In this paper we fabricate neutral density filter (NDF) for the visible region on the Borosilicate glass substrate at room tempreature. E-Beam coating unit is used for fabrication of Nickel thin film on the Borosilicate glass substrate under high vacuum. XRD measurement examined the amorphous growth of thin film at low thickness (t = 10 nm) while higher thickness supported crystalline growth. The Crystallite size (D) and lattice strain ( epsilon ) is decreasing with increasing the thickness. Microstructural investigation by atomic force microscope (AFM) revealed that surface roughness is decreasing with increasing of thickness i.e. From 0.018 to 0.008 nm. The decreasing of roughness prevents scattering loss in neutral density filter. Optical transmittance spectra are obtained using UV-visible spectrophotometer. Nickel 70 nm thickness is an optimum thickness to achieve high optical density (OD = 2.5) but neutrality is poor for higher thickness of filter. Hence the spectral variation of thin filters in our case 10 nm has least spectral variation (Delta OD = 0.11) for stable and durable NDF.

This paper provides the design, construction, and characterization of a neutral density filter (NDF) for the visible spectrum and investigate the thickness effect on their various properties. In this work, Nichrome single layer was designed by the Essential Macleod modelling software. The Co-evaporation ofss nickel and chromium was used to construct a filter on a glass substrate by thermal vacuum coating unit under high vacuum. Low thickness supports amorphous nature examined by XRD diffractogram. Energy-Dispersive X-ray Spectroscopy (EDAX) examinations of the thin films revealed that high thickness has slight variation in constant stoichiometry for the chosen Nickel/Chromium ratio (80:20) during co-evaporation and confirm the deposition is successfully done. Additionally, Atomic Force Microscopy (AFM) analysis revealed that surface roughness decreased from 6.034 to 2.895 in correlation with increased layer thickness. These methods made it possible to produce NDFs with optical densities ranging from 0.5 OD at 10 nm film thickness to 2.7 OD at 70 nm thickness. As a result, for steady and long-lasting NDF, the spectral fluctuation of thin filters in our case is lowest at 10 nm (Delta OD= 0.08). A good match data was found between optical transmission and absorption spectra of the designed and the deposited films. The designed NDF's applicability and effectiveness for color sorting tasks were subsequently examined, marking a promising step towards advancing optical engineering solutions in this specific application domain.

Tin doped vanadium oxide thin films were deposited on the glass substrate by thermal evaporation technique with 3%, 6%, 9% and 12% by weight of SnO2. The deposited films were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectrometer, atomic force microscopy (AFM) and UV-Vis spectroscopy. The amorphous nature of all deposited films was confirmed by the X-ray diffraction method. The elemental analysis of the films was confirmed by EDX analysis. UV-Vis spectroscopy is used for optical analysis such as optical transmission, absorption and band gap analysis of the thin films in the range 300-800 nm. The nonlinear optical parameters of the deposited thin films were estimated by empirical relations. Based on all these characterizations, the films are practical for linear and nonlinear applications. (C) 2021 Elsevier Ltd. All rights reserved.