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An active coronagraph using a liquid crystal array for exoplanet imaging:principle and testing

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Research in Astronomy and Astrophysics 2012年第5期12卷 591-600页

作者： Xi Zhang De-Qing Ren yong-tian zhu Jiang-Pei Dou National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China Key Laboratory of Astronomical Optics&Technology National Astronomical Observatories/Nanjing Institute of Astronomical Optics&TechnologyChinese Academy of SciencesNanjing 210042China Physics&Astronomy Department California State University Northridge18111 Nordhoff StreetNorthridgeCalifornia 91330-8268USA Graduate University of Chinese Academy of Sciences Beijing 100049China

High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their best performance. To solve this problem, we propose a novel high-contrast imaging coronagraph which combines a liquid crystal array （LCA） for active pupil apodization and a deformable mirror （DM） for phase correction. The LCA we use is an amplitude-only spatial light mod- ulator. The LCA is well calibrated and compensates for its amplitude non-uniformity and nonlinear intensity responsivity. We measured the imaging contrasts of the coron- agraph system with the LCA only and without the DM deployed. Imaging contrasts of 10-4 and 10-5 can be reached at an inner working angular distance of 2.5 and 5A/D, respectively. A simulation shows that the phase errors on the coronagraph pupil limit the contrast performance. The contrast could be further improved if a DM is deployed to correct the phase errors induced by the LCA and coronagraph optics.

关键词： instrumentation: coronagraph liquid crystal array - techniques high-contrast imaging exoplanet detection

Design and experimental test of an optical vortex coronagraph

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Research in Astronomy and Astrophysics 2017年第6期17卷 101-106页

作者： Cheng-Chao Liu De-Qing Ren yong-tian zhu Jiang-Pei Dou National Astronomical Observatories/Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Nanjing 210042 China Key Laboratory of Astronomical Optics & Technology National Astronomical Observatories/Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Nanjing 210042 China Physics & Astronomy Department California State University Northridge 18111 Nordhoff Street Northridge California 91330-8268 USA

Using an optical vortex coronagraph （OVC） is one of the most promising techniques for di- rectly imaging exoplanets because of its small inner working angle and high throughput. This paper presents the design and laboratory demonstration performance of an OVC based on liquid crystal polymers （LCPs） at 633 nm and 1520 nm. The OVC can deliver good performance in laboratory tests and achieve a contrast of 10-6 at an angular distance of 3A/D, which can be implemented for imaging young giant exoplanets in combination with extreme adaptive optics.

关键词： instrumentation coronagraph- techniques optical vortex - methods laboratory

Portable adaptive optics for exoplanet imaging

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Research in Astronomy and Astrophysics 2021年第4期21卷 110-118页

作者： yong-tian zhu Jiang-Pei Dou Xi Zhang Gang Zhao Jing Guo Leopoldo Infante National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyChinese Academy of SciencesNanjing 210042China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China Las Campanas Observatory Observatories of the Carnegie Institution of WashingtonColina El Pino S/N Casilla 601 La SerenaChile Institute of Astrophysics Pontificia Universidad Catolica de ChileAv.Vic Mackenna 4860SantiagoChile Nucleo de Astronomfa de la Facultad de Ingenierfa y Ciencias Universidad Diego PortalesManuel Rodriguez Sur 415SantiagoChile

The portable adaptive optics(PAO)device is a low-cost and compact system,designed for 4-meter class telescopes that have no adaptive optics(AO)system,because of the physical space limitation at the Nasmyth or Cassegrain focus and the historically high cost of conventional *** initial scientific observations of the PAO are focused on the direct imaging of exoplanets and sub-stellar *** paper discusses the concept of PAO and the associated high-contrast imaging performance in our recent observational *** deliver a Strehl ratio better than 60%in H band under median seeing conditions of 1".Combined with our dedicated image rotation and subtraction(IRS)technique and the optimized IRS(O-IRS)algorithm,the averaged contrast ratio for a 5≤V_(mag)≤9 primary star is 1.3×10^(-5)and3.3×10^(-6)at angular distance of 0.36"with exposure time of 7 minutes and 2 hours,*** has successfully revealed the known exoplanet ofκAnd b in our recent observation with the 3.5-meter ARC telescope at Apache Point *** have performed the associated astrometry and photometry analysis of the recoveredκAnd b planet,which gives a projected separation of 0.98"±0.05",a position angle of 51.1°±0.5°and a mass of 10.15_(-1.255)^(+2.19) *** results demonstrate that PAO can be used for direct imaging of exoplanets with medium-sized telescopes.

关键词： stars:imaging instrumentation:adaptive optics instrumentation:high angular resolution methods:observational techniques:image processing

A high-contrast imaging polarimeter with a stepped-transmission filter based coronagraph

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Research in Astronomy and Astrophysics 2016年第5期16卷 25-30页

作者： Cheng-Chao Liu De-Qing Ren yong-tian zhu Jiang-Pei Dou Jing Guo National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China Key Laboratory of Astronomical Optics&Technology National Astronomical Observatories/Nanjing Institute of Astronomical Optics&TechnologyChinese Academy of SciencesNanjing 210042China Physics&Astronomy Department California State University Norihridge 18111 Nordhoff StreetNorthridgeCalifornia 91330-8268USA University of Chinese Academy of Sciences Beijing 100049China

The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.

关键词： instrumentation: polarimeter coronagraph-- techniques: polarimetric -- methods: laboratory

Design and calibration of a high-sensitivity and high-accuracy polarimeter based on liquid crystal variable retarders

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Research in Astronomy and Astrophysics 2017年第1期17卷 87-96页

作者： Jing Guo De-Qing Ren Cheng-Chao Liu yong-tian zhu Jiang-Pei Dou Xi Zhang Christian Beck National Astronomical Observatories/Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Nanjing 210042 China Key Laboratory of Astronomical Optics & Technology Nanjing Institute of Astronomical Optics & TechnologyChinese Academy of Sciences Nanjing 210042 China Physics and Astronomy Department California State University Northridge 18111 Nordhoff Street NorthridgeCalifornia 91330-8268 USA National Solar Observatory Boulder CO 80303 USA

Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than 5.7 × 10-3 can be achieved by using a single short-exposure image, while an accuracy on the order of 10-5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.

关键词： instrumentation polarimeters - methods laboratory - Sun magnetic fields - tech-niques polarimetric

A high-contrast coronagraph for direct imaging of Earth-like exoplanets: design and test

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Research in Astronomy and Astrophysics 2015年第3期15卷 453-460页

作者： Cheng-Chao Liu De-Qing Ren Jiang-Pei Dou yong-tian zhu Xi Zhang Gang Zhao Zhen Wu Rui Chen National Astronomical Observatories/Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Key Laboratory of Astronomical Optics & Technology National Astronomical Observatories/Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences University of Chinese Academy of Sciences Physics & Astronomy Department California State University Northridge

A high-contrast coronagraph for direct imaging of an Earth-like exoplanet at the visible band needs a contrast of 10^-10 at a small angular separation of 4λ/D or less. Here we report our recent laboratory experiment that approaches these lim- its. Our test of a high-contrast imaging coronagraph is based on our step-transmission apodized filter. To achieve this goal, we use a liquid crystal array as a phase correc- tor to create a dark hole based on our dedicated algorithm. We have suppressed the diffraction and speckle noise near the point image of a star to a level of 1.68 × 10^-9 at 4λ/D, which can be used for direct imaging of Jupiter-like exoplanets. This demon- strates that a telescope incorporating a high-contrast coronagraph in space has the potential to detect and characterize Earth-like planets.

关键词： instrumentation: coronagraph liquid crystal array -- techniques:apodization -- methods: laboratory

Minimum secure speed of fully mechanized coal face based on critical temperature of coal spontaneous combustion

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Journal of Coal Science & Engineering(China) 2013年第2期19卷 147-152页

作者： Wei LIU Yue-Ping QIN yong-Jiang HAO tian-zhu GUI Jing-Yan JIA Faculty of Resources & Safety Engineering China University of Mining & Technology (Beijing) Beijing 100083 China

The critical temperature theory of spontaneous combustion of coal and the numerical simulation method are used to explore the minimum secure speed of fully mechanized coal face to prevent the spontaneous combustion in goaf. Combined with the actual situation of workface 31005 in a coal mine, the highest temperatures in goal at different advancing speeds were obtained by the numerical simulation of spontaneous combustion in goal, and then a power function equation between the highest temperature and the advancing speed was achieved by regression analysis. The advancing speed corresponding to the critical temperature value was taken as the minimum safe speed of workface based on the equation. Finally, the accuracy and reliability of the speed were verified by the actual advancing process of workface 31005. The results of this research show that the new judgment method of the minimum safety speed has a higher value to be applied in the field.

关键词： goal spontaneous combustion critical temperature workface advancing speed

Duodenal pseudolymphoma: A case report and review of literature

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World Journal of Gastroenterology 2011年第27期17卷 3267-3270页

作者： yong-Heng Huang, tian-zhu Long, Zhi-Yu Xiao, Hua Ye, Yun-Le Wan, Jie Wang yong-Heng Huang, tian-zhu Long, Zhi-Yu Xiao, Hua Ye, Yun-Le Wan, Jie Wang, Department of Hepatobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University Haizhu District, Guangzhou 510260, Guangdong Province, China Department of Hepatobiliary Surgery Sun Yat-sen Memorial Hospital Sun Yat-sen University Haizhu District Guangzhou 510260 Guangdong Province China.

We report a rare case of duodenal pseudolymphoma without any symptoms. The lesion located in front of the head of the pancreas was found accidentally during a medical examination. The findings of computed tomography and positron emission tomography-computed tomography suggested a stromal tumor or malignant lymphoma. Surgical resection was performed. The lesions were patho- logically diagnosed as duodenal pseudolymphoma.

关键词： Pseudolymphoma Duodenum

“One stone, two birds”: Salt template enabling porosity engineering and single metal atom coordinating toward high-performance zinc-ion capacitors

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Journal of Energy Chemistry 2025年第1期100卷 637-645页

作者： Chunliu zhu Huanyu Liang Ping Li Chenglong Qiu Jingyi Wu Jingwei Chen Weiqian tian Yue zhu Zhi Li Huanlei Wang School of Materials Science and Engineering Ocean University of China Department of Chemical and Materials Engineering University of Alberta

Zinc-ion hybrid capacitors （ZIHCs） have received increasing attention as energy storage devices owing to their low cost,high safety,and environmental ***,their progress has been hampered by low energy and power density,as well as unsatisfactory long-cycle stability,mainly due to the lack of suitable electrode *** this context,we have developed manganese single atoms implanted in nitrogen-doped porous carbon nanosheets （MnSAs/NCNs） using a metal salt template method as cathodes for *** metal salt serves a dual purpose in the synthesis process:It facilitates the uniform dispersion of Mn atoms within the carbon matrix and acts as an activating agent to create the porous *** applied in ZIHCs,the MnSAs/NCNs electrode demonstrates exceptional performance,including a high capacity of 203 m Ah g-1,an energy density of 138 Wh kg-1at 68 W kg-1,and excellent cycle stability with 91%retention over 10,000 *** calculations indicate that the introduced Mn atoms modulate the local charge distribution of carbon materials,thereby improving the electrochemical *** work demonstrates the significant potential of carbon materials with metal atoms in zinc-ion hybrid capacitors,not only in enhancing electrochemical performance but also in providing new insights and methods for developing high-performance energy storage devices.

关键词： Zinc ion hybrid capacitors Cathodes Carbon materials Heteroatoms Single atoms