Military rocket launching once required tremendous skill and experience, whether firing from the ground or from an aircraft. From the ground, tedious measurements were needed to estimate where a rocket would land. From the air, striking a target meant estimating target distance, rocket trajectory, weather/visibility conditions, and aircraft control. Such variable precision meant inefficiency in terms of rocket/missile consumption, along with the associated inefficiency in the cost for these armaments.

Improvements in missile guidance were made around the midpoint of World War II when various participants in that conflict—including the United States, Great Britain, Russia, and Germany—began to incorporate radio-frequency (RF) technology via guidance systems that would improve the likelihood of finding a target. With the development of RF guidance systems, rockets evolved into guided missiles. Missiles guided by RF and radar signals proved practical for some applications, if not perfect for all. They worked well when the target was large, such as a ship or building, but were less efficient at finding smaller targets. Early RF guidance circuits were also extremely sensitive to environmental effects, and jamming technologies were quickly developed in response to RF/radar-guided missiles to degrade their target-seeking accuracy.

When the first light amplification by stimulated emission of radiation (laser) device emerged from Hughes Research Laboratories around 1960, the defense market saw immediate potential for lasers in missile-guidance systems. Some of the first laser-guided weapons found employment during the Vietnam War and proved to be so accurate that they earned the name “smart weapons.” With further advances in laser technology, electronics, and computers, laser-guided missiles played a starring role in Operation Desert Storm in the early 1990s.

A laser-guided missile consists of six basic sections: the photo sensor (laser seeker) with optical filter, control circuitry, guidance section, fuse, propulsion section, and the warhead with fuse (Fig. 1). Two design topologies are used for laser-guided missiles. In the “beam rider” approach, the missile’s photo sensor detects light emanating from the launch site, such as a ground station or aircraft. The laser beam carries directional data, which the control section interprets to adjust the missile’s steering fins accordingly. In the alternative approach, a missile’s on-board sensors make use of laser-light reflections from a target. The launch vessel beams a laser onto a target and launches the missile, which measures the distance between itself and the target via the on-board sensors. Control circuitry is used to adjust the missile’s navigation equipment for accurate delivery of the payload.

Of course, the nature of military electronics is to develop a countermeasure system. In the case of guided missiles, which have improved in accuracy over time, the United States Army’s Common Infrared Countermeasures (CIRCM) program was initiated to disrupt the accuracy of laser-guided weapons systems. Replacing older programs like the Advanced Threat Infrared Countermeasures (ATIRCM), the CIRCM initiative promotes the development of a lightweight, low-cost, and modular laser-based infrared jammer subsystem for US helicopters and slow-moving aircraft. The primary goal is to protect against shoulder-fired, heat-seeking missiles.

Earlier this year, major contracts were awarded to BAE Systems and Northrop Grumman Corp.—valued at $38 million and $31.4 million, respectively—to develop missile-jamming lasers for helicopters. BAE Systems’ Boldstroke® directable infrared countermeasures (DIRCM) system is a weapon against optically guided weapons (Fig. 2). It incorporates laser-based and point-and-track technologies with an architecture that can be readily upgraded.

The Boldstroke DIRCM system features proven hardware and algorithms; a compact pointer and tracker based on a gimbal design; laser technology providing spectral diversity and power margin; direct or fiber coupling between the laser and pointer/tracker; and a modular open-system architecture for compatibility with a wide range of warning systems (i.e., the Common Missile Warning System and Joint and Allied Threat Awareness System). Boldstroke is contained within two separable line-replaceable units (LRUs) that can be independently removed and replaced without any alignment, greatly simplifying maintenance. The system’s optical path incorporates real-time auto boresight capability, and the Boldstroke has been designed with 60% fewer parts than previous generation DIRCM systems for higher reliability and lower cost.

Northrop Grumman’s Solaris™ is a mature and compliant CIRCM system (Fig. 3) that integrates a quantum cascade laser (QCL) from Daylight Solutions. A leader in DIRCM design and development with more than 2400 lasers fielded, Northrop Grumman has had its DIRCM systems installed in more than 750 aircraft. The QCL integration into Solaris results in a system capable of protecting both fixed- and rotary-wing aircraft against guided missile threats, including man-pack portable weapons. Like Boldstroke, Solaris also employs an open architecture to support long-term system upgrades and evolution against emerging counter threats.

The military electronics pursuit of responding to an opponent’s actions through a suitable countermeasure has resulting in a defense against laser-guided missiles, using laser-jamming technology to prevent laser-guided missiles from hitting their targets. Because these laser-based jammers employ open architectures, they can be modified and evolved in response to changing threat scenarios without major effort and expense.