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Discussion in 'Off-topic' started by AzB, Jul 26, 2020.
I bet in the future police will able to shoot and kill someone with a laser and get away with it.
I'm still trying to figure out how to apply the numbers and the different units and scales. What think I have gathered so far is that the welding glasses could lessen the damage, but not eliminate it.
Not if someone with a laser shoots and kills the police with a laser first.
You heard it here first, folks!
For laser protection, you'll see an optical density rating (OD) associated with a specific wavelength.
OD is a logarithmic function, so an OD of "2" is 10X more absorbent than an OD of "1"; each "+1" is 10x absorbance. So if a lens has an OD of 4.3 at 532nm, that means only about 10^(-4.3) fraction of the intensity passes through... or another way of putting it, about 1/10,000th.
So the higher the OD for a given wavelength, the more it blocks *that* specific laser. Most specs will guard preferentially against 532nm and 808nm (green and red), because those are the most common lasers in typical application. Offhand, a rating of 2 or better is good (absorbing basically 99% of the intensity.)
The more "protections" you layer on glasses/goggles, the less overall light transmission you have through the lens (because there's some overlap and diffusion), until eventually you wind up with a "use the Force, Luke!" blast helmet you can't see through
Since this discussion started, I've been visualizing a dynamic lens system which senses an incoming frequency and then adjusts to block it (via an electrochromic effect called the Kerr effect) - maybe that's my billion-dollar idea? Of course, you have femtoseconds to sense and adjust... tall order!