Femtosecond laser surface modification of magnesium aluminate spinel and its effect on polishing

Magnesium aluminate spinel is a promising material for optical windows due to its outstanding comprehensive properties. However, the highly efficient polishing of spinel by traditional processing is difficult due to its high hardness, high strength and chemical inertness. In this study, a femtosecond laser was used to induce micronanostructures on the spinel surface to improve its machinability. The effects of laser power, scanning speed and scanning interval on the surface morphology of the spinel were studied. The experimental results indicate that the femtosecond laser modification reduced the surface hardness of the spinel, and the critical cutting depth was increased. Moreover, the micro-nanostructures resulting from the laser modification improved the contact area between the slurry and the substrate, which improved the polishing performance. Experiments were carried out to prove that the chemical mechanical polishing (CMP) process of spinel can be promoted by femtosecond laser surface modification. This method provides a new perspective for high-performance spinel ultra-precision manufacturing.