| 摘要 |
Apparatus for altering the IR characteristics of a body (1) comprising a surface having at least two discrete areas (5a, 5b, 5c, 8, 9, 11a, 11b, 16) possessing different IR characteristics, masking means (3, 10, 15) for masking different portions of the surface, and controlling means for operating the masking means arranged such that operation of the controlling means alters the relative exposures of the two or more areas of the surface such as to impart desirable IR characteristics to an aspect of the body as detected from a remote point. In particular, an IR signalling apparatus comprising an inelastic surface (12) composed of alternating low IR emissivity elements (8) and high emissivity elements (9). The inner face of the surface (12) is bonded to a body (1) while the outer face is bonded to a polythene core (13) which is divided into individual nitrogen-filled chambers (14). Masking means (15) in the form of parallel inelastic strips (16) are bonded to the outer face of the core (13). These strips (16) have an inner side which is composed of low IR emissivity material (16a) and an outer side composed of medium to low IR emissivity material (16b) also coloured in the visible. The apparatus is mounted on a body (1) for signalling to a remote detector (6). The masking means (15) is located above the surface (12) so as to achieve a desired overall IR characteristic, and relative motion is introduced between the two at a known frequency. The detector (6) is filtered at this frequency.
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