Concerns about violet lasers.

[Low-Q]

Hi,

I just wonder if there is any concerns regarding violet lasers. I think about skin exposure, and the posibility to develope skin cancer. We know that the radiation of violet and UV light from the sun can result in skin cancer. A 200 - 400mW violet laser radiates maybe 100 times that energy locally on you skin with a somehow focused 405nm laser. So what is the posibilities to develope skin cancer? It should be quite high if you're not careful!!


Any thaughts about this?

Br.

Vidar

 

[borgqueenx]

ive read a article some time ago. seems the skin can heal itself pretty good from laser burns. not sure though.

 

[lazer]

The most a violet laser will do is burn you. You are not at any risk of skin cancer by using violet lasers.

 

[ElektroFreak]

Pretty much anything above 350nm is safe.. here's a link to a short article about this very thing..

 

[Jaseth]

The wavelength is above the threshold for cancer-developing radiation. It will not cause cancer, but very quickly give you one hell of a burn. Blu-ray is more efficient at burning than other wavelengths, especially skin and light material.

 

[Meatball]

Blu - ray is just a deep violet wavelength. UV starts < 400nm. Ionization starts ~350nm. Blu- rays are cancer free, but they are definitely burners.

 

[digital_blue]

A 200 - 400mW violet laser radiates maybe 100 times that energy locally on you skin with a somehow focused 405nm laser. So what is the posibilities to develope skin cancer?

It's not the energy density of the dot; it's the amount of energy each photon (of a specific wavelength) carries.

 

[Low-Q]

Thanks all for the information. I have felt the 405nm laser. It hurts even without focusing it to a small point (If I do, it REALLY hurts!!).

Anyway, I did perform a little visual spectrum analysis of the dot hitting my skin. I used a CD to see how the 405nm light converts into a wide spectrum light when it hits an absorbing material. The 405nm reflection decrease quite much, and the rest of the energy is converted into everything from purple to deep red. That witness of a great absorbtion the skin has on 405nm light. So, it isn't strange these lasers is clearly burning skin. Sure much of the energy is converted into IR light as well - but I could not see that visually ofcourse.

Have you btw. tried to light through a saturated red transparent glass? The 405nm light is 100% absorbed, but left you can in fact see inside the LD housing that the laser diode chip lights also a small amount of a very deep red light - like the colour of a 808nm laser.

Are these 405nm lasers somehow excited by a red laser? Is red light a biproduct of the 405nm light? Is it 810nm (405nm x 2) light, due to unlinearity, I see? Or do I see a result of a very hot LD that emits a hot glowing light?

Vidar

 

[millirad]

Remember, unless a diode laser is DPSS, which uses an IR laser diode to excite a crystal which doubles the frequency, it is a monochromatic single wavelength. (In the case of a DPSS, some IR leaks with the green or blue if unfiltered). Therefore non-DPSS diode lasers are a very pure single wavelength. When a laser such as an Argon, emits radiation, it is passing what is known as multiline radiation. Multiline emission is a combination of more than one single frequency of light energy. With a blu-ray, you are only going to get a singe frequency between 400 and 410 nanometers of light. So remember, it is always pure monochromatic(single wavelength) coherent(lightwaves moving in step, or in-phase) light. Hope this clears it up for you.
Regards.

 

[Low-Q]

I understand. I have tried to light through other filters too. A green one - actually green liquid soap. The emitter is also glowing quite bright green. So now I assume the whole emitter emits white light, not only green or red. I believe it does because of:

1. the heat

2. the emitter absorbs violet light and therfor emitts white light.

It is the whole cube shaped chip that glows, so the red or the green light is not coming out of the tiny laser aperture of this cube ship.

 

[chipdouglas]

Hey lowq, the colors you are seeing are from the objects being hit by the blu-ray flouresing. like when a black light makes white t-shirts glow. well a blu-ray makes many objects floures, but it doesn't mean the the blu-ray is changing its own color.

 

[scopeguy20]

There is a small amount of radiant heat, this is partially IR of course and not laser IR light. -Glenn

 

[Low-Q]

OK. I guess then the material in the laser cavity is glowing. I did a quick spektrum analysis with a CD. I removed the lens and fired the laser. From the side there is no emitting laser light, so I angled the laser, and looked at it in a CD. I see the violet color, but also the whole spectrum of light. I have attached a picture of it. I know for sure it is the laser chip that is glowing. So the material in that is obviously a flourecent material.

 

[chipdouglas]

the extra colors are probably coatings of the cd flouresing. if you wiki lasers it gives a pretty good answer to how lasers are made.

 

[Low-Q]

the extra colors are probably coatings of the cd flouresing. if you wiki lasers it gives a pretty good answer to how lasers are made.

It is not the CD fluorensing. If I point the laser directly to the CD, I can see only violet light. It is only when I angle the laser away from the CD surface, so I am not pointing the laser beam into the CD, I can see the spectrum - as all diode lasers are working, the LD chip lights visible light outside the lease direction too - like an ordinary LED. It is this light I try to analyse with the spectrum provided from the reflective CD surface. It lights violet like the laser light, but also the rest of the spectrum. I haven't seen similar with red diode lasers, because red are in the low end of the visible spectrum.
Besides, a fluorecent CD would not give that effect like the one seen in the picture, but a more uniform color - not separated into wavelengths.

I will ask wiki lasers for answers to my question. Thanks for the tip!

Vidar

 

[maxh]

Shine your violet laser through a prism and see what comes out the other side. It'll be a single line of violet. Or you can use a real diffraction grating instead of a CD.