Optics For The Eye-In-The-Sky

A prolific range of EO/IR sensors provides intelligence gathering capability from manned long range patrol aircraft to unmanned platforms.

- Michael J. Gething

The past two decades have seen electro-optic/infrared (EO/ IR) technology evolve from a specialised sensor to an almost ubiquitous ‘must-have’ for the world of ISTAR (Intelligence, Surveillance, Target Acquisition and Reconnaissance).

If one breaks down the ISTAR acronym, Intelligence is the prime goal, Surveillance and Reconnaissance the means of gathering that intelligence, and Target Acquisition a principle outcome. Today’s airborne EO/IR sensor unit is mounted in a gyroscopic gimbal, referred-to as a sensor ‘ball’ or turret, and can be fitted with various types of sensor payload in a variety of configurations, depending on the application.

As EO/IR technology had evolved, its application has spread across virtually the whole spectrum of military aviation (as well as into Space, beyond the scope of this feature). The following selection of systems and applications does not claim to be comprehensive but can be considered as representative of what is available on the market.

In the days of the Cold War, the Maritime Patrol Aircraft (MPA) was a large, long-range aircraft, typified by the P-3 Orion, and designed for antisubmarine warfare (ASW). Since then, as EO/IR sensors have become more compact, smaller types, mainly derived from transport aircraft, have been recruited into the patrol/surveillance roles, notably for anti-narcotic and illegal immigration missions.

However, for the larger MPA, L3 Wescam’s MX-20 turret appears to be the go-to system. Depending on the model, it can be equipped with up to eight sensor payloads, including two MWIR (mid-wave infrared) thermal imagers in standard definition (640x480 pixels) and high definition (1,280x1,024 pixels), a continuous zoom daylight camera (2 megapixels), a daylight spotter camera (2 megapixels), a low-light spotter, an SWIR (short-wave infrared) spotter, laser rangefinder/designator, laser ranger and laser spot tracker.