What is the Difference Between Scanning Electron Microscope and Optical Microscope
1. Different definitions:
Optical microscope is an optical instrument that uses optical principles to magnify and image tiny objects that cannot be distinguished by the human eye, so that people can extract microstructure information.
The application of fully automatic scanning electron microscopy technology is based on the optical microscope. 1000x magnification.
2. Different categories:
Optical microscopes have a variety of classification methods, which can be divided into trinocular, binocular and monocular microscopes according to the number of eyepieces used; stereoscopic and non-stereoscopic microscopes can be divided into stereoscopic and non-stereoscopic microscopes according to whether the image is stereoscopic; Biological and metallographic microscopes, etc.; can be divided into polarized light, phase contrast and differential interference contrast microscopes according to optical principles.
Automatic scanning electron microscopes can be divided into transmission electron microscopes, scanning electron microscopes, reflection electron microscopes and emission electron microscopes according to their structure and use.
3. The composition structure is different:
The optical system of a microscope mainly includes four parts: objective lens, eyepiece, reflector and condenser. Broadly speaking, it also includes illumination light sources, filters, coverslips and slides.
The automatic scanning electron microscope consists of three parts: the lens tube, the vacuum device and the power cabinet.
Compared with optical microscopes and transmission electron microscopes, scanning electron microscopes have the following characteristics:
1. The structure of the sample surface can be directly observed, and the size of the sample can be as large as 120mm×80mm×50mm.
2. The sample preparation process is simple and does not need to be cut into thin slices.
3. The sample can be translated and rotated in three-dimensional space in the sample chamber, so the sample can be observed from various angles.
4. The depth of field is large, and the image is full of three-dimensional effect. The depth of field of a scanning electron microscope is hundreds of times larger than that of an optical microscope, and dozens of times larger than that of a transmission electron microscope.
5. The magnification of the image is wide and the resolution is relatively high. It can be magnified from ten times to hundreds of thousands of times, and it basically includes the magnification range from magnifying glass, optical microscope to transmission electron microscope. The resolution is between the optical microscope and the transmission electron microscope, up to 3nm.
6. The damage and contamination of the sample by the electron beam are small.
7. While observing the morphology, other signals from the sample can also be used for micro-area composition analysis.
