Light Amplification vs Thermal Imaging|
There are only two major types of night vision technology that have proven themselves both effective and practical for regular use; light amplification and thermal imaging. Although both offer a once unheard of ability to literally see in almost total darkness, how they manage this feat is accomplished in two totally different ways. It’s these fundamental differences in method that are also responsible for the benefits and drawbacks which each type of night vision technology represents.
The first true night vision devices appeared during World War 2 and were crude and primitive by today’s technological standards. These devices relied almost entirely on what is known as active infrared imaging to allow users to see enemy combatants during nighttime missions. Active infrared imaging is when a device uses an infrared light source or projector to create light in the infrared spectrum which is then directed at the object to be viewed. Although this infrared light is invisible to the human eye, it still behaves like regular light and is reflected off of any objects it is shown on. This infrared light then reflects back at the device which receives it through a lens, much like a camera. The infrared light passes through cathodes and anodes within the device and is ultimately processed into an image which is viewed through an eyepiece or on a small screen.
This type of technology quickly progressed and in a short period of time passive infrared technology appeared and greatly improved low light imaging abilities. Passive infrared technology makes use of whatever light is available, starlight, moonlight, ambient light from other sources, and amplifies it thousands of times. This allows night vision devices to be used without the need for an infrared emitter to provide a light source. This type of technology has gone through several stages, with each successive improvement designated as a generation of night vision technology. This is why you will almost always hear references to 1st, 2nd, 3rd, or 4th generation when night vision devices are being discussed. Each successive generation represents a large improvement over the former in matters of resolution and sensitivity.
As you can imagine, first generation night vision equipment produces the least resolution and detail, while 4th generation equipment provides the best. As you can also imagine, 4th generation is also the most expensive and is at this time still priced well beyond what the casual user would be able to spend. In fact, 4th generation night vision is still a federally controlled technology and not readily available to the public. Because of this pricing and availability, 1st and second generation night vision is the most commonly utilized technology. What is important to note here, however, is that all types of night vision technology that relies on light amplification can benefit from an added infrared light source because these devices amplify light from the invisible lower infrared end of the light spectrum as well as from the visible portion. This type of technology has as one of its greatest benefits the ability to produce images that are clearly defined, and represent a truer appearance of any objects viewed despite a lack of true color rendering. With this kind of device, you will be able to identify a person, a weapon, or even the wording on a sign in near total darkness. This kind of capability is what has made active and passive infrared technology the dominant form of night vision in the law enforcement and security industries.
Thermal imaging works on a different principal than light amplification and relies on infrared radiation emitted as heat by objects to produce an image. Thermal imaging devices sense the temperatures in a given area and note any differences, then use the contrasts produced to form an image which is then displayed on a screen. This type of technology is very effective in providing an image regardless of whether any kind of light is present as well as being able to identify objects under inclement conditions such as fog or rain. Objects viewed by thermal imaging appear true to their general shapes and forms, and in some variations of thermal imaging devices, colors are introduced which further improves the ability to discern between objects. Thermal imaging is very effective when used in targeting and locating concealed or obscured objects or people and is seeing widespread use in military and law enforcement applications as a result. It does not matter if an object is obscured by brush or fog, a thermal imager will reveal its presence and location. One of the factors that severely limit thermal imaging’s effectiveness, however, is its lack of detail and resolution. Since thermal imaging devices rely on a contrast in temperatures, the coolest objects appear dark and the hottest objects appear very bright. This results in images where the clothes of a person being viewed may appear gray, while their head or any exposed skin will appear white. Even in devices where sensitivity is at its maximum and artificial color has been introduced, there is still too little resolution to make an effective determination as to a person’s identity.
All of these factors and more relate to the effectiveness of one night vision technology’s superiority over another. Although both have their drawbacks and advantages, for sensitive and critical applications where positive identification is mandatory, only light amplification technology has this capability. When light amplification technology of any generation is paired with an infrared illuminator like the Larson Electronics IR LED Light Bar, an unparalleled ability to produce high resolution images in the absence of visible light is created that allows the user to not only locate and monitor a subject in total darkness, but make a positive identification as well. Since the IR illumination produced by an emitter is invisible to the human eye without the proper equipment to view it, this is an excellent way for those engaged in covert operations to monitor and identify subjects while remaining undetected. Light emitters also greatly improve the ability to use light amplification devices under conditions that would normally prohibit their use, such as cloudy or moonless nights, or in enclosed buildings where no ambient light is present.
The ability to make a definitive identification is perhaps the most crucial aspect of many military and law enforcement covert operations. Not all activities involve combat, but many combat missions rely on solid and reputable intelligence data in order to avoid unnecessary casualties, while law enforcement applications benefit from the ability to insure that who or what they are observing is indeed their intended target. Until thermal imaging technology catches up and is able to produce images of high resolution and detail, light amplification night vision and infrared illumination will remain the only technology that truly allows us to literally see in the dark.