報告題目：High-precision Astrometry (高精度天體測量)
報告人：周建鋒，清華大學工程物理系副教授、博導(dǎo)，寧波星帆信息科技有限公司創(chuàng)始人、總經(jīng)理
時間：2021年11月5日（周五）10:00
地點:天文大廈三樓大會議室
摘要：
For a long time, it has been generally believed that the accuracy of astrometry is mainly restricted by the resolution of the telescope. At the beginning of the 21st century, Mike Shao of Caltech pointed out that the Point Spread Function (PSF) of a telescope can be accurately reconstructed under the premise that the image satisfies the Nyquist sampling criteria. Accurate PSF can significantly improve the accuracy of the astrometry. For example, the measurement of a 1-meter telescope can reach micro-arcsecond accuracy. In the past ten years, our group has completed three main tasks in high-precision astrometry. 1. We found a strict correction formula that converts the CCD/CMOS integral sampling image into an impulse sampling image to achieve a true and accurate PSF reconstruction; 2. We proposed the field distortion model based on the Fredholm integral, which unifies the distortion of an imaging system and the non-uniformity of CCD/CMOS sensors. It can describe the point-to-point position distortion and the deformation of the PSF; 3. Establish an accurate image matching algorithm, including translation and rotation. With these efforts, we have developed applications such as Adaptive Image Stabilization (AIS) systems and ultra-high-precision dimensional measurement for machine vision in the industrial field. In the field of space astrometry, we propose a three-step approach to achieve related applications and scientific goals. The first step is to develop a star tracker with a diameter of about 5 cm to improve the attitude measurement of the spacecraft to milli-arcsecond level. The second step is to develop a wide-field astrometric and photometric telescope with a diameter of about 30 cm, which is launched into the earth orbit, verify the relevant key technologies, the measurement accuracy is about ten micro-arcseconds. The third step is to develop a wide-field astrometric and photometric telescope with an aperture of about 2m and launch it to the second Lagrangian (L2) point. The measurement accuracy can reach 0.1 micro-arcseconds, mainly used to detect extrasolar terrestrial planets, measure the property of the dark energy and dark matter distribution in the universe, and so on.
長期以來，人們普遍認為天體測量的精度主要受望遠鏡分辨率的限制。21世紀初，加州理工學院的Mike Shao指出，在圖像滿足奈奎斯特采樣準則的前提下，可以精確重建望遠鏡的點擴展函數(shù)（PSF）。精確的PSF可以顯著提高天體測量的精度。例如，1米望遠鏡的測量可以達到微角秒精度。十年來，我們課題組在高精度天體測量方面完成了三項主要任務(wù)。 1、我們找到了嚴格的校正公式，將CCD/CMOS積分采樣圖像轉(zhuǎn)換為脈沖采樣圖像，實現(xiàn)真正準確的PSF重建； 2.我們提出了基于Fredholm積分的視場畸變模型，它統(tǒng)一了成像系統(tǒng)的畸變和CCD/CMOS傳感器的非均勻性?？梢悦枋鳇c對點的位置畸變和PSF的變形；3. 建立精確的圖像匹配算法，包含了平移和旋轉(zhuǎn)。借助這些工作，我們在工業(yè)領(lǐng)域開發(fā)了自適應(yīng)圖像穩(wěn)定（AIS）系統(tǒng)和機器視覺超高精度尺寸測量等應(yīng)用。在空間天體測量領(lǐng)域，我們提出了一個三步走的策略來實現(xiàn)相關(guān)的應(yīng)用和科學目標。第一步是研制口徑約5厘米的星敏感器，將航天器的姿態(tài)測量精度提高到毫角秒量級。第二步是研制直徑約30厘米的寬視場天體測量及測光望遠鏡，發(fā)射到地球軌道，驗證相關(guān)關(guān)鍵技術(shù)，測量精度約10微角秒。第三步，研制口徑約2m的寬視場天體測量和測光望遠鏡，發(fā)射到第二拉格朗日（L2）點。測量精度可達0.1微角秒，主要用于探測太陽系外類地行星，測量宇宙中暗能量的性質(zhì)和暗物質(zhì)的分布等等。
個人簡介：
周建鋒，清華大學工程物理系副教授、博導(dǎo)，寧波星帆信息科技有限公司創(chuàng)始人、總經(jīng)理。國際天文學聯(lián)合會（IAU）會員，中國天文學會會員。國際期刊Applied Optics、JCS、RAA和多個國內(nèi)核心期刊審稿人；負責3項國家自然科學基金課題，負責1項教育部自主科研重點項目，參加3項國家973、863項目。發(fā)表論文40余篇、授權(quán)發(fā)明專利15余項。2001～2017，歷時17年參加我國重大空間科學項目硬X射線調(diào)制望遠鏡（HXMT），為DDM子系統(tǒng)及巡天成像子系統(tǒng)負責人。2014～至今，獲得寧波3315項目和奉化區(qū)鳳麓英才項目資助，創(chuàng)立星帆科技，致力于超高精度工業(yè)視覺測量技術(shù)，以及人工智能視覺檢測設(shè)備的開發(fā)與銷售。
