Is that speculation or is it based on something real?

I'd say, "No." If you're putting enough energy into a beam that it will...

a) Burn through a patch of armor,
b) Evaporate tens or hundreds of grams of water while putting a narrow hole through a body, and
c) Perform a) and b) in a short enough period of time (~0.1 seconds? preferably less) that the beam does not get wiggled and scribbled all over the target due to attacker and target movement...

...then you've got a beam that will dump it's energy into the target so quickly that there'll be a surface explosion, not a penetrating beam.

I think an adequately fast discharge will not give the surface matter (armor and upper layers of flesh) enough time to move (burn/boil/evaporate) out of the way before the beam is done discharging, so the beam energy will just get dumped into a hotter and hotter patch of surface material. Bang! Surface explosion. Quite a focused, intense little explosion that gets through armor pretty easily, apparently. Remotely generated shaped charges even.

Longer discharges that would burn through a body would end up scribbled all over the target, and you'd have low penetration (which isn't the case for SR lasers).

If you don't want that physics-based interpretation, consider that the base damage of the man-portable lasers in SR is Moderate, which indicates damage less severe than through-and-through penetration. Moderate wounds fall into the "nasty flesh wound" category. This is like a small knife wielded by a strong person: good armor penetration, low flesh penetration (high power, low wound code).

If you're successful enough with the Moderate-base attack to change it to Deadly, you probably hit a near-surface vital organ, like the brain, heart, or liver.

Those can't be normal mirrors. Weapon-grade lasers will probably wreck normal mirrors before they reflect much. You'll need those funny-colored specialty optics laser-grade mirrors.

A person would be hit once per emitter. You might manage to split the beam ("beam splitter" mirrors, prisms, whatever) to get multiple attack opportunities per emitter, but each beam would be weaker than normal, and each beam would still only have one attack opportunity.

That makes sense.

Nor in mine, so I never bothered with rules for it. Sorry.

Yep; that's why continuous-fire lasers don't work too well. Fortunately, a single brief pulse is best anyway, thanks to the wonders of capacitors. Same problem happens with metal, too, I hear; people end up with a little cloud of gaseous steel for a few hundredths of a second that means the process of cutting is slowed. That may or may not be true, though.

~J

Uh shtuh cuh thuk uh uhny.

That's why you have those nifty straps on all standard hero slicing tables.

"Goldfinger, surely you don't expect me to talk."
"No, Mr. Bond, I expect you to DIE..."

Talking about flash state-changes in human flesh when exposed to high-energy weapons...

He's right. Speaking in terms of physics, any coherent beam made of electromagnetic energy that has sufficient energy to harm a person will start burning them. Pretty basic, yeah? We all know that. Now, given that the laser has a base power of what, 15M? That means that the beam itself is not especially damaging in terms of surface area, blast, or wound cavity - but it IS extremely good at penetrating armor and near impossible to absorb with the body's own resilience. So it's a pretty tight, pretty damn hot beam.

At varying power levels, a laser will do a wide variety of things to a body. While we lack certain types of *really* high power lasers, people HAVE tested blocks of meat in the path of lasers. A couple of things happen:

The 'power' ratings here are wholly arbitrary, mind you.

1) Low power - the meat has a hole burned in it, nearby flesh melting and running away in the same way that fat melts and runs when you're cooking a burger or rendering tallow for candles. The moisture in the meat boils and expands, cooking said meat in a very similar way to how meat is cooked in a microwave.
2) Medium power - the inherent moisture in the meat is heated so rapidly it becomes steam, tearing the meat apart from the inside. This would PROBABLY (because I can't claim to have seen anything first hand) take the form of shredded cracks running out from the heated point (re: entry wound of laser) along stress points in the muscle or bone. If a bone was struck at this power, the marrow and liquids in the center of the bone would cause it to split, if not shatter.
3) High power - Steam is no longer the only cause of damage; the extreme heat of the laser blast would cause some measure of flash-vaporization of tissue itself. Suddenly super-heating portiions of a body would cause them to... well, not be there any more. Such a rapid expansion would also be like unto having a small explosion go off near that portion of the body. I.E. there would probably be some secondary damage from shockwaves and overpressure.

Make sense?

Basically, any laser hot enough to cut through armor or penetrate thin walls (a 15M weapon) would have at least the 'low-power' effect.

That's cool. That's how I'll describe it from now on.

I was kind of trying to avoid that sort of speculation Sounds like that "medium power" steam-explosion thing has actually happened to meat, though, so I'm satisfied. Thanks

Thing is, body armor can handle explosions and heat rather well. At least a whole lot better than a human. So if there indeed is some sort of explosion when the beam hits the armor, the subsequent damage to the subject beyond should be significantly lesser.

There are many levels of "nasty damage". Getting a 6" blade jammed into your stomach might seem like "nasty damage" to most people, but in SR terms it might be 4M.