Asymmetric Beam Combination for Optical Interferometry
Asymmetric Beam Combination for Optical Interferometry
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DOI：
10.1086/320288
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发表时间：
2001-03
影响因子：
3.5
通讯作者：
J. Monnier
中科院分区：
文献类型：
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作者：
J. Monnier
光学干涉仪越来越多地使用单模光纤作为空间滤波器，将变化的波前失真转换为强度波动，可以监测这些波动，以便精确校准条纹幅度。在这里，我建议使用一个不对称的耦合器，使每个望远镜光束的光度强度进行测量的同时，条纹的可见性，但不需要专用的光度输出，这减少了光的干涉通道的吞吐量。在红外线中经常遇到的读取噪声受限的情况下，我表明，与具有50%光度抽头的平衡耦合器设置相比，可见度幅度测量的信噪比提高了53%（例如，Fluor实验）。在适用于可见光的泊松噪声极限下，改进降低到仅1.8%。该方案还降低了光束组合的成本和复杂性，因为需要更少的组件和检测器，并且因为它可以扩展到两个以上的望远镜，用于“一体化”或成对光束组合。非对称光束组合也可以用于监测系统中的闪烁和吞吐量变化，而无需空间滤波。
Optical interferometers increasingly use single‐mode fibers as spatial filters to convert varying wave‐front distortion into intensity fluctuations which can be monitored for accurate calibration of fringe amplitudes. Here I propose using an asymmetric coupler to allow the photometric intensities of each telescope beam to be measured at the same time as the fringe visibility but without the need for dedicated photometric outputs, which reduce the light throughput in the interferometric channels. In the read‐noise–limited case often encountered in the infrared, I show that a 53% improvement in signal‐to‐noise ratio for the visibility amplitude measurement is achievable, when compared to a balanced coupler setup with 50% photometric taps (e.g., the FLUOR experiment). In the Poisson‐noise limit appropriate for visible light, the improvement is reduced to only ∼8%. This scheme also reduces the cost and complexity of the beam combination since fewer components and detectors are required and since it can be extended to more than two telescopes for “all‐in‐one” or pairwise beam combination. Asymmetric beam combination can also be employed for monitoring scintillation and throughput variations in systems without spatial filtering.