Femtosecond Laser Direct Writing of Diffraction Gratings for Modifying the Refractive Index of Intraocular Lenses

An advanced femtosecond laser experimental platform with high precision was developed for the reconstruction of the refractive index of intraocular lenses (IOLs), and its accuracy was rigorously evaluated. Diffraction gratings were inscribed on the surface of an acrylate sample utilizing a fiber femtosecond laser operating at a wavelength of 515 nm with a repetition rate of 40 MHz. The samples were subsequently measured using an Abbe refractometer to assess the alterations in their refractive index induced by the femtosecond laser scanning process. Scanning electron microscopy, confocal Raman microscopy, and X-ray photoelectron spectroscopy were employed to examine the morphology of the diffraction grating on the sample surface following femtosecond laser scanning. Additionally, these techniques were utilized to investigate the alterations in molecular structure within the material postlaser scanning, as well as to elucidate the underlying mechanisms responsible for changes in refractive index. Furthermore, the parameters of the femtosecond laser utilized in this study were compared with those of lasers commonly employed in clinical settings.