인문학
사회과학
자연과학
공학
의약학
농수해양학
예술체육학
복합학
DBpia AI
AI 에이전트
AI 아이디어
AI 리더
AI 뷰어
Citeasy
크롬 서지관리 다운로드
지원사업
학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
커뮤니티
연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
초록·키워드
Context . Direct imaging of circumstellar environments around nearby stars requires eXtreme Adaptive Optics (XAO) systems. These systems must integrate advanced wavefront sensors (WFSs) to reach a high Strehl ratio (SR) in the near-infrared and at visible wavelengths on future giant segmented mirror telescopes (GSMTs). Direct detection of faint exoplanets with these extremely large telescopes will require tens of thousands of correction modes. In addition, highly accurate and sensitive WFSs set key requirements. The precise measurement of the wavefront degradation for both static and dynamic aberrations with a limited number of photons is still an issue for most WFSs, which are often limited either in sensitivity or in dynamical range. Aims . We present the integrated Mach–Zehnder (iMZ), a self-referenced interferometric WFS developed for XAO and implemented on an XAO test bench at CRAL. The WFS concept consists of creating two opposite sets of interferences between the wavefront phase to be measured and the spatially filtered reference beam. We describe the implementation of this concept, including the scheme we have developed to extend its dynamical range by using phase diversity. Methods . We present an iMZ physical model that allows the performance of this sensor to be studied in closed loop for different telescopes (the Very Large Telescope (VLT) and the Extremely Large Telescope (ELT)) in different turbulence regimes and including island effects, cophasing residuals, or low wind effects. A calibration method adapted to the iMZ that takes into account the nonlinearities of the signal was developed to use this WFS for diverse types of phase measurements. We analytically computed the photon noise error propagation of the iMZ, setting its ultimate sensitivity, and we compared it with several WFSs used in adaptive optics. Finally, we demonstrated the performances of the iMZ in closed loop by using end-to-end (E2E) simulations and experimental validations. Results . The proposed iMZ WFS demonstrates a significant gain in sensitivity compared to the Shack–Hartmann WFS traditionally used in AO. The iMZ dynamical range, reduced to a wavelength in closed-loop operations, can be extended to several wavelengths by using phase diversity strategies developed in this paper. We demonstrate, with simulations and experimentally, a new calibration method for the iMZ, which is an essential step for the precise reconstruction of the phase. It is achieved by solving an inverse problem based on the interferometric model of the data. Our E2E numerical simulations confirm the very good performances of this sensor and the possibility of using it without a first stage of correction in good turbulence conditions. Experimental laboratory results demonstrate the efficiency of the iMZ in closed loop under good seeing conditions. The development of the iMZ is also motivated by the arrival of GSMTs leading to challenging new optical aberrations, such as differential pistons between different segments constituting the pupil and the pupil fragmentation (also called petal modes). The iMZ can efficiently measure these type of aberrations as well, to which most WFSs are not sensitive or are only slightly sensitive because their responses are generally proportional to the derivative of the incident wavefront. With its two complementary outputs, the iMZ WFS also offers the possibility of measuring the amplitude of the incident wave jointly with its phase without sensitivity loss, which makes it possible to consider correcting the effects of scintillation due to the atmosphere. Conclusions . We conclude that the iMZ is an excellent WFS candidate for future XAO systems, in particular on GSMTs.
인공지능 문자 인식 모델을 통해 추출된 텍스트로, 일부 오타나 오류가 포함될 수 있으나 지속적으로 개선 중입니다.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
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