Wen Chenyang, Feng Fu, Ren Mindan, Somekh Michael G, Zhao Ni, Chen Shih-Chi
Opt Lett. 2019 Aug 15;44(16):4083-4086. doi: 10.1364/OL.44.004083.
In this Letter, we present a spatially resolved pump-probe microscope based on a digital micromirror device (DMD). The microscope system enables the measurements of ultrafast transient processes at arbitrarily selected regions in a 3-D specimen. To achieve random-access scanning, the wavefront of the probe beam is modulated by the DMD via binary holography. By switching the holograms stored in the DMD memory, the laser focus can be rapidly moved in space in a discrete fashion. The microscope system has a field of view of 65×130×155 μm in the x, y, and z axes, respectively; and a scanning speed of 8 kHz which is limited by the response time of the lock-in amplifier. To demonstrate the pump-probe system, we measured the ultrafast transient reflectivity of 2-D gold patterns on a silicon substrate and on silicon nitride cantilever beams. The results show an excellent signal-to-noise ratio and spatial-temporal resolution, as well as the 3-D random scanning capability. The new pump-probe microscope is a versatile instrument to characterize ultrafast 3-D phenomena with high spatial and temporal resolution, e.g., the propagation of localized surface plasmon resonance on curved surfaces.
在本信函中，我们展示了一种基于数字微镜器件（DMD）的空间分辨泵浦 - 探测显微镜。该显微镜系统能够对三维样本中任意选定区域的超快瞬态过程进行测量。为实现随机访问扫描，探测光束的波前由DMD通过二元全息术进行调制。通过切换存储在DMD存储器中的全息图，激光焦点可在空间中以离散方式快速移动。该显微镜系统在x、y和z轴上的视野分别为65×130×155μm；扫描速度为8kHz，这受锁相放大器响应时间限制。为展示泵浦 - 探测系统，我们测量了硅衬底和氮化硅悬臂梁上二维金图案的超快瞬态反射率。结果显示出优异的信噪比和时空分辨率，以及三维随机扫描能力。这种新型泵浦 - 探测显微镜是一种多功能仪器，可用于以高空间和时间分辨率表征超快三维现象，例如，局域表面等离子体共振在曲面上的传播。
