  Polyethylene Naphthalate (PEN) plastic scintillator has been identified as
potential self-vetoing structural material in low-background physics
experiments. Scintillating components have been produced radio-pure from PEN
using injection compression molding technology. These low-background PEN
components will be used as active holders to mount the Germanium detectors in
the \legend-$200$ neutrinoless double beta decay experiment. In this paper we
present the measurement of the optical properties of these PEN components.
Thus, the emission spectrum, time constant, attenuation and bulk absorption
length as well as light output and light yield are reported. In addition, the
surface of these PEN components has been characterized and an estimation of the
surface roughness is presented. Moreover, the light output of the final
\legend-$200$ detector holders has been measured and is reported. These
measurements were used to estimate the self-vetoing efficiency of these
holders.
