Comparison Levenhuk Ermenrich NS100 vs Armasight Avenger Gen 2+

The greatest distance at which a night vision device is capable of detecting individual objects.

The methods by which manufacturers determine this parameter may vary in detail, but the general principle is the same. Usually, the distance is indicated at which, with an illumination of 0.05 lux (a quarter of the moon) and a medium-contrast background, a rather large object can be seen — for example, a human figure with a height of about 170 cm is most often taken. of this object, but only to notice the very fact of its presence. Simply put, a detection range of, say, 200 m means that “something that looks like a person” can be seen in such a device at a distance of 200 m, but individual parts (head, hands) cannot be disassembled.

It is also worth noting that in fact this parameter is highly dependent on the characteristics of the situation. For example, a dark object on a very light background will be visible further, and on a dark one it may not be noticeable even up close; a similar phenomenon is observed for thermal imagers (see "Type"), only regarding the difference in temperature, and not in colours.

The principle of operation of the module that provides amplification of visible light. This parameter is indicated only for classic night vision devices (see "Type"), because thermal imagers work on the same principle, and they do not need clarification.

— EOP. Abbreviation for "electronic-optical converter". Also, such night vision devices can be called analogue, as opposed to the digital ones described below. The principle of their operation is as follows: a special electrode (the so-called photocathode) converts a weak light flux or infrared radiation into a stream of electrons in a vacuum tube, and under the influence of these electrons, the screen visible to the user already glows (a similar principle was used in kinescope TVs). At the same time, on the way to the screen, the electrons are accelerated in order to ensure the normal brightness of the visible “picture”. Roughly speaking, the image intensifier tube “pumps” the invisible light flux to the required brightness level. The main advantage of this option is the low cost due to the simplicity of the design; moreover, they can be made quite sensitive. At the same time, most image intensifier tubes do not tolerate bright light well: they are prone to spurious illumination (when a point source of illumination blurs into a large spot, clogging the image around), and when used during the day, such a sight may fail altogether. And there are usually fewer additional functions i...n analogue devices than in digital ones. Note that today there are several generations of image intensifier tubes; the newer the generation, the better, more complex and more expensive the converter. At the same time, the quality of night vision devices as a whole largely depends on other factors, so the “old” or “new” image intensifier tube itself is not an unambiguous indicator.

— Digital. Night vision devices of this type are actually a kind of video cameras: the image falls on a digital matrix (usually of the CCD type), is processed by electronic circuits and displayed on a monitor visible to the user (in this case, a small screen, similar to those used in video camera viewfinders). The possibility of night use is due to the fact that modern CCD matrices are able to respond to very weak light, as well as to infrared radiation, invisible to the human eye. At the same time, such devices can be used without problems during the day, because. daylight does not harm the matrix, and the settings, usually, provide the appropriate mode of operation of the electronics (up to automatic adjustment to brightness). The main disadvantage of digital night vision devices is the high cost due to the complexity of the design.

The generation of the image intensifier used in the device with the corresponding principle of operation (see above).

— I. The earliest and, accordingly, the least perfect generation of image intensifier tubes presented on the modern market. Allows relatively comfortable use of night vision devices under the condition of fairly bright "night" lighting (for example, on a moonlit night); in weaker light, active IR illumination is required. At the same time, image intensifier tubes of the first generation are inconvenient when working with point light sources — parasitic illumination appears and the light source “blurs” on the screen. And accidental illumination (for example, hitting the light of car headlights) most likely disables such a device: automatic protection against it is extremely rare, and it is not always possible to close or retract the lens in time. In addition, closer to the edges of the field of view, the resolution of the image in such an image intensifier tube noticeably decreases and distortions appear in it (for example, a square may look like a “cushion”). Simplicity and, accordingly, low cost can be called the unambiguous advantages of the first generation devices. The resource of such a converter is on average about 1000 hours, which is quite enough for infrequent "forays" into nature, but not enough for permanent use.

— I+. An improved and modified version of the...I generation image intensifiers described above. The main improvement was the use of the so-called fibre optic plate — thanks to it, it was possible to make the resolution the same throughout the entire field of view, and also to almost completely get rid of distortion. On the other hand, due to some technical features, such night vision devices at the same magnification turn out to be more expensive (sometimes several times) and bulkier than their predecessors, and they have no advantages over them, in addition to those described above. Because of this, the improved version of the first generation image intensifier is less common than the original.

— II. The key difference between the second generation image intensifier tube and its predecessors was a two-stage light amplification scheme: in the traditional way, as in the first generation, and then using a microchannel plate. This made it possible to significantly increase the degree of amplification, which made it possible to use night vision devices even on a dark night — by the light of stars in light clouds. In this generation, it was also possible to ensure uniform image quality over the entire field of view, to get rid of significant spurious flare (a point light source in the field of view almost does not blur). In addition, automatic protection against backlight has become almost mandatory for such devices, and the resource, compared to the first generation, has increased significantly — up to 3000 hours in some models. However the cost of night vision devices with such converters has increased significantly.

— II+. Improvement of the second generation transducers (see above), aimed, in particular, at reducing the size of night vision devices and further improving the quality of the "picture" (albeit at the expense of some reduction in the light amplification factor). Note that under this designation, both the “original” generation II + and its improved version Super Gen II + can be hidden. The latter option is able to provide a visibility range almost at the level of the image intensifier tube of the III generation, and at the same time it costs much less (although still more expensive than the device of the original generation II +).

— III. In the third generation of image intensifier tubes, manufacturers used an innovative material in the design of the photocathode, which made it possible to significantly increase the sensitivity (both general and in the IR range). Converters of this generation are capable of operating in extremely low light, provide a clear, high-quality image with high detail and have a resource of about 10,000 hours; thus, they are the most advanced on the modern civilian market. However, the main users of such equipment are the military and representatives of special services: it is for them that the described advantages are critically important, and III generation image intensifier tubes cost 1.5 – 2 times more expensive than II + (which are not cheap in themselves), which makes it difficult for civilians to use such devices. Another disadvantage of converters of this type is considered to be a rather significant sensitivity to side illumination.

The degree of image magnification that a night vision device is able to provide without digital image processing, solely due to the optical system. Such an increase is considered to be preferable to digital, because. it does not impair the clarity of the visible image; and for models based on image intensifier tubes (see "How it works"), this is generally the only available option.

Theoretically, the higher the magnification, the greater the detection range (see above), since a powerful increase allows you to see smaller objects. However, it does not always make sense to chase the maximum performance. The fact is that with increasing magnification, the angular field of view decreases and the minimum focus distance increases (see both below), which can create problems at close range. It is also worth noting that a high degree of magnification adversely affects the luminosity of the entire system — as a result, the actual detection range in complete darkness may be higher for a device with a lower magnification, because. it "catches" more light. Yes, and this parameter affects the cost accordingly.

Note that night vision devices, unlike classical binoculars and monoculars, most often have a fixed magnification. Models with the possibility of smooth adjustment are almost never found, and the only option is to use additional nozzles (see "Form factor").

Now on the market are night vision devices with the following optical zoom: 1x, 2 – 3x, 3.1 – 4x, > 4x

The maximum magnification that a night vision device can achieve through digital image processing.

This function is available only in thermal imagers and some digital models of classic night vision devices (see "How it works"). In general terms, it can be described as follows: the device electronics takes part of the image from the NVD receiver and “stretches” it to the entire frame visible to the user, due to which objects in the field of view look larger. At the same time, this procedure reduces the clarity of the visible image. Therefore, models with digital zoom are quite rare, and even in such cases it plays an auxiliary role and has a very limited magnification — usually less than 2x.

The focal length of a night vision device. This term means such a distance from the optical centre of the lens to the photocathode of the image intensifier tube or the matrix of a digital device(see "Operation principle"), at which a clear image is obtained on the photocathode/matrix.

In general, long focal lengths are characteristic of optical systems with a high degree of optical magnification (see above). However, in the case of night vision devices, this dependence is not rigid — it is simply easier to ensure a high magnification with long-focus optics. In fact, this means that models with the same focal length can differ markedly in magnification. But what this indicator directly affects is light transmission: other things being equal, longer optical systems transmit less light, which negatively affects the capabilities of the device. This is also true for thermal imagers (see "Type"), because their working infrared range in this case also obeys the general laws of optics.

The resolution of the visible image created by the night vision device. Indicated by the number of lines (strokes) per millimetre; the higher this indicator, the more detailed the image is capable of creating the night vision device, the better small details will be visible on it. However such devices will cost accordingly.

In models with an image intensifier tube (see "How it works"), the resolution is highly dependent on the generation of the transducer.

The angle of view provided by a night vision device — that is, the angle between the lines connecting the observer's eye with the two extreme points of visible space. Wide viewing angles allow you to cover a large area, but the magnification factor (see above) is low; in turn, increasing the magnification leads to a decrease in the field of view.

The smallest distance to the observed object, at which it will be clearly visible through the night vision device. For normal use of night vision devices, it is necessary that this distance does not exceed the minimum expected distance to the objects in question; thus, it must be borne in mind that the higher the magnification factor (see above), the greater the focus distance, usually.