A midwave hand-held two-band infrared imager has been developed to measure the emissivity image of aircraft surfaces. Its purpose is to detect changes in IR surface properties of aircraft coatings. This system has been designed for use in field environments such as an aircraft carrier hangaer and other maintenance facilities where the object being measured is static and cooperative but the environment is not well controlled. It thus requires real time monitoring of the environmental reflections off the surface and algorithms to correct for this reflected radiance. This correction for the environment using calibrated paint patchescoupons is a novel feature of this new technology. The camera output includes two band radiance images, temperature images, and the novel emissivity imagery for which eCAM has been named. It has long been known that two-band infrared measurements can be used to optically determine temperature and solid angle-emissivity products of a greybody surface. This measurement becomes considerably more complex when the environmental foreground reflecting off the surface is a significant part of the infrared-based measurement. This paper will describes the theory behind making foreground- reflection- corrected emissivity image measurements. It will includes material on the calibration of the IR sensor and its specially designed optics and the custom emissivity calibrated patches that are an integral part of the design. It will also shows laboratory test results and field test data taken in an aircraft maintenance hangar.
The advent of missile seekers with dual-spectrum (simultaneous radar frequency/millimeter wave (RF/MMW) and optical) tracking systems has led to a requirement to develop the simulation tools necessary to test these systems. One of the most important tools for testing missile hardware is a full-seeker hardware-in-the-loop (HWIL) simulation. There is a substantial effort to improve the ability to generate and project RF/MMW imagery and optical imagery separately to systems under test. However, the dynamic real-time generation and simultaneous projection of realistic dual-band imagery to these seekers continues to be a major technological challenge. The purpose of this paper is to discuss methods and issues inherent in dual-spectrum seeker HWIL simulation.
The optical aspects of infrared projectors designed specifically for application within real-time hardware-in-the-loop simulation systems are examined. Particular attention is paid to the form of the spatial frequency transfer function and thereby to the factors that affect the spatial resolution within the composite optical system defined by the infrared projector and the imaging unit under test. Expressions are also developed allowing the calculation of both the output signal radiance and effective blackbody temperature for reflective infrared projectors, thus enabling the direct comparison of the radiant output capabilities of projectors of the emissive and reflective types.