Two thin convex lenses of focal lengths
f1 and
f2 are separated by a horizontal distance
d (where
d>f1,d>f2), and their centre are displaced by a vertical separation
Δ as shown in figure. Taking the origin of coordinates,
O, at the centre of the first lens, the
x and
y coordinates of the focal point of this lens system, for a parallel beam of rays coming from the left, are given by