Technological advances provide the means to target the enemy more effectively. If you can see the adversary before he sees you, monitor his moves continuously and target him effectively, the victory scales would axiomatically tilt in your favour. In this era of hybrid warfare and heavy exchanges of fire astride the Line of Control (LoC) periodically, the role of electro optical systems both in small arms and the artillery are important, coupled with the fact that a battlefield surveillance system perhaps is still a decade away. On one hand, there is advanced research of organic electro-optic (EO) materials and their hybrid systems for device applications, like polymer sol—gel waveguide modulators, polymer silicon slotted waveguides, and EO polymerclad silicon nitride ring resonators, providing new paradigm of high bandwidth, small footprint, and low energy consumption EO devices for telecom, datacom, and sensing applications. But at the same time, research and development is being undertaken globally to enhance the reach, improve the resolution and reduce the weight of sights in order to provide a better edge to own side. Small arms and the artillery must be able to accurately engage the target both by day and night, also pinpointing where enemy fire is coming from and neutralizing it. In terms of indigenous EO products, we need to catch up with the foreign counterparts in terms of dimension, weight and performance. The ‘Make in India’ project and the Strategic Partnership Model (SPM) have opened avenues for developing state-of-the-art EOs for our military.

Weapon Sights

Most modern assault rifles in use have optical sights like red dot sights and diopter sights. Most can be fitted with detachable scope mounts and night vision devices (NVDs). The Israreli Tavor TAR-21 assault rifle in use by our PARA (Special Forces) has a a standard Picatinny-type rail and is compatible with various scopes or night vision systems, the red-dot sight being standard issue. Optical sights allow users to see the image of an aligned aiming point in the same focus as the target. These include telescopic sights and reflex sights. There are also sights that project an aiming point onto the target itself, such as laser sights. A telescopic sight is based on an optical refracting telescope, equipped with some form of graphic image pattern (a reticle) mounted in an optically appropriate position in their optical system to give an accurate aiming point. The reflex sight is generally nonmagnifying optical device that allows the user to look through a glass element and see a reflection of an illuminated aiming point or some other image superimposed on the field of view. Then there are collimator sight (also termed ‘blind sight’) that allows the user looking into it to see an illuminated aiming point aligned with the device the sight is attached to regardless of eye position (with little parallax).

Laser Sights comprise lightweight laser placed on a handgun or rifle that is aligned to emit a beam parallel to the barrel; the laser light appears as a small spot on the target and the barrel of the gun is aligned and fired. Most laser sights use a red laser diode. Others use an infrared diode to produce a dot invisible to the naked human eye but detectable with night vision devices. A standard red dot sight uses a red light-emitting diode (LED) at the focus of collimating optics which generates a dot style illuminated reticle that stays in alignment with the weapon the sight is attached to regardless of eye position - nearly parallax free. Telescopes have narrow field of view and therefore are often equipped with a secondary ‘finder scope’ such as a red dot sight. Finally, there are also Holographic Weapon Sights (HWS) that use a laser transmission hologram of a reticle image that is recorded in three-dimensional space onto holographic film at the time of manufacture. This image is part of the optical viewing window. The recorded hologram is illuminated by the collimated light of a laser diode built into the sight. The sight can be adjusted for range and windage by simply tilting or pivoting the holographic grating. To compensate for any change in the laser wavelength due to temperature, the sight employs holography grating that disperses the laser light by an equal amount but in the opposite direction as the hologram forming the aiming reticle. It is not ‘parallax free’ but can be offset by having a holographic image set at finite distance with parallax due to eye movement being size of the optical window at close range and diminishing to zero at the set distance; usually around a desired target range of 100m.

Night Vision Devices

NVDs comprise an image intensifier tube (IIT), a protective housing and a mounting system. Many NVDs also include sacrificial lenses, IR illuminators and telescopic lenses. Night vision goggles (NVGs), night-scopes, night-monocular, night weapon sights are vital to any army. Longer reach and improved resolution better the chances of winning. NVDs are of two types – Image Intensifiers (II) and Thermal Imagers (TI). Image Intensifiers are more common as their light amplification technology uses the small amount of ambient light like moon, stars-light and converts this light energy (Photons) into electrical energy (Electrons). To understand Thermal Imaging it is important to understand that Infrared (IR) can be split into three categories; Near IR (0.7 to 1.3 microns wavelength), Mid IR (1.3 to 3 microns wavelength) and Thermal IR (3 microns to over 30 microns wavelength). The key difference between Thermal IR and the other two is that Thermal IR is emitted by an object instead of reflected off it. Most thermal imaging devices scan at a rate of 30 times per second, sense temperatures from -20 degrees Celsius to 3,600 degrees Celsius and can detect changes in temperature of about 0.2 degrees Celsius. Thermal imaging devices are generally ‘Un-cooled’ or ‘Cryogenically Cooled’. The un-cooled ones are more common wherein the IR detector elements are contained in a unit that operates at room temperature. These devices are noiseless, activate immediately and have inbuilt batteries. Cryogenically cooled devices have elements sealed inside a container that cools them to below 0 degree Celsius. The advantage of such a system is the incredible resolution and sensitivity that result from cooling the elements. These systems enable identifying whether a person is holding a weapon more than 300m away. Thermal imaging can detect persons in near-absolute darkness with little or no ambient light.

Thermal imaging devices are generally ‘Un-cooled’ or ‘Cryogenically Cooled’. The un-cooled ones are more common wherein the IR detector elements are contained in a unit that operates at room temperature.

Fire Detection Systems

This is an electro-optical system designed to pinpoint the location and sources of small arms fire. The system can handle simultaneous, multiple fire sources, including small arms and sniper fire sources, during day and night. at long ranges and with high precision and detection probabilities. Such systems comprises a FLIR, CCD with continuous zoom, a Laser Range Finder, a GPS, a commander control system and multiple “subscribers”, located with the unit’s snipers. It analyses the fire sources detected, verifying that each source is actually enemy fire. When verified, data is transferred to the supported unit, which can engage them with fire support, snipers or indirect fire. An example of such system is SPOTLITE by Rafael that rapidly closes the sensor-toshooter loop targets by processing within relatively short “window of opportunity” characteristic of urban warfare scenarios. When required, the system can translate target data into coordinates for other shooters, or mark the target with a laser marker; distributing live images to relevant combat elements by day or night, supporting the platoon, company, battalion, reconnaissance units and special operations forces, by spotting fire sources with high level of precision, efficiently closing a “sensor to shooter” circuit at the tactical level:

Global Companies Dealing with Sighting Systems
The global market is awash with products of sighting systems and NVDs. Some of the leading companies in this field are listed below:

• Safran Vectronix AG. The company provides state-of-the-art optronic equipment, systems and sensors for military and civil applications including handheld laser rangefinders and NVDs, tripod-mounted orientation and positioning systems and sensor modules for OEM partners, exporting over 95 per cent of products worlwide. The company offers accurate, reliable, high quality products with combat-proven low failure rate, and flexibility to address specific customer requirements, create customized solutions and provide support over the complete product life cycle. The US Army has contracted the company to build the Army’s next-generation laser target locator; contract for $304.5 million announced in April 2017 to build the Laser Target Locator Module II (LTLM II) enabling foot soldiers identify target locations in daylight or at night, as well as in obscured-visibility such as fog or smoke.
  – The LTLM II is a lightweight, handheld system with day and night imagers, a laser rangefinder, digital compass, and a Global Positioning System (GPS) receiver:
  – Vectronix’ STERNA provides true north capabilities 24 x 7 in virtually any environment working in virtually all weather conditions; operating independently without GPS, celestial bodies, survey, or landmarks, and can operate in a magnetically charged environment, permitting soldiers to operate in virtually all battle and hostile environments:
  – Vectronix pocket laser range finder offers snipers/spotters, marksmen and forward observers the smallest, most powerful MILSPEC eye-safe laser range finder available, with ranging measurements up to 4,000m - weighing 500g and measuring only 131mm x 88mm x 56mm, the PLRF25C is ready for combat operations in the most extreme conditions. The PLRF25C fits easily in any pocket and is water resistant up to 1m deep for 30 minutes (optional 10m):
  – Other products include ‘thermal acquisition clip-on system for NVDs’ that add additional capabilities; low power consumption, optimal sensor technology and high-performance optics integrate seamlessly to provide state-of-the-art long-wave IR technology. Then is the ‘compact observation and location unit for day/night viewing, with geo-location functions in a compact and userfriendly package called ‘MOSKITO’ that measures range, azimuth and vertical angle. In addition, it incorporates the latest image intensifier technology for night time viewing, including self-regulation to different levels of brightness.
• Aimpoint AB. The company supplies electro-optical sighting systems including passive red dot collimator sight, laser device, fire control systems and mounts. It was awarded the first multi-year contract ever for red dot sights by the US Army in 1997. Aimpoint has continued to deliver large quantities of sights to the US Army, French Army, US Air Force, US SOCOM, Swedish Army, Norwegian Army, Dutch Army, Danish Army and Italian Army.
• Optex Systems. This US-based company manufacturing OEs has secured a contract to supply new periscopes for the US Army. Under the terms of the $8,41,000 deal, the company will supply an undisclosed number of periscopes to be installed aboard the army’s Abrams tanks. The periscopes will feature glass and plastic laser protection for soldiers’ eyes.
• Photonic. Photonic is a globally active contractor for optical and opto-electronic instruments, whose optical products provide for infantry and artillery weapon systems. The company has also developed a unique sighting system to lay muzzle-loaded indirect fire weapons such as 60mm mortars.
• Trijicon. This US company has led the industry in the development of superior any-light aiming systems since the company’s founding in 1981. Worldrenowned for its innovative applications of tritium and advanced fibre optics, Trijicon manufactures the most advanced riflescopes and sights for tactical and sporting applications. It manufactures optical sighting devices for firearms, specializing in self-luminous optics and night sights, mainly using the low energy radioactive isotope tritium,light-gathering fiber optics and batteries. Additionally, Trijicon is a contractor for the US military and supplies the Advanced Combat Optical Gunsight (ACOG) and RX01 reflex sights. The ACOG, Reflex, TriPower, AccuPoint, and Night Sights are available to military, law enforcement, and civilian markets.
• Thales Optics. The Sight Unit Small Arms, Trilux (or SUSAT) is a 4x with telescopic sight with tritium-powered illumination, utilised at dusk or dawn. The full name of the current model is the SUSAT L9A1. The SUSAT sight was developed in the United Kingdom by Royal Armaments Research Development Establishment (RARDE) and is manufactured by United Scientific Instruments and Avimo, now known as Thales Optics.

Conclusion

Conflict situations demand that we provide the wherewithal to our soldiers to have greater advantage through battlefield transparency by night including through poor visibility due to rain, fog, mist, snow, sandstorm, blizzards. Where the Indian defence market has opened up for joint ventures with OEMs, we must provide the state-of-the-art electro-optics technology to our soldiers for effectively target the enemy.