NOVEL DETECTORS

SUMMARY

This sub-theme addresses the development of detector technologies to provide enhanced capabilities; such as sensitivity, broader waveband coverage, and other novel detectors such as low pixel count focal plane arrays to investigate temporal signatures of targets.

MILITARY BENEFITS

The real military benefits for the use of novel detectors are numerous. The main thrust is to find more affordable solutions to the existing problems. Additionally, sensor performance in many cases is limited by resolution. If data can be extracted from sub-pixel targets using spectral or temporal information, then resolution restrictions will not be such an issue.

RESEARCH OBJECTIVE

Investigation of CMOS technology for low cost, low power consumption, high dynamic range sensors
Extraction of temporal information of targets using smart pixel arrays
Development of avalanche photodiodes capable of rapid, high sensitivity imaging and range-finding

RESEARCH OUTLINE

The aim of the research within this sub-theme is to investigate a family of detector devices. This will improve the ability of future sensing systems to operate at longer ranges and improve identification probability at lower cost than existing sensor systems.

CMOS detectors could be used in sights where man portability is important. This requires low power consumption and low weight. High dynamic range will also allow the sensors to be used in a wider range of lighting conditions than that achieved by current image-intensified sights.

Conventional imaging sensors use spatial information in order to recognise and identify a target. Sensor technologies will be investigated that are able to capture the temporal signature of a target using low pixel count focal plane arrays. By comparing the acquired signature with those in a database the target can be recognised and identified. Heterodyne techniques already established in the radio frequency domain will be used to extract the temporal data of signatures of interest. The detected optical signal is heterodyned with a local oscillator and filtered in order to reduce the bandwidth of the signal processed on the focal plane array. This will allow the circuitry to be implemented at pixel level.

Laser range receiver performance is currently limited by the post-amplifier noise. Heterodyne techniques can be used to improve the sensitivity but the receiver then becomes more complex and more costly. Devices will be studied that use avalanche techniques that are capable of single photon detection at eye-safe laser wavelengths. Such devices have the potential for uncooled operation, low power consumption and high bandwidth.

Overall the longer term plan will be to identify the current limitations of existing sensors and identify technology gaps as they emerge. Further proposals will address solutions to improve sensitivity, multi-functionality, affordability, efficiency and reliability.

CO-ORDINATION WITH EXISTING / PREVIOUS RESEARCH

QinetiQ are nearing completion of a three year CRP contract investigating some of the fundamentals of improving CMOS technology. The CMOS aspect to this sub-theme will build on the results from this work. QinetiQ have previously conducted work under the CRP into temporal frequency pattern recognition techniques. This has indicated that intensity information up to the fifth harmonic component is required for identification purposes. Finally, the APD development work will build on preliminary work conducted under a MOD-sponsored EPSRC project and a DERA Malvern supported seed-corn project.

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