12 May 2016 Design of thin-film filters for resolution improvements in filter-array based spectrometers using DSP
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Miniature spectrometers have been widely developed in various academic and industrial applications such as bio-medical, chemical and environmental engineering. As a family of spectrometers, optical filter-array based spectrometers fabricated using CMOS or Nano technology provide miniaturization, superior portability and cost effectiveness. In filterarray based spectrometers, the resolution which represents the ability how closely resolve two neighboring spectra, depends on the number of filters and the characteristics of the transmission functions (TFs) of the filters. In practice, due to the small-size and low-cost fabrication, the number of filters is limited and the shape of the TF of each filter is nonideal. As a development of modern digital signal processing (DSP), the spectrometers are equipped with DSP algorithms not only to alleviate distortions due to unexpected noise or interferences among filters but also reconstruct the original signal spectrum. For a high-resolution spectrum reconstruction by the DSP, the TFs of the filters need to be sufficiently uncorrelated with each other. In this paper, we present a design of optical thin-film filters which have the uncorrelated TFs. Each filter consists of multiple layers of high- and low-refractive index materials deposited on a substrate. The proposed design helps the DSP algorithm to improve resolution with a small number of filters. We demonstrate that a resolution of 5 nm within a range from 500 nm to 1100 nm can be achieved with only 64 filters.
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Woong-Bi Lee, Woong-Bi Lee, Cheolsun Kim, Cheolsun Kim, Gun Wu Ju, Gun Wu Ju, Yong Tak Lee, Yong Tak Lee, Heung-No Lee, Heung-No Lee, } "Design of thin-film filters for resolution improvements in filter-array based spectrometers using DSP", Proc. SPIE 9855, Next-Generation Spectroscopic Technologies IX, 98550Q (12 May 2016); doi: 10.1117/12.2228441; https://doi.org/10.1117/12.2228441

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