A quantitative comparison of amplitude versus intensity interferometry for astronomy
A quantitative comparison of amplitude versus intensity interferometry for astronomy
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DOI：
10.1088/1367-2630/ac5f30
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发表时间：
2022-04-01
影响因子：
3.3
通讯作者：
von Zanthier, Joachim
中科院分区：
文献类型：
--
作者：
Bojer, Manuel;Huang, Zixin;von Zanthier, Joachim
天文成像大致可分为两类。第一种是振幅干涉测量法，包括常规光学望远镜和甚大基线干涉测量法。第二种类型是强度干涉测量法，它依赖于Hanbury Brown和Twiss类型的测量。在光学频率下，直接相位测量是不可能的，振幅干涉法具有有效的数值孔径，其受到光子可以相干干涉的距离的限制。另一方面，强度干涉法仅关联光子通量，因此可以支持更大的数值孔径，但由于热光中每模平均光子数较低，因此信号会减少。在现实条件下，哪种方法更上级，至今还不清楚。在这里，我们给出了振幅和强度干涉测量的性能的比较分析，我们将其与在任何物理测量中可以实现的基本分辨率限制。使用确定两个远距离热点源之间的间隔的基准问题，例如，两个相邻的恒星，我们给出了一个简短的教程最佳估计理论，并将其应用到恒星干涉测量。我们发现，对于非常小的角间距的大基线实现强度干涉可以超过补偿降低的信号强度。我们还探讨了非常大的基线强度干涉测量（VLBII）的实际实施方案。
Astronomical imaging can be broadly classified into two types. The first type is amplitude interferometry, which includes conventional optical telescopes and very large baseline interferometry (VLBI). The second type is intensity interferometry, which relies on Hanbury Brown and Twiss-type measurements. At optical frequencies, where direct phase measurements are impossible, amplitude interferometry has an effective numerical aperture that is limited by the distance from which photons can coherently interfere. Intensity interferometry, on the other hand, correlates only photon fluxes and can thus support much larger numerical apertures, but suffers from a reduced signal due to the low average photon number per mode in thermal light. It has hitherto not been clear which method is superior under realistic conditions. Here, we give a comparative analysis of the performance of amplitude and intensity interferometry, and we relate this to the fundamental resolution limit that can be achieved in any physical measurement. Using the benchmark problem of determining the separation between two distant thermal point sources, e.g., two adjacent stars, we give a short tutorial on optimal estimation theory and apply it to stellar interferometry. We find that for very small angular separations the large baseline achievable in intensity interferometry can more than compensate for the reduced signal strength. We also explore options for practical implementations of very large baseline intensity interferometry (VLBII).