Scientists Create an Optical Tractor Beam for Macroscopic Objects
Using a material engineered to create reverse temperature differences, scientists can now move objects with just lasers
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Inching ever closer to making Star Trek tech a reality, scientists from QingDao University of Science and Technology have created an optical tractor beam that can pull macroscopic objects via laser light. While the researchers stress that this new technique is currently a proof-of-concept, it may prove one day useful in controlling Martian vehicles as the Red Planet has environmental pressure low enough for this technology to work on its surface.
Contactless manipulation of objects via light has already advanced to practical application. For instance, scientists use optical tweezers to hold individual cells and even atoms in place. However, these techniques have been limited to microscopic objects. But the results of this new study, published in Optics Express, indicate that that may soon change.
In the study, the research team essentially amplified the force with which light can pull objects. They accomplished this by developing a composite structure made of graphene-silicon dioxide that, when irradiated with a laser, creates a reverse temperature difference—in other words, the side facing away from the laser warms up. This causes the gas molecules on their back side to receive more energy, pushing the object toward the laser’s source. When conducted in a rarified gas environment, the force was strong enough to move macroscopic objects.
“We found that the pulling force was more than three orders of magnitude larger than the light pressure,” said researcher Lei Wang. “In addition, the laser pulling is repeatable, and the force can be tuned by changing the laser power.”
Though the technology is promising, in its current iteration it is only a proof-of-concept. The team have identified several avenues of improving it, such as developing a “systematic theoretical model” to predict the pulling force when accounting for parameters such as the object’s geometry, surrounding media, and more. The team would also like to adapt it to work for a wider range of air pressures, rather than just rarified gas environments.
Optical waves aren’t the only avenue for contactless manipulation that researchers are exploring. In December 2022, researchers from the University of Minnesota developed a contactless manipulation technique built on acoustic waves. Both optic- and acoustic-based solutions may prove useful in a variety of industries.