The principle and structural characteristics of fluorescence microscope
Fluorescence microscopy uses a point with high luminous efficiency to emit light of a certain wavelength (such as ultraviolet light 3650 in or purple blue light 4200 in) through the filter system as the excitation light to excite the fluorescent substances in the specimen to emit fluorescence of various colors After that, observe through the magnification of the objective lens and eyepiece. In this way, under a strong contrast background, even if the fluorescence is very weak, it is easy to identify and has high sensitivity. It is mainly used for the research of cell structure and function and chemical composition. The basic structure of a fluorescence microscope is composed of an ordinary optical microscope plus some accessories (such as a fluorescent light source, an excitation filter, a two-color beam splitter and a blocking filter, etc.). Fluorescent light source—generally use ultra-high pressure mercury lamp (50-200W), which can emit light of various wavelengths, but each fluorescent substance has an excitation wavelength that produces the strongest fluorescence, so an excitation filter ( Generally, there are ultraviolet, purple, blue and green excitation filters), which only allow excitation light of a certain wavelength to pass through and irradiate the specimen, while absorbing other light. After each substance is irradiated by excitation light, it emits visible fluorescence with a longer wavelength than the irradiation wavelength in a very short time. Fluorescence is specific and generally weaker than excitation light. In order to observe specific fluorescence, blocking (or suppression) must be added behind the objective lens and used in conjunction with it.
The difference between fluorescence microscope and ordinary microscope
1. The illumination method is usually episcopic, that is, the light source is projected on the sample through the objective lens;
2. The light source is ultraviolet light, the wavelength is shorter, and the resolution is higher than that of ordinary microscopes;
3. There are two special filters, the one in front of the light source is used to filter out visible light, and the one between the eyepiece and objective lens is used to filter out ultraviolet rays to protect the human eye.
Fluorescence microscope is also a kind of optical microscope, the main difference is that the excitation wavelength of the two is different. This determines the difference between the fluorescence microscope and the ordinary optical microscope in terms of structure and usage.
Fluorescence microscopy is an essential tool in immunofluorescent cytochemistry. It is composed of main components such as light source, filter plate system and optical system. It is to use a certain wavelength of light to excite the specimen to emit fluorescence, and to observe the fluorescence image of the specimen by amplifying the objective lens and eyepiece system.
