# Laser Processing of Intraocular Lenses
## 3 Results
### CW Diode Laser Patterns  
A series of patterning experiments were conducted also with the CW laser at 405 nm as it provides very different laser characteristics compared to previous cases. However, due to a specific optical arrangement and horizontal exposure configuration of the writing system, the pattern generation was limited to a single line direction or stationary spot exposure. Specifically, for the acrylic IOLs, the translation distance range was set to 900 \(\upmu\)m, with a scanning speed of 1 \(\upmu\)m/s, and an order of magnitude smaller than the femtosecond setup. The power delivered on the surface was 10 mW, resulting in an intensity of 14 MW/cm\({}^{2}\). The final ablated line is 450 \(\upmu\)m in length and 3.5 \(\upmu\)m in width, as shown in Figure 8a, mainly influenced by the IOL curvature and limited depth of focus of the objective lens. The depth of ablation for the line, as measured with the surface profilometer, is approximately 400 nm as shown in Figure 8b. Considering the objective lens spot size of 300 nm and the observed line width of 3.5 \(\upmu\)m, thermal effects likely play a significant role in this process. Figure 7: SEM images (top view) of ablated spots on the acrylic IOL after irradiation with the ns laser for (**a**) 30 s; (**b**) 1 min; (**c**) 6 min. Additionally, we conducted experiments exposing a single point to varying durations of 1 s, 2 s, 5 s, and 10 s. These exposures resulted in ablated spots with crater dimensions of 0.6 \(\upmu\)m, 0.8 \(\upmu\)m, 1.2 \(\upmu\)m, and 2.1 \(\upmu\)m, respectively, as illustrated in Figure 9a. The experimental results, showcasing a gradual increase in the ablated area, indicate a linear correlation between exposure time and the size of the ablated spot, as indicated in Figure 9b, emphasizing the temporal dependence of the laser ablation process on the IOLs. The use of the 405 nm CW diode laser for patterning the PMMA IOL demonstrates its capability for precise and controlled ablation, despite the limited patterning data we have obtained in this study. However, in several patterning experiments, it was noticed that the exposed area was discontinuously patterned. This phenomenon can be partially attributed to the low exposure power for this material and the non-adaptive focusing of the beam when transferred in a non-uniform IOL with varying curvatures. However, it can also be attributed to the fact that the processing occurs in the thermal processing regime where the accumulation of continuous laser radiation or discrete multiple pulses lead to an increase in local temperature and modification of polymers' properties. The same phenomenon has been described in femtosecond laser patterning in [23]. Such discontinuous patterns are shown in the optical microscope image in Figure 10. Due also to technical issues with the gold post-sputter coating process before the SEM characterization, it was difficult to provide SEM images for the in-detail visualization of those discontinuous patterns. It should be stressed that this is the first demonstration of successful patterning of IOLs by  
Figure 8: (**a**) An SEM image (top view) of the ablated area on the acrylic IOL after irradiation with the CW, 405 nm laser; (**b**) depth measurement of the ablated line. Figure 9: (**a**) An SEM image (top view) of the ablated spots on the acrylic IOL after irradiation with the CW, 405 nm laser, with exposure times 1 s, 2 s, 5 s, and 10 s from left to right; (**b**) the correlation of ablated spots’ diameters and exposure time. a compact and low-power CW diode laser, which provides a considerable potential for low-cost IOL patterning; however, further studies are required to address these challenges and optimize the process. The process with the CW laser differs significantly compared to the other two lasers, due to the differences in wavelength and energy delivery mechanism or the materials' laser-induced modification processes.