Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche (CNR), Via Fosso del Cavaliere 100, 00133 Rome, Italy.
Department of Physics and Astronomy, University of Padova, Via Marzolo 8, I-35131 Padova, Italy.
Rev Sci Instrum. 2023 Feb 1;94(2):023704. doi: 10.1063/5.0133488.
Scattering scanning near-field optical microscopes (s-SNOMs) based on pseudoheterodyne detection and operating at ambient conditions typically suffer from instabilities related to the variable optical path length of the interferometer arms. These cause strong oscillations in the measured optical amplitude and phase comparable with those of the signal and, thus, resulting in dramatic artifacts. Besides hampering the comparison between the topography and the optical measurements, such oscillations may lead to misinterpretations of the physical phenomena occurring at the sample surface, especially for nanostructured materials. Here, we propose a stabilizing method based on interferometer phase control, which improves substantially the image quality and allows the correct extraction of optical phase and amplitude for both micro- and nanostructures. This stabilization method expands the measurement capabilities of s-SNOM to any slowly time-dependent phenomena that require long-term stability of the system. We envisage that active stabilization will increase the technological significance of s-SNOMs and will have far-reaching applications in the field of heat transfer and nanoelectronics.
基于伪外差探测的散射近场光学显微镜（s-SNOM）在环境条件下运行时通常会受到干涉仪臂光程变化相关的不稳定性的影响。这些不稳定性会导致测量的光振幅和相位发生强烈振荡，与信号的振幅和相位相当，从而导致明显的伪像。除了妨碍形貌和光学测量之间的比较外，这种振荡可能导致对样品表面发生的物理现象的误解，特别是对于纳米结构材料。在这里，我们提出了一种基于干涉仪相位控制的稳定化方法，该方法显著提高了图像质量，并允许正确提取微结构和纳米结构的光学相位和振幅。这种稳定化方法扩展了 s-SNOM 的测量能力，可以应用于任何需要系统长期稳定的随时间缓慢变化的现象。我们预计，主动稳定化将增加 s-SNOM 的技术意义，并在传热和纳米电子学领域具有广泛的应用。
