converting a laser beam into several spots. In this study, DOEs were fabricated through a direct laser lithographic system of which it is easy to fabricate a pattern on the specimen at low cost and under relatively simple process conditions. A commonly used method in laser direct laser lithography is the thermochemical technique. In this way, a single-line can be produced. At this time, when the high power of the laser is used, the laser ablation phenomenon occurs, so that a dual-line can be produced. As a result, it is possible to fabricate a pattern quickly with the proposed process method. And especially, it can increase the effect in repetitive patterns production. To fabricate repetitive fine patterns using dual-line, hexagonal and tripleshaped patterns were fabricated, by using the writing speed and laser intensity appropriately. Optical performance evaluation was performed by comparing the diffracted image of the fabricated hexagonal repetitive patterns with the simulation result.

An integrated simulation program for virtual laser ablation is developed to help understand and predict the effects of machining parameters on the final machined results. The main solver of the program is based on the model for polymer ablation with short-pulse Excimer lasers. The GUI of the program is built using Visual Fortran and OpenGL so that the user can work in a visual environment, such as Windows on a PC, where the important machining parameters can be input via a dialog box and the calculated results for the machined shape can be plotted by means of a 3D graphics window using OpenGL. The developed GUI can be implemented for use with most pre-developed FORTRAN solvers for Windows application, allowing the user to control the input parameters and to see the results in a 3D plot; hence most FORTRAN users could create their own visual programs on PC Windows systems similarly, widening the range of application of FORTRAN solvers.