Optical Sectioning Microscopy by Wavelength Scanning Digital Interference Holography

该奖项将开发一种简单但新颖和多功能的数字全息显微镜设备，用于对三维微观体物体进行成像。从该装置获得的合成图像在横向和纵向都将具有亚微米级的分辨率。此外，完全抑制了因物面失焦而造成的图像模糊和降级。该装置基于一系列数字记录的全息图像的数字重建和干涉，同时扫描照明激光的波长。由于全息图保留了光场的所有幅度和相位信息，并且由于全息图的数字操作的自由，所以有可能在数字虚拟空间中执行在物理空间中完全不可能的干涉过程。当多个不同波长的全息再现光场叠加时，如果波长是规则分布的，则它们之间的干涉导致光强度仅集中在物点--光在空间中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或不规则性相对应的点，例如细胞表面和结构，才会呈现明亮的图像斑点。显示效果类似于扫描共聚焦显微镜图像，但该系统显示出显著的潜在优势。它没有机械运动部分，图像采集由N次曝光的二维图像组成，而不是逐个像素地建立3D体积。可以成像的物体的物理尺寸和分辨率的范围很容易通过适当选择波长间隔来控制。并且利用容易获得的全息相位信息，进一步的干涉或全息图像处理是可能的。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，可以进一步操作以用于特定应用，如校正比例扭曲、任意截面和剪切视图，以及自动特征增强和识别。该系统提供了一种获取和处理显微物体的三维数字模型的简单而通用的模式，有可能对显微光学成像的一般领域产生影响。

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.