Archive for the ‘Optics’ Category

What’s in a picture


Today’s guessing game is:

What is this a picture of?



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Charles K. Kao, Willard S. Boyle and George E. Smith share this years Nobel prize in Physics for their contributions to the transmission and detection of light. Congratulations to the three of them.

Charles K. Kao did research in material science of glass, and argued that the losses in glass fibers available in the 1960’s where mostly due to impurities in the material. A few years later glass of sufficient purity was made by Corning, and modern fiber optics telecommunications where born. Nowadays, this technology impacts us directly by making the infrastructure that handles the information traffic of the internet possible.

Willard S. Boyle and George E. Smith created the CCD. This is one of the main technologies in modern photography. It make the capture and reading of light fast and efficient and it essentially made photographic film obsolete: the cost of capturing an image went down to essentially zero. It is also one of the standard technologies for astrophysics and most importantly, it is not restricted to the visible spectrum. It can be used to read light from distant sources very fast, data that can be transmitted to researchers all over the world very quickly (we don’t have to wait to develop the film), and being in electronic format, it is easy to manipulate, send and store. This is anther technology that has wide applications on the Internet, capturing live images that end up in U-Tube and Flicker.

Lubos laments the fact that the Nobel prize went just for technology. Although I sympathize, I think that this is not a bad choice at all. Although one can call this applied physics rather than fundamental physics, the technological breakthroughs enabled by these inventions is truly remarkable. Nowadays, we take it for granted. But it is truly a marvelous thing. Today,  I can have a video-phone conversation on the Internet with someone on the other side of the planet, for a costs that is essentially zero. This is a science fiction idea that did come through, but not necessarily the way they were originally envisioned.

You should also consider that modern telecommunications account for a big chunk of the worlds GDP, and it will surely grow in the future. The technologies that make this possible come from Physics research, and it might take many years before the engineering issues and the costs can be lowered enough so that we all benefit from them. Besides, the whole architecture of the modern Internet came out from CERN. A lot of people needed to look at large chunks of data with completely independent computer systems ans operating systems. A common message protocol for communications and standards for addressing data was born from these necessities. It would be hard to give a Nobel prize for that.

I would wish that the public at large was more aware that the technologies of today are the product of years of development, starting from physics discoveries and inventions and refined by engineers so that they can be mass produced with quality that can be controlled. Without the first invention, the rest of the process doesn’t work.

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Recently I went to the dentist and had a full set of routine X-rays taken. The technology has changed a lot since my childhood. Mostly because now my dentist hooks up his laptop to an electronic device that is put in my mouth and the X-rays are ready within fractions of seconds after exposure. This way I don’t have to wait as much for the X-ray films to be developed and in the end this is a cheaper way to get the information. I’m also assured that the new electronic readers require less exposure than film so that my total radiation exposure is reduced by quite a bit.   I also get to wear the lead apron to prevent some of the soft tissues in my chest cavity and lower body from being exposed to unnecessary radiation. 

So what do X-rays actually measure? This is what I thought I would ask and answer today for my first post in a long time. Part of this question is about how the photons in the X-rays interact with matter and why is lead used to stop X-rays. 

This is very different than the superhero X-ray vision. Surprisingly, for most superheroes it is still true that lead will stop them from seeing an object.


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Stereography: It’s in 3D

I went to see Coraline this weekend. It is an animated movie made with stop motion animation (and it is supplemented by usual CGI effects). I like the medium of stop-motion very much, particularly because it is harder to achieve a good result. The most interesting thing about the movie is that it was filmed in 3D, which gives it a much more eerie feeling. The storyline was ok and there were various aspects that were very predictable. There are some elements of it that reminded me of my childhood: I used to be especially afraid of dogs and I met a lot of kids that didn’t fit in well. I also ended up eating more beets than I liked when I was growing up. Now I really love them, so I can understand a few obsessions that are portrayed in the movie. I think the thing I liked the most was that they did not use the 3D to do that usual ‘trick’ of having objects point towards the audience over and over again. There was a  bit of that at the very beginning, but it soon faded away. (For an example of bad – or you could also say tasteless- uses of 3d, see this blog review of Beowulf)

Now, back to the 3D. Just to tell you a  little bit about the technology involved (feel free to go to wikipedia for more info). The basic idea is that we have stereographic vision: we have two eyes, which is really good for measuring distances by angles of triangles. So ideally, each eye sees a slightly different image and our brain reconstructs a 3D map from two 2D-images.


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