1.8 m太阳望远镜偏振标定单元设计

姚本溪, 饶长辉, 顾乃庭. 1.8 m太阳望远镜偏振标定单元设计[J]. 光电工程, 2018, 45(11): 180058. doi: 10.12086/oee.2018.180058
引用本文: 姚本溪, 饶长辉, 顾乃庭. 1.8 m太阳望远镜偏振标定单元设计[J]. 光电工程, 2018, 45(11): 180058. doi: 10.12086/oee.2018.180058
Yao Benxi, Rao Changhui, Gu Naiting. Polarization calibration unit design of 1.8 m Chinese large solar telescope[J]. Opto-Electronic Engineering, 2018, 45(11): 180058. doi: 10.12086/oee.2018.180058
Citation: Yao Benxi, Rao Changhui, Gu Naiting. Polarization calibration unit design of 1.8 m Chinese large solar telescope[J]. Opto-Electronic Engineering, 2018, 45(11): 180058. doi: 10.12086/oee.2018.180058

1.8 m太阳望远镜偏振标定单元设计

  • 基金项目:
    国家自然科学基金资助项目(11178004, 11727805)
详细信息
    作者简介:

    姚本溪(1991-), 男, 博士研究生, 主要从事太阳望远镜偏振测量技术的研究。E-mail:yao_b_x@126.com

    通讯作者: 饶长辉(1971-), 男, 博士, 研究员, 主要从事大口径高分辨率光学成像望远镜技术研究和系统研制工作。E-mail:chrao@ioe.ac.cn
  • 中图分类号: O436.3

Polarization calibration unit design of 1.8 m Chinese large solar telescope

  • Fund Project: Supported by National Natural Science Foundation of China (11178004, 11727805)
More Information
  • 中国1.8 m太阳望远镜(Chinese large solar telescope, CLST)致力于对太阳偏振的高精度及高灵敏度测量。然而其系统本身会引入仪器偏振, 并且在望远镜运行的过程中, 仪器偏振会随其指向的变化而变化。这就降低了系统的测量精度。因此, 需要一个偏振标定单元对其仪器偏振进行标定。为此, 本文对偏振标定的原理和方法进行了研究, 并且给出了针对CLST的偏振标定单元设计方案。

  • Overview: Practically all solar phenomena are more or less relative to the solar magnetic field. It produces relativelystable structures like sunspots or prominences and is responsible for spectacular dynamic phenomena like flares or coronal mass ejections. However, the generation, amplification and destruction of magnetic fields remain poorly understood. The knowledge of its magnitude and direction is crucial for interpreting measurements of other parameters, and itcan be measured usually by a polarimetry at some special spectral lines, which should be sensitive to the Zeeman effect.To answer what physical mechanisms are responsible for heating the corona, what causes variations of radiative outputin the Sun, and what mechanisms trigger flares and coronal mass ejections and so on, many large aperture solar telescope have been developed (such as VTT, GREGOR, NST) or have being developed (such as DKIST, EST), and theStokes polarimetry is their most important observational device for determining the magnetic field. The Chinese largesolar telescope (CLST) with a 1.8-m aperture is a classic Gregorian configuration telescope with an alt-azimuth mount.It will be the second largest solar telescope in the world for a long time. And it is the main task for the Chinese largesolar telescope (CLST) to measure the solar polarization with a high accuracy and sensitivity. However, as a classic Gregorian configuration telescope with an alt-azimuth mount, the telescope system itself will introduce instrumental polarization. And it also will change constantly with the rotating of the telescope. Therefore a calibration unit which produces light of known polarization states is necessary to measure the Muller matrix of the system and apply the correction numerically on the measured Stokes vector.

    In this paper, we introduced the polarization calibration method and proposed a calibration progress. Since the telescope is rotational, symmetric down to M4, the position of the secondary focus F2 is appropriate for a calibration unitbecause the components before it do not contribute to the Muller matrix. F2 is an extremely useful position in CLST. Itshould be used not only for polarimetric purposes but also for internal alignment. Thus the calibration unit becomes amore versatile device. Then we design the structure of CLST calibration unit with two turnplates. The calibration unitoptics equipped on these turnplates will consist of a rotatable linear polarizer, and two rotatable achromatic quarter waveplates which are in use alternatively for visual range or infrared observations. And there are also some other space on theturnplates to realize the internal alignment purposes.

  • 加载中
  • 图 1  CLST光学系统图

    Figure 1.  Optical scheme of CLST

    图 2  偏振标定原理示意图

    Figure 2.  Optical scheme of polarization calibration method

    图 3  标定单元在CLST中的位置

    Figure 3.  The place of calibration unit in CLST

    图 4  CLST标定转盘结构示意图

    Figure 4.  Structure diagram of CLST calibration rotator

    图 5  CLST标定单元封装结构示意图

    Figure 5.  Configuration diagram of CLST calibration unit

    表 1  CLST系统参数指标

    Table 1.  The parameters of CLST system

    Parameter Value
    Aperture size of M1/mm Φ1800
    Field of view (FOV)/(′) ≥Φ3
    Wavelength cover/nm 380~2500
    Image space F# F/54.5
    Focal length/m ~96
    下载: 导出CSV

    表 2  偏振调制方案

    Table 2.  Polarization modulation program

    Number Polarizer angle/(°) λ/4 wave plate angle Stokes
    1 0 none [1 1 0 0]T
    2 45 none [1 0 1 0]T
    3 90 none [1 -1 0 0]T
    4 0 45° [1 0 0 1]T
    下载: 导出CSV

    表 3  偏振标定单元精度要求

    Table 3.  Accuracy requirement of polarization calibration unit

    Parameter Error
    κ < 0.001
    θ1/(°) < 0.05
    δ/(°) < 0.1
    θ2/(°) < 0.05
    下载: 导出CSV

    表 4  F2焦点系统参数

    Table 4.  System parameters in F2

    Parameter Value
    Circular diameter/mm 27
    Image scale/(″/mm) 18.93
    Focal length/mm 10897
    F ratio 6.2
    Power density/(W/cm2) 26
    Power/W 160
    下载: 导出CSV

    表 5  驱动电机性能要求

    Table 5.  Requirements for motor drives

    Drive A Drive A1 Drive B Drive B1
    Position precision/(°) < 0.05 < 0.05 < 0.05 < 0.05
    Position repeatability/(°) < 0.1 < 0.1 < 0.1 < 0.1
    Rotation speed/(rpm) < 3 >10 >3 >10
    下载: 导出CSV

    表 6  转盘各通光孔装置及应用

    Table 6.  The device and their useful on the rotator

    Device Application
    A1 Rotating polarizer 1 To introduce linear polarization In visible wavelength
    A2 Rotating polarizer 2 To introduce linear polarization In near infrared wavelength
    A3 Full FOV
    A4 Fiber adapter Holder for a fiber
    A5 Empty For later use
    A6 Empty For later use
    B1 λ/4 wave plate 1 To introduce circular polarization In visible wavelength
    B2 λ/4 wave plate 1 To introduce circular polarization In near infrared wavelength
    B3 Full FOV
    B4 Pinhole To align the wave front sensor and so on
    B5 Resolution target Used for focusing M3
    B6 Slanted edge target To measure directly the MTF
    下载: 导出CSV
  • [1]

    Hofmann A, Rendtel J.Polarimetry with GREGOR[J].Proceedins of SPIE, 2003, 4843:112-121. doi: 10.1117/12.458615

    [2]

    Beck C, Bellot Rubio L R, Kentischer T J, et al.Two-dimensional solar spectropolarimetry with the KIS/IAA Visible Imaging Polarimeter[J].Astronomy & Astrophysics, 2010, 520:A115. http://arxiv.org/abs/1007.1153v2

    [3]

    Von Der Lühe O, Schmidt W, Soltau D, et al.GREGOR:a 1.5 m telescope for solar research[J].Astronomische Nachrichten, 2001, 322(5-6):353-360. doi: 10.1002/(ISSN)1521-3994

    [4]

    Cao W, Ahn K, Goode P R, et al.The new solar telescope in big bear: polarimetry Ⅱ[C]//Proceedings of ASP Conference, 2011: 345-349.

    [5]

    Keil S L, Rimmele T R, Oschmann J, et al.Science goals and development of the advanced technology solar telescope[J].Proceedings of the International Astronomical Union, 2004, 2004(IAUS223):581-588. doi: 10.1017/S1743921304006933

    [6]

    Matthews S A, Collados M, Mathioudakis M, et al.The European solar telescope (EST)[J].Proceedings of SPIE, 2016, 9908:990809. doi: 10.1117/12.2234145

    [7]

    屈中权, 张霄宇, 陈学昆, 等.太阳光谱望远镜和Stokes光谱测量[J].天文学进展, 2001, 19(2):139-140. doi: 10.3969/j.issn.1000-8349.2001.02.012

    Qu Z Q, Zhang X Y, Chen X K, et al.Solar spectroscopy telescope and the stokes spectrometry[J].Progress in Astronomy, 2001, 19(2):139-140. doi: 10.3969/j.issn.1000-8349.2001.02.012

    [8]

    方成, 黄佑然.南京大学太阳塔及多波段太阳光谱仪[J].天文学报, 1983, 24(3):189-195. doi: 10.15940/j.cnki.0001-5245.1983.03.001

    Fang C, Huang Y R.The solar tower telescope of Nanjing university and its multiple solar spectrograph[J].Acta Astronomica Sinica, 1983, 24(3):189-195. doi: 10.15940/j.cnki.0001-5245.1983.03.001

    [9]

    许方宇, 徐稚, 徐世春, 等.抚仙湖一米新真空太阳望远镜6米近红外光谱仪装调及太阳1.56微米光谱的初步观测结果[J].天文研究与技术, 2014, 11(2):168-175. doi: 10.3969/j.issn.1672-7673.2014.02.012

    Xu F Y, Xu Z, Xu S C, et al.Installation/adjustment of a 6m near-infrared spectrograph for the 1m new vacuum solar telescope in the Fuxian-Lake solar-observation station and preliminary observation results of solar spectra around 1.56 μm using the spectrograph[J].Astronomical Research and Technology, 2014, 11(2):168-175. doi: 10.3969/j.issn.1672-7673.2014.02.012

    [10]

    Yuan S.Polarization model for the new vacuum solar telescope[C]//Proceedings of APS Conference, 2014: 297.

    [11]

    Hofmann A.Polarimetry with GREGOR-an ongoing project[J].Sun and Geosphere, 2007, 2(1):9-12. http://adsabs.harvard.edu/abs/2007SunGe...2....9H

    [12]

    Bettonvil F C M, Collados M, Feller A, et al.The polarization optics for the European Solar Telescope (EST)[J].Proceedings of SPIE, 2010, 7735:77356I. http://proceedings.spiedigitallibrary.org/data/Conferences/SPIEP/5979/77356I_1.pdf

    [13]

    Rao C H, Gu N T, Zhu L, et al.1.8-m solar telescope in China:Chinese large solar telescope[J].Journal of Astronomical Telescopes, Instruments, and Systems, 2015, 1(2):024001. doi: 10.1117/1.JATIS.1.2.024001

    [14]

    Azzam R M A, Masetti E, Elminyawi I M, et al.Construction, calibration, and testing of a four‐detector photopolarimeter[J].Review of Scientific Instruments, 1988, 59(1):84-88. doi: 10.1063/1.1139971

    [15]

    Krishnan S.Calibration, properties, and applications of the division-of-amplitude photopolarimeter at 632.8 and 1523 nm[J].Journal of the Optical Society of America A, 1992, 9(9):1615-1622. doi: 10.1364/JOSAA.9.001615

    [16]

    Snik F.Calibration strategies for instrumental polarization at the 10-5 level[J].Proceedings of SPIE, 2006, 6269:62695P. doi: 10.1117/12.671425

    [17]

    侯俊峰.偏振分析器的高精度偏振定标方法研究及其应用[D].北京: 中国科学院大学, 2013.

    Hou J F.Studies and applications of polarimeter's polarization calibration with high precision[D].Beijing: University of Chinese Academy of Sciences, 2013.

    [18]

    Almeida J S, Pillet V M.Instrumental polarization in the focal plane of telescopes[J].Astronomy and Astrophysics, 1992, 260(1-2):543-555. http://adsabs.harvard.edu/abs/1992A&A...260..543S

  • 加载中

(5)

(6)

计量
  • 文章访问数:  11530
  • PDF下载数:  2618
  • 施引文献:  0
出版历程
收稿日期:  2018-01-29
修回日期:  2018-04-08
刊出日期:  2018-11-01

目录

/

返回文章
返回