Schott SF 18, 365nm - 2325nm
USER
2 1
SQRT(1+B1*wvl^2/(wvl^2-C1)+B2*wvl^2/(wvl^2-C2)+B3*wvl^2/(wvl^2-C3))
0
B1	1.56441436E+00;
B2	2.91413580E-01;
B3	9.60307888E-01;
C1	1.21863935E-02;
C2	5.35567966E-02;
C3	1.11451201E+02;