Reverse-engineering the untouchable and measuring the unseen

Having studied creative writing at university, I can recount how perhaps the majority of my three years' bachelors amounted to the old adage 'show, don't tell.' Whenever there is a need for a piece of fiction to establish itself as being set in a different reality, or a different timeline to our own, there are many techniques that can be employed to portray this difference from what we are used to. It's clearly better to do this through visual means, as opposed to lengthy exposition. One example of a simple item that can instantly tell the viewer that what they're watching is not set in our own world is a piece of technology that we don't encounter anymore, such as vacuum tubes. 

Vacuum tubes fascinate me: they're this beautifully rustic, mechanical, industrial and diverse thing that doesn't really seem to exist in the modern day anymore, yet used to be quite common a few decades ago. Especially the vacuum tubes displaying digits with a fiery glow just have such an iconic look to them that makes me wish they were still in common use today. 

Avid readers may remember that I did an interview with Andreas Bastian and Jon Brumer from Lumafield a while ago, for a feature article in TCT magazine. I also wrote an article related to it, in which I mentioned how they had Mythbusters co-host Adam Savage over for a visit. Since then, Mr Savage has returned to Lumafield multiple times to have more of his workshop oddities scanned and, in the latest episode, had some vacuum tubes scanned. 

These were not the standard 'Nixie tube' type that you might find in retro clocks, but instead they were a photomultiplier and a thyratron tube. Both are quite advanced pieces of technology: a photomultiplier is used to turn light into a measurable current and is somewhat of a precursor to modern digital camera light sensors. However, this one in particular is precise enough to detect as little as a single photon. A thyratron tube is essentially a very advanced, high capacity switch, handling up to 25,000 volts and 1,000 amps. 

Another interesting CT scan that I came across this week was done by Nikon: the fuel tank of a Mk 19 Spitfire. This one was done specifically because the original plans for the part of the WWII-era aircraft were no longer available. That means that if a replacement needs to be manufactured, it would be difficult to get close to the original specifications. For a sealed, hollow object like a fuel tank, an approach like laser scanning or using a CMM might deliver accurate measurements of the outside, but leaves the inside and its production techniques a mystery. 

Likewise, for something like a vacuum tube, the translucency of the glass can present problems to some laser scanning solutions. In addition to that, an accurate measurement of the outside may be achieved with conventional measurement solutions, but all the intricate technology is hidden, sealed inside a vacuum (or in hydrogen gas in the case of the thyratron tube). A further complication is that the glass part of the thyratron tube was handmade by a glass blower, something which is practically unheard of in high performance parts in modern production. CT scans offer a non-intrusive way of accurately inspecting the entirety of such objects, even allowing for assessing what materials different components are made of, thanks to a density heat-map revealing all components. 

Whether it's for museum restoration, refitting older machinery, or recreating old parts without blueprints, it may be necessary to do some reverse-engineering. CT scanning offers a chance for accurate and full insights in a non-intrusive way.