Mowing the Lawn With Lasers, For Science

Imagine the thrill of cutting grass with lasers—a concept that sounds straight out of a sci-fi movie. Lasers, often seen as magical beams of light, seem like they could effortlessly slice through anything, including grass. In reality, as demonstrated by Allen Pan in his video, we are reminded that we live in a physics-based universe where lasers don’t function like lightsabers that magically cut through everything. His attempt to create a laser-powered lawn mower reveals the complexities and limitations of using lasers for practical tasks like lawn maintenance.

The initial attempt involved attaching two diode lasers to a spinning configuration, mimicking the cutting blades of a traditional lawn mower. However, this setup faced immediate issues with focusing, which were partially resolved by removing the focusing lenses. Despite this adjustment, the laser beams didn’t stay on any single blade of grass long enough to be effective. To address this, the solution was to use more lasers in a stationary grid pattern, creating a cutting field reminiscent of the deadly traps seen in the “Resident Evil” movies—except this one targets grass rather than intruders.

But does this method actually work? The results are mixed. While the stationary grid of lasers can cut grass, the process is slow and inefficient, particularly when dealing with thick grass that contains a lot of moisture. The lasers must evaporate the moisture before they can effectively burn and cut the grass. This not only reduces cutting efficiency but also increases the risk of igniting a fire, especially in dense patches of grass—a problem Allen and his co-conspirator encountered during their trials.

Interestingly, the best documented attempt to cut grass with lasers was made by rctestflight two years ago. He used a stationary 40-watt diode laser that swept across an area, gradually cutting the grass. When mounted on a slowly moving platform, this setup could, theoretically, cut a lawn over several days. This pales in comparison to a conventional lawn mower with rapidly spinning blades that can accomplish the same task in mere minutes. In conclusion, while cutting grass with lasers is a fascinating idea, it turns out that the age-old method of spinning blades remains far more practical and efficient.

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