电子显微镜是如何工作的？
发布日期：2023年07月16日 分类：物理学
电子显微镜是一种强大的工具，它使用电子束而不是光束来观察样品。它能够提供比光学显微镜更高的放大倍数和更高的分辨率。
首先，电子显微镜包含一个电子枪，它产生出速度极高且带有较短波长的电子束。电子束经过电磁透镜系统进行聚焦，然后射向样品。
当电子束与样品相互作用时，它们会发生散射和吸收。样品中的原子和分子会散射电子，这导致产生电子衍射图案。这些电子衍射图案包含了关于样品的结构和组成的信息。
电子束在样品上的散射后，进入到检测器中。最常用的检测器是底片或荧光屏。底片会记录电子通过样品时的强度变化，而荧光屏则可将电子的能量转化为可见光，并通过摄像机进行捕捉。
为了提高分辨率，电子显微镜使用了极为精确的透镜系统和准确的对焦机制。它们通过调整透镜的焦距来聚焦电子束，以便在样品上形成清晰的图像。
电子显微镜还可以使用扫描电子显微镜（SEM）模式或透射电子显微镜（TEM）模式来观察样品。SEM模式使用电子束扫描样品的表面，通过收集从样品表面散射的电子来重建图像。而TEM模式则使电子束透过样品，并记录透过样品的电子的衰减和散射情况，以产生高分辨率的图像。
总而言之，电子显微镜通过使用电子束和高度精确的透镜系统来观察样品。它们能够提供比光学显微镜更高的放大倍数和更高的分辨率，使我们能够看到细胞、纳米级结构和微小颗粒等微观尺度的细节。
首先，电子显微镜包含一个电子枪，它产生出速度极高且带有较短波长的电子束。电子束经过电磁透镜系统进行聚焦，然后射向样品。
当电子束与样品相互作用时，它们会发生散射和吸收。样品中的原子和分子会散射电子，这导致产生电子衍射图案。这些电子衍射图案包含了关于样品的结构和组成的信息。
电子束在样品上的散射后，进入到检测器中。最常用的检测器是底片或荧光屏。底片会记录电子通过样品时的强度变化，而荧光屏则可将电子的能量转化为可见光，并通过摄像机进行捕捉。
为了提高分辨率，电子显微镜使用了极为精确的透镜系统和准确的对焦机制。它们通过调整透镜的焦距来聚焦电子束，以便在样品上形成清晰的图像。
电子显微镜还可以使用扫描电子显微镜（SEM）模式或透射电子显微镜（TEM）模式来观察样品。SEM模式使用电子束扫描样品的表面，通过收集从样品表面散射的电子来重建图像。而TEM模式则使电子束透过样品，并记录透过样品的电子的衰减和散射情况，以产生高分辨率的图像。
总而言之，电子显微镜通过使用电子束和高度精确的透镜系统来观察样品。它们能够提供比光学显微镜更高的放大倍数和更高的分辨率，使我们能够看到细胞、纳米级结构和微小颗粒等微观尺度的细节。
How does an electron microscope work?
The electron microscope is a powerful tool that uses an electron beam instead of a light beam to observe specimens. It can provide higher magnification and resolution than an optical microscope.
First, the electron microscope consists of an electron gun that produces a highly accelerated electron beam with a shorter wavelength. The electron beam is then focused through an electromagnetic lens system before it is directed towards the specimen.
When the electron beam interacts with the specimen, scattering and absorption occur. The atoms and molecules in the specimen scatter the electrons, resulting in electron diffraction patterns. These diffraction patterns contain information about the structure and composition of the specimen.
After scattering on the specimen, the electron beam enters a detector. The most commonly used detectors are film or a fluorescent screen. The film records the intensity changes of the electron beam passing through the specimen, while the fluorescent screen converts the energy of the electrons into visible light, which is then captured by a camera.
To enhance the resolution, electron microscopes employ highly precise lens systems and accurate focusing mechanisms. They focus the electron beam by adjusting the lens focal length to form a clear image on the specimen.
Electron microscopes can also be used in scanning electron microscope (SEM) mode or transmission electron microscope (TEM) mode to observe specimens. SEM mode scans the surface of the specimen with the electron beam and reconstructs the image by collecting electrons scattered from the surface. TEM mode allows the electron beam to pass through the specimen and records the attenuation and scattering of electrons, resulting in high-resolution images.
In conclusion, electron microscopes observe specimens using an electron beam and highly precise lens systems. They provide higher magnification and resolution than optical microscopes, allowing us to see details at the microscale such as cells, nanoscale structures, and tiny particles.
First, the electron microscope consists of an electron gun that produces a highly accelerated electron beam with a shorter wavelength. The electron beam is then focused through an electromagnetic lens system before it is directed towards the specimen.
When the electron beam interacts with the specimen, scattering and absorption occur. The atoms and molecules in the specimen scatter the electrons, resulting in electron diffraction patterns. These diffraction patterns contain information about the structure and composition of the specimen.
After scattering on the specimen, the electron beam enters a detector. The most commonly used detectors are film or a fluorescent screen. The film records the intensity changes of the electron beam passing through the specimen, while the fluorescent screen converts the energy of the electrons into visible light, which is then captured by a camera.
To enhance the resolution, electron microscopes employ highly precise lens systems and accurate focusing mechanisms. They focus the electron beam by adjusting the lens focal length to form a clear image on the specimen.
Electron microscopes can also be used in scanning electron microscope (SEM) mode or transmission electron microscope (TEM) mode to observe specimens. SEM mode scans the surface of the specimen with the electron beam and reconstructs the image by collecting electrons scattered from the surface. TEM mode allows the electron beam to pass through the specimen and records the attenuation and scattering of electrons, resulting in high-resolution images.
In conclusion, electron microscopes observe specimens using an electron beam and highly precise lens systems. They provide higher magnification and resolution than optical microscopes, allowing us to see details at the microscale such as cells, nanoscale structures, and tiny particles.