GRAHAM WARWICK / WASHINGTON DC
Harris-led team demonstrates sensor's ability to see through foliage or camouflage under DARPA-funded programme
US development of laser imaging sensors could deny an enemy the sanctuary of concealment. A Harris-led team has demonstrated the identification of targets under naturaland camouflage cover using an airborne laser radar (ladar), under the US Defense Advanced Projects Agency's Jigsaw programme. The concept uses a flash ladar to produce three-dimensional images of armoured vehicles concealed by foliage or camouflage.
Under another DARPA programme, Northrop Grumman and Raytheon are to demonstrate airborne interferometric synthetic-aperture ladars capable of producing high-resolution three-dimensional imagery at long ranges. Bothwere awarded competitive contracts last month for the Synthetic-Aperture Ladar for Tactical Imaging (SALTI) programme.
Jigsaw is part of the DARPA-led Future Combat Systems (FCS) US Army re-equipment programme. The sensor produces a 3D hologram of targets under cover, exploiting the laser's ability to "poke through" gaps in netting and foliage. The multiple returns from a flash ladar are used to separate camouflage and leaves from targets.
The demonstration at Redstone Arsenal, Alabama, used a large-scale prototype on board a Bell UH-1N helicopter, but Jigsaw is intended to be carried by unmanned platforms including the small organic air vehicle under development as part of the FCS and the US Army's higher-altitude tactical unmanned air vehicle.
The 51-month SALTI programme aims to demonstrate the ladar equivalent of an active-array radar - a multi-channel, multi-colour system made up of fibre-laser transmit/receive modules, producing a mosaic image using synthetic-aperture processing.
The goal is to combine the long-range day/night capability of a high-altitude X-band synthetic-aperture radar with the 3D imaging ability of a ladar and the ease of interpretation of electro-optical images. DARPA believes a ladar could provide twice the range of a radar with one-sixth the aperture size.
The demonstration will involve high-altitude flight testing of the coherent laser sensor, with ground processing of the data. The system will process optical phase and range-Doppler data into synthetic-aperture imagery. In an alternative mode, DARPA says, the ladar will accomplish highly accurate ground moving-target indication (GMTI).
DARPA has demonstrated the ability to penetrate foliage and detect stationary targets using an airborne ultra-wideband VHF/UHF synthetic-aperture radar.
The follow-on Forest programme aims to combine foliage-penetration GMTI radar with electronic support measures to detect and track targets moving under the cover of trees.
Source: Flight International
