Principle, Characteristics, and Usage of Fluorescence Microscope
The principle and structural characteristics of fluorescence microscope: Fluorescence microscope uses a highly efficient point light source to emit a certain wavelength of light (such as ultraviolet light 3650 or purple blue light 4200) through a color filter system as excitation light, which excites fluorescent substances in the specimen to emit various colors of fluorescence, and then observes through the magnification of the objective lens and eyepiece. In this way, even with weak fluorescence in a strong background, it is easy to recognize and has high sensitivity. It is mainly used for the study of cell structure, function, and chemical composition. The basic structure of a fluorescence microscope is composed of a regular optical microscope and some accessories such as a fluorescent light source, excitation filter, dual color beam splitter, and blocking filter. Fluorescent light source - usually uses ultra-high pressure mercury lamps (50-200W), which can emit light of various wavelengths, but each fluorescent substance has an excitation light wavelength that produces the strongest fluorescence. Therefore, excitation filters (usually ultraviolet, purple, blue, and green excitation filters) need to be added to allow only a certain wavelength of excitation light to pass through and irradiate the specimen, while absorbing all other light. After being irradiated with excitation light, each substance emits visible fluorescence with a wavelength longer than the irradiation wavelength in a very short period of time. Fluorescence has specificity and is generally weaker than excitation light. In order to observe specific fluorescence, a blocking (or suppressing) filter needs to be added behind the objective lens.
Its functions are twofold: first, to absorb and block excitation light from entering the eyepiece to avoid disturbing fluorescence and damaging the eyes; second, to select and allow specific fluorescence to pass through, exhibiting a specific fluorescent color. Two types of filters must be used in combination.
