ANALYTICAL 4D INFRARED TOMOGRAPHY USING AN INSB FOCAL-PLANE ARRAY SENSOR .2. 4D INFRARED TOMOGRAPHY (MULTIWAVELENGTH APPROACH)

A focal plane array InSb image detector has been used for noninvasive spectroscopic infrared tomography of visually turbid polymer bodies, T omographic images from a rotating sample, illuminated by infrared ligh t, were taken under distinct, equidistant angular views. Several IR wa velengths were used simultaneously for illumination. This provided for each analyzed sample a four-dimensional data set consisting of three geometric dimensions (x, y, z) and the wavelength axis (lambda). Conce aled or secret parts inside rite turbid hollow polymer body were visua lized by three-dimensional numerical computer-assisted tomographic rec onstruction using tile back-projection algorithm, IR tomography at dif ferent wavelengths provided the possibility of differentiation between distinctly absorbing materials inside a visually turbid material, The name 4D IR tomography or spectroscopic infrared tomography is propose d for this new analytical method.