## 1 Introduction
[PERSON] et al. presented a method to fix the distortion of the scanned image by controlling the driving voltage compensation [22]. Another voltage controlling solution was conducted by [PERSON]'s team [23]. [PERSON], [PERSON] et al. introduced combined scanning of the galvanometer scanner and the subsystem with two A.O.D.s for high efficiency on 74% of the scan field of the f-theta lens they use [24]. [PERSON] et al. used a coaxially coupled vision device combined with a self-designed calibration plate to reduce field distortions [25]. [PERSON] et al. presented another approach using freeform surfaces to correct 2D-telecentric scanning systems [26]. Some studies on 2D scanning systems used three galvanometers, in which two mirrors were used for the \(X\)-axis and one mirror for the \(Y\)-axis [27; 28]. It is also commercially available with a scan field that significantly enlarges the working area compared to conventional 2D scanning systems [29]. The ISO standard 11145 provides a set of basic terms, symbols, and units of measurement related to the field of laser technology, in which beam ellipticity or beam roundness is used for the analysis and evaluation of the improved efficiency of the 1D scanning system using two galvanometers, compared to a commercial 2D scanning system [30]. The roundness of the laser beam is the ratio of the minimum diameter to the maximum beam diameter. For the beam roundness evaluations, an ISO standard roundness value of greater than 87% of micro-holes can be regarded as circular, with a value of greater than 90% to meet industrial standard [24; 31]. In this study, the evaluation for the effective scan length extension will be evaluated against the criteria of the ISO standard. The improvement in laser beam quality can be classified in two main directions: the first is to improve the structure of the f-theta lens, and the second is to add additional optical components to improve the beam quality. The telecentric error can be reduced by using two additional free surfaces in the f-theta lens for a conventional 2D galvanometer scanning system [26]. Using a 2D galvanometer scanning system combined with a non-mechanical scanning system with 2 AODs can improve laser beam roundness by more than 90% over using only conventional 2D scanning systems, as shown in [24]. A 2D scanning system using three galvanometer mirrors is now available on the market, as an alternative to the traditional 2D scanning system using two mirrors, to expand the effective working area and improve the focus of the laser spot size [29]. In this study, inspired by the above ideas, a 1D scanning system using two mirrors in combination with the f-theta lens is proposed and implemented to reduce telecentric errors, improving laser beam quality and extending the effective working length. This research will include two main parts: simulation with ZEMAX software and experimental setup with Lab's prototype. However, adding one galvanometer mirror to correct aberration and telecentric in simulation and experiment has not been studied. In the simulation, the tilt angle of 2 mirrors was optimized by the DLS (Damped least squares) algorithm in the ZEMAX optical design software [32]. The beam profile will be observed and collected for analysis. Then, an experimental setup with a laboratory scale will be conducted to collect results and compare them to the simulation to meet the requirements of ISO 11145:2018. Before the wafer dicing, applications such as laser-based scribing and grooving on silicon wafers are critical processes for integrated circuit production, so a silicon wafer is used for the laser- processing demonstration experiments.