Human Eyesight Capable of Verifying Nanoscale Variations in Color

When it comes to spotting nanoscale differences the “Eyes” have it.

How precise is human vision? It couldn’t possibly be more accurate and quicker than expensive digital equipment, could it? According to researchers at the University of Stuttgart and the University of Eastern Finland, the answer may surprise you.

While working together, these two university teams set out to measure the human eye’s ability to distinguish between objects of different thicknesses. Easy right? Not when the different thicknesses are only a few different nanometers apart.

Amazingly, the researchers were able to train humans to pick up the subtle differences in thickness by using colored light and training the human subjects to notice the subtle color variations. We’re talking about thickness about the size of a cell membrane.

Training people is one thing, but to be scientific, the teams wanted to see just how precise human eyeballs are when looking for subtle color variations. Using the kinds of thin films you might find on solar panels, they used layers of film to control the thickness of various surfaces.

The samples were then placed on a LCD monitor set to display pure white color except for a colored reference area that could be used to calibrate the various thicknesses. The color of the reference field was changed by the human subject until it matched the thickness and color of the reference sample. With differences in thickness of just a nanometer, human eyes determined the correct color and thickness within two to three minutes.

Surprisingly, traditional automated methods of determining the same films take anywhere from five to ten minutes to ascertain making the human eye quicker. While this is great for confirming consistency, color measurement instruments remain superior in measuring and reporting the exact gradient of difference between the two colors. And color instruments do not tire like the human eye does, meaning that long-term manufacturing processes should still rely on color measurement instruments to ensure consistent quality.

So is there a place for the human eyes in industrial calibration of thickness? Yes, they can be used to check quickly that the machines are doing their job and verify their accuracy. So as you can see when it comes to verifying color accuracy, the human eye still has what it takes to help the process along.