## 1 Introduction
Instead, only a small fringe of the laser beam (near the laser spot) is made incident on the surface of the cut edge. The laser energy density located around the fringe of the laser beam is very low. In this low-fluence regime, the laser beam power is switched from laser beam cutting to laser beam polishing, and has a low-fluence finishing effect. The flatness of the cut edge and the surface roughness is improved. [PERSON] and [PERSON] [21] used a femtosecond laser and multiple horizontal shifting to produce a nitinol stent. The processed stent had high surface quality with no apparent thermal residual stress. Moreover, the femtosecond laser-beam energy is a Gaussian distribution; this characteristic could trim the stent to achieve a rounded edge. [PERSON] et al. [22] applied the laser hardening process with scanning optics to AISI 1045 steel. The scanner-based laser hardening process presented an inherent variation of the temperature due to the scan effect of the laser beam. The test results showed two different regimes, relatively smooth and rippled, depending on the scanning speed and feed rate values. [PERSON] et al. [23] studied laser machining for the preparation of cutting edges of cemented carbide inserts. The laser parameter settings applied for the preparation were varied, and the analysis reveals that the surface, the surface integrity and the tool performance are significantly affected by the parameter sets used for laser machining. The less heat dissipates from the processing area into the adjacent material, the more efficient the material removal, and the lower the surface roughness and the undesired alteration of the sub-surface properties. Traditionally, the diamond-wheel-grinding technique is used to finishing PCD cutting tool blanks after WEDM cutting. However, owing to its poor efficiency, this technique is unsuitable for processing complex geometric-shapes tools [10; 11; 12; 13; 14]. Previous studies have reported methods involving the use of pico- and femto-second lasers as potential alternatives to the WEDM cutting and diamond-wheel-grinding techniques [17; 18; 19]. However, these laser-based methods are expensive, and their high maintenance cost could hinder their widespread industrial utility. This study used a nanosecond fiber-optic laser system with an adjustable pulse width (maximum average power of 30 W) by referring to the studies by [PERSON] et al. [20] and [PERSON] [21], and established a horizontal shifting and vertical layered processing method to achieve a high-quality processed PCD workpiece. The relationship between the laser focus position and kerf width was first studied. The effects of various laser parameters such as the laser pulse width, repetition rate, peak energy, pulse energy, processing scan rate, and number of machining passes on the kerf depth and material removal rate were examined. Next, the feasibility of applying the horizontal shifting and vertical layering processing methods to cut through a PCD workpiece with a nanosecond fiber laser was investigated. Then, the effects of variation in the operating parameters on the morphology of the cut surface and surface quality were explored. This study proposes three different processing paths to perform the laser finishing and achieve improved cut surface quality. Moreover, it discusses the effects of the variation in pulse widths on the results of the finished surface. The tilting of the cutting edge after laser cutting, due to the physical characteristics of the laser beam energy, is addressed. Finally, the parameter settings for achieving the best results for processing the PCD tools by nanosecond fiber laser processing are summarized.