Figure 1-9. Low Panoramic Photo.
d. IR imagery is next in resolution to conventional photography.
An IR
system is a passive sensor which detects emitted and reflected thermal
radiation coming from the terrain and objects on the terrain.
However,
emitted IR energy is rapidly reduced by the heat absorbing characteristics
of rain, snow, clouds, foliage, and hail.
There are also periods during
daylight that false signals will be imaged.
To achieve the maximum
capability, the IR system must operate at low altitudes. Its scan coverage
is limited to the area directly below and adjacent to the flight path of the
aircraft; therefore, it is normally used only for point, linear, or small
area targets. Since this sensor is passive, in that it does not depend upon
detecting the reflection of transmitted energy as does radar, it is
impossible to jam, but it may be deceived by the enemy's deliberate use of
heat-producing devices. (Figures 1-10 and 1-11).
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