2016/05/15

The Actor's Best Critic

Stuff about my lasers, most of it involving their lenses one way or another. Hence the title, a Sydney Greenstreet quote:
The lens is the actor's best critic... showing his mind more clearly than on the stage. You can get wonderful cooperation out of the lens if you are true, but God help you if you are not. ... You're at the mercy of the camera angles and the piecemeal technique.
Discovered a reason not to use c. one-micron wavelength for the near-infrared lasers zledo use: it's still a blindness-hazard at that wavelength. Went with c. one and a half microns—the blindness-risk is between 350 and 1400 nanometers (near-UV poses some risk of physically burning the surface of the eyes themselves, but they are at least opaque to it). Of course, with both zled and human medicine of my books' era, they can actually re-grow your retina if they have to, but that's probably a costly, time-consuming, and possibly painful procedure. (Presumably they can also correct for the vision-problems albinos have, by the same methods...though that might have to involve straight-up dyeing their eyes, since there is actually a reason their retinas don't grow in right, and giving a normal retina to someone whose eyes still can't block light is probably flat-out dangerous.)

Might need to double-check when they use green lasers, while I'm at it—maybe they don't? Visible light is bad RE: blindness-risk because, y' know, your eyes are designed to catch as much of it as they can, and all. Think their civilian lasers are only near-infrared, since at the range of most civilian self-defense even that's adequate even against their body-armor (and near-UV, since it can over-penetrate, is probably a liability risk). Also not having the frequency-adjuster probably keeps the price down, always more of an issue for the private individual than for a professional military.

Also discovered that c. 250 nanometers, which I'd had as their near-UV band, is UV-C and, apparently, gets quite attenuated by air—as in the attenuation-graphs I can find seem to stop cold at 300 nanometers (I think they might be assuming the ozone-layer, rather than the low-ozone lower atmospheric layers, since ultraviolet light you're likely to need to know about, is mostly part of sunlight). Went with just over 320 nanometers, just inside the UV-A range, but still outside the blindness-risk range. UV-A can go easily through air, and even window-glass—which is opaque to UV-B and UV-C. I think UV-A also has the least attenuation in air of any part of the UV (lower than 200 nanometers, air, as such, becomes completely opaque to ultraviolet; ozone, mostly found in the upper atmosphere, is mostly opaque to UV-B and completely opaque to UV-C, but transparent to UV-A).

A nice thing about changing these is that laser-ranges seem to scale linearly with wavelength—a 532-nanometer green laser has half the range (ignoring atmospheric attenuation) of a 266-nanometer near-UV laser, and twice the range of a 1,064-nanometer near-infrared laser. So changing from c. 1 micron to c. 1.5 microns just meant I had to divide the ranges by 1.5; changing from c. 250 to c. 320 is going to mean dividing by 1.25 (or multiplying by .8)—because they're actually 1/400,000th of a zled unit vs. 1/500,000th, which makes their ratio much tidier than 25/32nds.

On the other hand, discovered the lenses I'd given them were actually too small, for decent ranges. For some ungodly reason, the laser-performance calculator I use, uses lenses' radiuses, when one normally talks about them in terms of diameter (not just lasers, either—a 50-millimeter camera lens is its diameter, not its radius).

In view of this, made the hand laser, which had been one-quarter bãgh, or 3.2175 centimeters, one-third, or 4.29 centimeters. This makes its heat-exchanger, still 5.813 square centimeters in total area, a mere 3.389 millimeters wide, because the outer diameter of the laser is 5.46 centimeters (I realized I'd made the outer casing way too thick, 1/11th bãgh rather than, much more reasonably, 1/22nd—since even that is 5.85 millimeters.) Its nanotube spring, on the other hand—same diameter as the lens—would be 1.06 centimeters wide. Since that's just the spring, and it has a thick casing (because springs are freaking dangerous), as thick as that around the laser itself, we wind up with a spring-cartridge 2.23 centimeters wide.

The long laser goes from being one-half bãgh, 6.435 centimeters, to being two-thirds, 8.58 centimeters. Its heat exchanger, still needing an area of 52.495 square centimeters, is only 17.138 millimeters wide (its outer diameter is 9.75 centimeters, since its casing is also thinner now). The nanotube spring to power it, at the new diameter of the lens, is 2.44 centimeters wide, in its cartridge-casing 3.61 centimeters.