Reflectivity measurements in the far-infrared region irrefutably show the consequence of the Peierls instability in the blue bronze

K_{0.3}

{MoO}_{3}

system. At 5 K, a very strong polarization-dependent phonon spectrum is observed: At photon energies below 8 meV, a giant, nearly undamped structure dominates the whole spectrum polarized along the

b

axis. The structure, reaching reflectivity values of 97%, is assigned to the oscillation of the pinned Fröhlich charge-density-wave (CDW) (

A_{-}

) mode. Optical constants are calculated by means of the Kramers-Kronig relation. The results are compared to the predictions of mean-field theory (

m_{CDW}^{*}

λ

T_{c}^{MF}

) and to the experimental results on

K_{2}

{Pt (CN)}_{4}

{Br}_{0.3}

{\cdot 3 H}_{2}

O (KCP). No softening of the (

A_{-}

) mode or of the CDW energy-loss spectrum was observed. A midgap absorption can be related to the presence of solitons (dislocations in CDW lattice) and will be discussed with the latest results on the non-Ohmic conductivity.

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