Structure and Main Components of a Fluorescence Microscope
(1) Light source
Nowadays, a 200W ultra-high pressure mercury lamp is commonly used as the light source. It is made of quartz glass and has a spherical shape in the middle, filled with a certain amount of mercury. During operation, the discharge between two electrodes causes mercury evaporation, and the pressure inside the bulb rapidly increases. When the mercury completely evaporates, it can reach 50-70 standard atmospheric pressures, which generally takes 5-15 minutes. The luminescence of ultra-high pressure mercury lamps is the result of the discharge between electrodes, which continuously dissociates and reduces mercury molecules, emitting light photons. It emits strong ultraviolet and blue violet light, sufficient to excite various fluorescent substances, therefore, it is widely used in fluorescence microscopes.
(2) Color filter system
The color filter system is an important part of a fluorescence microscope, consisting of an excitation filter plate and a suppression filter plate. The filter plate model and manufacturer names are often inconsistent. Filter plates are generally named after basic color tones, with the letters in front representing color tones, the letters behind representing glass, and the numbers representing model characteristics. Olympus microscope
(3) Objective lens
All kinds of objective lenses can be used, but achromatic lenses are suitable for fluorescence due to their extremely low self fluorescence and light transmission performance (wavelength range). Due to the fact that the fluorescence brightness of an image in the microscope field is directly proportional to the square of the aperture ratio of the objective lens and inversely proportional to its magnification, in order to improve the brightness of fluorescence images, an objective lens with a larger aperture ratio should be used. Especially at high magnification, its impact is very significant. Therefore, for specimens with insufficient fluorescence, an objective lens with a high aperture ratio should be used, combined with an eyepiece lens as low as possible (4 ×, 5 ×, 6.3 ×, etc.).
(4) Reflective mirror
The reflective layer of a mirror is usually coated with aluminum because aluminum absorbs less ultraviolet and visible light in the blue purple region, with a reflection rate of over 90%, while silver only reflects 70%; Generally, flat mirrors are used.
