Night vision devices for armored vehicles-..

Night vision devices for armored vehicles-..

NIGHT VISION DEVICES FOR ARMORED VEHICLES  

Modern armored vehicles on wheels and tracks must be able to perform a variety of special equipment tasks: observation, aiming and firing, escorting and transporting special cargo, etc. These tasks must be performed both during the day and at night. In this regard, night vision devices (NVD) are widely used for armored vehicles. They can be made on the basis of various physical design principles:

— NVD based on image intensifier tubes (EIT).
— Low-level television systems.
— Active-pulse (AP) NVD.
— Thermal imaging (TIV) devices.
— Combined devices.

This article presents the first three types of these devices. The last two types deserve separate consideration.

According to the functions of the armored vehicle crew, there are three types of NVGs for them:

— NVG for driving armored vehicles.
— NVG for the commander.
— NVG for the gunner.

In addition to these specialized NVGs, which occupy a very specific position on the armored vehicle and are connected to its on-board network, the armored vehicle crew uses autonomous NVGs: night vision goggles, night monoculars, night binoculars. They are used for orientation on the terrain, reading maps and other documents, inspecting and repairing equipment, etc. In some cases, night vision goggles can be used for driving armored vehicles at night (photo 1) either directly (photo 1a), or when working through a daytime periscope (photo 1b). There are cases of using portable night vision devices (for example, 1PN54 [2]), fixed outside the armored vehicle using a special bracket. All these night vision devices are considered in sufficient detail in the works [1, 2].

a)

b)
Photo 1. Use of night vision goggles for direct driving of an armored vehicle [19] (a) and use of ACN-1 goggles (Table 1) for driving an armored vehicle while observing through a daytime periscope (b)

All three types of specialized NVDs form a single night vision instrument complex, mutually complementing each other in their parameters and characteristics. In particular, NVDs for driving have a magnification of 1x and a maximum field of view angle compared to other NVDs of armored vehicles: 40 — 500. This is necessary for effective driving of an armored vehicle at night. At the same time, the range of the NVDs is relatively small. On a clear starry night with a level of natural night illumination E = 3×10-3 lux, the range of recognition of a full-length human figure against an autumn-summer background is 200 m [3].

The armored vehicle commander must direct the actions of the crew. In this regard, the commander's night vision device also has a longer range with a fairly wide field of view, although smaller than that of the driving night vision device. Since the requirements for a significant range and a wide field of view are contradictory, a compromise solution is usually adopted: under the above conditions, the vehicle recognition range is 600–800 m with a field of view of 10–150 and a magnification of 5–6x.

The gunner's night vision device must ensure the maximum possible recognition range and ensure firing at a target at this range. In this regard, the vehicle recognition range under the above conditions for the gunner's night vision device is 1,200–2,000 m with a field of view of 6–80 and a magnification of 10–12x.

Very often the commander's and gunner's night vision devices are combined: in addition to the night channel based on the image intensifier tube, they contain a daytime observation and aiming channel. Usually, in the gunner's night vision device, the daytime channel contains a laser rangefinder.

All three types of NVDs are passive-active. Their main operating mode is passive (without illumination). However, on very dark nights, NVDs can operate in active mode with illumination by infrared (IR) radiation from spotlights. The latter can be multifunctional devices. This means that they are used not only for IR illumination, but also for work in white light, including for the purpose of creating powerful light interference for optical and optical-electronic means of the enemy.

Night vision devices based on image intensifiers are the cheapest, simplest and most reliable devices. However, television (TV) devices have also appeared in recent decades. They are used to create daytime TV channels, as well as nighttime ones – NTVS. Initially, NTVS were built on the basis of an image intensifier coupled with a supersilicon. Currently, daytime TV channels use TV cameras based on color or black-and-white CCD matrices. NTVS use hybrid modular image converters (image intensifier + black-and-white CCD matrix) [4]. Compared to optical daytime channels and, accordingly, nighttime channels based on image intensifiers, TV channels have a number of advantages:

— remote image transmission;
— more effective suppression of light interference;
— the ability to duplicate the image on several TV monitors for each member of the armored vehicle crew or for an observer-operator outside of it;
— real-time image processing, mixing it with the thermal imaging image and changing the electronic magnification for both the entire image as a whole and for its individual fragments;
— automatic lens focusing and wide-range image brightness adjustment;
— convenience of entering various digital, symbolic and alphabetic information into the electronic channel with its subsequent prompt update;
— ease of coupling with thermal imaging radar surveillance channels.

However, TV systems also have certain disadvantages:

— higher cost compared to day and night channels based on EOP, respectively;
— decrease in image quality compared to the specified channels.

In this regard, a combination of a daytime optical channel with an image intensifier tube-based channel is most often used. In cases where a daytime TV channel is used, a duplicate optical daytime channel is often used.

In all these channels, the ability to observe and aim is sharply reduced when the transparency of the atmosphere deteriorates (haze, fog, rain, snowfall, etc.) and when exposed to intense light interference (IR spotlights, headlights, flashes of explosions, shots, tracer radiation, fire flames, etc.). In this regard, AI NVDs have appeared [5]. They ensure operability in these conditions. In addition, they allow for high-precision measurement of the distance to the object of observation, provide vision of low-contrast objects and their detection by glare from the optical and optoelectronic means of these objects. The disadvantage of AI NVDs is the limited field of view when operating in the AI ​​mode, the impossibility of conducting a search in this mode. Therefore, the use of AI NVDs is most appropriate as part of an instrument complex containing an additional search and detection channel.

All the devices considered are part of the armored vehicle fire control system. This system includes various sensors (wind speed and direction, temperature, pressure, armored vehicle speed, its coordinates, etc.), as well as an on-board computer, which, based on the readings of these sensors, signals about the distance to the object of observation received from the laser rangefinder, data on the selected type of ammunition, automatically prepares the initial data for firing. The gunner only needs to keep the aiming mark on the observed target and open fire. However, consideration of such systems is beyond the scope of this article.

Let us dwell on individual types of night vision devices for armored vehicles. The parameters of typical night vision devices for driving are presented in Table 1. All devices are periscopic, as are other night vision devices for armored vehicles based on an image intensifier tube. Depending on the type of armored vehicle, the periscopic range can be 170-220 mm. Night vision devices for driving can be made using a binocular or biocular design. The binocular design is used less frequently. It provides for two identical night channels and a rigid positioning of the driver's face relative to the eyepieces. The biocular design provides for a large-diameter magnifying glass, which allows simultaneous observation of the image with both eyes. This solution allows the driver to position himself more freely relative to the device.

Table 1. Main parameters of night vision devices for driving armored vehicles (according to company brochures)

Some night vision devices for driving are a combination of night and day channels. For example, the TVK-1 model (PO GUP «NPZ», Russian Federation) has two channels with 1x magnification. The field of view of the night channel is 22.5×27.50, and the night channel is 11×310. The device also contains a prismatic viewing device with a field of view of 38×1200.

The focusing of the NVDs varies from 4 to 15 m to ?. Diopter adjustment can be carried out within ± 3 diopters, (-6) to (+2) diopters, or remain without adjustment within (-1) to (± 0.5). The devices allow driving armored vehicles at night at a speed of up to 40 km/h. The resolution of the NVDs is usually 1.2 — 1.3 mrad. Some NVDs allow an azimuth view within the range of ± 200 to ± 450. A typical diagram of the NVD for driving is shown in Fig. 1, the appearance of some NVDs for driving is shown in Photo 2.

Fig. 1. Typical NVD driving scheme

a)

b)

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г)
Photo 2. External appearance of typical driving NVDs: a TVN-5 (OAO LZOS, Russian Federation); b – AN/VVS-2(V) (Litton, USA); c CN-2-55 (Sopelem, France); d – location of DND-5 driving NVD (SAGEM, France) inside the armored vehicle; the biocular magnifying glass with cut-off upper and lower segments is clearly visible

The commander's NVGs are usually combined. They contain day and night channels. The main parameters of typical commander's NVGs are given in Table 2. Most often, they are binocular. The commander's NVG focusing is within the range of (10 — 20) m — µ. Diopter adjustment is carried out within the range of ± (3 — 5) diopters. The resolution of the NVGs is 0.3 mrad. The commander's NVGs allow an azimuth view within 3600, and a target elevation view within the range of (-10 — 20)0 — (+30 — 40)0. A typical diagram of the commander's NVGs is shown in Fig. 2, the appearance of some typical commander's NVGs is in Photo 3. Some NVGs contain a laser rangefinder and have gyrostabilization. In particular, TV devices HL-70 (HL-80) by SAGEM (France) and CCS by Electro Optic Systems Pty Ltd Austria) have a built-in laser rangefinder with a wavelength of 1.54 µm, which is considered safe for vision. Night vision devices SP-T-694 by Officine Galileo (Italy) and HL-70 (HL-80) have a gyrostabilization of the head mirror with an accuracy of up to 0.03 mrad. The daytime channel of most night vision devices is not television, but optical. This is due not only to the lower cost and greater simplicity of the optical channel, but also to its higher image quality.

Table 2. Main parameters of the commander's night vision devices (according to company brochures)

Rice. 2. Typical diagram of a commander’s NVG:
1 – night channel lens;
2 – image intensifier;
3 – night channel eyepiece;
4 – daily channel

а)

b)

в)

г)

д)
Photo 3. External appearance of typical commander’s night vision devices: a TKN-1M (GUP PO “NPZ”, Russian Federation); b – TKN-3M (GUP PO “NPZ”, Russian Federation); c – NV46 (same company); d – No 37 mk 4AV (AVIMO, UK); d – M36E1 (Optic Electronic Corp., USA)

When talking about TV devices for armored vehicles, it is necessary to mention the earliest model PZB-200 by Telefunken (Germany) [6]. The TV camera of this night gunner's sight was made on the basis of an image intensifier tube, coupled with a supersilicon. The TV camera was installed on the gun mantlet of the Leopard 1 tank, and the TV monitor with a linear field of view of 90×120 mm together with the control panel was at the gunner's workplace. The TV camera operated in the illumination range of 10-4 – 10 lux. Later, the PZB-200 device was additionally equipped with a TPV device. This complex was called the IRS100 PZB-200/IRS100. The presence of an additional TPV channel ensured the operation of the complex in a wide range of changing external conditions. The TV and TPV cameras of the complex were installed on the tank's gun mantlet. The IRS100 TPV device contained a photodetector based on PbSe and operated in the spectrum range of 3–5 µm. The HL-70 (HL-80) and CCS devices already mentioned were based on a third-generation image intensifier coupled with a CCD matrix. The Vingoye night sight by Vinghog (Norway) for armored vehicles of the US Army was also based on an image intensifier + CCD matrix (photo 4a, b) [7]. The CCD matrix with a 1/3-inch format contains 768×494 or 752×582 pixels. Its sensitivity is 6×10-3 lux, the resolution is 570 TV lines, and the dynamic range is 36 dB. A lens with a variable focal length is used in the TV camera of the lens. It allows smooth change of the field of view angle within the range from 2° to 45°. The TV system magnification (using additional electronic image scaling) can be adjusted within the range from 1 – 30x. The focusing limits are 1.8 m – µ. The accuracy of line of sight stabilization is ± 1 pixel. The TV camera is powered by a constant voltage of 16 – 36 V from the on-board network and has a power consumption of 22 W in the operating temperature range of (-40) – (+70) ° C. The weight of the TV camera is 2.6 kg, dimensions are 143x138x280 mm.

a)

б)

в)

Photo 4. External appearance of TV systems for armored vehicles: a Vingoye (VINGHOG AS, Norway); b – the same on an armored vehicle; c RVC-01 (SEKAI, USA); d – view of the terrain depicted by this TV system

The original RVC-01 TV system for the driver was developed by SEKAI Electronics Ltd. (USA (photo 4c) [8]. The device is based on a black-and-white 1/3-inch CCD matrix with 512×492 pixels. The minimum operating illumination is 0.05 lux, the horizontal field of view is 720, and the vertical field of view is 540. The TV camera symbol generator creates a series of marks in the TV monitor’s field of view (photo 4g). The horizontal strokes on the left and right correspond to a range of 3 m and are used to adjust the position of the TV camera axis when it is mounted in the rear of the armored vehicle. Three pairs of light dots indicate the transverse dimensions of the armored vehicle at ranges of 5, 10, and 15 m, respectively. The dynamic range of the TV camera is 63 dB. The operating temperature range is (-46) – (+71)0 C, the dimensions of the TV camera are 114x256x165 mm, and its electronic unit is 260.35×160.3×92 mm.

A number of compact TV monitors operating in harsh conditions have been developed for TV systems in armored vehicles. Their main parameters are given in Table 3, and the appearance of a typical TV monitor is shown in Photo 5. TV monitors can be made using black-and-white or color cathode-ray tubes (CRTs), or flat panels using liquid crystal matrices (LCDs) [9–12]. TV monitors have fairly high performance characteristics. In particular, they operate at high humidity of up to 98% at ambient temperatures of up to 300 C, withstand vibrations with an acceleration of 5g in the frequency range of 1–500 Hz, single impacts with an acceleration of 150g, and multiple impacts with an acceleration of 15g [10, 11].

Table 3. Main parameters of TV monitors of TV systems for armored vehicles

Photo 5. TV monitor for armored vehicles VM9-37V
(KB “Display”, Belarus)

Let us now consider the AI ​​NVG for armored vehicles. The scientific and technical foundations for the creation of the AI ​​NVG were developed at the State Unitary Enterprise “NPO Orion” [5]. The AI ​​NVG for armored vehicles can be represented by the historically first serial device 1PN61 for the combat reconnaissance vehicles “Nard” and “Rys” [13 – 15]. The device allowed observation at night in poor visibility conditions and ensured the measurement of the distance to the object of observation. The AI ​​NVG 1PN61 was used in combination with the TPV device 1PN71 [12, 13]. This expanded its search capabilities at extreme viewing ranges. The AI ​​NVG 1PN61 (photo 6a) has a magnification of 7x, a field of view angle of 3.70 in passive mode, 1×0.50 in active-pulse mode, a recognition range of 1.3 km in passive mode, 2.5 km in active-pulse mode, and provides range measurement in the range of 0.5 – 5 km [12]. The dimensions of the AI ​​NVG 1PN61 are 750x538x395 m, and its weight is 80 kg. The AI ​​NVG is based on a first-generation 3-module pulsed image intensifier and a 2-module laser illuminator based on ILPI-110 pulsed laser semiconductor emitters with a wavelength of 0.85 μm. The TKN-AI commander's AI NVG (Table 2, photo 6b) uses a generation II+ image intensifier and a single-module laser illuminator based on an ILPI with a wavelength of 0.85 μm. The AI ​​NVG can detect objects of observation by glare at a distance of up to 3 km [16]. The LEM CE 624 AI night tank sight-rangefinder from Eltro (Germany) for the Leopard-1 tank provided a vision range of up to 2 km when operating in active-pulse mode and range measurement with an accuracy of ±10 m [17] (photo 6c).

a)

b)

c)
Photo 6. AI NVG for armored vehicles: a – 1PN61 (GUP PO Refinery”, Russian Federation); b – TKN-AI (same); in – LEM CE 624 (Eltro, Germany)

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