SHIP NIGHT VISION DEVICES (Part 1)
VOLKOV Viktor Genrikhovich, Candidate of Technical Sciences, Associate Professor
Night vision devices (NVD) are widely used for observation and aiming at dusk and at night .
The features of ship night vision devices are: an additional function in relation to ship radar stations (RLS) in cases where radars are ineffective (in the presence of electronic countermeasures, the need to detect high-speed flying targets at close range , ensuring navigation in narrow straits or for observing the coastline during the landing of troops); less stringent requirements for weight and dimensions compared to the requirements for night vision devices for armored vehicles or for aviation night vision devices.
Naval night vision devices can be installed on surface ships and submarines.
They can be implemented in the form of low-level television systems (LLTVS) [1], active-pulse night vision devices (APNV) [2, 3], thermal imaging devices (TID) [4], as well as in the form of multi-channel systems [3], including all of the above devices in various combinations.
Multichannel systems may include daytime color TV cameras [5], laser rangefinders [6], and target tracking radars [7].
All devices are installed on gyrostabilized platforms, which are mounted on support columns (for surface ships) and on periscope lifting masts (for submarines). The ship's wheelhouse has a display for controlling the night vision device or multichannel system.
It is possible to view the space horizontally and vertically at a certain speed. Let us now consider in more detail all the specified types of ship NVD and multichannel systems based on them.
The NVD “NVD-500” “Chibis” [8], designed for installation on ships of all classes and purposes, is an autonomous means of observation when a ship is moving in areas of intensive shipping with limited visibility, to ensure maneuvering in narrow sections of port waters and roadsteads, orientation in the coastal zone and river beds.
The NTVS is especially convenient for providing navigation of high-speed hydrofoil vessels, for conducting rescue and search operations at sea, and solving security and surveillance tasks.
The NTVS complex consists of a TV camera mounted on a support and rotary device, a gyrostabilizer with horizon correction, a control panel with a built-in TV monitor that allows smooth and discrete rotation of the TV camera along the ship's course, a remote TV monitor, a power supply with a video information generation unit, and three IR illuminators.
Observation is provided by two TV monitors.
The vessel is oriented using luminous markers on the TV monitor screen.
The detection range at a natural night illumination level (ENL) of 3×10-3 lux is: swimmer's head, log — 0.3 km, boat — 0.9 km, shore — 1 km, ship — 5 km.
The field of view angle can be selected to be 10×70, 12×90, 15×110.
The range of working illumination is 10-4 — 104 lux.
The viewing sector and the rotation speed of the TV camera are respectively ±1800 and 0 – 8 deg./s horizontally, from +50 to –150 and 0 – 1.5 deg./s vertically.
The accuracy of vertical field of view stabilization is 30′, the resolution is not less than 300 TV lines, the weight (depending on the configuration) is 70 – 100 kg, the power consumption is 50 W (without spotlights), the supply voltage is 27 V.
The brightness of the TV monitor screen can be automatically adjusted depending on changes in ambient illumination within the range of 10-4 – 102 lux.
Photo 1a shows an example of a typical NTVS [9], and photo 1b shows a typical image in an NTVS.
a – typical view of a ship's NTVS;
b – typical image observed in NTVS in comparison with the image observed in a daytime color TV camera;
c – image observed in a daytime color TV camera
Photo 1.
Bell Aerospace and Technologies Corp. ALLMTV (All – Light Level Marine Television Camera) [10] developed an NTVS based on a third-generation image intensifier tube coupled with a CCD matrix.
Strobing the image intensifier tube allows for attenuation of light by a factor of 3×104 and provides for observation both at night and on a bright sunny day.
The NTVS has a diagonal field of view that can be changed using a varifocal lens within the range of 2.5 – 250.
The spectral operating range of the NTVS is 0.55 – 0.95 µm, the horizontal resolution is over 500 TV lines with a resolution of 1032 pixels per line, the signal/noise ratio is 40 dB. The NTVS weighs 21.4 kg, the dimensions are O203x483 mm, the power consumption is 30 W, the supply voltage is 20 V, the operating temperature range is from –20 to +600 C.
Low contrasts of typical objects of observation on the water surface make the use of AI NVG as a ship surveillance tool particularly effective [11].
In addition, the AI NVGs provide the ability to observe at night in conditions of low atmospheric transparency (haze, rain, fog, snowfall, etc.), as well as when exposed to powerful light interference [2, 3]. The AI TV NVG described in [11] was implemented on the basis of a second-generation image intensifier tube, coupled with a PTU-64 TV camera based on the LI-702-4 supersilicon.
The magnification of the observation device was 15.x, the field of view angle in the passive mode was 1.5×1.170, in the active-pulse (AP) mode 42’x21′. The same illumination angle was provided by the pulse laser illuminator, based on a pulse laser semiconductor emitter with an average radiation power of 0.2 W, at a wavelength of 0.85 μm, at a frequency of 5.2 kHz and a radiation pulse duration of 100 ns.
When the device was operating in passive and AI modes under conditions of normal atmospheric transparency, EHO level = (3 – 5)10-3 lux and sea surface roughness up to 1 point, the recognition range of a diver’s head was 0.25 and 0.9 km, respectively, a boat (side) 0.65 and 2 km, a small boat 0.8 and 3.2 km, a large boat 3.2 and 5 km, and a small tug 5 and 8 km. The advantage of the AI mode is obvious here.
The AI TV NVG “Tuman-07” [12], designed to provide night navigation for vessels of all classes, has a boat recognition range of 1 km, and a full-length human figure of up to 0.4 km.
The recognition range in fog with a meteorological visibility range (MVR) of 200 m is 0.6 km, and with a MVR of 50 m – 150 m.
The range measurement accuracy is ± 10 m, the field of view angle in passive mode is 110, in AI mode 3×60, power consumption is less than 6 W, weight (without TV monitor) is 1.1 kg, dimensions are 300x150x70 mm.
AI TV NVG Sea Lynx [13] (photo 2), designed for observation and navigation of ships on seas and rivers and used in combination with other navigation systems, has a boat detection range in passive mode of 0.5 km, in active-continuous mode 0.7 km, in AI mode 1 km.
The recognition range is 0.15 km, 0.3 km, 0.6 km respectively. The depth of the viewed space when working in AI mode is 50 — 350 m, the field of view angle is 6×4.80 (9×60), the resolution is 450 TV lines, the power consumption is 60 W with a power supply of 24 V or from a network of ~220 V (50 or 60 Hz).
The dimensions and weight are 190x430x370 mm and 15 kg for the optical-electronic unit, 230x250x220 mm and 6 kg for the TV monitor with a 9-inch screen diagonal, and 95x350x305 mm and 10 kg for the control unit. The nature of the image observed in the AI TV NVD is shown in photo 3.
Photo 2. AI TV NVD Sea Lynx
a – boat with oars (side view);
b – the same, view from the stern;
c – head of a diver;
d – rower on a boat and figure of a diver
Photo 3. Nature of the night vision image observed in AI TV:
All the considered NVDs used pulsed laser illuminators based on injection pulsed laser semiconductor emitters.
They have high efficiency, minimal weight, dimensions, energy consumption, and high performance characteristics.
However, there are pulsed illuminators based on semiconductor lasers with electron pumping (PLEN) [14].
While inferior to injection semiconductor laser emitters in efficiency, they have an important advantage: they generate short (up to 5 ns) and powerful (up to 15 MW) radiation pulses at a frequency of less than 15 Hz.
This creates favorable conditions for suppressing backscattered radiation in the atmosphere and radiation of light interference.
The weight of such an illuminator does not exceed 22 kg, dimensions 310x310x150 m, power consumption 30 W [14].
For vessels where the limitations of these indicators do not play a significant role, the AI TV NVD with such an illuminator can be effectively used to observe various objects on the water surface.
The AI TV NVD with an illuminator based on the PLEN provides a night vision range of up to 1 km for a swimmer with adjustable visibility depth within 3-30 m, has an adjustable field of view angle within 1.5-150, and a resolution of 300 TV lines [14].
In the presence of sufficiently high temperature contrasts of objects observed on the water surface, TVP observations can be used.
The main parameters of such devices are given in Table 1, their appearance is in photos 4, 5, the view of the control panel is in photo 6.
Table 1. Main parameters of ship thermal imaging devices (according to company brochures)
a – V3800 TVP (TICM II TVP) in combination with a radar; the image of the ship, observed from the TV monitor of this device:
b – negative contrast,
c – positive contrast; general modules of the device:
g – photodetector device and units of the optical-mechanical image scanning unit,
d – electronic units.
Photo 4.
a – Ophelios;
b – ATTICA;
in – HDIR;
g – VAMPIR.
Photo 5. TVP:
Photo 6. a, b – typical monitoring and control units for a ship's night vision devices
In TVP, the image can be observed at the operator's discretion in negative (photo 4b) or positive (photo 4c) contrast.
However, at low temperature contrasts, the recognition range in TVP drops sharply.
In addition, the background surrounding the target, the sea surface, and the horizon line are poorly visible in TVP. In this regard, multichannel ship systems are widely used.
Literature.
1. Volkov V.G. Ultra-high-sensitivity television systems./Special equipment, 2002, 4, pp. 2 – 11.
2. Volkov V.G. Active-pulse night vision devices./Special equipment, 2002, No. 3, pp. 2 – 11.
3. Geykhman I.L., Volkov V.G. Fundamentals of improving visibility in difficult conditions. Moscow, Nedra-Business Center, 1999, 286 p.
4. Volkov V.G., Kovalev A.P., Fedchishin V.G. New generation thermal imaging devices./Special equipment, 2001, No. 6, pp. 16 – 21, 2002, No. 1, p. 18 – 24, 26.
5. Volkov. V.G. Small-sized television systems. Review No. 5591, Moscow, NTC Informtekhnika, 2000, 157 p.
6. Volkov. V.G. Portable laser rangefinders./Special equipment, 2001, No. 6, pp. 2–13.
7. Jane’s Weapon Systems, USA, 2004.
8. Night vision device PNV-500 “Chibis”. Prospectus of PO KOMZ, Russian Federation, Tatarstan, Kazan, 1990.
9. We ensure clear vision. Optics and Optronics for the navy. Prospectus of Zeiss Optronic GmbH, Germany, 2004.
10. Jane's Ship Weapon Control Systems, USA, 2003, p. 64.
11. Volkov V.G. Application of active-pulse surveillance devices for vision of marine objects./Questions of defense equipment, ser. 11, 1995, issues 1-2 (144-145), pp. 8-11.
12. Anti-fog active night-vision surveillance system “Tuman-07”. Prospectus of NPP Senet, RF, M., 1992.
13. Sea Lynx. Laser night vision locator. Prospectus of TURN Ltd. RF, M., 2000.
14. Golchenko A.N., Olikhov I.M. Semiconductor laser with electron pumping – a new short-pulse radiation source/Electronic Industry, 1996, No. 3, pp. 65-72.