Design and Fabrication of a Cost-Effective Optical Notch Filter for Improving Visual Quality

Chuen-Lin Tien,Hong-Yi Lin,Kuan-Sheng Cheng,Ching-Ying Cheng,Chun-Yu Chiang

doi:10.3390/coatings12010019

Chuen-Lin Tien, Hong-Yi Lin + Show 3 more

Open Access

https://doi.org/10.3390/coatings12010019

Copy DOI

Journal: Coatings	Publication Date: Dec 24, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Feng Chia University, Chung Shan Medical University

Abstract

This study presents a multilayer design and fabrication of an optical notch filter for enhancing visual quality. A cost-effective multilayer design of notch filter with low surface roughness and low residual stress is proposed. A 9-layer notch filter composed of SiO2 and Nb2O5 with a central wavelength of 480 nm is prepared by electron beam evaporation combined with ion-assisted deposition. The optical transmittance, residual stress, and surface morphology are measured by a UV/VIS/NIR spectrophotometer, Twyman-Green interferometer and field emission scanning electron microscopy (FE-SEM). The transmittance of the notch filter at the central wavelength is above 15%, and the average transmittance of the transmission band is about 80%. The residual stress of the notch filter is −0.235 GPa, and the root mean square surface roughness is 1.85 nm. For improving the visual quality, a good image contrast can be obtained by observing the microscopic image using the proposed notch filter.

Highlights

IntroductionOptical notch filters based on thin film coatings have many important applications
Optical notch filters based on thin film coatings have many important applications.Such filters are usually used for the transmission of some wavelengths, and blocking and/or reflection of other wavelengths
Notch filters play an important role in analog signal processing as both electronic and optical filters

Summary

Introduction

Optical notch filters based on thin film coatings have many important applications. Such filters are usually used for the transmission of some wavelengths, and blocking and/or reflection of other wavelengths. Electron beam evaporation technology has the potential for industrialized mass production and application. Electron beam evaporation can produce significantly higher deposition rates and can be widely used for optical coatings such as high purity thin film and conductive glass. Compared with other PVD processes, electron beam evaporation has a very high material utilization efficiency, thereby reducing manufacturing costs. Zhang et al [8] presented the design and production approach of an ultra-steep notch filter by ion-assisted electron-beam deposition. The research challenge is how to produce these notch filters with high reproducibility, high layer quality, low surface roughness, reasonable film stress and cost effectiveness (low manufacturing costs)

Methods

Results

Conclusion