Shankar Nayak Abani, Poletti Thomas, Sharma Tarun Kumar, Madhav Kalaga, Pedretti Ettore, Labadie Lucas, Roth Martin M
Opt Express. 2020 Nov 9;28(23):34346-34361. doi: 10.1364/OE.405896.
We show the results of simulation and experimental study of a 4-telescope zig-zag discrete beam combiner (DBC) for long-baseline stellar interferometry working at the astronomical L band (3 - 4 µm) under the influence of a narrow bandwidth light source. Following Saviauk et al. (2013), we used a quasi-monochromatic visibility-to-pixel matrix (V2PM) for retrieving the complex coherence functions from simulated and experimentally measured power at the output of the device. Simulation and coefficient of determination (R) measurements show that we are able to retrieve the visibility amplitudes with >95 % accuracy of our chromatic model source up to a bandwidth of 100 nm centred at 3.5 µm. We characterized a DBC manufactured by 3D ultra-fast laser inscription (ULI) written on gallium lanthanum sulphate (GLS). Experimental results showed retrieval of visibility amplitude with an accuracy of 80-90 % at 69 nm bandwidth, validating our simulation. The standard deviation of experimental phase residuals are between 0.1-0.4 rad, which shows that the retrieval procedure is sufficient to get good quality images, where phase perturbations of less than 1 rad are expected under good seeing conditions for astronomical applications.
我们展示了一种用于长基线恒星干涉测量的4望远镜之字形离散光束组合器（DBC）在窄带宽光源影响下，于天文L波段（3 - 4 µm）工作的模拟和实验研究结果。遵循萨维亚克等人（2013年）的方法，我们使用准单色可见度到像素矩阵（V2PM）从该设备输出端的模拟和实验测量功率中检索复相干函数。模拟和测定系数（R）测量表明，我们能够以大于95%的精度检索可见度幅度，对于以3.5 µm为中心、带宽达100 nm的色度模型源而言。我们对通过在硫酸镧镓（GLS）上进行3D超快速激光刻写（ULI）制造的DBC进行了表征。实验结果表明，在69 nm带宽下，可见度幅度的检索精度为80 - 90%，验证了我们的模拟。实验相位残差的标准偏差在0.1 - 0.4弧度之间，这表明该检索过程足以获得高质量图像，在天文应用的良好视宁条件下，预期相位扰动小于1弧度。
