{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:05:19Z","timestamp":1760148319379,"version":"build-2065373602"},"reference-count":33,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2023,4,23]],"date-time":"2023-04-23T00:00:00Z","timestamp":1682208000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003052","name":"Institute of Civil &amp; Military Technology Cooperation funded by the Defense Acquisition Program Administration and Ministry of Trade, Industry and Energy, Republic of Korea","doi-asserted-by":"publisher","award":["17-CM-DP-02"],"award-info":[{"award-number":["17-CM-DP-02"]}],"id":[{"id":"10.13039\/501100003052","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Mercury bromide (Hg2Br2) has been used to develop acousto-optic tunable filters (AOTFs) because it has several advantages, including a high refractive index, a broad optical bandwidth, and a relatively high figure of merit. Therefore, the measurement of its birefringence is a highly important factor for ensuring AOTF quality. However, for single crystals, it is difficult (at the millimeter scale) to quantify the birefringence using an ellipsometer, as this equipment is only designed to conduct measurements on thin films. In this study, a simple birefringence measurement system for Hg2Br2 was developed based on Brewster\u2019s angle at the millimeter scale. The planar distributions of the Hg2Br2 crystal along the (100), (010), and (001) planes were used in the experiments. The developed measurement system can measure the reflected light intensity of the Hg2Br2 crystal depending on the incidence angles (rotations at 0.01125\u00b0 steps) and can calculate the ordinary and extraordinary refractive indices and birefringence. The calculated birefringence of the Hg2Br2 crystal was 0.8548; this value exhibits an error of 0.64% compared with a value of 0.86 reported in the literature. The developed measurement system demonstrates the ability to be used to evaluate the quality of birefringent single crystals.<\/jats:p>","DOI":"10.3390\/s23094208","type":"journal-article","created":{"date-parts":[[2023,4,24]],"date-time":"2023-04-24T03:04:08Z","timestamp":1682305448000},"page":"4208","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Development of a Mercury Bromide Birefringence Measurement System Based on Brewster\u2019s Angle"],"prefix":"10.3390","volume":"23","author":[{"given":"Oh-Tae","family":"Kwon","sequence":"first","affiliation":[{"name":"Department of Biosystem Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6274-3649","authenticated-orcid":false,"given":"Geonwoo","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Biosystem Bio-Industrial Machinery Engineering, College of Agricultural and Life Science, Gyeongsang National University, 501 Jinju-daero, Jinju 52828, Republic of Korea"},{"name":"Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyungjin","family":"Bae","sequence":"additional","affiliation":[{"name":"Department of Biosystem Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jaeyeol","family":"Ryu","sequence":"additional","affiliation":[{"name":"Department of Space Optics R&D, Green Optics, 45, Ganri 1-gil, Cheongwon-gu, Cheongju 28126, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sikwan","family":"Woo","sequence":"additional","affiliation":[{"name":"Department of Space Optics R&D, Green Optics, 45, Ganri 1-gil, Cheongwon-gu, Cheongju 28126, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8397-9853","authenticated-orcid":false,"given":"Byoung-Kwan","family":"Cho","sequence":"additional","affiliation":[{"name":"Department of Biosystem Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea"},{"name":"Department of Smart Agricultural System, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1109","DOI":"10.1364\/JOSAA.34.001109","article-title":"Aberration Analysis of AOTF-Based Spectral Imaging Systems","volume":"34","author":"Machikhin","year":"2017","journal-title":"J. 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