July 10, 2015 | David F. Coppedge

Human Eye Has Nanoscale Resolution

No more complaining about bad design in the human eye. Optical experts prove it can distinguish differences at billionths of a meter.

The Optical Society of America begins an article debunking an alleged weakness in eye design:

The human eye is an amazing instrument and can accurately distinguish between the tiniest, most subtle differences in color. Where human vision excels in one area, it seems to fall short in others, such as perceiving minuscule details because of the natural limitations of human optics.

In a paper published in The Optical Society’s new journal Optica, a research team from the University of Stuttgart, Germany and the University of Eastern Finland, Joensuu, Finland, has harnessed the human eye’s color-sensing strengths to give the eye the ability to distinguish between objects that differ in thickness by no more than a few nanometers — about the thickness of a cell membrane or an individual virus.

The new-found ability of the naked eye may even be better than optical devices built to measure these differences:

This ability to go beyond the diffraction limit of the human eye was demonstrated by teaching a small group of volunteers to identify the remarkably subtle color differences in light that has passed through thin films of titanium dioxide under highly controlled and precise lighting conditions. The result was a remarkably consistent series of tests that revealed a hitherto untapped potential, one that rivals sophisticated optics tools that can measure such minute thicknesses, such as ellipsometry.

“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,” said Sandy Peterhänsel, University of Stuttgart, Germany and principal author on the paper. The actual testing was conducted at the University of Eastern Finland.

We’ve all seen the moving color patterns on soap bubbles. Those are examples of interference effects between layers of thin films. Knowing that some experts had a knack for correctly estimating thickness of these films, the researchers were inspired “to test the limits of human vision to see how small of a variation could be detected under ideal conditions.” Optically, “the spatial resolving power of the human eye is orders of magnitude too weak to directly characterize film thicknesses,” they said, but the eye’s perception of subtle color differences provides an indirect means of achieving nanoscale resolution.

How well did test participants do? Some could give answers in one to two minutes of observing, and got results within 1 to 3 nanometers of the measurements made by technical instruments.

This level of precision is far beyond normal human vision.

Compared to traditional automated methods of determining the thickness of a thin film, which can take five to ten minutes per sample using some techniques, the human eye performance compared very favorably.

The researchers don’t expect to replace instruments with human subjects; eyes can get tired easily, for one thing. But a skilled technician might be able to provide a quick check faster than a machine could.

The article ends with praise for the eye and other human senses:

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

The researchers speculate that it may be possible to detect even finer variations if other control factors are put in place. “People often underestimate human senses and their value in engineering and science. This experiment demonstrates that our natural born vision can achieve exceptional tasks that we normally would only assign to expensive and sophisticated machinery,” concludes Peterhänsel.

Nothing was said about evolution.

Once again, observation and experiment debunks the canard that the human eye is a bad design. Every little part, from the tear ducts to the vision center in the brain, is so over-the-top sophisticated, it astonishes researchers who look into these things. For more, see Randy Guliuzza’s recent article at ICR about just the front of the eye. Look at the diagram. Before you even get to the lens, the design will blow you away.

An evolutionist would have to say that this “exceptional” trait described above, that meets or exceeds the specs of our “sophisticated machinery,” arose by merely for survival by a long chain of little accidents. But is it necessary to detect the thickness of the tears on the whites of a predator’s eyes down to a few nanometers to survive? Come on. If you find the Darwinian explanation plausible, your blind mind is imagining shadows on wall of Plato’s cave. Come out into the sunshine.


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