Intense light produced when burning with 200mw

[treybadd]

Hello all,

I am fairly new here but have been fascinated by lasers for years now and this site is very informative. I own a 200 mw 650nm focusable and a 50 mw 532 pen style. I have had them both for 2 years now and still enjoy them regularly. I noticed that when burning with my red laser ( blue eagle pair glasses on!!!!!!!) it produces a bright flash when the material burns. I use this as a reference to focus the laser for the best burn. I am however concerned about looking at this intense light through glasses that are rated for red laser light. It almost looks like a miniature arc produced from a welder or a plasma cutter. I am sure that everyone has seen this when burning as well. I have not been able to find any information on this subject and am very curious if it is harmful without additional protection. Thanks.

 

[jeffreythe00]

I'm not sure what that light is but I know what you are talking about. My 50W co2 laser does the same thing and the light emitted frombit is completely invisible yet somehow this super intense white spot appears at the focal point!

Here's a thread someone made a while back. Maybe you can get some information from it until someone with knowledge of the phenomenon.

http://laserpointerforums.com/f50/strange-maybe-not-thing-when-burning-red-54815.html

 

[Flaminpyro]

I have seen the bright spot you talk about and it only happens when you at at optimal focus on the thing you are burning.

I have not seen this discussed here before so lets start right now.

What the hell is that ?

why dose a bright spot happen only when optimal focus is achieved ?

I have noticed this when burning with 405nm also.

 

[Lase]

why dose a bright spot happen only when optimal focus is achieved ?

I have noticed this when burning with 405nm also.

Must be some kind of reward.

I too have noticed the flash with a 405.

Lase

 

[treybadd]

Burning with 200 mw - YouTube

Here is a vid through my blue glasses burning black leather.

 

[treybadd]

This has puzzled/amazed me since the day I got this laser so I guess it's time to see if any physics gurus can offer an explanation.

Question 1: What is the light produced?
Question 2: Is it safe to look at even through laser safety glasses?

Thanks for replies!

 

[bennett326]

i see it too crazy mystery lets call the hardy boys, scratch that lets call nancy drew :tinfoil:

lol but seriously i see it too when its focused right ,kinda weird now that i think about it

 

[InfinitusEquitas]

It doesn't seem like a mystery at all to me, although I could be completely wrong:tinfoil:

Goggles only protect you from certain wavelengths.

When you reach the optimal focus and see that intense light, you're seeing the light being produced from the combustion/degradation of the material, across the spectrum. (Pretty sure those are the wrong terms, but can't think of the correct one at the moment.)

No different from say staring a sparkler... or welder's arc. Those would also appear very bright through goggles only meant to block one wavelength

 

[treybadd]

Well, after reading the thread Jefferythe00 referenced, It is safe to assume that it is not safe to burn and look at this spot of intense light even with glasses on unless they are specifically designed to block light of that wavelength. ( welding hood or welding goggles!)

 

[treybadd]

Look at this little moron!!! What's wrong with this video??

200mw Red laser from budget gadgets HLP18130 - YouTube

 

[RA_pierce]

Well, after reading the thread Jefferythe00 referenced, It is safe to assume that it is not safe to burn and look at this spot of intense light even with glasses on unless they are specifically designed to block light of that wavelength. ( welding hood or welding goggles!)

The white light produced in this instance is not going to be more intense than the laser used to produce it. If so, that would imply that more energy is being produced than you started with... in other words, a >100% efficient light to light conversion. Most of the energy carried in the photons is going to be converted to heat. My guess is that this white light is just incandescence from the burning material being heated rapidly by a very intense light source and is negligible at the power we are dealing with.

 

[Ibuprofen200mg]

Infinit is correct I believe, the bright light you see at that pin point is not from the laser itself but from the breaking of chemical bonds (combustion) of the material itself which unlike the laser, is emitted over much of the range of the visible spectrum and well into the ir (heat), that's why it appears whitish, a blend of many wavelengths and is not blocked by your eye-wear.

beat me to it RA!

 

[Flaminpyro]

Ibuprofen200mg come here and bring 4 of your buddies I have a splitting head ache !!!

 

[Benm]

My guess is that this white light is just incandescence from the burning material being heated rapidly by a very intense light source and is negligible at the power we are dealing with.

I'd agree on this - its thermal emission from material being heated up or even combusing at the focal point. This would generally produce visible light beyond red when the temperature exeeds 1200 celcius or so on the spot. It's likely that this happens with materials that arent very thermally conductive and prefereably combustibe, such as wood, charcoal and some plastics.

I doubt it would pose a serious hazard - perhaps comparable to striking a match and looking at it. Only if the termpature goes up so far the spot starts to emit UV you may have a problem - similar to a welding arc.

Most laser goggles are made from polycarbonate though, and the transmission of this plastic rapidly drops off with wavelengths shorter than 400 nm - probably enough to protect you from any uv produced at the hotspot.

 

[InfinitusEquitas]

Ibuprofen200mg come here and bring 4 of your buddies I have a splitting head ache !!!

Had a migraine ALL DAY yesterday... Ibuprofen wasn't working... maybe he was slacking off

I'd agree on this - its thermal emission from material being heated up or even combusing at the focal point. This would generally produce visible light beyond red when the temperature exeeds 1200 celcius or so on the spot. It's likely that this happens with materials that arent very thermally conductive and prefereably combustibe, such as wood, charcoal and some plastics.

I doubt it would pose a serious hazard - perhaps comparable to striking a match and looking at it. Only if the termpature goes up so far the spot starts to emit UV you may have a problem - similar to a welding arc.

Most laser goggles are made from polycarbonate though, and the transmission of this plastic rapidly drops off with wavelengths shorter than 400 nm - probably enough to protect you from any uv produced at the hotspot.

The white light produced in this instance is not going to be more intense than the laser used to produce it. If so, that would imply that more energy is being produced than you started with... in other words, a >100% efficient light to light conversion. Most of the energy carried in the photons is going to be converted to heat. My guess is that this white light is just incandescence from the burning material being heated rapidly by a very intense light source and is negligible at the power we are dealing with.

Infinit is correct I believe, the bright light you see at that pin point is not from the laser itself but from the breaking of chemical bonds (combustion) of the material itself which unlike the laser, is emitted over much of the range of the visible spectrum and well into the ir (heat), that's why it appears whitish, a blend of many wavelengths and is not blocked by your eye-wear.

Thanks for confirming what I suspected guys:beer:

 

[Ibuprofen200mg]

@Flaminpyro, one of these days I might upgrade to 500mg as the world around seems to produce more and more cranial discomfort!