You have a rod of GRIN material and would like to make a lens that has a pitch of 0.23. The rod had a radius of 1.0 mm with a quadratic radial change in index. The maximum refractive index is 1.6 and the fractional change in index of refraction, A. is 0.05. To what length should you cut the rod to get a single lens of 0.23 pitch? Express your answer in mm to two decimal points.