http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/ Engadget Comments for Two-killowatt laser heats coffee, wows onlookers http://www.engadget.com/media/feedlogo.gif http://www.engadget.com en-us Copyright 2008 Weblogs, Inc. The contents of this feed are available for non-commercial use only. Blogsmith http://www.blogsmith.com/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 6:12AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 10:31PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 6:30AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/
SEATTLE - Starbucks Inc. readies their new weapon in the caffiene-delivery battle arsenal: the laser-guided half-caf quad venti raspberry organic no-whip white mocha.]]>Mar 25th 2007 8:36AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 8:36AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/]]>Mar 25th 2007 8:38AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/
- Tony R.]]>Mar 25th 2007 9:39AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/]]>Mar 25th 2007 1:32PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/
Just my two cents, I just wish I had something stronger than a laser pointer o.x.

- Tony R.]]>Mar 25th 2007 9:44AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 9:50AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 10:52AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/* Assume the cups are 8 ounces, which is ~237 cc of water
* Water has a specific heat of 1.0 -- it takes 1 Joule to heat it 1 degree celsius per cc
* That's 237 Joules per degree celsius
* Room temperature water = 21 degrees celsius, boiling = 100, so that's an increase of 79 degrees celsius
* 79 degrees Celsius * 237 Joules per degree celsius = 18723 joules to heat 8 ounces of water to boiling.
* The light was lit for 20 seconds on the first cup
* 18723 joules / 20 seconds = 936 watts

Possible sources of error:
* Incorrect estimation of cup size
* Water was not room temperature coming from the tap

Possible sources of lasing inefficiency:
* Inefficiency in the laser
* Reflection of light off the water
* Loss of heat due to convection at the top of the cup
* Frequency of laser was not tuned to the absorbtion frequency of coffee (water ~= 2.4Ghz)
* Probably lots of others since I know nothing about lasers :-)]]>Mar 25th 2007 2:27PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/
Cheers!]]>Mar 25th 2007 5:51PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 11:00PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/
1) Your numbers are incorrect. The specific heat of water is 4.186 Joule per gram degree celcius, not 1. You are thinking in terms of calories.

2) Also, the laser they were using was most likely an industrial CO2 laser (which is QUITE efficient, might I add), with a mean wavelength of about 10 micrometers, which translates into a frequency of about 30GHz, so the laser is not exactly at microwave frequency, but close enough.

3) Your possible "source of error: Reflection of light off the water" is complete nonsense.

]]>Mar 25th 2007 11:42PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 3:18PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 3:36PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/I see a potential application in the vending machine of the future...

Of course they would have to get rid of the Nescrappie that they used in this prototype...

Now all we will need is an industrial robot with a special attachment to grind up the beans...

Bob]]>Mar 25th 2007 7:06PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 25th 2007 8:18PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 26th 2007 1:29AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 26th 2007 8:36AMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 26th 2007 2:08PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Mar 26th 2007 3:29PMhttp://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/http://www.engadget.com/2007/03/25/two-killowatt-laser-heats-coffee-wows-onlookers/Actually the source of error is your calculation. The specific heat of water is 4.194 J/ºC. Your calculation is for calories not Joules. So assuming the rest of you math is correct then, the correct # of watts is 3916. Also, if you noticed, the cups are not full.
-Ted]]>Jul 1st 2007 12:02PM