（9月10日）Roger Proksch 博士（突破噪声极限：利用干涉式原子力显微镜揭示隐藏的结构与动态）

广东省磁电物性分析与器件重点实验室学术讲座（第九十一期）

报告人: 

Dr. Roger Proksch（Oxford Instruments）

题目: 

突破噪声极限：利用干涉式原子力显微镜揭示隐藏的结构与动态

地点：

中山大学南校园550栋二楼报告厅

时间: 

2026年9月10日（星期四）下午15:00

主持人：

张潇悦 副教授

报告简介：

Many AFM measurements are limited by detector noise and bandwidth rather than cantilever motion. Conventional optical beam deflection typically has a displacement-noise density of  often requiring filtering, averaging, resonant amplification, or larger excitations that can obscure dynamics or perturb sensitive materials. Quadrature phase differential interferometry (QPDI) detection reduces this noise to approximately  below the Brownian motion of many AFM cantilevers. This enables a variety of measurements that have previously been hidden from view. In the first example, we will explore force-distance curves, in some sense the most direct and common measurement an Atomic Force Microscope (AFM) can make. To date, the vast majority of force curves measured are filtered well below the cantilever resonance, often to accommodate high detector noise levels and effects that are labeled as “noise” or “parasitic”. Improved noise performance uncovers hidden dynamics in ambient force curves, including oscillations driven by discontinuous changes as the tip experiences both the air-liquid and solid-liquid interface. Notably, the sensitivity of the method is high enough to directly measure the contact resonance of the probe – driven by only the snap to contact and Brownian motion – without any other actuation. This enables real-time contact resonance stiffness and dissipation mapping. In the second example we will explore is Piezoresponse force microscopy (PFM), a widely used technique for nanoscale electromechanical imaging. Quantitative measurements — especially on weak or fragile ferroelectrics — are often limited by displacement detector noise. In conventional optical beam–deflection PFM, researchers frequently increase the AC drive voltage to overcome this noise, which can introduce electrostatic crosstalk, Joule heating, charge injection/ionic motion, and even unintended tip-induced switching that modifies the very domain structures under study. These constraints are particularly severe for emerging low-voltage, weak-response materials such as hafnia-based thin films, anti-ferroelectrics, and 2D ferroelectrics, where reliable imaging and switching spectroscopy at small biases is essential but difficult to achieve with state-of-the-art approaches. We present interferometrically detected, resonance-enhanced dual AC resonance tracking (iDART), which combines femtometer-scale displacement sensitivity from quadrature phase differential interferometry (QPDI) with contact-resonance amplification and dual-frequency tracking. This hybrid approach delivers a ≥10× improvement in signal-to-noise relative to leading PFM modalities, enabling imaging and switching spectroscopy at substantially reduced excitation levels, down to a few thermal voltages.

报告人简介：

Roger Proksch 博士是原子力显微镜（AFM）领域公认的领军人物， Oxford Instruments 集团首席技术官、Asylum Research 联合创始人兼首席技术官，同时担任 University of Tennessee, Knoxville 材料科学系兼职教授，全球材料学科学家排名8000名。

Roger 博士拥有 University of Minnesota 凝聚态物理博士学位，早年曾任职于全球首家AFM商业化公司 Digital Instruments 担任 Staff Scientist，深耕 AFM 技术研发与产品优化，积累了丰富的纳米表征技术产业化经验。1999年他联合创立 Asylum Research，从零起步打造出 Cypher、Vero、Jupiter Discovery 等多款行业标杆级 AFM 产品，其中 Vero AFM 斩获2024年 R&D 100奖。

学术与行业影响力方面，Roger 博士发表超100篇顶级期刊论文，h -index 52，拥有39项美国授权专利，专利技术应用于数千台设备。他曾任 American Physical Society（APS）仪器与测量科学专题组主席，是 NASA “Icy Worlds”论坛成员、Piezoresponse Force Microscopy（PFM）创始董事会成员，多次组织国际学术研讨会，还曾荣获多项 R&D 100奖项。

作为兼具学术高度与产业深度的专家，Roger 博士始终引领 AFM 技术创新方向，推动纳米表征技术的跨界应用与成果转化，是行业内公认的技术引领者与创新推动者。