Optical Guitars: Sound and Light - Raman Kashyap
October 20, 2011
Explore how NSERC-funded research is using fibre optics to re-discover the guitar. Featuring the work of Raman Kashyap (École Polytechnique de Montréal).
|Dr. Raman Kashyap||
My father was an eminent surgeon and a very great inventor. Actually, he was a great inventor, and I think he opened the doors for me. I have him to blame. He encouraged me to try to solve problems, physical problems, and come up with solutions myself, although he must have known the solutions himself. So I ended up filing my first patent when I was 13 years old.
The story goes back a long time. My daughter, when she was three years old, she started playing the cello. And it was a very heavy, big instrument. So I – and she said, you know, this is a heavy instrument. So I said maybe we can make it light. So what's lighter than light? And it just so turned out and developed like that, that we realized that we could replace the strings of the – all the strings of the guitar with one single fibre.
So let's take the example of a normal guitar string. How does it make a sound? It makes a sound by stretching the string between two points and tensioning it, and it's a certain length. And that determines the frequency with which it oscillates. And when it oscillates – when you pluck it, it'll oscillate, and it'll set up a sound wave. And this sound wave is through the movement of atoms, the air that is around the string.
Now, how do we translate this into light, into a light pick-up? And we do this by launching light into this optical fibre, which we now replace the string with. And what happens is that there are many rays of light that are going inside this fibre. And what we are interested in is how the difference in the time that light takes to reach the output of the fibre, how that varies as a function of time. We are picking up the difference in the change in length of the output, or the time of arrival of light at the output, from between these two rays of light. And when we look at the difference, the variation in that, that is giving us the signature of the vibration of that string.
I think in particular the Discovery Grants Program has been a key cornerstone of research. It's a small amount of money, but it lasts a long time, over many years. This has also been an envy of a lot of people, even in America, because they have to fight for their money very hard because that includes all sorts of different things. This is a small amount of money which allows you to engage maybe a research assistant or a couple of PhD students and work with them over the long term. And this has also been instrumental in building this optical guitar that you've seen today.