By John Rhea
WASHINGTON - Sensor designers at Hughes Aircraft are readying a fourth-generation sensor package spanning the entire visual and infrared spectra, even while they pitch their third-generation forward looking infrared (FLIR) technology based on indium-antimonide for what they hope eventually will equip the U.S. Navy`s entire fleet of F/A-18 Hornet jet fighter-bombers.
The first and second generations of FLIRs used mercury-cadmium-telluride (HgCdTe) sensors to cover the far infrared portion of the spectrum (8-12 and 8-10.5 microns, respectively) The proposed fourth generation will also employ HgCdTe sensors plus advanced signal processing techniques to cover the entire span of visual (0.4-0.7 micron), near and mid infrared (up to 5 microns) and far infrared. The third generation covers the 0.5-5 micron region.
All these sensors are cryogenically cooled. Work is being done at the Hughes Sensors and Communications Systems segment in El Segundo, Calif.
The third-generation FLIRs, moreover, are being developed under an open system pre-planned product improvement concept so that they can readily accommodate the fourth generation sensors when they become available, explains Arsian Safyurtlu, director of business development at Hughes Sensors and Communications.
Safyurtlu and his colleagues described the evolution of FLIRs at the annual Hughes technology briefing last month in Washington.
He notes that the first generation employed its rotating scan mirror with 60 to 180 elements, each about 40 microns in size. The second generation, which is particularly popular for Army night vision applications, retains the rotating scan mirror, but has 1,900 elements at a feature size of about 30 microns.
The third generation employs the staring approach, reduces the detectors to 20 microns, and uses 307,000 elements. It produces frames of about 15 milliseconds each, essentially cutting the wavelength in half, and the signal processor integrates the time delays to improve resolution.
The net result is a high-resolution passive sensor able to penetrate virtually any adverse weather condition except clouds with twice the range of the second generation and four times the range of the first generation.
Hughes engineers earlier this year delivered the first third-generation sensor package to Boeing Co. in Seattle, for the AAQ-16 subsystem of the V-22 Osprey tiltrotor aircraft. Hughes has two other customers involved with the U.S. Navy Los-Angeles-class attack submarines (SSN-688) plus the Tier 2+ Global Hawk unmanned aerial vehicle.
Hughes officials are proposing the upgradable third-generation FLIRs initially for the Navy F/A-18 E and F jet aircraft, but envision retrofitting them eventually into the C and D models.
The fourth-generation FLIRs are being groomed for infrared search and track applications in Global Hawk and the Navy Northrop Grumman E-2C radar and early warning turboprop.
Safyurtlu explains that the supporting electronics are also being upgraded with digital signal processors capable of taking "hyperspectral slices" of targeting information to achieve higher resolution. And, since the generations are evolving one to another, he maintains this approach can use more non-developmental-item equipment, thus reducing life-cycle costs.
In a demonstration of its third-generation FLIR, Hughes Aircraft experts took this picture of the site of the 1915 Panama-Pacific Exposition site, which today is a park in San Francisco, with their Terminator I pod mounted in the company`s A-3 aircraft.
