Focal ratio degradation in lightly fused hexabundles
Focal ratio degradation in lightly fused hexabundles
复制标题
DOI：
10.1093/mnras/stt2254
复制
发表时间：
2013-11
影响因子：
4.8
通讯作者：
J. Bryant;J. Bland-Hawthorn;L. Fogarty;J. Lawrence;S. Croom
中科院分区：
文献类型：
--
作者：
J. Bryant;J. Bland-Hawthorn;L. Fogarty;J. Lawrence;S. Croom
我们现在正在进入一个多目标宽场测量的时代，传统上使用单根光纤同时观察许多目标，可以利用紧凑的积分场单元代替单根光纤。目前的多目标积分场仪器，如SAMI（Croom等人，2012年; Bryant等人，2012年a），推动了多目标光谱仪新型成像光纤束（六束）的开发。我们已经表征了具有不同包层厚度的hexabundles的性能，并将其与相同类型的裸光纤的性能进行了比较，跨越IFU仪器中可能的填充分数和输入f比范围。当用F/3.4至>F/8的输入进料时，测试具有7-芯和61-芯的六束的焦比退化（FRD）、通量和串扰。五个7芯束的包层厚度范围为1至8微米，61芯束的包层厚度为5微米。正如预期的那样，FRD随着输入焦比的减小而改善。我们发现，FRD和吞吐量的核心在hexabundles匹配的性能相同的材料在低输入f-比率的单纤维。所给出的性能结果可用于根据计划仪器允许的最大损耗对系统的f比设置限制。我们的研究结果证实，hexabundles是一个成功的替代光纤成像设备的多目标光谱的宽视场望远镜，并促使进一步发展的hexabundle设计与六角形包装和方形核心。
We are now moving into an era where multi-object wide-field surveys, which traditionally use single fibres to observe many targets simultaneously, can exploit compact integral field units in place of single fibres. Current multi-object integral field instruments such as SAMI (Croom et al. 2012; Bryant et al. 2012a) have driven the development of new imaging fibre bundles (hexabundles) for multi-object spectrographs. We have characterised the performance of hexabundles with different cladding thicknesses and compared them to that of the same type of bare fibre, across the range of fill-fractions and input f-ratios likely in an IFU instrument. Hexabundles with 7-cores and 61-cores were tested for focal ratio degradation (FRD), throughput and cross-talk when fed with inputs from F/3.4 to >F/8. The five 7-core bundles have cladding thickness ranging from 1 to 8 microns, and the 61-core bundles have 5micron cladding. As expected, the FRD improves as the input focal ratio decreases. We find that the FRD and throughput of the cores in the hexabundles match the performance of single fibres of the same material at low input f-ratios. The performance results presented can be used to set a limit on the f-ratio of a system based on the maximum loss allowable for a planned instrument. Our results confirm that hexabundles are a successful alternative for fibre imaging devices for multi-object spectroscopy on wide-field telescopes and have prompted further development of hexabundle designs with hexagonal packing and square cores.