Nanotechnology In Ancient Rome? There Is Evidence

Anything related to nanotechnology feels fairly modern, doesn’t it? Although Richard Feynman planted the seeds of the idea in 1959, the word itself didn’t really get formed until the 70s or 80s, depending on who you ask. But there is evidence that nanotechnology could have existed as far back as the 4th century in ancient Rome.

That evidence lies in this, the Lycurgus cup. It’s an example of dichroic glass — that is, glass that takes on a different color depending on the light source. In this case, the opaque green of front lighting gives way to glowing red when light is shining through it. The mythology that explains the scene varies a bit, but the main character is King Lycurgus, king of Edoni in Thrace.

So how does it work? The glass contains extremely small quantities of colloidal gold and silver — nanoparticles of gold to produce the red, and silver particles to make the milky green. The composition of the Lycurgus cup was puzzling until the 1990s, when small pieces of the same type of glass were discovered in ancient Roman ruins and analyzed. The particles in the Lycurgus cup are thought to be the size of one thousandth of a grain of table salt — substantial enough to reflect light without blocking it.

The question is, how much did the Romans know about what they were doing? Did they really have the means to grind these particles into dust and purposely infuse them, or could this dichroic glass have been produced purely by accident? Be sure to check out the videos after the break that discuss this fascinating piece of drinkware.

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All About Dichroic Optical Filters

[IMSAI Guy] presents for your viewing pleasure, a nice video on the topic of optical filters and mirrors. (Video, embedded below) The first optical device is a simple absorption filter, where incoming light is absorbed in a wavelength-selective manner. Much more interesting however is the subject of interference or dichroic filters. These devices are constructed from many thin layers of a partially reflective material, and operate on the principle of interference. This means that photons hitting the filter stack will interfere either constructively or destructively giving the filter a pass or stop response for a particular wavelength.

As [IMSAI Guy] demonstrates, this makes the filters direction-specific, as photons hitting the stack at a different angle will travel slightly further. Longer travel means the interference effect will be different, and so will the filtering response. You can see this by playing around with one in your hands and seeing the color change as your rotate it. Dichroic filter films can also make for some stunning optical effects. Very cool stuff.

By creating a filter stack with a wide enough range of inter-layer thicknesses, it’s possible to construct a mirror that covers the full spectrum with excellent reflectivity.  Since you can tune the layers, you can make it reflect any range of wavelengths you like. One thing we’ve not seen before is a wedge-like optical filter device, where the layer thicknesses progressively increase lengthways, creating a variable optical frequency response along the length. We guess this would be useful for diagnostics in the field, or perhaps for manually tuning a beam path?

We like the applications for dichroic films – here’s an Infinity Mirror ‘Hypercrystal’. If you don’t want to buy off-the-shelf films, perhaps you could sputter yourself something pretty?

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