As an electrical engineer, I am an amateur on optics, but I really could use some help. I am making a lens of PMMA, 2D. To 'convert' a rotary movement into a sweep. The lens needs to be 120mm long, with its focus at a max distance of 80mm the light traveling out of the lens needs to be parallel with the main axis of the lens. To clarify, I’ve uploaded an image. Could someone help me calculating the curvature of the lens?