Lasers
drorzel | March 31, 2010Physics Central is having a contest:
Do you love lasers? Ever wanted to unravel the mystery of the stimulated emission? Then the LaserFest video contest is for you. Take any laser you want and use it to somehow express a physics concept. Shine, lase, bounce and wave your way into physics history.
The winner will receive a trophy lovingly made by APS staff from some of our favorite laser toys as well as $1,000 cash. All entries must be received by May 16th at midnight.
If you know how to make videos for YouTube, and know something about physics, here's your chance at (Internet) fame and (…
drorzel | March 25, 2010I did one sketchy update from Portland last Tuesday, but never wrote up my impressions of the rest of the March Meeting-- when I got back, I was buried in grading, and then trying to put together Monday's presentation. And, for reasons that will become apparent, I was unable to write anything up before I left Portland
Anyway, for those who care, here are my impressions from the rest of the meeting:
Tuesday
In the 8am session, I went to the polymer physics prize talk by Michael Rubinstein, which was a sort of career retrospective, talking about how he wandered into the disreputable field of…
drorzel | March 15, 2010I'm terrible about taking notes on conference talks, especially when I'm jet-lagged and was sleep deprived even before I got on the plane. I do jot down the occasional paper reference, though, so here are the things I wrote down, and the talks they were associated with. This should give you some vague idea of what the meeting was like on Monday.
From Joel Moore's talk on topological insulators, one of the Hot New Topics in condensed matter, a review in Nature.
From Phillip Treutlein's talk on optomechanics, a recent preprint on coupling atoms to mechanical oscillators.
From Nathaniel Brahms'…
drorzel | February 23, 2010What's the application? CD and DVD players use lasers to read (and in some cases write) digital information from convenient plastic disks.
What problem(s) is it the solution to? 1) "How do we store a large amount of digital information in a convenient and stable fashion?" 2) "How do we make everybody buy the White Album a second time?"
How does it work? The optics at the core of a CD player are very simple, and illustrated in this graphic that I lifted from the excellent explanation at HyperPhysics:
Light from a diode laser is collimated and then focused down onto the surface of the CD. The…
drorzel | February 23, 2010A couple of weeks ago, I announced a contest to determine the Most Amazing Laser Application. What with one thing and another, this didn't get posted last week, but I don't intend to drop it completely, and will be finishing the series up in the next week or so. Here's the list of finalists, with links to those already written up:
Cat toy/ dog toy/ laser light show
Laser cooling/ BEC
Lunar laser ranging
Optical tweezers
Optical storage media (CD/DVD/Blu-Ray)
LIGO
Telecommunications
Holography
Laser ignited fusion
Laser eye surgery
Laser frequency comb/ spectroscopy
Laser guide stars/…
drorzel | February 12, 2010What's the application? Optical tweezers use focused light beams to trap small particles in the focus of the beam, and drag them around by moving the beam.
What problem(s) is it the solution to? 1) "How do we move these tiny little things around without touching them?" 2) "How do we measure the forces exerted by biological molecules?" 3) "How do we tie knots in DNA strands?"
How does it work?The basic optical tweezer scheme uses a single beam of light focused down to a very small spot. If you take some small (mostly) transparent object and place it in the beam, it will feel a force pulling it…
drorzel | February 11, 2010What's the application? Measuring the distance from the Earth to the Moon by bouncing a laser off one of the retro-reflector arrays left there by the Apollo missions.
What problem(s) is it the solution to? 1) "How does the distance from the Earth to the Moon vary over time due to things like tidal drag?" 2) "Does the strength of gravity change over time?" 3) "What can we do with a laser to really cheese off people who think the Moon landings were fake?"
How does it work? This concept is simplicity itself. You simply point a laser at the Moon, fire off a short pulse of light, and wait for it…
drorzel | February 10, 2010What's the application? Using lasers to reduce the speed of a sample of atoms, thereby reducing their temperature to a tiny fraction of a degree above absolute zero.
What problem(s) is it the solution to? 1) "How can I make this sample of atoms move slowly enough to measure their properties very accurately?" 2) "How can I make this sample of atoms move slowly enough for their quantum wave-like character to become apparent?"
How does it work? I've written about laser cooling before, but the nickel version of the explanation is this: You can think of a beam of light as being made up of photons…
drorzel | February 8, 2010What's the application? The use of lasers to provide an entertaining light show for humans, dogs, or cats.
What problem(s) is it the solution to? 1) "How will I entertain my dog or cat?"
2) "How can we distract people from the fact that Roger Daltrey has no voice left?"
Why are lasers essential? Lasers provide coherent beams of light, which remain small over very large distances, allowing you to project a small spot or a tight beam across a room, or even a football stadium.
Why is it cool? Duuuuude! Lasers, duuuuude!
Why isn't it cool enough? 1) It's fundamentally just a toy. 2) No amount…
drorzel | February 8, 2010A couple of weeks ago, I announced a contest to determine the Most Amazing Laser Application. After a follow-up post listing the likely candidates, we have a final list of candidate applications, an even dozen of them (after consolidating some related topics):
Cat toy/ dog toy/ laser light show
Laser cooling/ BEC
Laser ranging/position measurement
Optical tweezers
Optical storage media (CD/DVD/Blu-Ray)
LIGO
Telecommunications
Holography
Laser ignited fusion
Laser eye surgery
Laser frequency comb/ spectroscopy
Laser guide stars/ adaptive optics
Here's how this will work: over the next week…
drorzel | February 1, 2010Last week, I asked for nominations of the most amazing laser application, with the idea being that I will collect a list, write up the top vote-getters in a series of blog posts, and then we will have a vote to determine what is THE coolest laser application of ALL TIME!
At least, you know, as far as you can do that on a blog...
Nominations will remain open until next Monday, but I wanted to remind people, and give you a list of the top nominees thus far. These will be pretty hard to top, but there are still lots of laser applications that have not been mentioned, so be sure to get your vote…
rallain | October 23, 2008I am sorry to point this out, but I can't help it. My kids watch this show "Fetch with Ruff Ruffman". It's mostly an ok kids show. However, there was a problem. In one episode, some kids were in the desert and measuring temperature with (they said it several times and it was even a quiz question at the end) - a LASER. Here is the device they used:
This is an infrared thermometer with a LASER aiming system. The laser is only there to help you aim. The temperature is determined by measuring the infrared…