MRI: Development of Zernike Phase Contrast For Biological Electron Microscopy

这项主要研究仪器奖资助加州大学伯克利分校开发一种用于低温透射电镜的新型泽尼克激光相位板。在泽尼克相衬显微镜中，物镜焦平面上的四分之一波片改变光束未衍射部分的相位，以提供最佳的相位调制转换为图像对比度。新的激光相位板将允许研究人员在最佳相位对比模式下无限期地操作tem。与散焦明场法相比，生物大分子和超分子结构成像的对比度可提高10倍之多。此外，制造微小焦点的可能性和光学调谐的可能性使得成像更低的空间频率成为可能，并提供比微制造相板更大的灵活性。这种新的相对比系统将用于研究分子和细胞生物学中的问题，这些问题超出了现有技术在电子显微镜，x射线晶体学或多维核磁共振光谱中的范围。最后，我们期望在基础物理学中有更多的应用，例如，为几乎任何物种的原子和分子开发光学偶极子阱，甚至能够捕获室温样品。发展工作的成果将通过摘要和同行审查的出版物以及学生和教员积极参加专业会议而广泛传播。

This Major Research Instrumentation award funds the development of a novel Zernike laser phase plate for cryo-TEM at University of California-Berkeley. In Zernike phase contrast microscopy, a quarter-wave plate in the focal plane of the object lens shifts the phase of the undiffracted part of the beam to provide optimal conversion of phase modulations into image contrast. The new laser phase plate will allow researchers to operate TEMs in an optimal phase-contrast mode for indefinite periods of time. Compared with defocused bright field method, the contrast in the imaging of biological macromolecules and supramolecular structures could be as much as ten times greater. Moreover, the possibility to make a tiny focus and the possibility to tune it optically makes it possible to image lower spatial frequencies and offers greater flexibility than with microfabricated phase plates. This new phase contrast system will be used to investigate problems in molecular and cell biology that are out of the reach of existing techniques in electron microscopy, x-ray crystallography, or multi-dimensional NMR spectroscopy. Finally, we anticipate additional applications in fundamental physics, e.g., developing an optical dipole trap for atoms and molecules of almost any species, with the ability to trap even room-temperature samples. The results of the development effort will be broadly disseminated through abstracts and peer reviewed publications, as well as by active participation of students and faculty at professional meetings.