commonly referred to as FLIR (forward looking 

 infrared) sensors in military airborne recon- 

 naisance. 



Photographic film can be made sensitive to near-IR energy 

 (i.e., less than 1 \i) , and in a common reconnaisance and resources assess- 

 ment application can provide "false color" images that reveal factors 

 not apparent in visible-light pictures, LWIR observations are only pos- 

 sible with sophisticated electronic systems. 



The arsenal of available optical detection and surveil- 

 lance systems may be listed in ascending order of sophistication (and, 

 therefore, cost): 



• The human eye, directly and as aided by optical 

 systems such as binoculars and telescopes. 



• Electronically augmented viewing systems, such 



as the "starlight scopes" that came into prominence 

 during the Southeast Asia conflict; these allow the 

 extension of the visual image into the near IR part 

 of the spectrum. 



• Film cameras, including the use of special filters 

 and false-color IR; these may be "single-shot" 

 framing cameras or moving-film mapping/ reconnaissance 

 cameras that provide a strip chart of the area 

 overflown by an aircraft. 



3 



• Low-light-level television systems (L TV), usually 



sensitive to visible and near-IR wavelengths and 

 embodying an electronic image intensifier (i.^., 

 light amplifier). This technology has progressed 

 rapidly in recent years to the point that relatively 

 clear images of a scene illuminated only by an 

 overcast, moonless sky can be obtained. 



• FLIR imaging systems (operating in the LWIR), pro- 

 viding a thermal "map," or picture, with resolution 

 comparable to the best TV systems, which may be 

 viewed on a screen or recorded on tape or film. 

 These systems are not dependent on illumination and 

 can reveal surface characteristic differences dra- 

 matically (as in the detection of oil slicks on the 

 water surface). Since even minute temperature 



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