McGill University develops ‘gentler, more precise’ laser cutting with visible light

05 Jul 2022

Cold photo-carving uses just a fraction of energy of conventional laser cutting.

Laser cutting techniques are usually powered by high energy beams, so hot that they melt most materials. Now scientists from McGill University, Montreal, Canada, have developed what they are calling “a gentler, more precise technique using low-power visible light”.

The new process called “cold photo-carving” uses a fraction of the energy required in traditional laser cutting techniques.

The work is reported in a Nature Chemistry paper, entitled Cold photo-carving of halogen-bonded co-crystals of a dye and a volatile co-former using visible light, authored by T. H. Borchers et al.

Professor Tomislav Friščić, of the Department of Chemistry, commented, “We engineered crystal building blocks that can be cut by low-power light with amazing precision. Unlike traditional heat cutting methods, sculpting down to a resolution of nanometres is possible with our approach because light can be focused more precisely than heat can.

According to the researchers, the new technique could also be used to engrave complex patterns into surfaces. Professor Friščić added, “Imagine taking the famous geoglyphs in the Nazca Desert in Peru and engraving that pattern at a million-times the reduced size.”

The McGill researchers hope that the new approach could one day be developed to create new materials like metals or ceramics that are easily shaped or cut using low-power light and are now looking at potential applications in solar cell materials.

Paper abstract

The Nature Chemistry abstract states: “The formation of co-crystals by the assembly of molecules with complementary molecular recognition functionalities is a popular strategy to design or improve a range of solid-state properties, including those relevant for pharmaceuticals, photo- or thermoresponsive materials and organic electronics.

“McGill reports halogen-bonded co-crystals of a fluorinated azobenzene derivative with a volatile component—either dioxane or pyrazine—that can be cut, carved or engraved with low-power visible light. This cold photo-carving process is enabled by the co-crystallization of a light-absorbing azo dye with a volatile component, which gives rise to materials that can be selectively disassembled with micrometre precision using low-power, non-burning laser irradiation or a commercial confocal microscope.

It concludes: “The ability to shape co-crystals in three dimensions using laser powers of 0.5–20 mW—substantially lower than those used for metals, ceramics or polymers—is rationalized by photo-carving that targets the disruption of weak supramolecular interactions, rather than the covalent bonds or ionic structures targeted by conventional laser beam or focused ion beam machining processes.”

Video explainer