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Proceedings Paper

Soft x-ray holographic tomography for biological specimens
Author(s): Hongyi Gao; Jianwen Chen; Honglan Xie; Ruxin Li; Zhizhan Xu; Shiping Jiang; Yuxuan Zhang
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Paper Abstract

In this paper, we present some experimental results on X -ray holography, holographic tomography, and a new holographic tomography method called pre-amplified holographic tomography is proposed. Due to the shorter wavelength and the larger penetration depths, X-rays provide the potential of higher resolution in imaging techniques, and have the ability to image intact, living, hydrated cells w ithout slicing, dehydration, chemical fixation or stain. Recently, using X-ray source in National Synchrotron Radiation Laboratory in Hefei, we have successfully performed some soft X-ray holography experiments on biological specimen. The specimens used in the experiments was the garlic clove epidermis, we got their X-ray hologram, and then reconstructed them by computer programs, the feature of the cell walls, the nuclei and some cytoplasm were clearly resolved. However, there still exist some problems in realization of practical 3D microscopic imaging due to the near-unity refractive index of the matter. There is no X-ray optics having a sufficient high numerical aperture to achieve a depth resolution that is comparable to the transverse resolution. On the other hand, computer tomography needs a record of hundreds of views of the test object at different angles for high resolution. This is because the number of views required for a densely packed object is equal to the object radius divided by the desired depth resolution. Clearly, it is impractical for a radiation-sensitive biological specimen. Moreover, the X-ray diffraction effect makes projection data blur, this badly degrades the resolution of the reconstructed image. In order to observe 3D structure of the biological specimens, McNulty proposed a new method for 3D imaging called "holographic tomography (HT)" in which several holograms of the specimen are recorded from various illumination directions and combined in the reconstruction step. This permits the specimens to be sampled over a wide range of spatial frequencies to improve the depth resolution. In NSRL, we performed soft X-ray holographic tomography experiments. The specimen was the spider filaments and PM M A as recording medium. By 3D CT reconstruction of the projection data, three dimensional density distribution of the specimen was obtained. Also, we developed a new X-ray holographic tomography m ethod called pre-amplified holographic tomography. The method permits a digital real-time 3D reconstruction with high-resolution and a simple and compact experimental setup as well.

Paper Details

Date Published: 14 October 2003
PDF: 9 pages
Proc. SPIE 5143, Novel Optical Instrumentation for Biomedical Applications, (14 October 2003); doi: 10.1117/12.499544
Show Author Affiliations
Hongyi Gao, Shanghai Institute of Optics and Fine Mechanics (China)
Jianwen Chen, Shanghai Institute of Optics and Fine Mechanics (China)
Honglan Xie, Shanghai Institute of Optics and Fine Mechanics (China)
Ruxin Li, Shanghai Institute of Optics and Fine Mechanics (China)
Zhizhan Xu, Shanghai Institute of Optics and Fine Mechanics (China)
Shiping Jiang, National Synchrotron Radiation Lab. (China)
Yuxuan Zhang, National Synchrotron Radiation Lab. (China)

Published in SPIE Proceedings Vol. 5143:
Novel Optical Instrumentation for Biomedical Applications
Albert-Claude Boccara, Editor(s)

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