Optical Adjustment of the FITE Interferometer
Optical Adjustment of the FITE Interferometer
复制标题
FITE 干涉仪的光学调整
DOI：
10.1142/s2251171720500026
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发表时间：
2020
影响因子：
1.3
通讯作者：
Narita Masanao
中科院分区：
文献类型：
--
作者：
Sasaki Ayana;Shibai Hiroshi;Matsuo Taro;Sumi Takahiro;Itoh Satoshi;Ohyama Teruhira;Tani Yoshito;Saiki Morito;Tsuboi Takahiro;Narita Masanao
我们研制了气球载远红外干涉仪——远红外干涉望远镜实验（FITE）。空间分辨率的最终目标是 100m 处 1 角秒。作为第一步，我们的目标是在 155m 处实现 5 角秒的空间分辨率，基线为 6 米。 FITE 是一种双光束干涉仪，类似于迈克尔逊的恒星干涉仪。所有镜子的位置和姿态都需要在发射前检查其对准情况并可能进行调整，并在观察期间进行检查。我们必须满足三个要求：每束光束的相位重合（波前误差）、两束光束在（公共）焦点处的图像质量以及对于天体而言两束光束之间没有光程差。为了实现前两个要求，我们开发了干涉仪调整系统，该系统使用了新开发的干涉仪测量仪器。该仪器采用Shack-Hartmann波前传感器同时测量两个离轴抛物面镜的波前误差。借助该系统，作为JAXA 2018年澳大利亚气球实验活动，在澳大利亚爱丽丝泉气球基地对FITE干涉仪进行了调整。现场调整成功；两个离轴抛物面镜的波前误差分别为1.78m和4.99m（峰谷），哈特曼常数为13角秒。对于光程差，我们通过折叠平面镜的步进位移来达到要求。结果满足针对 155m 波长设计的干涉仪的要求。提高远红外波长的空间分辨率对于原行星盘、晚型恒星的星周尘埃壳和恒星形成星系的研究无疑具有重要意义。我们开发的方法对于未来的空间干涉仪也很有用。
We have developed a balloon-borne far-infrared interferometer, the Far-infrared Interferometric Telescope Experiment (FITE). The final goal of spatial resolution was one arcsec at 100m. As a first step, we aimed to achieve a spatial resolution of five arcsecs at 155m with a 6-m baseline. FITE is a two-beam interferometer like Michelson’s stellar interferometer. Positions and attitudes of all mirrors required to have their alignment checked and possibly adjusted before launch and were checked during observation. We had to satisfy three requirements: the coincidence of the phases of each beam (wavefront error), image quality of the two beams at the (common) focus, and no optical path difference between the two beams for celestial objects. In order to achieve the former two requirements, we developed an interferometer adjustment system that used a newly-developed interferometer measurement instrument. This instrument adopted a Shack–Hartmann wavefront sensor to measure wavefront errors of the two off-axis parabolic mirrors, simultaneously. With this system, the adjustment of the FITE interferometer was carried out at the Alice Springs balloon base in Australia as the JAXA’s Australia balloon experiment campaign of 2018. On-site adjustment was successful; wavefront errors of the two off-axis parabolic mirrors were 1.78m and 4.99m (peak-to-valley), and the Hartmann constant was 13 arcsecs. As for the optical path difference, we achieved the requirement by step-wise displacement of a folding plane mirror. Results satisfied the requirements for an interferometer designed for a wavelength of 155m. Improvement of spatial resolution at far-infrared wavelengths is undoubtedly important for research on protoplanetary disks, circumstellar dust shells of late-type stars, and star-forming galaxies. The method we have developed is also useful for future space interferometers.