Dr. Heesu Yang Profile

Dr. Heesu Yang

principal researcher at Korea Astronomy and Space Science Institute

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Author

Publications (4)

Proceedings Article | 23 August 2024 Poster + Paper

Polarimetric characterization of the coronal diagnostic experiment (CODEX)

Marta Casti, Jeffrey Newmark, Yeon-Han Kim, Gerardo Capobianco, Hervé Haudemand, Donguk Song, Sung-Hong Park, Su-Chan Bong, Kyungsuk Cho, Seonghwan Choi, Qian Gong, Ji-Hye Baek, Jongyeob Park, Jihun Kim, Heesu Yang, Nelson Reginald, Nicholeen Viall, Silvano Fineschi, Federico Landini, Davide Loreggia, Luca Zangrilli, Lucia Abbo, Jason Budinoff

Proceedings Volume 13092, 130927O (2024) https://doi.org/10.1117/12.3020730

KEYWORDS: Polarization, Coronagraphy, Equipment, Polarimetry, Sensors, Demodulation, Polarized light, Modulation, Linear polarizers, Polarization imaging

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Proceedings Article | 23 August 2024 Presentation + Paper

CODEX optical design and alignment

Qian Gong, Jeffrey Newmark, Yeon-Han Kim, Marta Casti, Lucia Abbo, Ji-Hye Baek, Su-Chan Bong, Jason Budinoff, Gerado Capobianco, Kyungsuk Cho, Seonghwan Choi, Silvano Fineschi, Hervé Haudemand, Jihun Kim, Federico Landini, Davide Loreggia, Sung-Hong Park, Jongyeob Park, Nelson Reginald, Donguk Song, Heesu Yang, Luca Zangrilli

Proceedings Volume 13092, 130922I (2024) https://doi.org/10.1117/12.3020705

KEYWORDS: Diffraction, Coronagraphy, Optical alignment, Telescopes, Stray light, Cameras, Vignetting, Optical design

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The COronal Diagnostic EXperiment (CODEX) is a Heliophysics mission to measure the density, temperature, and velocity of the electrons in the solar corona with the primary goal of improving our understanding of the physical conditions of the solar wind in the acceleration region. The temperature and velocity measurement requires much higher signal-to-noise ratio than the density measurements. In solar coronagraphs, the diffraction of the solar disk light due to the occulting element is the dominant source of noise. Therefore, to further suppress the diffracted sun light with respect to the existing coronagraphs is a critical element of the CODEX design. To minimize the stray light due to diffraction, the selected optical design is a two-stage standard coronagraph with an external occulter, an internal occulter, and a Lyot stop. What is unique for this design is that a focal mask was inserted at the telescope focal plane. It works together with the field lens suppressing the stray light down by ~ another order of magnitude as compared to a traditional three-stage approach. During the optical design, a Fourier Transform based beam propagation software, i.e., GLAD, was used to model the beam path through the full coronagraph, from the external occulter to the detector array. All diffraction sensitive elements: external occulter, internal occulter, focal mask, and Lyot stop were carefully modeled and optimized. As a result, the requirement of achieving a stray light level which is one order of magnitude lower than F-corona was satisfied. On the other hand, to achieve the final suppression, a precision optical alignment is another must. This paper also presents our creative alignment procedure: using the combination of metrology, precision alignment equipment, and real time diffraction ring monitoring to minimize the diffraction. The final test results show that the suppression ratio (B/B0) reaches 10-11 level, which is equivalent to one order of magnitude lower than F-corona.

Proceedings Article | 29 August 2022 Poster

Design and analysis of the SiC solar telescope for extreme environments

Jihun Kim, Seonghwan Choi, Jeong-Yeol Han, Yunjong Kim, Ji-Hye Baek, Jongyeob Park, Heesu Yang, Sujin Kim, Young-Soo Kim, Jaegun Yoo, Youra Jun, Bi-Ho Jang, Il Kweon Moon, Dohoon Kim, Minkyum Kim, Gwanghui Jeong, Myung Cho

Proceedings Volume 12182, 1218233 (2022) https://doi.org/10.1117/12.2628857

KEYWORDS: Solar telescopes, Optical instrument design, Silicon carbide, Telescopes, Mirrors, Bridges, Off axis mirrors, Light scattering, Tolerancing, Temperature metrology

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Proceedings Article | 19 September 2017 Presentation

Development of the camera lens system for total solar eclipse observation (Conference Presentation)

Jihun Kim, Seonghwan Choi, Ji-Hye Beck, Jongyeob Park, Su-Chan Bong, Bi-Ho Jang, Heesu Yang, Jinho Kim, Geon-Hee Kim, Kyungsuk Cho, Sung-Joon Park

Proceedings Volume 10401, 104010Q (2017) https://doi.org/10.1117/12.2272190

KEYWORDS: Cameras, Imaging systems, Polarizers, Bandpass filters, CCD cameras, Astronomy, Coronagraphy, Image quality, Optical engineering, Analytical research

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