The Texas Petawatt Laser

Roland Piquepaille notes the hype surrounding what the University of Texas at Austin is calling the world's most powerful laser. During a tenth of a femtosecond this laser is 2,000 times more powerful than all the power plants in the US, and is brighter than sunlight on the surface of the Sun. On his own blog Roland points out that UT's is not the first petawatt laser; that distinction belongs to a system installed at Lawrence Livermore National Laboratory in 1996.

link to project page

[dermond]

http://www.ph.utexas.edu/~utlasers/texas_petawatt_files/texas_petawatt.htm [utexas.edu]

with fotos and shematics, etc..

Wrong about the Sun and petawatts

[Ancient_Hacker]

A petawatt is only 10^15 watts.

Our Sun puts out about 4 x 10^24 watts, continuously, for billions of years.

So this laser is only putting out about one four-billionth of the Sun, and only for a very split second.

It's also very misleading if they intended to compare brightness per unit area. Even a cheap laser pointer is brighter than the surface of the Sun.

Re:We're all wondering...

[odourpreventer]

Where do they get the power to run this thing anyway?

In case this was a serious question: Giant capacitors, connected in parallel.

picosecond, not femtosecond

[The Bender]

The pulse length is ~100 fs (0.1 ps), not 0.1 fs. 100 fs is already about as short as laser pulses can get - and 0.1 fs is much shorter than the length of a single electromagnetic wave.

Obvious mistake in TFA

[justkeeper]

One femtoseocnd is 10 to the power of -15 of a second,NOT one trillionth of a second.Thus the pulse duration should be 100 fs,which is realistic.State of the art technology can't yet produce high power sub-femtosecond(i.e attosecond) pulses ,due to low conversion efficiency of energy concentrated on the low-frequency spectrum to the high-frequency spectrum using currently available methods(for an attosecond pulse a Fourier Transform will show that you have mostly X-ray frequency components in the frequency spectrum). Discaimer:I'm a Ph.D student working on high-power laser systems.

Soon to be a Dime a Dozen

[djtachyon]

University of Rochester is building a petawatt laser of capable of picosecond pulse lengths. http://omegaep.lle.rochester.edu/ [rochester.edu]

Re:We're all wondering...

[yoavi]

This is not accurate. Watts are indeed rates of energy consumption, that is, the amount of energy consumed per unit time (Watt stands for Joule per second). Now, if we squeeze 100 Joules in into 10^-13 of a second, then the *instantaneous* power during those 100 femtoseconds (and yes, the story has got it wrong, it's a tenth of a picosecond, not femtosecond, which makes a hundred femtoseconds) is one petawatt. The average power, assuming we operate at 0.1Hz (which I think will be the laser's repetition rate) is only 10 Watts.

This also answers the "heating" problem. These lasers carry a relatively small amount of energy, and produce very little heat. However, the electric field that is produced when the beam is focused is huge, and many interesting phenomena can be studied with such a laser.

Btw, for the same reason, this type of laser is completely useless as a weapon. In order to cause any real damage one has to deposit energy into the substance that is to be damaged, and again, these laser pulses carry a relatively small amount of energy.

Re:We're all wondering...

[The Bender]

Obviously the energy is built up over the period between pulses. And since the repetition rate is only 1 shot per HOUR, the average power output is only 0.1 W [calctool.org]!

That wouldn't even put a dent in my electricity bill.

Yes I know, I know...

Re:global warming

[Whiney Mac Fanboy]

Petawatt Lasers use, wait for this, petawatts of power.

Yes, peta watts (10 ^ 15) for less than a femto (10 ^ -15) second)

A mere blip compared to other power uses. I don't think this research is particularly relevant to climate change, the OP was trying to start a flamewar.

How you think that power is generated? Nice clean nuclear? Hahahaha.

Probably natural gas. And carbon-neutral is a better way to describe nuclear than clean.

Re:Time duration?

[MLCT]

They aren't ridiculous - and you are ill informed to say that they are. Average power vs. peak power. Those two variables are highly relevent for a pulsed laser. Your "torch" isn't even pulsed.

A lot of ground breaking research is undertaken *utilising* the ability to deliver very short very high energy pulses - for doing that you can deliver a huge amount of energy in a very tiny amount of time - then observe what happens. Indeed a lot of the very high energy regions cannot be accessed with anything but ultrafast pulsed systems, as CW setups would just destroy themselves (and even using UF systems chirping "tricks" are used to reduce peak powers until the final moment to ensure the optics aren't burnt out).

See http://en.wikipedia.org/wiki/Chirped_pulse_amplification [wikipedia.org]

Nope. You are a factor of 1000 out.

[Maddog Batty]

Nope. The key ring laser pointers are 1mW to 5mW so this thing is 2000 to 10000 times the average power. A 10W laser is very good at setting fire to things but won't drill a hole through your still twitching body.

It's what they don't say

[cnosh]

You have to put this in perspective. They may have made a laser with highest peak intensities but it's nowhere near the most energetic laser out there. According to their press release their pulses have 150 J of energy. Compare this to the National Ignition Facility at Lawrence Livermore laser, which will produce 1.8 MJ per shot when it is completed next year, or to the laser at the University of Rochester, which will produce several kJ. Though not yet finished, both these lasers have already demonstrated many kJ of energies.

Roland the Plogger again

[Animats]

More Roland the Plogger blogspam, driving traffic to his useless ad-laden blog. To get around the block on links to his own site, he's now submitting links disguised via "tinyurl".

Slashdot covered this laser weeks ago.

Nope. You are definitely wrong.

[celtic_hackr]

10W lasers are frequently used for engraving in metals and will, if left on long enough burn a hole through steel. While it may take a while, and your body will no longer be twitching, it can and will eventually burn a hole through a human body. The grandparent of your post is wrong about the "heat thing" is also wrong. You have to use the instantaneous power. While the explosive power of firecrackers exploded 1 per second is small, one firecracker explosion is enough to do serious harm to a finger. If any of you think this petawatt laser isn't producing significant energy output, I dare any of you to stick your finger in it's path. I guarantee, you'll lose some flesh and bone.

BTW, surgical lasers are generally in the range of 3-100W and a 30 watt laser will rapidly burn a hole completely through your hand, and you won't even know it happens until it's done. It will be quite painless. Maybe some residual heat, or a reaction from a nerve after the fact. And a 5mW Laser will easily burn through your retina, depending on the wavelength of the laser. Of course a single look in a 5mW laser will leave a very small bindspot, unless you keep it on your eye looking at it from lots of angles.

Naturally there is a difference between pulsed and continuous beam lasers, and this petawatt laser is not a continuous beam. There are no continuous beam lasers in this region of energy output, because nothing could hold up to the continuous heat produced by one.