wavelength   index    wavelength   wavenumber   ang frequency          speed
in vacuum  of refr.   in glass     in glass      in glass            in glass
 (nm)                   (nm)         (rad/m)        (rad/s)            (m/s)
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                                             7                 15                  8
 500   1.5214   328.6446694  1.911847626 x 10  3.767303135 x 10    1.970503865 x 10


                                             7                 15                  8
 505   1.5211   331.9965814  1.892545183 x 10  3.730003104 x 10    1.970892499 x 10


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