Interested in how it's even possible to see clearly and in detail, all while in the dark? Everything you need to know behind how night vision goggles work
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Without any visible light, night vision devices can help individuals see clearly in the dark for a number of different reasons. In this article, we’ll go over how night vision goggles gather “unseen” light, create usable imagery, the differences between night vision generation, and more! It’s time to bring this topic to the light and find out exactly how night vision goggles work. Understanding Electromagnetic Spectrum and Infrared Light Before we can really explain how night vision goggles work, you need to have a basic understanding of the electromagnetic spectrum and the different forms of light found within, such as infrared light. That’s because night vision goggles can actually detect and use infrared. But what exactly is infrared light? Well, it turns out what light we can actually perceive is just a narrow slice of what is known as the electromagnetic spectrum. The electromagnetic spectrum is the entire range of different electromagnetic (EM) radiation that exists. And visible light is an EM wave that falls squarely in this range. But there are many other forms of EM radiation and light that our eyes just cannot perceive on their own — such as infrared. Do you remember the order in which a rainbow’s colors are set? It starts with red followed by orange, yellow, green, blue, and then violet. Well, it turns out that these colors are represented in that same order on the EM spectrum. And infrared literally means “before red”. So, infrared light is light just below our eyes’ visible range. But just because we can detect infrared light with our own eyes doesn’t mean we can’t put infrared to use. That’s exactly where night vision goggles come into play. How Do Night Vision Goggles Work? Night vision goggles work on the premise of amplifying the infrared light and other faint visible light around your target to electronically produce a clear usable image. We want to be clear that some semblance of visible light must be present in order for night vision technology to work. But this can be moonlight, starlight, or other distantly produced light. There are only a few situations where you’ll have zero visible light to work with. So, when a night vision device captures this faint and infrared light, it is directed to a photocathode. The photocathode is a very important part of the night vision assembly. It collects and converts the photons (light packets) into usable electrons. After the electrons are created, they next head to the image intensifier tube — or IIT, a type of photo-multiplier. The IIT is what actually accelerates, amplifies, and converts the signal emitted from the electrons back into a usable image that you can see through the eyepiece. Why is Night Vision Green? So, what makes that trademark green output color? And why? Well, when night vision imagery is originally produced, it’s only produced in black and white. There’s actually a special filter that your goggles will pass the light through in order to turn the image green. Image Credit: AlexPlank, Wikimedia Green is a very important color in terms of visible light. Remember the rainbow order from earlier? Green falls smack in the middle of our visible light spectrum making our eyes the most sensitive and receptive to that color. This means that we can look at green lighting for a longer period of time with minimal eye fatigue. As technology has progressed, so have advances in night vision capabilities. Each major shift in night vision technology is called a generation. The above description described basic Generation 1 tech. And while Gen1 is essentially obsolete, the underlying principles remain the same. Gen2 Night Vision Generation 2 night vision is another older form of night vision, but it hasn’t been phased out just yet. Gen2 improves upon Gen1 by introducing a microchannel plate to the night vision apparatus. The microchannel plate is a direct improvement to the IIT. It’s a photosensitive plate that contains millions of independently working detecting and amplification channels. So instead of having a fewer number of channels wor...