InGaAs shortwave infrared enables imaging of invisible lasers

Princeton, N.J. - The expansion of military efforts has resulted in a dramatic increase in the number of electro-optic (EO) systems installed on military hardware. ­Electro-optic imaging systems are now on everything from aircraft carriers to unmanned aerial vehicles (UAVs) to individual soldiers’ rifles and helmets. These EO systems not only enable the users to “see” their surrounding environment in the day or night, in low-light or no-light conditions, but also to get range information to the target and aim laser-guided weapons. The use of EO systems helps protect the soldier by enabling him to view the battlefield from a relatively safe distance or position while gaining critical information about the scene.

Many new EO systems have thermal cameras as their major imaging component. These cameras detect radiation of longer wavelengths than 3 microns, in either the midwave infrared (MWIR: 3 to 5 microns) or longwave infrared (LWIR: 8 to 12 microns), enabling the war fighter to see heat from people, buildings, or vehicles.

Traditionally, EO systems have visible cameras or intensified charged-coupled-device (I2CCD) cameras also, permitting the user to see the scene in a wavelength band similar to human vision or night-vision goggles. Electro-optic systems have begun to proliferate through the military, yet the systems, as they are currently configured, are not as useful in every situation as they could be. This is the reason that designers must consider other technology that expands the wavelength bands and enhances EO imaging system capabilities.

The largest drawback of thermal imagers is their inability to see laser designators and rangefinders. The three most common lasers in the field that are invisible to the eye, emit light at 850 nanometers, 1.06 microns, and at 1.54 microns (also known as “eye-safe” lasers). It is important to note that these wavelengths may vary slightly, contingent on the lasing material used.

Click here to enlarge image

null


A camouflaged HUMVEE is patterned to blend into the environment in the visible (top) but in the SWIR the camouflage is much less effective (bottom).
Click here to enlarge image

The 1.54-micron lasers have many advantages to the military beyond being eye-safe and thereby protecting friendly soldiers from the reflected light. They are also invisible to the enemy because image-intensifier tubes cannot see them.

Currently, nearly all EO systems assume that lasers are properly aligned in the optical train and the laser spot is on the target. The laser spot is invisible to current thermal imagers employed in these EO systems. In addition, the optical alignment can be easily compromised in the heat of battle. The potential for misalignment is especially high on long-range targets where alignment is critical. Giving the operator the capability to image the actual laser spot on the correct target is critically important to minimize collateral damage or “friendly-fire” incidents.

An indium gallium arsenide (InGaAs) shortwave-infrared (SWIR) camera resolves this problem by expanding the EO system’s range to include these common laser wavelengths. These commercially available cameras have sensitivity ranges from 900 to 1700 nanometers with newer versions that extend the detection range from the visible to the near-infrared waveband regions (400 to 1700 nanometers).

The new, dual-wavelength visible/InGaAs MiniCamera from Sensors Unlimited offers added benefits for imaging operations and can be easily incorporated into the traditional EO imaging systems. The visible sensor can eliminate the need for a complementary-metal-oxide-semiconductor (CMOS) camera and the SWIR sensor can supplement the current thermal imaging system thus enabling the user to image the reflected light from currently used laser designators or laser range finders. As noted earlier, the shortwave infrared sensor can image the actual laser spot on the correct target, to help ensure that laser alignment is in place and substantially reduce the margin for error.

The option of adding only a SWIR camera is a relatively easy upgrade to an existing EO system because no custom optics are required. The SWIR sensor uses standard glass optics and can “share” the visible camera lenses. These cameras are small, compact, and as easy to operate as visible CMOS or CCD cameras. They require low power to output analog video as well 12- or 14-bit digital information to digital standards like Camera Link and RS-422.


The man pictured is standing in the middle of a dark, moonless field at night under starlight-only conditions.
Click here to enlarge image

The focal-plane arrays (FPAs) are uncooled, which means they operate at room temperature, eliminating the need for large vibration-prone sterling cycle-coolers or multistage thermoelectric coolers (TECs). Additionally, no infield NUCs (nonuniformity corrections) are necessary. The miniature SWIR cameras have no moving parts and can be installed in spaces where volume and weight is a consideration, such as helmets, mini or micro UAVs, gimballed mounts, or rifles.

The SWIR imagers are all-solid-state devices. InGaAs imagers can be hit with light many orders of magnitude beyond their saturation point for long periods of time with no detrimental effects.

There are other distinct advantages to imaging in the SWIR waveband, beyond seeing the lasers on the battlefield. Imagery in the short-wave infrared looks similar to visible imagery, making scene analysis and interpretation easier. The images from SWIR cameras show signs, roads, buildings and vegetation looking similar to visible imagery.

It is very easy to distinguish street lights and car brake lights, for example, making complex operations like driving or flying much simpler than with thermal imaging. Moreover, objects are visible in day and/or night, having the sun or only starlight illumination as the light source. The SWIR imager also works very well during the crossover points at dawn and dusk. Thermal imagers have difficulty during these times because of varying emissivities and cooling rates that cause a lack of contrast between objects in the scene. Camouflage patterns are also specifically designed to fool our eyes by minimizing the contrast on a given surface. In the short-wave IR waveband, the fabrics and paints used to camouflage objects have a different reflectivity, thus making them less effective.

Dr. Martin H. Ettenberg is director of imaging products at Sensors Unlimited Inc. in Princeton, N.J. He can be contacted at mettenberg@sensorsinc.com.


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

XPedite7574 | 5th Generation Intel® Core™ i7 Broadwell-H Processor-Based Conduction- or Air-Cooled 3U VPX-REDI Module

The XPedite7574 is a high-performance, 3U VPX-REDI, single board computer based on the 5th genera...

XCalibur1645 | Freescale Eight-Core P4080 Processor-Based Conduction-Cooled 6U VPX Module

The XCalibur1645 is a high-performance, 6U VPX, single board computer supporting Freescale QorIQ ...

XCalibur5090 | Dual Virtex-7 Based Digital Signal Processing 6U LRM FPGA with Quad 2500 MSPS DAC and 3200 MSPS ADC

The XCalibur5090 is a high-performance, reconfigurable, conduction-cooled 6U LRM module based on ...

ScanFaker DRSii - Networked Radar Simulator

High resolution radar stimulator supporting analog and LAN output. Resolution down to 1m is possi...

Body Worn Antennas

Body Worn Antennas from SWA are ideal for covert surveillance applications where the radio and an...

4G LTE Cellular Omni Concealment Antenna

The 4G LTE Cellular Omni Concealment Antenna from Southwest Antennas measures only 4.70" x 1.70" ...

Ultra-Flex Omni Antennas

The Southwest Antennas Ultra-Flex is a line of S-Band & C-Band omni antennas with a unique enviro...

S & C Dual-Band Omni Antennas

SWA Dual-Band Omni Antennas are designed to cover the S & C bands, and are available with multipl...

DNA-1553-553

Dual Channel MIL-STD-1553 interface board for Cube I/O chassis with 2 independent, dual redundant...

PowerDNR HalfRACK

Half-width 3U Gigabit Ethernet Data Acquisition and control chassis allows the installation of up...

Related Companies

TEN TECH LLC

Is a mechanical engineering consulting company headquartered in Los Angeles, CA with operations in Billerica, MA, pro...

Dspnor AS

Offers radar signal processing and distribution. The products interface to virtually any radar system in use today. T...

Curtiss-Wright Defense Solutions

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

PALMARII Dynamics AB

PALMARII Dynamics is a Swedish company incorporated in 2012 as a competence centre for specialist naval architecture ...

PELORUS NAVAL SYSTEMS Inc

Pelorus Naval Systems is a specialist naval defense engineering and support services company with headquarters in Ran...

Southwest Antennas

Southwest Antennas designs and manufactures high-performance RF & Microwave antennas and accessories designed for tod...

CORWIL Technology Corp

CORWIL Technology, the premier US based, IC assembly and test services subcontractor, offering full back-end assembly...

IndustryARC

IndustryARC primarily focuses on Cutting Edge Technologies and Newer Applications of the Market. Our Custom Research ...

United Electronic Industries Inc

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

RPMC Lasers Inc

Offers 1500 DPSS lasers, lamp lasers, fiber lasers and diode lasers. Provides, ultrafast, picosecond, nanosecond, cw ...

Webcasts

Harsh Environment Protection for Advanced Electronics and Components

This webinar will offer an opportunity to learn more about ultra-thin Parylene conformal coatings – how they are applied, applications they protect today, and the properties and benefits they offer, includin...

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:

Press Releases

CURTISS-WRIGHT AWARDED CONTRACT BY SIERRA NEVADA CORPORATION

Curtiss-Wright Corporation today announced that its Defense Solutions division has received a contract from Sierra Nevada Corporation (SNC) to supply its small form factor ...

Innovative Integration Announces the FMC-Servo

Camarillo, CA June 19, 2015, Innovative Integration, a trusted supplier of signal processing and data acquisition hardware and software solutions, today announced the FMC-S...

METADATA SUPPORT ENHANCES INDUSTRY-LEADING HD VIDEO MANAGEMENT SYSTEM FROM CURTISS-WRIGHT

Curtiss-Wright Corporation today announced that its Defense Solutions division has further enhanced its innovative VRD1 high definition (HD) video management system (VMS) w...

All Access Sponsors


Mil & Aero Magazine

August 2015
Volume 26, Issue 8
file

Download Our Apps



iPhone

iPad

Android

Follow Us On...



Newsletters

Military & Aerospace Electronics

Weekly newsletter covering technical content, breaking news and product information
SUBSCRIBE

Cyber Security

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

Defense Executive

Monthly newsletter covering business news and strategic insights for executive managers
SUBSCRIBE

Electronic Warfare

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

Embedded Computing Report

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

Unmanned Vehicles

Monthly newsletter covering news updates for designers of unmanned vehicles
SUBSCRIBE