The communication deals with some features of the diffraction and interference effects in the optical spectra of nuclear filters (NF) modified by silver nanostructures (Ag-NS) deposited on the NF surface by the aerosol dry deposition [1]. Whose origin could be connected with the interaction between photons and surface plasmon polaritons as well as localized plasmons. NF samples on the base of PolyethyleneTerephthalate (PET) films with a thickness of 10 μm had numerous micropores with an effective diameter of 0.2 μm after the Xe-ion irradiation followed by chemical treatment in the alkali water solutions. The surface density of microspores was ~3·108 cm-2. Ag-NS have been formed during the passage of the spray of silver nano-/microparticles through the NF micropores.     Three types of Ag-NS have been discovered through studies by the scanning electron microscopy (SEM) and the atomic force microscopy (AFM) [1]: i) islet films in the form of the separate silver nano- and microparticles and their individual clusters distributed over the NF surface were observed at initial stages of the deposition process; ii) a set of Ag-NS, resulting from the clogging of the NF micropores by silver particles were recorded at the intermediate stages of the deposition process; iii) at the end of the deposition process the porous silver film appeared on the NF surface.     The NF modification by Ag-NS resulted in the following changes in the optical spectra: i) multidirectional shifts of the interference pattern; ii) the change of the spectral shape of the far edge of the light scattering strip, due to the Ag-NS contribution; iii) the effects of "enlightenment" associated with the increase in the intensity of the NF optical transmittance in the near IR-region of the spectrum after the Ag-coatings application.     It was found that observed optical effects are mostly pronounced in the NF modified by Ag-NS of the second type. A possible reason of these effects may be the interaction between Ag plasmons localized in the NF micropores with diffraction and interferometric modes expanding in the NF volume (the so-called “light localization” [2]). Evaluating the deposited Ag film thickness on the base of the measured shift of the interference pattern, it can be stated that it is in good agreement with the results of the AFM measurements. It was also found that calculated values of the Ag-NS refractive index (~10-3) were much lower than in the case of the bulk silver (~2.4 in the near IR spectral region), which is in agreement with literature data [3].   The present study has been partially supported by the Russian Foundation of Basic Research (Project No. 14-07-00025).