Shortwave infrared laser detection and tracking on the battlefield

By Devon Turner and Martin H. Ettenberg

As warfare modernizes, improving communications, developing more precise munitions, reducing collateral damage, and reducing sensor-to-shooter timelines are critical to ensuring the warfighter’s continued in-theater success. Achieving these goals requires improved pointing, targeting, and designating capabilities, while remaining covert to the enemy and at longer standoff distances than present technology allows.

Indium gallium arsenide (InGaAs)-based shortwave infrared (SWIR) technology is helping to meet these critical goals with advanced solid-state SWIR cameras that can detect most of the lasers in theater.

A 1064-nanometer laser designates a target in field about two kilometers away.
Click here to enlarge image

Laser designation requires precise and direct communication between ground-based and air-based forces at all times in all conditions. The goal today is to reduce the sensor-to-shooter timeline to engage targets quickly, while at the same time reduce fratricide and collateral damage.

The development of laser-guided munitions was the first step in reducing collateral damage and improving weapon precision. In World War II it could take 9,000 bombs to hit a target the size of an aircraft shelter. In Vietnam it took 300 bombs. By the mid 1990s it took only one laser-guided munition (LGM).

LGMs consist of four parts: a computer control group (CCG), guidance canards at the front of the bomb for steering, a warhead section containing the explosives, and a wing assembly at the rear for stability.

A 1064-nanometer laser designates a building as a target. These images were taken with the Sensors Unlimited NIR/SWIR KTX camera at night.
Click here to enlarge image

A detector at the front of the munition detects the laser and the CCG, then sends commands to the canards to change the LGM’s flight path. Using pulsed lasers and munitions programmed with different frequency codes, multiple targets can be attacked by a single aircraft simultaneously. These weapons can be guided using lasers fired from the same aircraft, a different aircraft, or by ground forces.

One common aircraft-based designation system is Northrop Grumman’s LITENING pod mounted on aircraft like the A-10, B-52, and F-16. The most popular ground-based designating system is the man-portable Special Operations Forces Laser Marker (SOFLAM). Both types of designators/rangefinders use a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with a wavelength of 1064 nanometers (see photos 1 and 2, page 22).

1550-nanometer and (right) 850-nanometer IR markers designate the target in nighttime conditions.
Click here to enlarge image

Because this wavelength is outside the visible spectrum and outside the detection range of night-vision goggles (NVGs), seeing where the laser beam is pointed, or verifying that it is bore sighted with the scope, is challenging at night and even more difficult during the day using currently fielded indium antimonide (InSb)-based systems.

These InSb-based thermal imagers have thinned substrates to aid in detecting light with wavelengths much shorter than are typically detected in its main application of mid-wave IR (thermal) imaging. The thinning process allows the InSb-based systems to detect light down to 1000 nanometers, although the quantum efficiency of these imagers at 1064 nanometers is quite low, approximately 20 percent. These systems also require cryogenic coolers to work properly. This cooling process further requires the use of significant amounts of power and a large form factor. The large power draw and form factor, combined with the high cost of these imagers, makes it difficult for these systems to be widely deployed.

This quantum efficiency chart illustrates the response curves for silicon, night-vision goggles, NIR/SWIR InGaAs, and Standard InGaAs in the visible and shortwave infrared wavelengths. The Standard and NIR/SWIR InGaAs curves are based on back-side illuminated InGaAs detectors. Key laser wavelengths are also noted.
Click here to enlarge image

In contrast, indium gallium arsenide cameras operate at room temperature. This leads to a system that draws significantly less power at a much lower cost. InGaAs cameras are able to see the 1064-nanometer laser designators because of the high quantum efficiency at 1064, which is over 65 percent (see chart at left). The cameras are smaller, lighter, and consume less power, while providing improved capability for laser detection. Under identical conditions as the InSb-based systems, not only can InGaAs-based imagers see the laser spot easily, but they can also see the entire laser beam at night. This allows the user to see the target being designated and the person designating the target, thus reducing the chances of fratricide.

To use designating lasers from the air, planes either need to be “talked-in” to targets, given GPS or latitude/longitude coordinates, or shown the location of the target by a Terminal Air Controller (TAC) using an IR marker. In a typical scenario, a ground-based TAC would sparkle a target with an IR marker, which would then be seen by someone in the air. In the past, these IR markers, which are invisible to the human eye, could only be seen with NVGs, and were thus solely used during night operations, because night-vision goggles are unusable during daylight hours. However, recent technological advancements have allowed SWIR-InGaAs cameras, sensitive to light between 700 and 1700 nanometers, to give users the capability to image not only the 1064-nanometer laser designators described earlier, but also the shorter wavelength IR markers traditionally only used with NVGs (see photo 3, page 22). InGaAs imagers were previously restricted to a smaller wavelength range, between 900 and 1700 nanometers. This recent advancement in InGaAs cameras has widened the detection wavelength spectrum and in turn made the cameras backwards-compatible with NVGs, such as the PVS-14. In addition to its other benefits, this also allows pilots and ground troops with NVGs to see IFF (Identify Friend or Foe) tags used by soldiers at night.

A 1550-nanometer laser pointer “marks” the roof of a boat (in foreground) in daylight conditions. The laser spot is indicated by a red circle.
Click here to enlarge image

A third laser with a longer wavelength (typically 1550 nanometers), is for range-finding on the battlefield. Similar in functionality to radar, these lasers send out a pulse and the detector measures the time for the reflection to return. The time of flight of the laser is used to calculate range to the target. The 1550-nanometer lasers are eye-safe at much higher powers and much closer distances than 850- and 1064-nanometer lasers due to its longer wavelength with the physiology of the human eye. This laser’s wavelength also falls in the middle of the InGaAs detection band. The other advantage of these lasers is that they are undetectable by off-the-shelf silicon cameras or night-vision goggles.

As InGaAs-based imagers become more commonplace in land and air- based systems, one can envision this longer (and more covert) SWIR wavelength replacing the 850-nanometer IR markers and illuminators that can be easily spotted with NVGs.

In addition to the night operations, with the inclusion of appropriate bandpass filter(s) to block light with unwanted wavelengths, these InGaAs imagers can also see marking, designating, and range-finding lasers during daylight hours (see photo on page 23). This new day/night SWIR-InGaAs imaging capability is not attainable with any competing imaging technology while maintaining the imager at room temperature. The ability to see the imagers day and night by ground troops and pilots can significantly reduce the sensor-to-shooter timeline. It allows validation of target designation and therefore supports the rules of engagement. It also supports maintaining the chain of custody through positive target hand over to weapons platform from the original designator. These advances will help prevent fratricide. The ability to see these different lasers under a wider range of conditions (including daytime) has the potential to revolutionize the military’s CONOPS.

In addition to being able to see both types of lasers (IR and designators), shortwave infrared (SWIR) InGaAs-based imagers also have the ability to be used for surveillance during the day and night. During night operations, InGaAs imagers passively image using SWIR photons always available in the night sky. This light source, often referred to as night glow, is available even if there is no moon light available. Also, because these imagers detect reflected light as opposed to emitted light (thermal), the images look similar to a monochrome daytime visible image and can be easily understood.

Devon Turner is an applications engineer and defense specialist with Sensors Unlimited Inc., a Goodrich company in Princeton, N.J. Dr. Martin H. Ettenberg is director of imaging products at Sensors Unlimited. Visit Sensors Unlimited online at

Get All the Military Aerospace Electronics News Delivered to Your Inbox or Your Mailbox

Subscribe to Military Aerospace Electronics Magazine or email newsletter today at no cost and receive the latest information on:

  • C4ISR
  • Cyber Security
  • Embedded Computing
  • Unmanned Vehicles

Get All the Military Aerospace Electronics News Delivered to Your Inbox or Your Mailbox

Subscribe to Military Aerospace Electronics Magazine or email newsletter today at no cost and receive the latest information on:

  • C4ISR
  • Cyber Security
  • Embedded Computing
  • Unmanned Vehicles

Military & Aerospace Photos

Most Popular Articles

Related Products

XPand6020 | Small Form Factor (SFF) System Featuring XPedite5205 Running Cisco IOS® and XPedite7450

The XPand6020 is a Small Form Factor (SFF) system that features an XPedite5205, which runs Cisco ...

XPedite5401 | Freescale Eight-Core P4080 Conduction-Cooled PrPMC/XMC Module with Two GbE Ports

The XPedite5401 is a high-performance PrPMC/XMC, single board computer supporting Freescale QorIQ...

XPort3200 | Freescale QorIQ P1020 Processor-Based Conduction- or Air-Cooled XMC/PMC IEEE 1588v2 Grandmaster Clock Module

The XPort3200 is a rugged, IEEE 1588v2 Precision Time Protocol (PTP) ordinary clock with grandmas...

XChange3018 | 3U VPX 10 Gigabit Ethernet Switch with Optional Layer 2 Switching and Layer 3 Routing Management Support

The XChange3018 is a conduction- or air-cooled, 3U VPX, 10 Gigabit Ethernet switch module. The XC...

XPedite7472 | Intel® Core™ i7 Processor-Based Conduction- or Air-Cooled 3U VPX-REDI SBC with SecureCOTS™

The XPedite7472 is a secure and high-performance, 3U VPX-REDI, single board computer based on the...

XPand4200 Series | ½ ATR Lightweight Forced-Air-Cooled Chassis for Conduction-Cooled Modules

The XPand4200 Series redefines the limits of power, performance, and functionality in a sub-½ ATR...

XPedite5500 | Freescale P2020 QorIQ Conduction- or Air-Cooled PrPMC/XMC Module

The XPedite5500 is an XMC/PrPMC mezzanine module targeting the Freescale QorIQ P2020 processor. W...

XCalibur1603 | Freescale QorIQ Eight-Core P4080 Processor-Based Air-Cooled 6U cPCI SBC

The XCalibur1603 is a high-performance, 6U cPCI, single board computer supporting Freescale QorIQ...

XPort5005 | XMC Form Factor PCIe Mini Card Carrier Board

The XPort5005 is an XMC module that can be quickly configured to support a platform’s specific I/...

XChange3019 | 3U VPX 10 Gigabit Ethernet Switch with XMC and Optional Managed Switching and Routing Support

The XChange3019 is a conduction- or air-cooled, 3U VPX, 10 Gigabit Ethernet switch module. It pro...

Related Companies

General Atomics Aeronautical Systems Inc

GA-ASI is a leading manufacturer of proven, reliable Remotely Piloted Aircraft (RPA) systems, radars, and electro-opt...

DiCon Fiberoptics Inc

Offers fiber optic switches, tunable filters, and VOAs. Founded in 1986, the company is a US based, AS9100 certified,...

Curtiss-Wright Defense Solutions

About Curtiss-Wright Defense Solutions Curtiss-Wright Defense Solutions (CWDS) is a long established techno...


Offers complete solutions for embedded software developers with a focus on mission- and safety-critical applications....

Harris Corporation

Harris provides advanced, technology-based solutions that solve government and commercial customers' mission critical...

United Electronic Industries Inc

UEI is a leader in the PC/Ethernet data acquisition and control, Data Logger/Recorder and Programmable Automation Con...

Crane Aerospace & Electronics

When failure is NOT an option...rely on Crane Aerospace & Electronics. We supply high-density, high-reliability c...


Signal integrity leaders and preferred vertically integrated manufacturer of high-performance electrical and electron...

AcQ Inducom

Develops and produces non-certified and certified high-tech modular hardware- and software solutions for on-board and...

Advanced Conversion Technology Inc

ACT designs and manufactures, since 1981, an extensive range of AC-DC and DC-DC power supplies (switching, linear, ra...
Wire News provided by   

Press Releases

Model INCX-4001

The INCX-4001 consists of a high quality audio transceiver specifically designed to implement a complete fiber optic intercom.

Model PS-1210

The PS-1210 is a 1A, 12VDC stand-alone or rack mountable non-switcher (no RF noise) power supply.

Model OS-3121

Optical switches are utilized to disconnect, bypass and reroute fiber optic communications. All of these optical switches are purely optical path, there is no optical to e...


New Design Tools That Help You Develop Radar That Sees the Un-seeable and Detects the Undetectable

Xilinx EW/ISR System Architect, Luke Miller, has new tricks and he’s going to tell you all about them in a new Xilinx Webinar—for free. His Webinar will cover new ways to implement Radar functions including ...
Sponsored by:

All Access Sponsors

Mil & Aero Magazine

June 2015
Volume 26, Issue 6

Download Our Apps




Follow Us On...


Military & Aerospace Electronics

Weekly newsletter covering technical content, breaking news and product information

Cyber Security

Monthly newsletter covering cyber warfare, cyber security, information warfare, and information security technologies, products, contracts, and procurement opportunities

Defense Executive

Monthly newsletter covering business news and strategic insights for executive managers

Electronic Warfare

Quarterly newsletter covering technologies and applications in electronic warfare, cyber warfare, optical warfare, and spectrum warfare.

Embedded Computing Report

Monthly newsletter covering news on embedded computing in aerospace, defense and industrial-rugged applications

Unmanned Vehicles

Monthly newsletter covering news updates for designers of unmanned vehicles