The internet sites that sell them use the term interchangably. Which one gives you the multicolored view like in the “Splinter Cell” series of games, and the “Predator” movie series?
The terms do seem to be used kind of interchangeably.
This link here makes me think the thermal ones are the ones that display color.
I’ve used both types of optics, but I’ve never seen a multi-coloured display.
In military parlance, at least in my experience (I put down my rifle many years ago), “infra-red” is used to describe a set of goggles or scope that registers reflected infrared light - in other words, an infrared (search)light is needed to illuminte the target. This technology has fallen into disuse due to lack of volunteers to hold the infrared light source on a battlefield where the enemy may also be holding infrared scopes… The image you get - again, in my experience - is a monochrome image in black and green.
The next generation is “light amplification”, which is a 100% passive device that simply amplifies the ambient light. Surprisingly effective, but it also shows a monochrome image. Some light amplification goggles come with a small infrared LED light for map reading etc.
Finally, “thermal” is a different passive technology, where the target’s thermal radiation is displayed - the brighter the pixel, the hotter the object. Again, all I’ve seen is monochrome - no gaudy colours needed, it actually works great.
As seeing in monochrome is our default for dark conditions anyway, I don’t think there’s much gained by adding colours to the viewfinder.
Current military Night Vision does amplify the amount of available light, but it also picks up part of the IR Spectrum as well. Newer models have a built in IR light to add some illumination. You also have IR filters for your weapon lights and hand held lights. And your weapon will have an IR Flood Light and IR Laser. So IR still plays a major role in modern military night vision.
Here’s a page with some good examples of various thermal imaging technologies. It appears the monochrome versions display heat as lighter (or darker) images while the polychromatic versions falsely apply colors to these different temperatures.
Whats the term thats actually used to describe the ones that give you a blue/red image rather than green/black? Is there some sort of designation I should look for, or what?
Many camera sensors use silicon to detect visible or NIR (near infrared) light. In fact, silicon sensors are generally sensitive to both, and to make them sensitive to just the visible light requires building color filters into them, often on the chip itself. Silicon imaging chips can be as cheap as a few dollars. NIR is emitted by hot objects, but only objects that are almost hot enough to glow visibly. Most of the time when you image things with NIR you’re using available light or your own NIR source. The longest wavelengths these things work with are around 0.8 or 0.9 micrometers.
Thermographic cameras using other sensing means can detect the longer wavelengths that are thermally emitted by things at room and outdoor and body temperatures. Generally the sensors themselves will detect any wavelength that can be absorbed by a surface, and the wavelength range used by the camera is defined by what wavelengths the lenses are transparent to. On such cameras the lenses look funny, and sometimes look like they are made of solid metal (they may be solid germanium, which is a semimetal). Common ranges are around 6 or 7 micrometers to around 12 or 15 micrometers. The cheapest cameras I know of that do this cost $7000.00.
Any of these sensors can be connected to a display that maps various colors or shades of gray to various sensed brightnesses. Many such cameras have several choices built in for different grayscale and color schemes.
I dont think you’re going to find that in a military device outside of Hollywood, though. There’s no benefit to it.
Maybe in a laboratory or something, scientists would have some use for the different colors.
>I dont think you’re going to find that in a military device outside of Hollywood, though. There’s no benefit to it.
Polychromatic display makes for pretty pictures in sales literature.
Some infra-red satalite weather images are in colour.
At work (civilian) we have an infra-red camera that is monochrome grey. We also have night vision goggles that are monochrome green. The infra-red camera works purely on passive IR while the NVGs amplify low levels of light.
The NVGs require some light to work, even though they are sensitive to near infra-red. They do have an infra-red light that illuminates near objects and allows the NVGs to operate with no light at all, but in general they need something (moon, stars, city glow, etc.)
The FLIR, on the other hand, doesn’t need light and can operate in pitch black conditions.
If yer interested, here’s a military thesis on the Impact of Fused Monochrome and Fused Color Night Vision Displays on Reaction Time and Accuracy in Target Detection. It talks about reaction times for regular monochrome goggles versus colored ones.
Also, this news article talks about a company trying to make nightvision googles that show true colors in the dark.
Just to make sure I’m reading that summary correctly, it’s saying that–contrary to their hypothesis–the color version decreased target aquisition/identification time. Am I reading it wrong?
From the summary: “An ANOVA on the output and a subsequent review of the images revealed that fusion significantly impacted local (target) contrast and that, coupled with scene content, decreased performance on the task.”