This work presents research results of surface, including optical characteristics of poly (ethylene terephthalate) film under the influence of heavy ion radiation and following chemical etching for use as light filter. The optical density of the films and track membranes was determined in the wavelength range of 310-990 nm. Optical density measurements were carried out with gap of 50 nm. Track membrane was researched with the track diameters of 300 nm and concentration of 4·108см-1. It is determined, that the optical density of the initial film and irradiated are comparatively low in the entire researched wavelength range and does not exceed the value of 0.1. It is shown that for the track membrane in the ultraviolet region there is a sharp rise in the optical density values, at the wavelength of 650 nm to the maximum value, and the values gradually decrease in visible color and continue to decrease in the IR region.