J. Eur. Opt. Society-Rapid Publ. 22, 45( 2026) 447
Appendix A: Laser processing setup
The primary source is a nanosecond IPG laser operating at a wavelength of 532 nm, with a pulse duration of 1.3 ns, a Gaussian intensity profile and a circular beam cross-section. It is focused on the sample surface by a 10 cm focal length f-theta lens that is mounted on a scanner head enabling the precise control of the spot location in the focal plane( plane of the sample surface) over a maximum field of 6 6cm 2. The intensity profile is transformed into a top-hat profile and the circular shape is converted into a square shape by the CANUNDA beam-shaping module from Cailabs, which is located before the scanner head. The focused square spot has a nearly flat intensity profile over a width of 13.5 lm( full width at 90 % of the maximum) Figure A1 and a Rayleigh length of 150 lm. The beam is linearly polarized. The laser power and repetition rate, the beam path and the scanning speed are computer controlled. Each printed pixel is a square of 50 lm width and is obtained by drawing hatched lines oriented at 45 ° from the x and y directions on the sample plane and separated by a distance of 10 lm.
Appendix
B: In line measurement setup.
The laser-induced colors were measured in line using a Nikon Z7 II camera mounted above the scanner head. The camera was equipped with a macro lens providing a working distance of approximately 20 cm and a field of view covering the entire sample area( 5 cm). This configuration allows the acquisition of highenough resolution images where each inscribed square( 200 lm 200 lm) is captured with a sufficient number of pixels to be able to perform an averaging of the color. A schematic of the color measurement setup is shown in Figure C1.
To ensure uniform sharpness across the entire sample surface, focus bracketing was employed during image acquisition as illustrated in Figure B2. It means taking several images focused at different depths and combining them to get one image that’ s sharp everywhere. The use of the same camera and illumination setup for both measurement and final image production ensures consistency across all iterations of the optimization process.
Figure
B. 1. Measurement setup using a basic camera equipped with macro objective and two light sources, one for specular reflection( dark blue ray), one for the scattered reflection( red ray), the last one in the other side is for transmission in the case of the semi-transparent mesoporous film.
Figure A. 1. Square top hat beam shape.
Figure B. 2. Focus bracketing performed on 4 images taken with the focus being on different locations of the sample, the red rectangle indicates where the image is.