The birth of fiber optics – Faust, fountains and crossbows

As you may already know, fiber optics are kind of important. They are the linch pin that currently holds our massive high data rate internet together. Without fiber optics, we’d all have spent the summer watching Stranger Things at a resolution of about 4 pixels, instead of being able to see all the gory goo in glorious high definition.

But the technology behind fibers and the fibers themselves pre-date the computers that are full of the content they contain. At their core they are a very simple concept – if you shine light into a glass tube, light at the correct angle is reflected internally down the tube with no losses.

Now if you go back to Egyptian times there are several reports of quartz glass rods being used to direct light into burial chambers, many people suggest that the Egyptians were the first discoverers of this way of directing light from the sun to a thing with something more than just a shiny bronze surface. However most of these people are forum users not academics and despite many fascinatingly long posts, theres no apparent evidence – for example, we’ve not actually discovered any glass rods doing this, which you’d think would be a big clue that they weren’t. Also I found in researching this, that most of these forum posts end with a breathy and excited postulation that aliens clearly helped them. So probably take it all with a pinch of salt.

A slightly more believable start for this story is in 1841, in both France and Switzerland where there is ample non-internet forum evidence that two scientists both discovered a way of bending light at virtually the same time.

french-v-swiss

A Swiss man named Daniel Colladon and a Frenchman called Jaque Babinet both demonstrated an optical trick known as total internal reflection. This is where light is internally reflected within a medium like water or glass, totally. It was clearly named by someone who wanted to be very clear about what it does, and didn’t have time for fancy scientific names.

Now Babinet and Colladon did this by shining a bright light in one side of a vessel at a small jet of water on the other side. Instead of simply passing through the jet, the light was then reflected within the water and followed the curve down into the pan below.

At the very least it made for a very visually exciting demonstration! Babinet in particular, was already well known for exciting demos, and lecturers added it to his growing list of sci comm friendly experiments. Colladon however, was more practically minded and was less interested in wowing people and more interested in what modern academics would refer to as an ‘impact case study’. In short, he wanted to find applications.

Now to most, being able to bend light a bit round a thin stream of water is not the most immediately applicable discovery. But Colladon managed to get an opportunity to apply it to the world of Opera – in particular, for a performance of Faust, where he used the trick to create a red stream depicting the devils trident, illuminated by an arc lamp. It was so popular that the theatre started charging people just to come and see this marvel in private viewings. People in the 1800s were easily amused and apparently “come see a bright light” was all it took.

From here the next step towards the discovery of the internet was obvious – large outdoor fountains.

fountain

Seeing this amazing new lighting display, an Englishman called Bolton seized upon the idea of building not a single lighting display, but several as part of a giant fountain at the World’s Fair in London. He developed jets specifically to shoot water, with light from arc generators to make a fountain that sparkled. Sadly his design had one or two minor flaws. Firstly his nozzles were not nearly as refined as Colladon’s and in all likelihood made water spray rather than jet and so didn’t actually reflect the light down them. Lucky for Bolton, people like bright lights and probably didn’t even notice. Secondly, to power the fountain required several arc lamps and pumps, all of which were housed in the centre of the fountain. These needed to be operated by a team of men in cramped conditions while the generators produced fumes and high voltage sparks next to their heads. Most of them ended up ill, several ended up ill to the point where they were actually dead. But accounts said it looked pretty.

But water wasn’t the only pretty trick that Colladon and others had begun investigating. Both Colladon and Babinet had mentioned in their papers that the same trick would work for glass rods. They realised it was pretty useful to try and direct light into places away from noisy, worker killing, arc lamps. An American called Wheeler had the brilliant idea of building a house that had glass rods running throughout the building down to an arc generator in the basement which would, by total internal reflectance, provide light to the whole house. This brilliant idea that could revolutionise the way houses were lit hit one very small historical snag.

glass-vs-the-light-bulb

With the invention of the lightbulb people started caring a great deal less about ways to move light away from arc lamps via large glass rods (which seemed almost immediately slightly ridiculous up against replaceable bulbs and thin copper wiring). So Wheeler’s invention was consigned to the patent office pile of ‘poorly timed patents’ and his future ideas focused less on illuminating houses of the future and more towards dentistry and illuminating cavities.

However, while all this was going on, there was another scientific race not in optics and light but in creating glass fibers. During the early 1800s, people had started to realise that you could make thin glass strands that had many interesting mechanical properties. But discoveries had hit a wall of sorts as no one could work out how to make long, uniformly sized fibers reliably. Short stubby ones or spools of bent ones were easy enough to spin up, but anything else was a non starter.

This is where a man called Charles Vernon Boys comes in. He was one of the 1800s great instrument makers. He put his mind to this problem and designed several possible way of making glass fibers in beautifully detailed lab notes.

Like any good scientist, his first idea was to get a small container of molten glass and blow it up. His reasoning was that as it arched though the air, it would form threads. But it would be hard to control. His next idea was to use a gun, like an explosion but more focused. However, he said that building a special gun would be a lot of work and he’d rather not bother. Next he looked at rocketry, and reasoned that the acceleration of a rocket would be perfect for pulling the glass, However, he also noted that anyone in the same room as a rocket covered in molton quartz might quickly realise why this isn’t a good idea. Which is fair.

So finally he settled on his highly scientific solution – a crossbow.

crossbowNow Boys doesn’t go into much detail about his crossbow and seems to describe it as though there was a standard set of lab crossbows that every 1800s scientist had. However, in his 12 page paper he devotes 20% to copious notes on the design of the glass carrying bolts. By comparison the actual formation of glass fibers gets about one and a half paragraphs before launching into the applications of his work. But in this paragraph he reported making the very first 9 foot long fiber optic. He also didn’t just stick to playing with quartz, he tried rubies, sapphires and zirconia – basically anything a bit glassy he could get his hands on. In researching this, I learnt that apparently you can make fiber optics with emeralds!

Somewhat amazingly though, this is where our story ends. Boys had successfully made glass fibers – he hung weights off them, put light through the side of them, and made notes on every aspect of their shape and formation, but at no point does he ever mention holding the end of one up to the light and seeing if it did anything interesting. It has to be a case of one of the most baffling misses in science. He was certainly aware of Colladon’s work, and almost certainly had seen Bolton’s fountain but for some reason he never connected the dots between light guiding water and glass rods and his newly constructed glass fibers!

For almost 30 years after, these discoveries were not combined. Even more strangely, the bringing together of these two great discoveries came from scamming the CIA. But that will have to wait for a followup article.

3 Comments for “The birth of fiber optics – Faust, fountains and crossbows”

says:

It is fascinating that Boys hung weights from glass fibers…. little did he know that in 2015 long-thin glass fibers (specifically non-hollow silica glass fibers) would be used to hang 40 kg mirrors in the LIGO gravitational wave detector, and consequently, revolutionize physics! However, the LIGO team don’t use a crossbow to make their glass fibers: instead they use a laser to melt the glass and robots to stretch it (which is almost as cool). [Details: http://authors.library.caltech.edu/46365/1/0264-9381_31_10_105006.pdf%5D

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