5
1.0
1.6236565 0.0 50.00 1.0
1.657624 3.0 -100.00 1.0
1.0 2.0 25.00 1.0
1.48779356 3.0 27.00 1.0
1.0 2.0 -105.00 1.0


at (450/500/550/600/650)
NF2: 1.6388446/1.629930/1.6236565/1.619016/1.615448
KZFSN5: 1.672092/1.663660/1.657624/1.653101/1.649587
N-KF51A: 1.4926672/1.489867/1.48779356/1.48620/1.48493748

NF2:
C1 = 1.39757037; C2 = 0.00995906143; C3 = 0.159201403; C4 = 0.0546931752; C5 = 1.2686543; C6 = 119.248346

KZFSN5:
C1 = 1.47727858; C2 = 0.00975488335; C3 = 0.191686941; C4 = 0.0450495404; C5 = 0.897333608; C6 = 67.8786495

N-KF51A:
C1 = 0.971247817; C2 = 0.00472301995; C3 = 0.216901417; C4 = 0.0153575612; C5 = 0.904651666; C6 = 168.68133

n^2 - 1 = C1*x^2/(x^2 - C2) + C3*x^2/(x^2 - C4) + C5*x^2/(x^2 - C6) 
where x is the wavelength in microns, and the C constants are as above

def nfunc(lam):
  n2m1 = C1*lam*lam/(lam*lam-C2)
  n2m1 += C3*lam*lam/(lam*lam-C4)
  n2m1 += C5*lam*lam/(lam*lam-C6)
  n = math.sqrt(n2m1+1.0)
  return n