OMFG! "Cancer ray"!!!!

[digital_blue]

Actually, 355nm is not an ionizing wavelength so it won't damage DNA.

 

[Switch]

Actually, 355nm is not an ionizing wavelength so it won't damage DNA.

You keep telling yourself that :

 

[lasersbee]

Well... either way.. I'm not a guinea pig... and I wouldn't shine it on my skin... ;D

Jerry

 

[Cyparagon]

An intense pulse of UV could contain enough energy to cause cell damage even over such a short period of time as its the tissue penetration and energy transferred to the cells that does the damage not the duration.

Are you telling us we're just as likely to be sunburned in 5 minutes as 5 hours?

Average power might be 420mw.

Even less. At max. rep. rate I calculated 150mW average, but 3KW peak.

Actually, 355nm is not an ionizing wavelength so it won't damage DNA.

From wikipedia:

While "black lights" do produce light in the UV range, their spectrum is confined to the longwave UVA region. Unlike UVB and UVC, which are responsible for the direct DNA damage that leads to skin cancer, black light is limited to lower energy, longer waves and does not cause sunburn. However, UVA is capable of causing damage to collagen fibers and destroying vitamin A in skin.

 

[Alsone]

[quote author=Alsone link=1236568266/0#14 date=1236593447]An intense pulse of UV could contain enough energy to cause cell damage even over such a short period of time as its the tissue penetration and energy transferred to the cells that does the damage not the duration.

Are you telling us we're just as likely to be sunburned in 5 minutes as 5 hours? [/quote]

Laser light is much more intense than sunlight. A laser has the potential to expose you to levels in milli seconds what sunlight might take hours to do. eg. A sunbed can give you a 5 minute tan, a tan that would take hours outside but a sunbed has no where near the level of coherent light that a laser has.

[quote author=Alsone link=1236568266/0#14 date=1236593447]Average power might be 420mw.

Even less. At max. rep. rate I calculated 150mW average, but 3KW peak. [/quote]

I haven't done calculations but 3KW peak? Thats not eye or camera safe as I said. Pulsed lasers are very dangerous and should command a lot of respect.

Actually, 355nm is not an ionizing wavelength so it won't damage DNA.

From wikipedia:

While "black lights" do produce light in the UV range, their spectrum is confined to the longwave UVA region. Unlike UVB and UVC, which are responsible for the direct DNA damage that leads to skin cancer, black light is limited to lower energy, longer waves and does not cause sunburn. However, UVA is capable of causing damage to collagen fibers and destroying vitamin A in skin.

[/quote]

Can't argue with the Wiki but even UVA effects are undesirable from reading that and what the wiki doesn't tell you is about laser levels of intensity. Its surprising how innocuous things become dangerous at very high concentrations and assuming your calculations above were correct 3KW pulses of UVA aren't going to do your skin any good especially as to compare that not non coherently radiated UVA you're talking several thousand times that level, so potentially the equivalent of millions of watts of sunlight radiated UVA.

 

[digital_blue]

UVA will not cause DNA damage/cancer. It can however burn through several layers of skin and give you cataracts if you take a hit in the eye.

hivwhy not make a pulse source for it with a ne555

I'm not sure a 555 could provide the 3-4kHz I'm planning to drive this thing at. Besides, I already have a function generator and a few opamps lying around.

 

[Curiously_Coherent]

Not sure about the cancer risk but I have personally "sunburned" my skin quite badly with a 26W SW UV lamp that I photograph fluorescent minerals with.  I've always used UV goggles because the risk of cataracts is very high with UVA, but now I wear black sleeves & gloves and slather any exposed flesh in SPF40 sunscreen rated for UVB and UVA protection. (Ombrelle is the most effective)  My light source uses germicidal quartz UV fluorescent bulbs. They are normally used in water sterilization equipment and air ducts because they KILL things like bacteria.  Living things do not fare well under UVA light in general, so it couldn't hurt to be careful and take precautions.

It sounds like a cool laser... I'm sure you'll treat it with the respect it deserves.

Cheers, CC

 

[Switch]

but a sunbed has no where near the level of [highlight]coherent[/highlight] light that a laser has.

Does coherence really play a part here? :-/ Coherent or incoherent, the same power over the same area would probably have the same effects.

And this laser and even a blu-ray CAN give you cancer !!!11 Do I have to write it on wikipedia for you to believe it? : : : : : : : :

;D

 

[digital_blue]

I believe it has something to do with certain wavelengths carrying different levels of energy. Coherency simply means that all the light is "in phase"...

 

[Switch]

I believe it has something to do with certain wavelengths carrying different levels of energy. Coherency simply means that all the light is "in phase"...

Yea but when you have a fixed power rating beam hitting an area of fixed size the amount of energy absorbed and transformed to heat is the same.At least in the case where heat damage is all that occurs.Maybe where more complex proceses take place , like ionizing radiation, coherence does play a part. :-/ :-/

 

[laserwanabe]

what a tease, a laser with no beam pics =\

 

[lasersbee]

I'm not sure a 555 could provide the 3-4kHz I'm planning to drive this thing at. Besides, I already have a function generator and a few opamps lying around.

You can easily run a 555 Timer over a few Mhz...

Jerry

 

[GooeyGus]

Screw 355... Take the summing crystal out and you get a really strong pulsed green!

 

[Benm]

Not sure about the cancer risk but I have personally "sunburned" my skin quite badly with a 26W SW UV lamp that I photograph fluorescent minerals with.  I've always used UV goggles because the risk of cataracts is very high with UVA, but now I wear black sleeves & gloves and slather any exposed flesh in SPF40 sunscreen rated for UVB and UVA protection. (Ombrelle is the most effective)  My light source uses germicidal quartz UV fluorescent bulbs. They are normally used in water sterilization equipment and air ducts because they KILL things like bacteria.  Living things do not fare well under UVA light in general, so it couldn't hurt to be careful and take precautions.

There is a vast difference between the 253 nm UVC radiated from your germicidal lamp, and the 355 nm from this laser. 253 nm is very bad news for anything living, and prolongued exposure to that is a real skin cancer risk.

Sunlight does not contain anything as short at 250 nm - it is blocked by the ozone layer among other things, and is not something you are naturally exposed to, nor evolved to handle. Wavelengts beteen 300 and 400 nm are common in sunlight however... there is still a risk of sunburn and skin cancer after heavy exposure, but its nothing compared to what a germicidal lamp will do to you at equal power levels.

355 is still considered ionizing radiation, but its relatively safe - with this laser i suppose it will (if focussed) give you a thermal burn painful enough to avoid too much exposure next time

 

[digital_blue]

Screw 355... Take the summing crystal out and you get a really strong pulsed green!

Actually, if I ever get the second unit repaired, I'll probably end up converting the 1064nm line to a 532 and swapping out the summing crystal out for a KDP. With a harmonic separator, it should yield some decent 266nm UV

 

[Cyparagon]

The point I'm trying to make is it's not much more dangerous than your average YAG for example. As long as you wear your goggles and don't intentionally expose your skin to it you'll be fine. We don't need to shit our pants and hide under a table because it's UV.