Why Does Everything Look Green Through Night Vision Goggles?

istock.com/nightman1965
istock.com/nightman1965

The characteristic green tint is by design, for a few reasons. First, device makers have experimented with a few different colors and found that the different shades that make up the monochrome night vision image are most accurately perceived and distinguished when they’re green. In other words, while the night vision images you’ve seen in Silence of the Lambs and Call of Duty might seem a little clunky, green presents a night vision device wearer with the most accurate and user-friendly picture possible. What’s more, because the eye is most sensitive to light wavelengths near 555 nanometers - that is, green - the display can be a little dimmer, which conserves battery power.

Who Invented Night Vision?

The first practical night vision devices were developed in Germany in the mid-1930s and were used by both German tanks and infantry during World War II. U.S. Military scientists had simultaneously developed their own night vision devices that first saw use during WWII and the Korean War.

These “Generation 0” devices used active infrared to brighten up a scene. Soldiers carried an IR illuminator to shoot a beam of near-infrared light that then reflected off objects and bounced back to the lens of their scope and created a visible image of what they were looking at. The illuminators used by the German Nachtjägers, or "night hunters", were about the size of dinner plates and required a large power supply carried on the soldier’s back.

The technology made huge leaps in the following decades, and by the time the U.S. entered the Vietnam War, many troops were outfitted with passive "starlight scopes" that used image-intensifying tubes to amplify available ambient light (usually from the moon and stars, hence the name) and produce an electronic image of a dark area.

This “Generation 1” technology is still around today in the more budget-friendly consumer-grade night vision devices. Military and police forces have upgraded to successive generations of tech with new improvements over the years, but image intensifying night vision - there’s also another flavor, thermal imaging, but image intensification is almost always the kind you see in movies and games - still works on the same basic principles as these early models.

I Can See Clearly Now

The lens or lenses at the end of a night vision scope or pair of goggles gather available light, including some from the lower spectrum of invisible infrared, and focus it on a photocathode on the device’s image intensifier tube, which transforms the photons, or light particles, into electrons.

As the electrons move through the tube, they flow through a microchannel plate, which is a disc with millions of tiny holes, or microchannels, in it. As the electrons strike electrodes on the microchannels, bursts of voltage cause the motion of electrons to increase rapidly, forming a dense clouds of electrons that intensifies the original image.

At the far end of the tube, the electrons hit a screen coated with a phosphor, which is a substance that radiates visible light after being energized. (We talked about phosphors in relation to glow-in-the-dark toys a while ago.) The energy from the electrons excites the phosphor which converts the electrons back into photons. These are in the same alignment as the photons that originally entered the tube, and form the greenish image on the screen inside the viewing lens of the device.

10 Reusable Gifts for Your Eco-Friendliest Friend

Disposable tea bags can't compete with this pla-tea-pus and his friends.
Disposable tea bags can't compete with this pla-tea-pus and his friends.
DecorChic/Amazon

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By this point, your eco-friendly pal probably has a reusable water bottle that accompanies them everywhere and some sturdy grocery totes that keep their plastic-bag count below par. Here are 10 other sustainable gift ideas that’ll help them in their conservation efforts.

1. Reusable Produce Bags; $13

No more staticky plastic bags.Naturally Sensible/Amazon

The complimentary plastic produce bags in grocery stores aren’t great, but neither is having all your spherical fruits and vegetables roll pell-mell down the checkout conveyor belt. Enter the perfect alternative: mesh bags that are nylon, lightweight, and even machine-washable.

Buy it: Amazon

2. Animal Tea Infusers; $16

Nothing like afternoon tea with your tiny animal friends.DecorChic/Amazon

Saying goodbye to disposable tea bags calls for a quality tea diffuser, and there’s really no reason why it shouldn’t be shaped like an adorable animal. This “ParTEA Pack” includes a hippo, platypus, otter, cat, and owl, which can all hang over the edge of a glass or mug. (In other words, you won’t have to fish them out with your fingers or dirty a spoon when your loose leaf is done steeping.)

Buy it: Amazon

3. Rocketbook Smart Notebook; $25

Typing your notes on a tablet or laptop might save trees, but it doesn’t quite capture the feeling of writing on paper with a regular pen. The Rocketbook, on the other hand, does. After you’re finished filling a page with sketches, musings, or whatever else, you scan it into the Rocketbook app with your smartphone, wipe it clean with the microfiber cloth, and start again. This one also comes with a compatible pen, but any PILOT FriXion pens will do.

Buy it: Amazon

4. Food Huggers; $13

"I'm a hugger!"Food Huggers/Amazon

It’s hard to compete with the convenience of plastic wrap or tin foil when it comes to covering the exposed end of a piece of produce or an open tin can—and keeping those leftovers in food storage containers can take up valuable space in the fridge. This set of five silicone Food Huggers stretch to fit over a wide range of circular goods, from a lidless jar to half a lemon.

Buy it: Amazon

5. Swiffer Mop Pads; $15

For floors that'll shine like the top of the Chrysler Building.Turbo Microfiber/Amazon

Swiffers may be much less unwieldy than regular mops, but the disposable pads present a problem to anyone who likes to keep their trash output to a minimum. These machine-washable pads fasten to the bottom of any Swiffer WetJet, and the thick microfiber will trap dirt and dust instead of pushing it into corners. Each pad lasts for at least 100 uses, so you’d be saving your eco-friendly friend quite a bit of money, too.

Buy it: Amazon

6. SodaStream for Sparkling Water; $69

A fondness for fizzy over flat water doesn’t have to mean buying it bottled. Not only does the SodaStream let you make seltzer at home, but it’s also small enough that it won’t take up too much precious counter space. SodaStream also sells flavor drops to give your home-brewed beverage even more flair—this pack from Amazon ($25) includes mango, orange, raspberry, lemon, and lime.

Buy it: Amazon

7. Washable Lint Roller; $13

Roller dirty.iLifeTech/Amazon

There’s a good chance that anyone with a pet (or just an intense dislike for lint) has lint-rolled their way through countless sticky sheets. iLifeTech’s reusable roller boasts “the power of glue,” which doesn’t wear off even after you’ve washed it. Each one also comes with a 3-inch travel-sized version, so you can stay fuzz-free on the go.

Buy it: Amazon

8. Countertop Compost Bin; $23

Like a tiny Tin Man for your table.Epica/Amazon

Even if you keep a compost pile in your own backyard, it doesn’t make sense to dash outside every time you need to dump a food scrap. A countertop compost bin can come in handy, especially if it kills odors and blends in with your decor. This 1.3-gallon pail does both. It’s made of stainless steel—which matches just about everything—and contains an activated-charcoal filter that prevents rancid peels and juices from stinking up your kitchen.

Buy it: Amazon

9. Fabric-Softening Dryer Balls; $17

Also great for learning how to juggle without breaking anything.Smart Sheep

Nobody likes starchy, scratchy clothes, but some people might like blowing through bottles of fabric softener and boxes of dryer sheets even less. Smart Sheep is here to offer a solution: wool dryer balls. Not only do they last for more than 1000 loads, they also dry your laundry faster. And since they don’t contain any chemicals, fragrances, or synthetic materials, they’re a doubly great option for people with allergies and/or sensitive skin.

Buy it: Amazon

10. Rechargeable Batteries; $40

Say goodbye to loose batteries in your junk drawer.eneloop/Amazon

While plenty of devices are rechargeable themselves, others still require batteries to buzz, whir, and change the TV channel—so it’s good to have some rechargeable batteries on hand. In addition to AA batteries, AAA batteries, and a charger, this case from Panasonic comes with tiny canisters that function as C and D batteries when you slip the smaller batteries into them.

Buy it: Amazon

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What Are Those Frilly Paper Caps People Put On a Cooked Turkey's Legs?

All dressed up and nowhere to go.
All dressed up and nowhere to go.
Matt Cottam via Flickr // CC BY-NC-ND 2.0

Donning a chef’s hat while you cook Thanksgiving dinner is one thing, but sticking a tiny one on the end of each crispy turkey leg seems like it might be taking the holiday a bit too far.

Over the years, these traditional paper coverings have been called many creative names, including turkey frills, turkey booties, and even turkey panties. And while they’ve fallen out of fashion in recent decades, they originally served a very specific purpose. According to 19th-century writer John Cordy Jeaffreson, paper trimmings gained popularity in the 17th century as a way for women to keep their hands clean while they carved meat.

“To preserve the cleanness of her fingers, the same covering was put on those parts of joints which the carver usually touched with the left hand, whilst the right made play with the shining blade,” he explained in A Book About the Table in 1875. “The paper-frill which may still be seen round the bony point and small end of a leg of mutton, is a memorial of the fashion in which joints were dressed for the dainty hands of lady-carvers, in time prior to the introduction of the carving-fork.”

When etiquette books started encouraging "lady-carvers" to use carving forks, the paper didn’t become obsolete—it just got frillier. During the 19th and 20th centuries, chop frills were a cute and classy way to conceal the unsightly leg bones of roast turkey, lamb, chicken, or any other bird. “Dress up any leggy food with them for parties or the children’s birthdays,” Iowa’s Kossuth County Advance wrote in 1951. “They will be thrilled.”

If you’d like to dress up a leggy food or two this Thanksgiving, here are some instructions for making your own chop frills, courtesy of HuffPost.

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