In the wavelength range 200 - 3000 nm the transmittance and reflection of initial and implanted with high dose (D₁=5·10¹⁶ and D₂=1·10¹⁷ cm^-2) of iron ions thin (40 μm) films of polyimide were investigated. The calculated projected range of the implanted ions did not exceed 100 nm. Structural characterization of the implanted films showed that the roughness of the initial film during implantation varies in the range from 2 to 16 nm, and the modified layer contains up to 0.5 at% iron. The integral transmittance decreases by more than a factor of three upon implantation, and the integral reflectance has a non-monotonic dependence, showing an increase of 2.4 and 1.5 times at dose D₁ = 5∙10¹⁶ cm^-2 and light incident on the implanted and non-implanted sides, respectively, and decrease to the reflection value of the original film irrespective of the incident side at the dose D₂ = 1.25∙10¹⁷ cm^-2, caused by carbonisation of the ner-surface film layer and formation of iron inclusions in it. The absence of reflection bands characteristic of the initial film in the ultraviolet region (λ₁ = 247 and λ₂ = 307 nm) when light falls on the implanted surface and their presence and displacement into the shortwave region by ∆λ₁=2 and ∆λ₂=3 nm when reflected by the non-implanted side, due to the restructuring of the supramolecular structure of the polymer far beyond the ion projected range and relaxation of surface stresses on the opposite side of  the film during implantation.