Also referred to as night optical devices, night vision gadgets are optoelectronic gadgets that display images from a distance and in levels that are near to darkness. The image displayed by these devices is characteristically monochrome. By default, the best night vision, rifle scope, goggles, monocular, and binoculars night vision devices are designed to be used by law enforcement and military. However, they have been significantly espoused by the society for different occasions, including hunting, sightseeing, bird watching, and sporting events.
Different Types of Night Vision
There are two different types of night vision devices, including image intensifiers and thermal imaging systems.
Type 1: Image Intensifiers
These are devices that amplify feeble light of the sky glow, stars, and moon on a green display. Green is the default color used since the human eye can effectively differentiate more shades in green than in any other given color. Image intensifiers are basically light multiplication device. They are installed with an input window as well as an output phosphor.
The display on the phosphor output is much brighter than the incident one on the input window. They were mainly engineered for nocturnal seeing along with surveillance under starlight and moonlight alike. They are able of spotting as well as amplify weak emissions, producing sharp contrast images. They are not only useful for nocturnal viewing, but also for scientific research and industrial product inspection.
Type 2: Thermal Imaging Systems
Thermal imaging is the latest technology associated with night vision devices. This technique uses the heat of the target / object to display an image. This method extends one’s vision beyond the short wavelength into the far-flung infrared by displaying the light naturally radiated by warm objects, such as a wild animal or fellow human being.
Thermal imaging functions in environments that do not have ambient light. The tech can go through obscurants, including haze, fog, and smoke. Thermal imaging devices are installed with grey scale, meaning that white objects appear hot while black ones appear cold. The variations of the two are indicated by depth of grey. The heat energy produced by the target is referred to as heat signature.
There are two types of thermal imagers, including cooled and un-cooled thermal imagers.
- Cooled Thermal Imagers: They are made up of cooled detectors that are enclosed in a vacuum sealed cover, and they are cryogenically cooled. To avoid radiation blinding the detectors because of the semiconductor materials, the detectors are cooled. As far as performance is concerned, cooling of the conductors delivers grander image quality. Cooled thermal imagers are not only expensive, but also bulky. Unlike un-cooled detectors, these ones require a significant amount of time to cool down prior to using them again.
- Un-Cooled Thermal Imagers: The sensors used by these imagers are either made stable using control elements at room temperature, or make use of a sensor functioning at ambient temperature. Contrasting to cooled detectors, the uncooled versions use less power and offer fast operation. They are typically smaller as well as less expensive. They generally have low image and resolution qualities when compared to cooled thermal imagers.
Not like image intensifiers which definitely need ambient light to produce an image, thermal imaging devices can function in complete darkness by detecting the infrared radiation from the target (heat source). These devices transform thermal contrasts into visual contrasts, but they suffer from the inability to differentiate facial features, and lack of detail. However, there are significant merits of thermal imagers as to image intensifiers.
As mentioned earlier, thermal imagers can see images in total darkness by picking up the heat signature of the target or object. They are cable of capturing targets that are on the move in low light and in real time. They help to detect faults and the deliver immediate, accurate, and fast temperature measurements. Apart from hunting night vision, thermal imagers have an array of applications, including the following:
- Thermal mapping
- Nondestructive testing
- Chemical imaging
- Condition monitoring
Choosing between image intensifiers and thermal imagers is not as complicated as you would imagine. Irrespective of the high quality images produced by image intensifiers, they are certainly bulkier for outdoor activities, such as hunting and sightseeing. On the other hand, thermal imagers are conveniently small and lightweight. Advancements in technology have enabled these devices to be reduced in size, so as they can be easily handheld.
Difference between Night Vision Generations
Night vision devices first appeared during World War II. Ever since, they have developed through technological generations. They basically began with Generation 0, well-known as meta-scopes. Then they evolved to what most people know – Generation 3. The latest category of night vision devices is Generation 4.
To understand what Generations of night vision devices refer to you have to understand how they work. These technology function by gathering miniature particles of light and then focus them into the devices. The devices convert the particles to electrons, which are multiplied as well as projected based on the type of the device (image intensifier or thermal imager). The entire process is complex, and a number of things determine the produced image.
There are specific features that separate the least expensive from the most expensive night vision devices. These systems have been around for decades, and they have undergone a series of changes, which are generally referred to as Generations. The particular features that improve with each generation are: light gathering ability, range, and picture quality. Nevertheless, the price is dictated by all technical features and specifications.
This generation features the original night vision devices, which were developed by the US Army. These devices were put to use in the World War II. Their designs feature an attached IR illuminator that casts out a beam of IR. The beam is normally the same as that of a regular flashlight. It is the IR that reflects an object and then bounces back to the night vision device’s lens. The design incorporates the use of cathode and anode so as to accelerate the electrons. However, the acceleration of electrons presents a big problem, which is distortion of the displayed image.
Examples of Generation 0 NVDs are: AN/PAS-4, M3 Sniperscope, M2 Sniperscope, T-120 Sniperscope, SU49/PAS 5, PNV-57A Tanker goggles, and PAU-2.
Generation 1 night vision devices were engineered in the 1960s. They are still in use. These NVDs function well in visible light, but they tend to perform poorly in complete darkness. Their performance is boosted by the light from the moon and stars along with the additional infrared illumination. When compared to the succeeding models, Generation 1 NVDs are highly affordable.
Examples of Generation 1 NVDs are: PAS 6 Varo Metascope, PNV-57E tanker goggles, AN/PVS-2 starlight scope, and AN/PVS-1 starlight scope.
Generation II night vision devices were created in the 1970s. Unlike Generation 0 and Generation 1, Generation II NVDs have a remarkably longer life span. They do not need visible light to function properly. Therefore, they function exceptionally well in complete darkness. They provide improved resolution as to Generation 1 NVDs, and they are the ideal option for night hunting. The devices under this category are installed with an advanced image intensifier tube.
Examples of Generation 2 NVDs are: PNV-10T, SUPERGEN, AN/PVS-5, AN/PVS-4, and AN/PVS-3.
These are the state-of-the-art night vision devices for the money. They first emerged in the 1990. The major advancements of these night vision devices are based on the contemporary photocathode coating, along with refined P-20 phosphor screen, MCP, and control electronics. They have an extraordinary ability of gaining light as well as resolution as to all previous Generations. Generation III night vision devices have long tube life and remarkable low-light performance.
Examples of Generation 3 NVDs are: PN-21K, CNVS-4949, AN/PNVS-14, AN/PVS-14, AN/PVS-10, AN/NVS-7, and AN/PVS-7.
Generation 4 NVDs feature Gated Filmless and thin filmed technology, which according to the industry offer a noteworthy tube life of fifteen thousand hours. This tech also ensures that the tube is safeguarded from the exposure of bright light. The use of filmless and thin filmed tech results into the following: triple high light level clarity, improved performance in total darkness, and up to 100% improvement in photo response. Irrespective of the latest advancements, it is not certain that the filmless and thin filmed NVDs can collectively be referred to as the fourth generation.
How to Select the Best Night Vision Devices?
Knowing the differences in Generations of night vision devices is the first step you must take when learning how to choose the best NVD in the market. Basically, the choice you make is completely based on the various night vision device parameters. The main parameters that you must take into consideration are as follows.
1. Weight, Size, & Ergonomics
Weight, size as well as ergonomics are among the most important considerations when shopping for a night vision device. Usually, a more comfortable NVD is one that is lightweight and compact. In most cases, the weight of a given device is determined by the type and Generation, which refers to the features. For instance, image intensifiers are known to be less portable when compared to thermal imaging devices.
2. Working Range
The working range of a night vision device is an important factor. The detection, identification, and recognition of a night vision device are determined by the working range.
3. Field of View
The field of view is the amount of landscape that you can see through your night vision device. This is a crucial consideration when establishing the quality status of the night vision device you are about to buy. You should know that the quality of NVDs is determined by both ocular and objective field of view.
4. Eye Relief
This is the distance from the pupil of the eye to the ocular lens of a night vision device when the NVD is positioned far enough for the entire field of view to be seen. The amount of eye relief in a NVD will vary from one Generation to another and from one brand to another. The comfort of observing images via NVDs depends on how big the eye relief is at a given event.
Sensitivity to the action of radiant energy is associated with the minimum light levels needed for a night vision device to function properly. As far as photosensitivity is concerned, Generation 2 devices are better than Generation 1. This feature has been improved significantly in Generation 3 and 4 night vision devices.
6. Battery Life
Practically, the battery does significantly affect the quality of a night vision device, which depends on the capacity and weight of the battery. The continued demand as well as the capacity establish the length of time you will be able to use the device. Therefore, choosing a device with a longer battery life is important.
As much as you would want to overlook this factor, you still have to consider it before making purchase. Generation 1 NVDs are usually cheaper when compared to Generation 3. However, the features you can find in a Generation 1 device are not as advanced as those found in Generation 3. So, it all comes down to your budget.
Apart from the parameters, you have to consider the event and environment in which you will be using your NVD. This is particularly so when selecting a monocular or binocular. With respect to the environment, your first consideration should be distance. For instance, different binoculars have dissimilar distances. Therefore, the money you will spend is actually dictated by the distance of your target. You will definitely spend less for a gear that can cover short distances, and you will spend more for a gear that will cover longer distances.
The very final thing that you must settle for is the image quality. Well, the manufacturers can say whatever they like about their NVDs, but the final say is with you. Apart from the amazing features that come with these devices, you need to ensure that your device of choice comes with exceptional ergonomics. The rifle scope, goggles, monocular, and binoculars you choose should be better than expected the moment you learn the settings and operation.