Airborne imaging systems

The advent of a portable source of very high energy x-rays has opened up x-ray inspection possibilities in a wide range of environments. Applications include such fields as nuclear waste containers, bridges, nuclear and fossil power plants, surface and airborne transportation systems, space launch systems and other thick section NDT and other inspection problems that cannot be solved imaged using other NDT methods. 

Looking at the present state of marine pollution remote sensing it was outlined that basic and advanced sensors are available for an effective airborne surveillance. While the basic sensors (SLAR, IR/UV) are currently installed in nearly every platform, the advanced sensors (LFS, MWR) are only present at a few, dedicated aircraft. However this is likely to change, since several nations are at the step of defining new sensor systems in the next years. Within these system upgrades, FLIR thermal imagers with a laser illuminator will be prominent, since they offer... 

Fig. n.15 IR camera images in high-x ACRT slices from 33% start crystal grown in carbon-coated ampoule (number in brackets = cut-off wavelength of slice) (courtesy of SELEX Sensors and Airborne Systems Infrared Ltd.)... 

As with all chemically amplified resists, a major concern is, however, the latent image stabflity and the susceptibility to environmental conditions. With t-BOC deprotecdon systems, the influence of airborne nudeophilic contaminants has been recently demonstrated (23) the observadon of surface residues in a number of such materials (23, 24) may be traced back to the presence of ppb amounts of volatile bases. In the case of the acetal systems (19-21), the influence of trace bases is less pronounced, as even amine hydrochlorides are sdll sufficiendy addic to have some catatydc activity. Linewidth dianges with the interval between exposure and post exposure bake have been observed for both the t-BOC and the acetal systems. In the case of the t-BOC tystems, long intervals (several hoius) between exposure and post-e]q)osure bake will lead to a decrease of apparent sensidvity, which manifests itself as a linewidth inCTease, or, in extreme cases, as faUure to open the imaged areas. These effects are normally due to contaminadon by base traces, or, in cases where the presence of even ppb amounts of bases can be excluded, may be assumed to be the result of the same, unspecified chain terminadon (add annihilation) mechanism which is responsible for the containment of the calalytic reacdon to the immediate vicinity of the imaged resist. 

The holographic method is a relatively new imaging technique developed about three decades ago. Since then, this method has been used in the study of airborne and liquid-borne particulate systems in their real world environments [21]. In a holographic experiment, images are formed in a two-step process. In the first step, a collimated coherent light is used to illuminate the sample. A hologram is formed by the far-field diffraction patterns of all the particles in the... 

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