The nature of warfare has changed dramatically after the September 11 attacks on the World Trade Center. In Afghanistan and Iraq mass deployment of armor and air strikes alone are not enough to conduct effective counter insurgency operations.

During the news coverage of a senior NATO officer’s visit to Afghanistan, when he asked if there was anything specific in fact the soldiers needed; the reply was instantaneous “more NVG’s (Night Vision Goggles) Sir”. This response cements the necessity of NVG’s in the present and future conflict zones. NVG is a post World War II development. It is no longer a luxury item for the modern soldiers but vital equipment, which may determine their survival in war zones. NVG’s have the unprecedented features of being easy to deploy and to maintain, of providing a unique identification performance by night and to be relatively cheap but very rugged, unlike any other opto-electronic devices. Thus the US army is leading the way of all NATO countries by massively equipping all of their troops with at least one NV device per soldier.

Also for the 2008 Mumbai attacks which began on 26 November 2008 and lasted until 29 November, Night Vision was of importance. Night actions have taken place, by the early morning of 28 November, all sites except for the Taj hotel had been secured by Mumbai Police and security forces.

Night Vision is of crucial importance for India, as recent terror events have shown again among others the vulnerability at night of armed and security forces.

Chronological development of Image Intensification

The first night vision devices were introduced during World War II. These active devices required a large infrared light source to illuminate targets, and consequently were easily detectable to opposing forces using similar equipment.

The first true passive image intensifier (I2) devices, known as Generation I?, were introduced in the 1960s. These devices eliminated the need for external infrared illumination, as they intensified ambient light. These “Starlight Scopes” were extremely bulky since they required several vacuum tubes coupled together to intensify an image.

By the 1970s, night vision experienced a technological breakthrough when Generation II? introduced the integrated Microchannel Plate (MCP). This new MCP eliminated the need for multiple stages of amplification and allowed the tube to reach very high gains with very good low light level performance, increased tube life, lower power consumption and almost no distortions. All of these achievements could now be contained within a compact housing, allowing for the development of the first truly man-portable devices.

In the 1980s, some tubes had the photocathode made from gallium arsenide (GaAs) instead of Tri-Alkali (Na2KSb). While the GaAs photocathode did provide a better response to near-infrared light, these Generation III? tubes lost the ability to reliably “see” the blue light that is most common in desert, sandy or rocky environments. The Generation III tube also had a significantly shorter useful life, and required a protective ion barrier film to return to the Generation II tubes lifespan. Unfortunately this film also reduces the electro-optical performance of the tube since many of the electrons emitted by the photocathode are absorbed in the film and take no part in the amplification process, reducing the quality of the reproduced image.

1. Reduce Size & Weight.
2. Improve resolution and signal-to-noise ratio (both parameters combined into what is now recognized as the FOM – Figure-of-Merit)
3. Minimize and overcome the major enemy of I2 tubes which is excessive light.

In the late 1990s, advances in technology allowed new tubes such as the PHOTONIS XD-4™ to surpass the performance of Generation III tubes. This made the term “Generation” irrelevant in determining the performance of an I2 tube. By 2001, the United States government concluded that performance was not dependant on generation, and eliminated it as a basis for export regulations.

XD-4™ overview with Auto-Gating

XD-4™ technology enables the user to detect information easily during all types of operations. Its wide spectral sensitivity enables the soldier to operate in all star- or moonlight conditions, in urban, desert, arctic, wooded or jungle operational environments.

The prominent feature on the XD-4™ is the integrated auto-gated power supply. Auto-Gating is the electronic solution that reduces the duty cycle of the photocathode voltage by rapidly switching the voltage on and off. The autogating provides the unique feature of keeping the nominal MTF and resolution of the tube at high light levels (urban environment, above cities for pilots, …) unlike standard tubes whose resolution would drop to less than 20 lp/mm at high light levels. The image provided by an autogated tube keeps therefore in all conditions of light the best contrast. Dynamic lighting conditions define many of today’s missions. Having a device fitted with auto-gating might be a true life saver in emergency situations, such as field explosions, sudden flashes of light or in a twilight environment where a standard image intensifier would usually switch off lens focus.