GIVE ME THE NIGHT
These days it's as common for gamekeepers to use the term 'night vision' as it is the military, but it can still be confusing.
There are times when being able to see in the dark is desirable and times when it’s an absolute must.
Fortunately, night vision technology is available in many forms. Infrared (IR) technology is used in multiple applications. There are also low-light situations that don’t necessarily require the use of IR. In those instances green light is frequently used.
Here we will explain a few common terms for those trying to get a handle on this subject with a focus on the role flashlights have to play.
Sometimes also called image enhancement, this gives that familiar green appearance that many will associate with military images and footage (see main image above). The colour green is used because your eyes are more sensitive to green than other colours and it helps your eyes to adjust to the natural environment after using the equipment.
This works by taking low levels of light and amplifying it through a device such as a special camera, night vision goggles, or rifle scope. These are sometimes referred to as passive night vision devices that acquire atmospheric light and allow the user to view objects, animals, other people, and their surroundings in great detail over a very long distance.
If there isn’t enough light to amplify in the first place, then that’s where thermal imaging comes in…
Thermal imaging devices detect heat, naturally emitted by all objects as infrared radiation. Even though humans cannot see in this part of the electromagnetic spectrum naturally, using technology we can take advantage of it in a number of ways. This is useful for many applications because it makes it easy to recognise people and animals.
With thermal imaging devices and the assistance of a lighting tool, a firefighter can pick out someone who is stranded in a burning building waiting to be rescued, a police patrol can more easily spot a hiding fugitive on a housing estate, and a hunter can identify prey hiding deep in the woods. The displayed image is usually in shades of white to black.
Additional infrared light can be created in a process called active illumination where you can light up your surroundings with an IR device. This is particularly appealing for leisure hunting or for scenarios where there isn’t an issue revealing your location to enemy combatants.
Because this additional light reflects off of whatever you’re pointing at, the result is a much higher quality image. This functionality is commonly used in devices like surveillance cameras and camcorders with in-built lights but the technology for generating IR light is also available in flashlights.
Flashlights with IR capability can have many features. You can ‘light up’ an area with IR LEDs, offering the main benefit of wide awareness of the scene in front of you.
Another feature is made possible with IR lasers which can pinpoint targets when mounted to weapons. The Streamlight Sidewinder Compact ll is attached to your person or used as a headlight and has a low, covert output illuminator with a high output IR strobe for covert signalling.
All of these functions require an appropriate device to see what’s going on such as night vision goggles.
Green LED lights
There are many benefits of using green LEDs - one being the lower cost compared with using IR because you can see the images with the naked eye. Without the need for special optical equipment, a farmer can control vermin at night with a reduced risk of scaring the prey. While it’s true that using a green LED light will not completely eliminate the visibility of the light to animals, the light will appear much less intense than a white light so will be less startling.
From a law enforcement, fire & rescue, or military perspective, green LED lighting can play an important role because green light is also considered the best colour to preserve your own night vision. This is because it doesn’t constrict the pupils as much as white light does. Humans can also detect more light at lower brightness using green LEDs.
A point to highlight is that, regardless of the benefits of using green light, if used at high output it will still reduce your natural night vision capability. Therefore the most important characteristic of a night vision flashlight in this context is the option of low brightness functionality and the ability to adjust the output when required.