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AuroraAlpha
Wicked Lasers Master
Joined: 07 Oct 2005
Posts: 763
Picture(s): 55
Movie(s): 4
Location: North Chicago
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 Posted: 10/09/05, 9:10 AM Post subject: Experement |
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ok, bad title, but I don’t really know what to call it so...
When doing the experiments where the laser burns the match and such, do you put something off screen (like a matt black board) to absorb the rays, it seems like otherwise you wall would have some nice burning spots on it, it is reaching like 400 degrees.
Can anyone explain what they use? (Pictures are nice to.) |
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EGP
Fusion Laser
Joined: 05 Aug 2005
Posts: 327
Picture(s): 111
Location: Denmark
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| Posted: 10/09/05, 11:26 AM Post subject: |
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In general, materials have to be very dark and preferably non-reflective to absorb the energy of the laser. Thus, if you have light-colored walls, the laser hitting them really isn't a problem. Burning potential also decreases with distance, and you have to keep the dot very still in the same place, to allow heat buildup. This gets harder the further away you get from the laser. Biggest concern really is to avoid damaging reflections back into your own eyes IMHO.
Cheers,
Erling |
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Athoul
Wicked Lasers God
Joined: 13 Sep 2005
Posts: 7544
Location: Canada
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| Posted: 10/09/05, 3:35 PM Post subject: |
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Also to get a match to burn you usually need to have the match head colored black. This can be done with a black marker or by obtaining marches with a black head already.
cheers, |
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AuroraAlpha
Wicked Lasers Master
Joined: 07 Oct 2005
Posts: 763
Picture(s): 55
Movie(s): 4
Location: North Chicago
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| Posted: 10/09/05, 5:04 PM Post subject: |
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| Nah, what I meen is like when you are lighting the match, you obvoisly are going to miss some of the laser, and it will go past the match into something else. Do you guys use like a black object to absorb the laser, or just ignore it? |
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barisseker
25mW Classic Wicked Laser
Joined: 06 Oct 2005
Posts: 51
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| Posted: 10/09/05, 9:27 PM Post subject: |
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| Unless the paint on the wall is really dark and you placed your experiment right in front on the wall, I doubt you'll damage your paint/wall. But just to be safe you could place a card board or something in the back. my 2 cents... |
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Athoul
Wicked Lasers God
Joined: 13 Sep 2005
Posts: 7544
Location: Canada
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| Posted: 10/10/05, 3:02 AM Post subject: |
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Oh my bad! When the laser hits the match head, if it is only a few inches from the laser aperature, the beam will fully hit the match head. The beam is rated <1.5mRads, meaning <1.5 milimeter diameter per meter. At a few inches the beam is aproximatly 1 mm and a match head is about 2-2.5 mm. The only escaping light you will see is the light created from the heat spot on the match, this is diffuse and will not have any ability to burn or damage objects.
However if you hit the match indirectly and have part of the beam go past the match it would probably not be concentrated enough to make the match ignite, nor damage any objects behind it. However the reflection off of a highly reflective surface can reflect the partially blocked beam in your eyes to cause damage to them!
Note also in all references your eyes are not what I am considering objects, and the reflected light can still damage them from shiney surfaces! A match head can be a reflective surface to cause eye damage, so take the proper precautions!
Sorry if I overly stress the eye protection, but I don't want anyone to suffer eye injuries and it's easy to underestimate the power of these lasers due to their size!
cheers, |
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AuroraAlpha
Wicked Lasers Master
Joined: 07 Oct 2005
Posts: 763
Picture(s): 55
Movie(s): 4
Location: North Chicago
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| Posted: 10/10/05, 7:46 AM Post subject: |
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| Don't worry about me and eyes, on the first big laser I get I am getting 2 sets of goggles, and damn even though there only $50 with a laser, it adds another $100 to the total price. |
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