Laser Products I Hate • Hacker News Board

Re: Laser Products I Hate

#61

Post by agumonkey » Wed, Aug 30, 2017, 8:23 PM UTC

abakker wrote: post #40

I've got a 4x8 CNC router with a small 4W laser diode that I can add on for light engraving work. Discussions of safety, protective eyewear, interlocks, shielding are all very valid. the stray reflections cutting wood in open air mean that there is significant scatter. The other day I attempted to engrave cork and found the scatter to be terrible. BUT, all of that can be managed with shielding, eye protection, and wa…

this guy uses an engraving laser with copper film to quickly make traces/PCBs https://www.youtube.com/watch?v=GEABTyNZv1k [french]

Re: Laser Products I Hate

#62

Post by wnkrshm » Thu, Aug 31, 2017, 12:05 PM UTC

gambiting wrote: post #53

wnkrshm wrote: post #48

Earlier quoted context omitted.

A UV-laser would be humane, since UV (and shorter wavelengths) will interact with the outermost portion of your eye - visible light or the near IR (up to 1500) is what your imaging system operates on and it's focused onto the retina. Edit: Also, the blink reflex isn't fast enough to save you from damage if the Class is higher than Class 2 (and even then it's a roll of the dice, since there are some who don't have tha…

Can you expand on why that would be humane?

Shorter wavelengths (UV, extreme UV) are absorbed at the surface of organic tissue (and many other materials) and lead to ablation or heat transfer at the surface. So with shorter wavelengths, it'll mostly scar the cornea, which can be reshaped again using short wavelengths with a LASIK.

It might also cause damage to the lens and lead to cataracts, which can also be partially compensated today by getting a lens implant.

These ways of damaging your eye are extremely more preferable than having your retina or your nerves damaged in any way, since for that, no method of remedy exists yet.

Re: Laser Products I Hate

#63

Post by wnkrshm » Thu, Aug 31, 2017, 12:08 PM UTC

Filligree wrote: post #54

gambiting wrote: post #53

Earlier quoted context omitted.

Can you expand on why that would be humane?

At a guess, it might be possible to at least partially fix the damage afterwards, by scraping off the damaged cells. I wouldn't call that "humane", and it is a guess; it might not work at all. Nothing to do with war is 'humane', though.

You're right, my choice of words was poor there, I didn't want to imply that there are any humane weapons or ways to wage war.

I think what I was trying to say is that if I could choose the wavelength to hit my eye, I'd pick extreme UV.

Re: Laser Products I Hate

#64

Post by wnkrshm » Thu, Aug 31, 2017, 12:13 PM UTC

avian wrote: post #51

wnkrshm wrote: post #47

I work with lasers and we get a yearly security training on staying safe with lasers (the whole shebang, videos of cow-eyes exploding from diffuse scattering of a cutting laser, cutting pizza, photos of scars of accidents, post-trauma photos of retinas etc). It is indeed terrifying to see how easily you can get tools that can cripple people without people being aware of the danger.

I've spent some time in a lab with an optical table and what was probably a 10 mW helium-neon laser. Doors locked when the laser was on, warning signs, protective eyewear and strict procedures during experiments. And then you go out and see drunk people at parties with lasers from eBay of unknown power pointing them at random people. The lab experience made me really paranoid about anything that involves lasers and I…

Exactly. I've even seen 'party laser' products at dollar stores with moving diffraction gratings that project patterns on the walls, marketed like a kid's toy (and I think with a Class 2).

Even worse, the EU norm for lasers has been amended for incoherent sources. Previously, LEDs had to fulfill certain maximal radiance requirements to not need a laser sticker. They raised the radiance limit for LEDs by a factor of 100 (so if it was coherent it's about a Class 3 now). I treat bright LEDs/flashlights like lasers now at close distance.

Edit: (someone could classify a Class 4 diode laser array for heat treatment as an LED array now (given shitty M2) and avoid the laser norms altogether, despite the thing still being dangerous)

Re: Laser Products I Hate

#65

Post by wnkrshm » Thu, Aug 31, 2017, 12:19 PM UTC

anfractuosity wrote: post #50

wnkrshm wrote: post #49

Earlier quoted context omitted.

It's been researched in the 80s/90s. The best solution was a gas-dynamic laser with a Po-220 (the activity of U238 within its entire 10k years halflife packed into a time of two weeks) reservoir as a heat source.

Very interesting, I'd never heard of a gas dynamic laser before. Edit: Is it the Stavatti device you're referring to? Apparently there are some claims that it was a hoax.

Oh thanks, I've looked into it again and it seems it's highly controversial. I mean, even if it wasn't a hoax, the design is pretty much infeasible if you need a heat source that you can only store for less than a week and that'll kill everyone within line of sight if its container is breached.