Optical Sectioning Microscopy by Wavelength Scanning Digital Interference Holography

该奖项将开发一种简单而新颖的多功能数字全息显微镜设备，用于成像三维微观物体。从该装置获得的最终图像在横向和纵向上都具有亚微米分辨率。而且，完全抑制了因物面失焦引起的图像模糊和退化。该装置基于数字重建和许多数字记录全息图像的干涉，同时扫描照明激光的波长。由于全息图保留了光场的振幅和相位信息，并且由于全息图的数字操作的自由，因此可以在数字虚拟空间中进行在物理空间中完全不可能进行的干涉过程。当许多不同波长的全息再现光场叠加在一起时，如果波长是有规则间隔的，那么它们之间的干涉会导致光强度只集中在物体点上——光通过空间的传播实际上被消除了。当在图像平面上进行数值聚焦时，只有与物体的任何不连续性或不规则性（如细胞表面和结构）相对应的点才能呈现出明亮的图像点。由此产生的效果类似于扫描共聚焦显微镜图像，但该系统具有显著的潜在优势。它没有机械活动部件。图像采集由二维图像的N次曝光组成，而不是逐像素构建3D体积。通过适当选择波长间隔，可以很容易地控制被成像物体的物理尺寸和分辨率范围。由于全息相位信息容易获得，进一步的干涉测量或全息图像处理成为可能。此外，获奖系统的光学切片图像可以重新组装成三维数字模型，该模型可以进一步用于特定应用，例如比例失真的校正，任意切片和切割视图，以及自动特征增强和识别。该系统通过提供一种获取和操作微观物体三维数字模型的简单而通用的模式，有可能影响微观光学成像的一般领域。

This award will develop a simple yet novel and versatile digital holographic microscopedevice for imaging three-dimensional microscopic volume objects. The resultant imagesobtained from this device will have submicron resolution in both the lateral andlongitudinal directions. Moreover, the blurring and degrading of images due to out-of-focus object planes are completely suppressed. The device is based on numericalreconstruction and interference of a number of digitally recorded holographic images,while the wavelength of the illuminating laser is scanned. Because a hologram retainsall of the amplitude and phase information of the light field and because of the freedomof digital manipulation of the holograms, it is possible to carry out an interferenceprocess in the numerical virtual space that is quite impossible in physical space. Whena number of holographically recreated light fields of varying wavelengths aresuperposed, and if the wavelengths are regularly spaced, then the interference amongthem result in the light intensity being concentrated at object points only - propagationof light through space is in effect eliminated. When focused, numerically, on animage plane, only those points corresponding to any discontinuities or irregularities,such as cellular surfaces and structures, of the object render bright image spots. Theresulting effect is analogous to scanning confocal microscope images, but thissystem presents significant potential advantages. It has no mechanical moving parts.The image acquisition consists of N exposures of two dimensional images, instead ofpixel-by-pixel build-up of 3D volume. The range of physical sizes and resolution ofobjects that can be imaged is readily controlled by proper choice of the wavelengthintervals. And with the holographic phase information readily available, furtherinterferometric or holographic image processing is possible. Furthermore, the opticalsectioned images of the awarded system can be reassembled into a three-dimensionaldigital model that can be further manipulated for specific applications, such ascorrection of scale distortion, arbitrary section and cut-away views, and automaticfeature enhancement and identification. This system has a potential to impactthe general field of microscopic optical imaging by providing a simple and versatilemode of acquiring and manipulating three-dimensional digital model of microscopicobjects.