# How night vision goggles work

**URL:** <https://boards.straightdope.com/t/how-night-vision-goggles-work/257579>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [July 30, 2004, 11:52am UTC](https://boards.straightdope.com/t/how-night-vision-goggles-work/257579 "2004-07-30T11:52:44Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\
**Post date:** [July 30, 2004, 11:52am UTC](https://boards.straightdope.com/t/how-night-vision-goggles-work/257579/1 "2004-07-30T11:52:44Z")

</div>

In the latest Staff Report, [What’s the temperature of space?](http://www.straightdope.com/mailbag/mspacetemp.html), Planck’s black body radiation law is followed by the comment “Black body radiation explains how night vision goggles work.” I know it doesn’t have anything to do with the temperature of outer space, but I thought How Stuff Works’s [How Night Vision Works](http://science.howstuffworks.com/nightvision.htm) might fill out some of the explanation. Night vision is not just thermal imaging.

---

<div class="post-metadata">

**Author:** ![grg88](https://avatars.discourse-cdn.com/v4/letter/g/bbe5ce/32.png) [@grg88](https://boards.straightdope.com/u/grg88)\
**Post date:** [July 30, 2004, 12:55pm UTC](https://boards.straightdope.com/t/how-night-vision-goggles-work/257579/2 "2004-07-30T12:55:36Z")

</div>

> [@RM Mentock](#):
>
> In the latest Staff Report, [What’s the temperature of space?](http://www.straightdope.com/mailbag/mspacetemp.html), Planck’s black body radiation law is followed by the comment “Black body radiation explains how night vision goggles work.” I know it doesn’t have anything to do with the temperature of outer space, but I thought How Stuff Works’s [How Night Vision Works](http://science.howstuffworks.com/nightvision.htm) might fill out some of the explanation. Night vision is not just thermal imaging.

That’s a true, but mighty puzzling set of statements.  
\>“Black body radiation explains how night vision goggles work.”

SOME night vision goggles use the black-body radiation phenomenon, but I’d guess not MOST, and certainly not all, as that statement implies.

The black-body thermal-imaging kind are much more cumbersome and expensive than the plain old starlight-amplifying kind. You’ll tend to see thermal-imaging ussed more by police helicopters and other places that can afford the $$ and bulk and weight of these gadgets. Most of the head and camera-mounted ones seem to be the light-amplifying kind.  
Also note that “How things work” site seems to rely heavily on industry handouts, not first or even second-hand information, so some fuzzyness and even unintentional howlers are rampant.

---

<div class="post-metadata">

**Author:** ![Hussman32](https://avatars.discourse-cdn.com/v4/letter/h/8baadc/32.png) [@Hussman32](https://boards.straightdope.com/u/Hussman32)\
**Post date:** [August 6, 2004, 3:39pm UTC](https://boards.straightdope.com/t/how-night-vision-goggles-work/257579/3 "2004-08-06T15:39:46Z")

</div>

An interesting evolutionary note: The ‘visible light’ spectrum corresponds to the surface temperature of the sun (~5000 degrees Celsius). This implies that species evolved to see the wavelength frequency range with the greatest intensity.

It makes sense, if you can’t see the sabre tooth before it eats you, you probably won’t live long enough to produce.

---

<div class="post-metadata">

**Author:** ![Karen\_Lingel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karen_lingel/32/18649_2.png) [@Karen\_Lingel](https://boards.straightdope.com/u/Karen_Lingel)\
**Post date:** [August 6, 2004, 4:38pm UTC](https://boards.straightdope.com/t/how-night-vision-goggles-work/257579/4 "2004-08-06T16:38:34Z")

</div>

Hmmm. Did you learn that [here?](http://www.straightdope.com/mailbag/mvisiblelight.html)

---

<div class="post-metadata">

**Author:** ![Hussman32](https://avatars.discourse-cdn.com/v4/letter/h/8baadc/32.png) [@Hussman32](https://boards.straightdope.com/u/Hussman32)\
**Post date:** [August 10, 2004, 8:04pm UTC](https://boards.straightdope.com/t/how-night-vision-goggles-work/257579/5 "2004-08-10T20:04:10Z")

</div>

No, I learned it in advanced heat transfer during graduate school, and taught it to my heat transfer students back in 2000.

Good to see we’re on the same page though…