Positioned within the casing 52 is a main optical housing 56, a detector dewar 58, a scanner 60, {TAIL ~ an imager housing assembly} 62, switching motor mechanism 64 and {HEAD ~ the reflecting assembly switching assembly} 66 
Positioned within the casing 52 is a main optical housing 56 , a detector dewar 58 , a scanner 60 , { TAIL ~ an imager housing assembly } 62 , switching motor mechanism 64 and { HEAD ~ the reflecting assembly switching assembly } 66
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