Duarte Joana, Gonzalez Aura Inés, Cassin Rémy, Nicolas Rana, Kholodstova Maria, Boutu Willem, Fajardo Marta, Merdji Hamed
Opt Lett. 2021 Apr 1;46(7):1764-1767. doi: 10.1364/OL.413643.
Spatial coherence is an impactful source parameter in many applications ranging from atomic and molecular physics to metrology or imaging. In lensless imaging, for example, it can strongly affect the image formation, especially when the source exhibits shot-to-shot variations. Single-shot characterization of the spatial coherence length of a source is thus crucial. However, current techniques require either parallel intensity measurements or the use of several masks. Based on the method proposed by González et al. [J. Opt. Soc. Am. A28, 1107 (2011)JOAOD60740-323210.1364/JOSAA.28.001107], we designed a specific arrangement of a two-dimensional non-redundant array of apertures, which allows, through its far field interference pattern, for a single-shot measurement of the spatial coherence, while being robust against beam-pointing instabilities. The strategic configuration of the pinholes allows us to disentangle the degree of spatial coherence from the intensity distribution, thus removing the need for parallel measurement of the beam intensity. An experimental validation is performed using a high-harmonic source. A statistical study in different regimes shows the robustness of the method.
空间相干性在从原子和分子物理到计量学或成像等许多应用中都是一个有影响力的源参数。例如，在无透镜成像中，它会强烈影响图像形成，特别是当源表现出逐次变化时。因此，对源的空间相干长度进行单次表征至关重要。然而，目前的技术要么需要并行强度测量，要么需要使用多个掩模。基于冈萨雷斯等人提出的方法[《美国光学学会杂志A》28, 1107 (2011)JOAOD60740 - 323210.1364/JOSAA.28.001107]，我们设计了一种二维非冗余孔径阵列的特定排列，通过其远场干涉图样，可以对空间相干性进行单次测量，同时对光束指向不稳定性具有鲁棒性。针孔的策略性配置使我们能够从强度分布中解算出空间相干度，从而无需对光束强度进行并行测量。使用高谐波源进行了实验验证。在不同条件下的统计研究表明了该方法的鲁棒性。
