Christmas is over - but here's a very quick film I put out just before the holidays: https://www.youtube.com/watch?v=QK01AYjPSyY
The glass baubles (unused props from the 2012 Christmas Lectures) were each sealed with a tiny amount of water inside. As the water was heated under pressure it boils at a higher temperature and when it does evaporate within the sealed space, the internal pressure builds until the glass structure fails. At this point the water (heated beyond it's normal boiling point under atmospheric conditions) flashes into steam with explosive force and the bauble is shattered into a shower of glass fragments. All this happens extremely quickly, you hear a loud bang and then see a shower of glass - far too fast to be seen by the human eye (or a camera shooting at 25 fps).
It requires the muscle of a specialist high-speed camera to really catch a glimpse of what's going on here. For this film we used a Phantom v1610 - which provided extremely high frame-rates, just what you need to get a better glimpse of the action! However, even at a blistering 34,000 fps you can see just how quickly the explosion event occurs - within the space of 1 -2 frames! A rough calculation shows just how fast this is, with one frame at 34,000 being the equivalent of around 29 microseconds in real time, that's 0.000029 seconds!
You can see the unedited footage below:
As you increase the frame-rate on these cameras, you're reducing the amount of time each individual frame is exposed, so you need to shine a lot of light on your scene with the higher frame-rates in order to see anything. As you go up to the higher frame-rates you're also capturing a lot more information and to handle this the camera usually has to lower the resolution - this provides a rather agonising compromise between capturing something at very high-speed and retaining acceptable image quality.
Regardless of this, the results were simply breathtaking and why wouldn't they be? It's like being able to slow-time down and observe our world from a totally new perspective. Watch this space for more high-speed footage over the coming year.