Tuesday, March 31, 2009

Funny webs for funny science

Surfing into the net today, I have found two very amusing web sites that I strongly recommend you to visit.
  • The first one, "The Naked Scientists", is, in their own words, "group of physicians and researchers from Cambridge University who use radio, live lectures, and the Internet to strip science down to its bare essentials, and promote it to the general public". Simply wonderful.
  • The second one is "Cuaderno de bitácora estelar", by D. Barrado and B. Montesinos; it is a blog where interesting topics related with science and astrophysics fare presented so that everybody can understand them.

Enjoy them!

Monday, March 30, 2009

Laser cooling

If you want to know what laser cooling is, Nobel Laureate Steven Chu delivers a Lecture at UC Berkeley under the title "Laser cooling: from atomic clocks to watching biomolecules" that you can watch here:

Monday, March 23, 2009

The dancer



In which way is the woman dancing? Clockwise or anti-clockwise? Sure?
It spins in the way you want to!
Don't you trust us?
Think about the fact that the image is not a tridimensional (since it is on your PC screen, it can just have two dimensions), so it can not have a rotational movement. If you want to see it spinning on the other way, have a look for one moment to the other side of the screen.
But why do you see in one or the other way?
The image has been extracted from an austrilian newspaper:
http://www.news.com.au/heraldsun/story/0,21985,22556281-661,00.html
As it is explained here, it could depend on which side of your brain you use more.

Thursday, March 19, 2009

Transverse modes

Have a look at this video:



What you are watching here are acoustic harmonics (pay attention to the way they change depending on the sound frequency). The acoustic waves produce vibrations on the table which are proportional to the the intensity pattern.

In a very simple model, a laser can be described as a cavity with an active medium inside. The field pattern measured in a perpendicular plane to the cavity is the so called transverse mode. They depend on the cavity geometry.

Some examples:



They are denoted by TEMplq, where p is the number of radial zero fields, l is the number of angular zero fields and q is the number of longitudinal fields. The TEMoo is usually preferred as it is easier to be focused.

Tuesday, March 17, 2009

T. Maiman, inventor of the laser

In the CD player, in the pointer, in the printer, in the industry, in surgery... lasers are everywhere!

But do you know who was the person who developed the first laser?

As you will have already deduced from the title of this post, his name was Theodore Maiman.

Let's find out something more about him.

He was born in 1927 in Los Angeles. He inherited the liking for engineering from his father, who worked as electronics engineer and inventor.

He studied engineering physics at the University fo Colorado, where he got his BsC degree in 1949. Two years later he attended Stanford University and earned a master’s degree in electrical engineering and then a doctorate in physics in 1955.

In 1953, C. Townes together with J. P. Gordon and H. J. Zeiger, had invented the maser ("microwave amplification by stimulated emission of radiation"); two years later, inspired by this development and the basis set by C. Townes and A. Schawlow, Maiman built the ruby laser, considered to be the first functioning laser, in 1960, while working at Hughes Aircraft Company.

If you feel curiosity, you can download the original patent (US3353115) here: http://www.pat2pdf.org/pat2pdf/foo.pl?number=3353115

In 1962, he founded his own enterprise, Korad Corporation, to manufacture lasers; six years later he sold it to Union Carbide and established a new corporation, Maiman Associates.

Among the awards he received throughout his career, he was given the Japan Prize.

He died in 2007 in Vancouver.

PS: Maiman was not given the Nobel Prize (even though he was twice nominated)... surprising, isn't it?