Old 01-04-2008, 12:50 AM #1
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
benthegeek benthegeek is offline
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
Default 500 GW (500 mW), 800 nm, 130 fs

Just thought I would show you a video of one of the lasers I get to work with at the Australian National University.

It's a Titanium:Sapphire laser pumping out a thousand 120 femtosecond pulses of 800 nm light a second. Each pulse contains about 500 uJ of energy, giving a peak power of about 5 GW and an average of 500 mW.

The beam size is about 1 cm across when it leaves the laser, and even with that high peak power, you only start to cause some serious damage when you focus it down to a mm or less...and boy does it cause some damage! When you have peak powers like that focused down to such small areas, the intensity goes through the roof and the material, be it paper, plastic, metal or skin, is evaporated instantly. Don't think of it like the industrial laser cutters though, becuase its only 1000 pulses a second and each pulse is 120 femtoseconds long, that average power is quite low and it takes quite a lot of effort to make any serious impact on whatever you are irradiating.

The camera is not the best for showing it to you but its probably better than the human eye. Being 800 nm it's just on the edge of human visability and so while 500 mW in average power, it looks little more than a 5-10mW beam. The dyes in the paper even make it look pink. The camera also isn't the best at showing the result either, but you can see the vapour of the paper floating into the beam as the laser hits it, and you can hear the high pitch whine that the 1000 Hz pulse rate creates. Occasionally it also sounds like it stutters or stops, that occurs when the laser has burnt through the paper, and the laser passes through the hole.

Plastic makes it easier to see the effect. It burnt through a few pens of mine in a few seconds, and on the video you see it burn a swipe card I have. Just little tiny dots burnt into the plastic. Made visible through the use of a scanner that creates a spiral shape. I might post a few closeups of some of the things I have burnt later. For now though, enjoy the amature type video I made


The file is a 13 MB avi and goes for 2:20

I'de make it smaller, but I'de waste too much time trying to set up the right software.
Attached Files
File Type: avi 20080401_TiSap.avi (13.60 MB, 79 views)


benthegeek is offline   Reply With Quote


















Old 01-04-2008, 01:28 AM #2
Switch's Avatar
Class 3B Laser
 
Join Date: Dec 2007
Posts: 3,327
Rep Power: 2795
Switch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond repute
Switch Switch is offline
Class 3B Laser
Switch's Avatar
 
Join Date: Dec 2007
Posts: 3,327
Rep Power: 2795
Switch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Thats pretty cool.So what you're saying that the 500GW pulses have a very low frequency and last so little that the laser avareges at 500mW? Anyway, pretty cool....you just stuck your finger into a GW pulse
Switch is offline   Reply With Quote
Old 01-04-2008, 01:31 AM #3
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
wooooooolazer wooooooolazer is offline
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

So in other words a 900mw cw ir laser would be more powerful than that... weird, especialy since that peaks at 5gw. *Now we need to just get a 5gw cw laser, that woulda sting

...lazer... ;D ;D ;D
wooooooolazer is offline   Reply With Quote
Old 01-04-2008, 02:47 AM #4
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
benthegeek benthegeek is offline
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Yep, Power is measured as Energy/Time. If you take the same energy, and decrease the time that it is contained in, then you increase the power. That is what the Ti:Sapphire laser does. It pulses the light so that all the energy is compressed into a thousand 120 femtosecond pulses.

You can use some basic math to understand it.

- In one second there are 1000 pulses each with an energy E (Jouls) so the total energy in one second is 1000E (Jouls).
- As power is Energy/Time and the Watt is defined as Jouls per second the average power is therefore 1000E / 1 = 1000E W.
- The power meter measured 500 mW and so you can solve for E to get the pulse energy which is 500 uJ for a 500 mW beam.
- Knowing the pulse energy and the pulse duration you can find the peak power. E / 120 fs = 500 x10^-6 / 120 x10^-15 = 4.16 x10^9 Watts = 4.16 GW

The key is understanding the difference between average power and peak power.
benthegeek is offline   Reply With Quote
Old 01-04-2008, 03:24 AM #5
flogged's Avatar
Class 2M Laser
 
Join Date: Jul 2007
Posts: 530
Rep Power: 47
flogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond repute
flogged flogged is offline
Class 2M Laser
flogged's Avatar
 
Join Date: Jul 2007
Posts: 530
Rep Power: 47
flogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond reputeflogged has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Was the humming a 1000Hz tone caused by the paper acting as a speaker as the laser ablated it away at that freq? Interesting.
flogged is offline   Reply With Quote
Old 01-04-2008, 03:42 AM #6
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
benthegeek benthegeek is offline
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
Default Re: 500 GW (500 mW), 800 nm, 130 fs

I think the act of blasting away the paper creates sound itself which is why you hear the 1000 Hz. I don't think it would transfer that much energy to the paper to act as a speaker.
benthegeek is offline   Reply With Quote
Old 01-04-2008, 05:50 AM #7
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
wooooooolazer wooooooolazer is offline
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

No it wouldnt, they took the most powerful man-made light on earth andfocused it down to a small spot and shined it on some aluminum foil and it just barely started moving.

I saw that on some show where they were trying to use the sun as solor propolsion in outerspace by utilizing the energy to hit reflectors 50ft big to propel the space craft without needing fuel.

...lazer... ;D ;D ;D
wooooooolazer is offline   Reply With Quote
Old 01-04-2008, 03:14 PM #8
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,293
Rep Power: 211757
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,293
Rep Power: 211757
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Each pulse vaporises a small portion of paper, yes? This means the paper changes state from a solid to a gas. It expands quite a bit. If you pulse a laser beam on the paper at 1kHz, you get an incidental 1000 expansions of air per second - a 1kHz sound wave.

Very cool
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 01-04-2008, 04:29 PM #9
Switch's Avatar
Class 3B Laser
 
Join Date: Dec 2007
Posts: 3,327
Rep Power: 2795
Switch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond repute
Switch Switch is offline
Class 3B Laser
Switch's Avatar
 
Join Date: Dec 2007
Posts: 3,327
Rep Power: 2795
Switch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond reputeSwitch has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Yea I think that is what flogged wanted to say.I does sound like a good explanation especially since the humming sound has roughly the same pitch as a 1kHz soundwave :
Switch is offline   Reply With Quote
Old 01-05-2008, 05:22 AM #10
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
benthegeek benthegeek is offline
Member
 
Join Date: Jul 2007
Posts: 34
Rep Power: 0
benthegeek is on a distinguished road
Default Re: 500 GW (500 mW), 800 nm, 130 fs

The idea of using a laser as a source of force is not new, with the most recent case i can recall being: http://www.baeinstitute.com/pr1.html

Basicly, light has momentum but it is so small that you don't fly out of a room every time you switch on a light bulb. In fact, even when using weopens grade lasers, you only get around 35uN of force. That's MICRO newton. Apply that force to a 75kg person for a year and you will reach a grand speed of 53km/h. You can bump up the laser power, but you all know what happens with high powered lasers. A solar sail can help, but you them move into more material, weight and other problems.

A real use: http://www.photonics.com/content/spe...ech/87450.aspx
benthegeek is offline   Reply With Quote
Old 01-05-2008, 05:42 AM #11
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
wooooooolazer wooooooolazer is offline
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Quote:
Originally Posted by benthegeek
weopens grade lasers, you only get around 35uN of force. That's MICRO newton. Apply that force to a 75kg person for a year and you will reach a grand speed of 53km/h.
Although i think you would be nice and crispy before you even moved a mili-meter.

...lazer... ;D ;D ;D
wooooooolazer is offline   Reply With Quote
Old 01-05-2008, 10:16 AM #12
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,293
Rep Power: 211757
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,293
Rep Power: 211757
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

I'd move 10+mph before being hit. Does that defy the laws of physics?
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 01-05-2008, 05:52 PM #13
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
wooooooolazer wooooooolazer is offline
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,047
Rep Power: 457
wooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond reputewooooooolazer has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

LOL, good idea i dont want them pointing no 5 ton laser at me

...lazer... ;D ;D ;D
wooooooolazer is offline   Reply With Quote
Old 01-10-2008, 11:27 PM #14
Krutz's Avatar
Class 3R Laser
 
Join Date: Nov 2007
Posts: 1,733
Rep Power: 137
Krutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond repute
Krutz Krutz is offline
Class 3R Laser
Krutz's Avatar
 
Join Date: Nov 2007
Posts: 1,733
Rep Power: 137
Krutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond reputeKrutz has a reputation beyond repute
Default Re: 500 GW (500 mW), 800 nm, 130 fs

great video, one surely doesnt get to see such lasers often! :-)

like it!

manuel
__________________
Originally Posted by brtaman
"Some say he eats Gallium Nitride for breakfast, others say that he can moonwalk and still defeat a Ferrari on the quarter mile......all we know is, he's called IgorT."
Krutz is offline   Reply With Quote
Old 01-11-2008, 11:39 AM #15
Class 2 Laser
 
Join Date: Sep 2007
Posts: 415
Rep Power: 12
philguy is on a distinguished road
philguy philguy is offline
Class 2 Laser
 
Join Date: Sep 2007
Posts: 415
Rep Power: 12
philguy is on a distinguished road
Default Re: 500 GW (500 mW), 800 nm, 130 fs

Oh, it's really easy to calculate that impulse!

impulse of a photon is h/[ch955] (planck constant over wavelength), if you had a reflecting mirror (and wouldn't need to absorb it all, ha!), the change in impulse would be 2p.

So lets say you weight 70kg ( ~140 pounds) and want to move 1m/s (~2.2 mph), just hold a mirror and have your friend shine your laser at you.
The individual 532nm photon having 1.23e-27 kg*m/s and 3.73e-19 j, you'll need 2.83e28 photons or 1.05e10 j.
Assuming you have a 500mW laser, it would take you 670 years to reach you stinkin' 1m/s.
here


Ha! Talk about growing old?
Probably exceeds warranty? Or laser lifetime?
philguy is offline   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



























Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 01:57 AM.


Powered by: vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC