Mark A. Venables

Design and fabrication progress in BAe's high-complexity resistor-array IR scene projector devices

Developments are described in the design and manufacture of full 512 X 512 infra-red scene projector (IRSP) systems, as well as in a high complexity demonstrator program to realize 1024 X 1024 complexity. Design aspects include choice of drive circuit, the suspended resistor pixel design factors, the choice of busbar configurations, and the optimization of emissivity coatings. Design of the peripheral drive systems for the 512 system is outlined, and progress on manufacture reported. Development plans for the provision of suitable high complexity computer scene generation is outlined.

Practical application of a 1:1 mapped NUC system for IRSP arrays

The 1:1 projector:NUC sensor mapping system reported in 1999 showed that small sub-arrays of projector pixels could be corrected to a fine degree. This system has been developed to join together sub-arrays and complete the NUC operation on a whole resistor array in service. Outline detail is given of the general principle of the correction, the methods involved, covering merging of sub-arrays, strategies for dead pixels and the application of corrections in real time, together with comment on the measurement time and performance against specification.

Output accuracy and resolution limitations in resistor array infrared scene projection systems

There is a growing demand for high complexity infra-red scene projector devices with improved output accuracy and resolution. Sources of inaccuracies and limitations to resolution are discussed for both projector-alone and projector-in-simulation situations. Using experience of existing system design and performance, an attempt has been made to assign realistic percentage inaccuracy figures to the various relevant effects so that a perspective can be gained of their relative importance. Schemes for improving the accuracy and resolution performance are considered, both in terms of system techniques and array device design. A revised order of relative importance is presented to assess the residual accuracy perspective after application of practicable corrective measures. We conclude that the absolute accuracy to which a unit- under-tests collected input can be relied upon under all conditions is only 90 - 95%. However, it is essential to cater for a much finer output resolution than would be deciduate by the absolute accuracy figure, although it seems doubtful that the requirements of 12 bit resolution could be obtained except in very restricted simulation/scene conditions.

Refinements in practical accuracy factors for resistor-array IR scene projectors

We describe incremental improvements in measurement, understanding and control of sensor-perceived scene accuracy factors for BAe resistor-array IR scene projector devices by means of system and device design, analysis and measurement methodology. Progress has been made in the areas of fill- factor measurement, aliasing effects, dead pixel statistics, image spreading, the design of non-uniformity correction (NUC) systems, busbar robbing, heatsink effects and noise sources.

Practical accuracy factors in resistor-array infrared scene projector systems

This is the second in a series of papers describing an on- going investigation into the detailed performance of our resistor array infra-red scene projector devices and systems. The purpose is to extract understanding and information which will enable validation of simulations involving the systems, and design compromises to be resolved. Following last years conclusions, the importance of Non Uniformity Correction is reinforced and the concept of Local Step Error and its importance is developed and investigated practically. A test methodology is developed, and the first steps in practical measurements are reported.

Developments in the use and design of a suspended resistor IR scene projector technology

This paper describes two aspects of work carried out at British Aerospace on a family of suspended resistor infrared scene generators intended as sources for exercising infrared seeker systems in simulation environments. In the first aspect, a 256 X 256 system has matured and entered service with hardware-in-the-loop (HWIL) simulation facilities. This system, designated TPS4 (for thermal picture synthesizer) has performance suitable for air target tracking studies, and certain aspects of its characteristics in use are described. In the second aspect, research work has been carried out on the extension of the system performance to enable the representation of higher temperature targets, such as are required for countermeasures work. These improved devices are designated TPS5, and aspects of their rationale, design, and evaluation are described. Prototype arrays suitable for eventual systems of complexity 512 X 512 and beyond have been tested.

Design and fabrication concepts for a 1024 x 1024-pixel IR scene projector array

We are currently undertaking a design and development phase for the 1024 X 1024 complexity level of infra-red scene projectors based on the emitter resistor array principle. Our approach is based as for previous complexities, on commercially available CMOS with the addition of a custom suspended resistor pixel technology applied monolithically in our own facility. We have adopted the philosophy of continuing to develop the emitter pixel technology, whilst investigating CMOS design concepts, but delaying the detail- design and procurement of the CMOS until a firm commitment to build emerges, so as to allow maximum progress in the CMOS technologies available.

Developments in the design and performance of IR scene projector devices at BAE Systems

The status of development of resistor-array infra-red scene projector devices at BAE SYSTEMS is that two variants of a 512 X 512 array have each been brought to a second development stage, whilst work on higher complexity arrays is slow but purposeful. In this paper we describe the latest features of the 512 arrays, exhibiting on the one hand high fidelity performance through a ballast-load configuration, and on the other hand very high apparent temperature output, coupled with high speed performance. For higher complexity arrays we describe some of the system philosophy and preliminary design work.

Nonuniformity correction of resistor arrays with a precision projector/sensor mapping method

We present a description of a new non-uniformity correction system for infra-red resistor arrays which has been designed to produce the maximum uniformity of output from neighbor pixels achievable, with a special emphasis on performance at low (ambient) output radiance levels. The system is based on a precision 1:1 mapping between the sensor and projector pixels, and utilizes an all-on approach for projector pixel illumination. The philosophy for system choices is presented, together with analyses and measurements. The system hardware is outlined, and measurements are presented from the system in use showing that at ambient levels, uniformity of better than 100 mK can be achieved between neighbor pixels. This corresponds to a uniformity deviation of some 0.35%.

Update on BAe resistor-array design and development

We describe the status of various aspects of BAe resistor array infra-red scene projector systems for hardware-in-the- loop testing. The aspects covered include subsystem development on current 512 X 512 systems; electronic data handling and driver systems, optical projection collimators, heatsink, cooling and environmental gas control systems. Design aspects are sketched for the progression from existing demonstrator arrays of up to 1024 X 1024 into complete systems.