$v$	Fiber running speed in the spinline (m/s)
$v_0$	Feeding speed of the raw melt-spun fiber (m/s)
$D$	Diameter in the spinline (m)
$D_0$	Diameter of the raw melt-spun fiber (m)
$\dot{\epsilon }$	Strain rate (s−1)
$x$	Distance from the nozzle (mm)
$t\left(x\right)$	Residence time (s)
$A$	Absorbances
$K$	Absorption coefficient (m−1)
$T$	Transmittance
$x_t$	Thickness of the film (m)
$A_0$	Effect of the surface reflection
$\Delta n$	Birefringence
$R$	Optical retardation (nm)
$d$	Fiber diameter (μm)