There are two types of fluorescence microscopes in terms of their optical path
1. Transmission fluorescence microscope: The excitation light source is passed through the specimen material through a condenser lens to excite fluorescence. A dark field collector is commonly used, and an ordinary collector can also be used to adjust the mirror so that the excitation light is redirected and bypassed to the specimen. This is an older fluorescent microscope. The advantage is that the fluorescence is strong at low magnification, but the disadvantage is that the fluorescence decreases with the increase of magnification. Therefore, it is better to observe larger specimen materials.
2. Epi-fluorescence microscope is a new type of fluorescence microscope developed in modern times. The difference is that the excitation light falls from the objective lens down to the surface of the specimen, that is, the same objective lens is used as the illumination condenser and the objective lens for collecting fluorescence. A dichroic beam splitter needs to be added in the light path, which is 45° away from the light uranium. The excitation light is reflected into the objective lens and collected on the sample. The fluorescence generated by the sample and the excitation light reflected by the lens surface of the objective lens and the cover glass surface enter the objective lens at the same time, and return to the two-color beam splitter to make the excitation light Separated from fluorescence, residual excitation light is absorbed by blocking filters. Such as changing to a combination of different excitation filter/two-color beam splitter/blocking filter, it can meet the needs of different fluorescent reaction products. The advantage of this kind of fluorescence microscope is that the illumination of the field of view is uniform, the imaging is clear, and the greater the magnification, the stronger the fluorescence.
