Abstract
Doppler asymmetric spatial heterodyne spectroscopy is recently developed for spaceborne measurement of middle and upper atmospheric wind field, which relies on the accurate inverse of interferogram phase to calculate the Doppler shift of airglow emission lines. The change of temperature leads the optical and mechanical components to thermally deformed, causing the imaging plane to thermally drift relative to the detector, changing the distribution of interferogram phase on pixels, and directly introducing phase errors to affect the wind speed inversion. In order to reduce the influence of imaging thermal drift on phase inversion, the segmented fitting method is used in this paper to detect the sub-pixel edges of notch patterns and monitor imaging thermal drift accordingly. In the thermal stability test of a near-infrared Doppler asymmetric spatial heterodyne interferometer prototype, the thermal imaging drifts and ambient temperature show a high consistency in the trend of high-frequency oscillation, and the correlation coefficient can reach 0.86 after removing the baseline. After phase correct by using the thermal imaging shift, the high-frequency oscillation of interferogram phase shift is also greatly suppressed. In order to further verify the accuracy of the algorithm, the influence of the data signal-to-noise ratio and the data distribution characteristic parameter errors used in the fitting on the edge detection are simulated. The results show that the edge detection accuracy is restricted mainly by the data signal-to-noise ratio and the accuracy of the fringe frequency parameters. When the error of the fringe frequency parameter used for fitting is less than 0.5%, the error of other data distribution characteristic parameters is less than 5%, and the data signal-to-noise ratio is enhanced more than 35 times, the algorithm in this paper can achieve a detection accuracy higher than 0.05 pixels.
Highlights
中高层大气风场信息为建立中间层、低热层和电离层之间的动量和能量的耦 合提供参考,为中长期的天气预报提供数据支持,同时为军事和航天活动的顺利 开展提供可靠保障[1,2,3,4,5,6,7]。多普勒差分干涉仪是近年来发展的一种被动式风场干涉测 量技术,与传统的基于迈克尔逊(Michelson)干涉仪和法布里-珀罗(Fabry-Perot) 干涉仪的干涉测风技术相比,它具有结构简单、光通量大、装调精度要求低以及 具备多谱线探测能力、可以实现同步定标等优点,适合搭载于卫星平台进行中高 层大气风场测量[6,7,8]。2019 年 10 月,由美国海军实验室研制的基于多普勒差分干 涉 技 术 的 MIGHTI ( Michelson Interferometer for Global High-resolution Thermospheric Imaging)仪器已搭载于 ICON(Ionospheric Connection Explorer) 卫星任务成功发射并开始运行[9]。
Configuration of Doppler asymmetric spatial heterodyne interferometer and phase inversion process based on Fourier transform
Schematic gram of the influence of the relative error of notch width on the notch edge detection error
Summary
中高层大气风场信息为建立中间层、低热层和电离层之间的动量和能量的耦 合提供参考,为中长期的天气预报提供数据支持,同时为军事和航天活动的顺利 开展提供可靠保障[1,2,3,4,5,6,7]。多普勒差分干涉仪是近年来发展的一种被动式风场干涉测 量技术,与传统的基于迈克尔逊(Michelson)干涉仪和法布里-珀罗(Fabry-Perot) 干涉仪的干涉测风技术相比,它具有结构简单、光通量大、装调精度要求低以及 具备多谱线探测能力、可以实现同步定标等优点,适合搭载于卫星平台进行中高 层大气风场测量[6,7,8]。2019 年 10 月,由美国海军实验室研制的基于多普勒差分干 涉 技 术 的 MIGHTI ( Michelson Interferometer for Global High-resolution Thermospheric Imaging)仪器已搭载于 ICON(Ionospheric Connection Explorer) 卫星任务成功发射并开始运行[9]。. 基金: 国家自然科学基金(批准号:41005019)、中国科学院西部青年学者(批准号: XAB 2016A07)、陕西省自然科学基础研究计划(批准号:2019JQ-931)、中国科学院 西部之光交叉团队(批准号:E1294301) † 通讯作者.E-mail: fytciom@126.com 风速是风场信息中最重要的参数,多普勒差分干涉仪以大气气辉的辐射谱线 为探测对象,对干涉图相位进行精确反演,通过与零风速参考之间的相位差计算 气辉谱线的多普勒频移从而得到风速[10, 11]。多普勒差分干涉仪要达到实用的测风 精度(≤10m/s),需要测量相当于波长 1/3×10-7 级别的频移[7]。而工作环境温度的 变化会引起干涉仪光学元件和结构组件工作特性的变化,带来干涉图相位漂移、 调制度降低和倾斜畸变等负面影响,影响相位测量的精度和准确性[12,13,14]。其中结 Marr 等人在干涉仪光栅工作面刻蚀出周期刻槽图案,利用干涉图像中刻槽图 案像元位置的变化检测像面热漂移,其检测方法利用梳状函数、矩形窗函数以及 高斯扩展核函数的卷积生成周期刻槽模拟函数,结合刻槽内外的数据分布特征生 成仿真数据拟合刻槽的位置[9]。为获得准确的像面热漂移检测结果,该方法在先 行生成周期刻槽模拟函数时需要非常准确的刻槽周期、边缘坡度等参数,获取这 些参数需要对大量热稳定条件下的标定数据进行拟合并对结果平均,而且对刻槽 特征的周期性要求较高。本文提出了一种逐刻槽边缘分段拟合检测干涉图像中刻 槽图案亚像元位置的像面热漂移监测方法,不需要先行确定刻槽的特征参数,可 以单独检测每个刻槽边缘的亚像元位置,而且对刻槽特征的周期性要求较低。本 文基于近红外多普勒差分干涉仪样机的热稳定测试数据进行了像面热漂移监测, 对比了干涉图像中刻槽图案亚像元位置与环境温度的变化,利用刻槽漂移监测结 果进行了相位校正。最后仿真了数据信噪比、刻槽内外数据分布特征参数等对算 法的影响,分析了算法的精度表现。 多普勒差分干涉仪基于迈克尔逊干涉原理发展而来,干涉仪两臂为以 Littrow倾斜固定的光栅,两臂之间存在非对称偏置量△d,其基本结构如图1所 示。入射光经过准直镜准直到达分束器,被分为两条光臂,两臂的光各自经过 光栅的衍射作用返回分束器,在空间中相遇形成Fizeau干涉条纹,被条纹成像镜 成像于探测器[8]。目前多普勒差分干涉仪进行相位反演主要用的是基于傅里叶变
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
