High-Speed Midwave Infrared Cameras Enable Military Test Range Tracking System
Operating beyond the visible light spectrum, forward-looking infrared (FLIR) cameras use a thermographic imager (camera) that senses infrared radiation, or heat signatures. Advanced FLIR thermal imaging systems capture and display infrared wavelengths that are radiating energy. Infrared thermography consists of three specific wavelengths, including short-wave infrared (SWIR), midwave infrared (MWIR), and long wavelength infrared (LWIR).
MWIR imaging cameras have long been the preferred solution for clear thermal imaging at distances greater than one kilometer (km) for defense, unmanned aircraft systems (UAS), counter-UAS, security, and other longrange surveillance applications. To meet these imaging requirements, advanced MWIR camera systems are commonly integrated with infrared telescopes that feature a continuous zoom (CZ) lens assembly. Developing custom cameras and CZ lenses can be costly in terms of time and resources, and it can become complicated.
In addition, MWIR imaging systems can suffer reduced system performance and reliability due to compatibility tradeoffs. This leads to efficiency losses and unnecessary complexity in the system development process and integration, procurement, manufacturing, and eventual system support.
Midwave Infrared Systems
Typically defined as the 3.0 - 5.0 μm wavelength range, a MWIR camera system consists of multiple subsystems. Moving from left to right (Figure 1), the continuous zoom optics determine the field of view (FOV), or optical magnification, to the camera. The lens collects and focuses the MWIR energy onto the focal plane array (FPA) packaged into an integrated dewar cooler assembly (IDCA). Camera electronics process the information from the IDCA into usable data or an image supporting the camera output as well as the command-and-control software.
Following design, the integration of subsystems from multiple vendors can present additional challenges. Infrared CZ lenses are extremely complex and require precision alignment in five axes. This requires significant capital expenditure, potentially adding up to more than $400,000 through the purchasing of equipment such as collimators, temperature chambers, black bodies, modulation transfer function (MTF) test equipment, and vibration testing stations. Highly specialized test technicians and engineers then must be trained and funded to support the integration. Software protocols can also differ for each subsystem driving complication for both integration and support.
Once integrated solutions are in the field, support and service can also be difficult to execute. Generally, technical support to the customer must be handled by the integrator in conjunction with the IDCA and lens subsystem vendors to achieve satisfactory resolutions. A unit returned for service or repair must also be processed and dispositioned by the integrator before the relevant subsystem can be returned to the vendor for additional processing. This adds time and expenditure.
Application Examples: Automatic Target ID, Precise Targeting and Test Range
Based in Cagliari (Italy), Nurjana Technologies provides mission-critical engineering services and system integration for the aerospace and defense industries. The company has been successful in offering unique electro-optical systems for government test labs and military test range applications.
The latest addition to the company’s product portfolio is the NEOS (Nurjana Electro-Optical System), a complete hardware- and software-based system for real time optical tracking in longrange, high-precision measurement applications. The system was designed to fuse data from multiple sensors, including optical payload, telemetry, radar, and ranging measurement data. The optical payload is customized and composed of a visible-light tracking camera, a radiometric thermal imaging camera, a visible-light measurement camera, and a high-speed camera. Near real-time data fusion and computer vision are leveraged for detecting and tracking targets in the most demanding scenarios.
“A high-resolution thermal camera was essential for this type of application,” says Davide Piras, System Engineer at Nurjana Technologies. “A thermal camera does not only allow us to see targets in dark or adverse weather conditions, like cloudy weather or rain, but we were also looking for a highspeed, high-resolution thermal imaging solution that enabled us to see smaller objects at very long range.”
The company was already familiar with Teledyne FLIR thermal imaging cameras and based on the team’s previous experiences on test ranges all over the world, it was a natural decision to involve FLIR in the development of the NEOS product as well. The FLIR RS8500 high-speed midwave infrared (MWIR) camera proved to be the best solution for the application.
“We looked extensively at different camera types, but the image quality, high-speed features, and many different integration and connection options of the FLIR RS8500 made it the ideal solution to improve target visibility within NEOS,” Piras explains. Nurjana Technologies demonstrated the NEOS system and FLIR RS8500 at select firing test range facilities and centers of excellence for experimentation in the NATO domain. The demonstrations not only showed the FLIR camera’s impressive clarity and image quality but also its superiority to visual cameras in cloudy conditions.
“Thanks to the FLIR camera, we were able to overcome adverse weather conditions, improve target visibility with a clear identification of the target’s thermal signature, and see the target in almost any weather condition,” says Piras. “We are glad to have the chance to integrate such an extremely powerful camera into our solution.”
Nurjana Technologies also valued the straightforward integration using a GenICam protocol, which makes it easier for integrators and end customers to control the camera system over Linux. The NEOS system with the integrated FLIR camera is customizable and available for a wide range of automatic detection, recognition, identification and tracking applications, including bomb scoring, splash detection, impact point prediction, and accurate missile, projectile and rocket tracking. A downsized version of NEOS is available for civilian applications within the domains of critical infrastructure protection and monitoring.
Since the FLIR RS8500 is a radiometric infrared camera and the continuous metric zoom lens provides instantaneous focal length and position information on every frame, the system can also be used to capture target data, including signature and apparent temperature measurements.
Midwave infrared cameras and continuous zoom optics are the preferred solution for providing clear thermal image detail over a range of distances. MWIR imaging systems have made swift advancements to provide high-resolution thermal imaging detection and tracking in a variety of mil/aero and civilian applications. Improvements in MWIR detectors and continuous zoom optics are converging to allow new and exciting SWaP optimized MWIR integrated solutions. However, the advancements in technology add complexity to fabrication, assembly, and testing to meet performance specifications. Design teams face significant challenges to refine design processes and streamline design-to-manufacturing protocols to meet new applications needs. Working with a vertically integrated solution provider can result in a shorter design cycle, streamlined procurement process, and increased ability to create reliable solutions.
This article was written by David Cullin, Vice President Research, Technology and Product Development, Teledyne FLIR. For more information, visit here .