Question

What is the IFOV for a collimating lens of diameter 100mm, the distance between the collimating lens and combiner glass=50mm, the distance between pilot eyes and combiner glass=400mm?

(a) 25.0°

(b) 12.6°

(c) 28.0°

(d) 14.2°

Answer 1

The correct choice is (b) 12.6°

To elaborate: D=100mm, L=50+400 =450mm (Since L is the distance from the observer to the collimating lens)

IFOV = 2 x tan^-1 (D/2L) =2 x tan^-1( 100/2×450) = 12.6803° ≈ 12.6°