Naked Science Forum
Non Life Sciences => Technology => Topic started by: thedoc on 15/06/2010 18:50:48
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Hi Chris and team,
Curtains fade because of sunlight. The world has a problem with graffiti. Has anyone tried inventing a laser light that could be used to shine on the graffiti and fade it in a hurry?
Regards
Paul
NZ
Asked by Paul Anderson
Go to the show page. (http://www.thenakedscientists.com/HTML/podcasts/show/2010.06.13/)
or Listen to the Answer [chapter podcast=2730 track=10.06.13/Naked_Scientists_Show_10.06.13_6482.mp3","]Part 1[/chapter] [chapter podcast=2730 track=10.06.13/Naked_Scientists_Show_10.06.13_6483.mp3","]Part 2[/chapter] [chapter podcast=2730 track=10.06.13/Naked_Scientists_Show_10.06.13_6482.mp3](https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2FHTML%2Ftypo3conf%2Fext%2Fnaksci_podcast%2Fgnome-settings-sound.gif&hash=f2b0d108dc173aeaa367f8db2e2171bd)[/chapter]
...or download as MP3 [1] (http://nakeddiscovery.com/downloads/split_podcasts/10.06.13/Naked_Scientists_Show_10.06.13_6482.mp3) [2] (http://nakeddiscovery.com/downloads/split_podcasts/10.06.13/Naked_Scientists_Show_10.06.13_6483.mp3)
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You would need a laser that could be tuned to operate over a wide range of frequencies. If you had such a laser you wouldn't need to photograph the graffiti separately because you'd be able to use the laser to scan the graffiti and ascertain it's characteristics. Once you'd done that, all you'd then need to do is use the optimum wavelength of light, for the particular dyes you wish to remove, to burn those dyes off. All it needs is a tunable wide-band laser.
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We discussed this question in the 50 Years of Lasers show on the 13th of June... (http://"http://www.thenakedscientists.com/HTML/podcasts/show/2010.06.13/")
We posed this question to Graeme Hirst from the STFC Central Laser Facility...
Graeme: - Yes it can. They're already used in this application, certainly for cleaning expensive things. The trick is to choose a laser so that the colour of the laser light matches the colour of the graffiti ink. [that can then be used to heat the graffiti ink, and blow it off the wall without heating the wall up.] So, yes, it’s a very neat solution for cleaning dirty stuff off expensive things. Unfortunately, it’s not always cheap and you do have to make sure there’s no one around.
Ben: - Is it also true that you can use lasers to have a look through the paint and try, and find fraud in paintings?
Graeme: - Yes, you can. Again, you choose the right colour. Now, what you're looking to do is to choose a colour which is not absorbed by the top layer of paint so it goes straight through. It’ll be absorbed by something a bit lower down, it’ll bounce back off that and whether it’s there or not, you will get bounce-back or not and by mapping out the bounce-back, you can look at the layer below the paint layer.
Click to visit the show page for the podcast in which this question is answered. (http://www.thenakedscientists.com/HTML/podcasts/show/2010.06.13/) Alternatively, listen to the answer now [chapter podcast=2730 track=10.06.13/Naked_Scientists_Show_10.06.13_6482.mp3","]Part 1[/chapter] [chapter podcast=2730 track=10.06.13/Naked_Scientists_Show_10.06.13_6483.mp3","]Part 2[/chapter] [chapter podcast=2730 track=10.06.13/Naked_Scientists_Show_10.06.13_6482.mp3](https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2FHTML%2Ftypo3conf%2Fext%2Fnaksci_podcast%2Fgnome-settings-sound.gif&hash=f2b0d108dc173aeaa367f8db2e2171bd)[/chapter]...or download as MP3 [1] (http://nakeddiscovery.com/downloads/split_podcasts/10.06.13/Naked_Scientists_Show_10.06.13_6482.mp3) [2] (http://nakeddiscovery.com/downloads/split_podcasts/10.06.13/Naked_Scientists_Show_10.06.13_6483.mp3)
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Hmm... that must have been a very quite xmas eve, if I was posting stuff here just after 11 pm.