Table 1.

Coefficients ($\beta$) of the assumed absorption spectrum recovered for each base layer choice and top layer thickness. As the spectrum being fit is the reference data for bottom layer absorption, $\beta =1$ indicates perfect recovery.

Base layer	$90\text{-}\mu \mathrm{m}$ top layer $\beta$	$300\text{-}\mu \mathrm{m}$ top layer $\beta$
1	1.04	1.00
2	0.94	0.99
3	0.92	0.95