Infrared Imaging Systems

The horizon of infrared (IR) technology extends far beyond the stage of simple curiosity. Given the recent coyerage ofthe GulfWar, not only do the actual users of these systems know of their "smartness" potential, even the general public caught a glimpse ofthat potential. Interestingly, the manifestation ofthe IR portion ofthe spectrum is limited by physiology, not by physics. Thus, to see the unseen, the JR signal is routedthroughcomplicated optics, detectors, electronics, and displays. Finally, our eyes have to make sense ofthe displayed infonnation. To what extent the IR imaging systems are compatible with our various military and commercial needs is thus an important issue to be ascertained. The 20 papers in this special section on "Infrared ImagingSystems," summarizingthe works of 44 authors, are fortuitously categorized into four subareas: JR systems, JR systems characteristics and applications, JR systems evaluation, and JR systems modeling. The firstthree papers deal with JR systems in general. In the very first paper, Norton conducts an extensive review of various JR detector materials suitable for second-generation JR image sensors. This is followed by a paper by Stauffer and Cole who discuss the design of JR scene projectors using thermal-emitter arrays. Arrays fabricated as silicon microstructures are shown by the authors to eliminate problems such as thermal crosstalk and slow response time. In the third paper, Parsons and Tseng describe the development of a thennal monitoring system for aircraft cargo bay fire safety. Because of its reliability and immunity to false alarm, the system meets the new FAA regulations. The next three papers deal with JR systems characteristics. Inthe flrstpaper, Sanders, Currin, and Halford present the visual threshold criteria for the psychophysical JR imaging systems tasks on the basis of an experiment involving a rather large set of stimuli. In the second paper, Nelson, Johnson, and Lomheim discuss the general noise processes in hybrid IR focaiplane arrays. Besides considering the standard temporal noise sources, the authors provide an extensive review of various mechanisms that result in "pattern" noise. Next, Farmer presents an analysisofemissivityeffects ontargetdetectionthroughsmokes/ obscurants. The results show that the smoke screen requirement is affected significantly by ratio changes in target-to-background emissivity. The next five papers deal with several important applications and issues pertaining to those applications. Shushan, Meninberg, Levy, and Kopeika present the results of several experiments that relate weather parameters such as aerosolMTF, wind, solarfiux, humidity, and dew with the prediction of thermal image quality. In the next paper, Shepard, Sass, and Imirowicz use a line-byline image acquisition technique and a scanning imaging radiometerforenhancingtemporal resolution. Then, Sanders, Driggers, Halford, and Griffin present results of experiments using frequency-modulated reticles that encode pixellocation by light modulation. The technique demonstrated can be used to multiplex multiple pixels onto a fewer number of detectors. This is followed by a paper in which Althouse and Chang use a muliispectral thermal imager for chemical vapor detection applications. Finally, Schildwachter and Boreman present the characteristics of a Scophony-configuration JR scene projector. The third subarea of this special section concerns yet another important aspect of JR technology, namely, the development oftools forthe characterization ofJR imaging systems. In the first paper, Hubbs, Dole, Gramer, and Arrington use the Mosaic Array Test System for characterizing the radiation effects of JR focal plane arrays. Next, Cathcart and Sheffer show how three-dimensional geometric models with geographic databases, JR predictionmodels, and computergraphics canbe used to generate