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Can a laser cut glass

Cube777

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In Mission Impossible 4 Ethan cuts glass with a laser, is it even possible:thinking:? My theory is that the glass absorbs little or none of the light emitted from the laser, thus generating no or very little heat, not enough to cut glass. Am I correct or am I totally of track?:confused: Just one problem with that scene is that the light doesn't even go through the glass, it just stops there!:twak:
 

Quetzal

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Actually Cube,

Lasers CAN cut glass, but you'd need a very powerful laser to do it. In fact, many large companies use laser cutters as tool for cutting glass and other materials.

But you're correct, the part where the laser just stops at the glass is definitely cinematic liberty.
Also, the glass that Ethan cuts is probably not "glass" per se, more likely fiberglass, which would be cut pretty easily by a laser of enough power.
 

Cube777

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Thank you, can you maybe tell me how much power do you need to cut normal glass?
 

Quetzal

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ooh, tough one.

If I had to guess, I'd say something around 50 watts.

Just to put that in perspective: that's 10,000x more powerful than a regular laser pointer.
If you want to cut glass, don't use a laser. It's not efficient. If you have any other way of doing it, do that, because building a 50W laser is the kind of stuff that gets the NSA looking into you.
 
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InfinitusEquitas

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Bear in mind that we see only a very narrow band of the energy spectrum...



This means that what is transparent to you, and will pass through as visible light, will not pass through other wavelengths. The reverse is also true, and if we could see further into IR, well... let's just say modesty would be a thing of the past, whether you wear clothes or your don't.

Of course in the movie it was all special effects, but in reality, lasers are used to cut all kinds of materials, including glass.

Also, the pointers on this forum tend to be a bit more powerful, so the "0,000x more powerful than a regular laser pointer." statement isn't really accurate here :eg:
 

LarryDFW

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Lasers are used for cutting glass routinely.

My understanding is that "localized heating" is what actually fractures the glass.

LarryDFW
 
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As has been stated in many places/postings here before, the most common cutting/marking laser for glass is a CO2 unit.
The beam from a CO2 laser isn't in the visible spectrum and would not be visible, but that doesn't mean that any other visible laser can't be used as an indicator of the beam path of the invisible one.
Such systems are commonplace in surgical installations and such.

But, as pointed out, the power output of the CO2 laser would likely preclude it from being a small easily transported hand-held device.
At least at this time it still is. (Or isn't perhaps.)

As Larry there points out, the laser only needs to heat or etch into the surface layer of the glass to cause a controlled fracture point. Then a light tap or other impact can cause the glass to simply snap through.
 
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Cube777

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Thank you for all the replies, just wanted to know out of curiosity, don't intend to actually cut glass. But a 50 watt laser would be awesome:drool:! Do you think you can pop a balloon with?:crackup:(Don't have to answer, already know
 
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DrSid

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There are some videos with 50W CO2 lasers on youtube .. but the power itself would do nothing, the wavelength is the trick here. It also makes troubles with optics .. as they cannot be made from glass, as it is not transparent at this wavelength.

Anyway, common action movie knows nothing about lasers.
 
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Quetzal

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Yeah, when I said "0,000x more powerful than a regular laser pointer' I was referring to the 5mW, off-the-shelf kind that anyone can buy.
 

neomagik

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Hi everybody first post here. Sorry to bring up an old thread but Google led me to this thread and my question is kind of relevant to the topic.

Ok so if I have a laser capable of causing combustion and I point it at a piece of black plexi glass, it will start to melt right!

If I then replace it for a piece of clear plexi glass of the same size and thickness, will it melt, or could I hold something combustible on the other side and set it alight through the plexi glass?

If so, would the clear plexi glass experience any temperature rise at all?

I'm thinking of the sun and a magnifying glass as an analogy, does the shape of the "medium" in this case, the clear plexi glass have any effect?

Thanks

Rob
 

diachi

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Hi everybody first post here. Sorry to bring up an old thread but Google led me to this thread and my question is kind of relevant to the topic.

Ok so if I have a laser capable of causing combustion and I point it at a piece of black plexi glass, it will start to melt right!

If I then replace it for a piece of clear plexi glass of the same size and thickness, will it melt, or could I hold something combustible on the other side and set it alight through the plexi glass?

If so, would the clear plexi glass experience any temperature rise at all?

I'm thinking of the sun and a magnifying glass as an analogy, does the shape of the "medium" in this case, the clear plexi glass have any effect?

Thanks

Rob
It's all about the wavelengths that are absorbed by the material you are trying to cut. Visible wavelengths won't work on clear plexiglass because for the most part they pass right through it. However, a CO2 (10,600nm) laser will eat it right up, as would UV and other some other IR lasers.

Of course - some visible light will be absorbed by clear plexiglass, but it's a small amount - so you'd need a lot of power to heat it up/burn it/cut it.
 




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