Under the Hood

Thanks To Color Vision, The Human Eye Can Distinguish Between Most Subtle Nanoscale Differences

Human eye
The human eye, researchers found, is able to distinguish between remarkably subtle thicknesses due to its sharp color vision. Photo courtesy of Shutterstock

It may seem like there is only so much that we can see with the naked human eye — but new research suggests there's way more to our ocular power than we thought.

The study, published in the journal Optica, finds that our color vision gives our eyes the ability to make a distinction between things that differ in thickness by even just a few nanometers. That’s so miniscule, in fact, that it’s about the thickness of a cell membrane or even the size of a virus.

“We were able to demonstrate that the unaided human eye is able to determine the thickness of a thin film — materials only a few nanometers thick — by simply observing the color it presents under specific lighting conditions,” Sandy Peterhänsel of the University of Stuttgart, an author of the study, said in the press release.

The researchers conducted various experiments at the University of Eastern Finland, in collaboration with the University of Stuttgart, Germany. They gathered several participants, then trained them to identify extremely subtle color differences in light that passed through films of titanium dioxide, under very controlled lighting. What the researchers found was an “untapped potential” that “rivals sophisticated optics tools that can measure such minute thicknesses,” according to the press release. In other words, under highly controlled conditions, and with proper training, the human eye is able to identify changes in color that correspond to film thickness differences.

The researchers admit that there are some limitations to the human eye, and it’s unlikely that humans will replace current technological methods to determine film thickness (which is important for various commercial and manufacturing things — like solar panels).

“The intention of our study never was solely to compare the human color vision to much more sophisticated methods,” Peterhänsel said in the press release. “Finding out how precise this approach can be was the main motivation for our work.”

He concludes that we often underestimate our own abilities. “People often underestimate human senses and their value in engineering and science,” Peterhänsel said in the press release. “This experiment demonstrates that our natural born vision can achieve exceptional tasks that we normally would only assign to expensive and sophisticated machinery.”

Source: Peterhänsel S, Laamanen H, Lehtolahti J, Kuittinen M, Osten W, Tervo J. Human color vision provides nanoscale accuracy in thin-film thickness characterization. Optica, 2015.

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