Sam's Laser Repair FAQ
repairfaq.org
repairfaq.org
I'd never owned anything fancier than a Radio Shack laser pointer, but I'd read Sam's FAQ cover-to-cover out of sheer curiosity.
Sometime around 2010, I found myself dropping some things off at a convention, where I was not involved but knew some of the staff. This landed me in a conversation with one of the A/V crew for the dance (happening a few hours hence), specifically the guy who did the laser show equipment. Pretty fancy stuff, especially for 2010.
We end up talking a LOT about lasers, most of which I know from the FAQ, never having touched any of the stuff in the flesh. He takes me down to the ballroom to check out the setup, we play with it a bit, and I'm totally fascinated, not just with the hardware, but the controls that sequence the various show routines. Then he says something like "You seem to have a handle on this.. listen... I never get to GO TO the dance because I'm always back here. You wanna take a shift on the board?", and next thing you know, the lights are down, the fog is up, and the DJ is giving me hand signals to know when to change the laser wibbly-wobbly as he switches songs.
Mid-show, a costumed figure walks up to the board, laser-guy peeks out from behind the mask, "How ya doin? Need a breather?" and I'm like "Nah this is awesome, have fun out there!", and he disappears back into the crowd.
The laserfaq is what got my hooked into optics, which sent me down the career path that I am on now.
I owe it all to you Sam
What do you do now?
I still don't understand it.
DED - Dark Emitting Diode
I really don't understand why laser-pointers are even legal.
FYI, the general legal limit for "pointers" is 5mW.
https://www.repairfaq.org/sam/lasersaf.htm#saftoc
EDIT: I read it again and the crux of the matter seems to be this:
> The ability of the retina to dissipate heat is not dependent on the area covered, but the periphery (circumference) of the exposed area! The blood vessels are in the retina and not the sclera (the surface under the retina) - it is the blood flow that dissipates the heat and so can only act on the edge not the middle of the exposed area. In circumference terms, the ratio drops to 7 times. Furthermore because the larger spot is less efficient at dissipating heat, the effective power delivered by the laser beam is only about 2 times greater than that of the spot formed by the sun.
Lasers safety are also a small part of my job (military). I've got a pile of "pointers" that would blind in an instant, several in the watt-class (ie >1000mw). Anyone can buy 50,000mW laser "pointers" for a couple hundred bucks. I had everyone at work bring in their kid's laser "pointers" a few months ago. Almost every one of them tested above 5mW. 10-20mW was the norm. Assume that everything on ebay/amazon is above 5mW.
I refuse to stay in the same room as a working laser engraver/cutter. They are generally in the 2000-4000mW class, enough for even a slight reflection to instantly create a colour-specific blindspot.
And many of them are IR, so you wouldn't see the leaky beam at all until it zapped your eye.
A typical human eye will respond to wavelengths from about 380 to 740 nanometers.
The one I work with is 4000 watt, capable of cutting up to 20mm carbon steel, 20mm stainless, and 12mm aluminium.
It’s fully enclosed with dual electromechanical locks on each door, and an air extraction system with dust and collector.
I'm surprised it even bothers with HTTPS.
My only gripe is that the page's margins aren't a bit more narrow.
Agreed, I use a chrome extension 'Just Read' to fix websites that do this.
On the other hand, the downside is that you get used to that speed, and listening to people talk in realtime feels abysmally slow. Others may also ask you to slow down more frequently.
2x is a much better speed, but still, it's annoying to have to watch 6 minutes of video to get the single sentence you want.
I can confirm it doesn't translate well to a modern ultrawide monitor.