用于表面法向振动波形重建的基于事件的空间载波干涉术
Event-Based Spatial-Carrier Interferometry for Surface-Normal Vibration-Waveform Reconstruction
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中文总结 AI 辅助
该研究提出基于事件的空间载波干涉术，利用事件相机从移动干涉条纹重建表面法向振动波形，其结果与激光多普勒测振仪一致，为全场非接触振动测量提供了新方案。
中文摘要 AI 辅助
垂直于表面的微小振动的非接触测量可用于评估机械结构，但在基于相机的干涉测量中，帧率的提升会与视场和空间分辨率形成权衡。事件相机仅记录亮度变化，可避免该权衡并达到高时间与空间分辨率；我们此前报道的基于事件拓扑的视觉振动计可从表观运动中恢复振动。这种高速、高分辨率传感非常适用于全场测量，但此类振动产生的表观运动过小，无法捕获其波形。本文展示基于事件的空间载波干涉术可从移动干涉条纹中重建该波形。位移使条纹移动，从事件流构建的带符号事件密度图在空间载波处被解调，以恢复干涉相位并在转折点处修正原本模糊的运动方向。在宽驱动频率和振幅范围内，重建波形与激光多普勒测振仪的结果一致，其极限由最大条纹速度和传感器性能决定。重建受限于沿载波方向约2个条纹周期、沿条纹方向1个条纹周期的最小孔径，这使得可逐区域映射表面。这些结果为将事件相机作为非接触测量技术，实现全场、空间分辨的干涉振动测量提供了实验基础。
英文摘要
Non-contact measurement of small vibrations perpendicular to a surface supports the evaluation of mechanical structures, but in camera-based interferometry, increasing the frame rate makes a trade-off with the field of view and spatial resolution. By recording only brightness changes, event cameras avoid this trade-off and reach high temporal and spatial resolution; our previously reported event topology-based visual vibrometer recovers vibration from apparent motion. This high-speed, high-resolution sensing is well suited to full-field measurement, yet such vibration produces too little apparent motion to capture its waveform. Here we show that event-based spatial-carrier interferometry reconstructs that waveform from moving interference fringes. That displacement moves the fringes, and signed event-density maps built from the event stream are demodulated at the spatial carrier to recover the interferometric phase and fix the otherwise ambiguous motion direction at turning points. Reconstructed waveforms agree with laser Doppler vibrometry over broad drive-frequency and amplitude ranges, with limits set by the maximum fringe speed and the sensor performance. Reconstruction is limited by a minimum aperture of about two fringe periods along the carrier and one along the fringes, which allows the surface to be mapped region by region. These results provide an empirical basis for full-field, spatially resolved interferometric vibrometry with event cameras as a non-contact measurement technique.
