Pu Ye, Centurion Martin, Psaltis Demetri
Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Appl Opt. 2008 Feb 1;47(4):A103-10. doi: 10.1364/ao.47.00a103.
The process of second harmonic generation (SHG) has a unique property of forming a sharp optical contrast between noncentrosymmetric crystalline materials and other types of material, which is a highly valuable asset for contrast microscopy. The coherent signal obtained through SHG also allows for the recording of holograms at high spatial and temporal resolution, enabling whole-field four-dimensional microscopy for highly dynamic microsystems and nanosystems. Here we describe a new holographic principle, harmonic holography (H(2)), which records holograms between independently generated second harmonic signals and reference. We experimentally demonstrate this technique with digital holographic recording of second harmonic signals upconverted from an ensemble of second harmonic generating nanocrystal clusters under femtosecond laser excitation. Our results show that harmonic holography is uniquely suited for ultrafast four-dimensional contrast microscopy.
二次谐波产生（SHG）过程具有一种独特特性，即在非中心对称晶体材料与其他类型材料之间形成明显的光学对比度，这对于对比度显微镜而言是一项极具价值的资产。通过SHG获得的相干信号还能以高空间和时间分辨率记录全息图，从而实现对高动态微系统和纳米系统的全场四维显微镜成像。在此，我们描述一种新的全息原理——谐波全息术（H(2)），它在独立产生的二次谐波信号与参考信号之间记录全息图。我们通过飞秒激光激发下对由二次谐波产生纳米晶体簇集合上转换得到的二次谐波信号进行数字全息记录，对该技术进行了实验验证。我们的结果表明，谐波全息术特别适用于超快四维对比度显微镜成像。
