ACTIVE IMAGING

SUMMARY

This sub-theme addresses the use of active imaging to achieve a significant improvement in the ability to detect and identify difficult targets (i.e. camouflaged, at long range and/or placed in highly cluttered environments). It is envisaged that an active system will significantly increase the probability of correct classification compared to passive systems. This sub-theme will look at concepts such as, 3D laser imaging, improvements in the efficiency of the coherent detection process, target signature profiling and chemical/biological species detection, and alternative ways of analysing data from existing sensors.

MILITARY BENEFITS

Active imaging offers benefits mainly in the area of long range target detection and identification. Laser-gated imaging gives day / night capability with potentially higher resolution than the more conventional passive IR systems. Other active techniques could be employed to extract targets from concealment by exploiting the man made properties of the target (shape and paint/exhaust characteristic signatures).

RESEARCH OBJECTIVE

Investigate tuneable narrow-linewidth laser sources for multi-species (chemical/biological) detection
Investigate polychromatic laser sources for signature recognition capabilities
Develop reduced speckle laser sources, for recognition and identification of difficult targets
Improve signal to noise and reduce signal fluctuations of coherent laser systems for improved detection and identification of difficult targets
Develop active target discrimination techniques as an adjunct to passive large area coverage systems

RESEARCH OUTLINE

This sub-theme aims to address technology areas that support various imaging systems utilising laser radiation. The planned research is detailed here for the first phase of the DTC (one to three years) and covers emerging enabling technologies and enhancements to current systems (e.g. Lidar).

The planned research will include the development and characterisation of non-linear materials for the generation of visible, near and mid-IR radiation. Engineered devices will be identified, including narrow-linewidth monochromatic sources for single species detection and broad-bandwidth sources for signature profiling.

Speckle effects arising from the illumination of rough surfaces, seriously decrease the capability of laser ranging and imaging. Speckle reduction strategies will be examined based on increasing the optical bandwidth of the active illumination. This will lead to improved target recognition and identification capabilities, with the potential for active 3D imaging.

In order to better detect and identify difficult targets, improvements in signal to noise and signal fluctuation reductions are required. It is proposed to achieve this by detecting the received speckle more efficiently using a multi-mode local oscillator.

The problem of detecting and discriminating targets from cluttered backgrounds and/or from decoys will be addressed by examining active systems as an adjunct to other passive systems. This is likely to include multi-spectral processing techniques for signature profiling; laser-induced fluorescence and speckle pattern discrimination.

CO-ORDINATION WITH EXISTING / PREVIOUS RESEARCH

The JOANNA TDP is developing technology to use laser-gated imaging to enhance long range target identification. This TDP is taking detector technology from the SWISS beacon programme. There have also been a number of trials using the Intevac sensor from the USA conducted within QinetiQ. It is felt that existing research programmes cover this particular aspect of active imaging.

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