When z_low is set to anything other than 0, the reflectance values don't make sense

[victoriahwang89]

There is a bug when z_low is not set to 0. For example, setting z_low to 0.1 um for a sample thickness of 50 um gives a 100% reflectances, whereas setting z_low to 0 um gives a reflectance of 70%. We have no reason to believe, however, that this bug will affect calculations that assume a z_low of 0.