When the magnification of a video microscope increases, on one hand, the higher the magnification, the more lenses there are, and the more light is absorbed by the lenses; On the other hand, since the brightness of the field of view (referring to the range of specimens being inspected) is inversely proportional to the square of the magnification, meaning the higher the magnification, the darker the field of view. To achieve sufficient brightness, a condenser must be installed to focus light on the specimen to be observed.
The condenser height of the video microscope at that point during observation
During observation, the best observation effect must be ensured; the condenser's focus should be exactly on the specimen. To achieve this condition, the height of the condenser must be adjusted. When illuminated with parallel light, the condenser's focus is about 1.25mm above the center of the upper lens plane. Therefore, it is often required to raise the condenser to the height of the stage plane just below the upper lens plane during observation, so the focus may fall on specimens on standard-thickness slides. When using slides thinner than the standard thickness to hold specimens, the position of the condenser should be lowered accordingly; when using slides that are too thick, the focus of the light only falls below the specimen, which is not conducive to detailed observation.
The condenser of a video microscope should be used together with the objective lens
The so-called coordination here refers to making the numerical apertures of the condenser and objective lens of the video microscope consistent, enabling more precise observation. If the condenser's numerical aperture is lower than the objective lens, part of the objective's numerical aperture is wasted and cannot achieve its maximum resolution. If the numerical aperture of the condenser is larger than that of the objective lens, on one hand, the objective's specified resolution cannot be improved; on the other hand, the illumination beam will be too wide, causing a decrease in image clarity. The method for working with the objective lens is: after completing illumination and focusing, remove the eyepiece and look directly into the tube, turn the variable light aphrodist under the condenser to the minimum, then slowly increase it. Open until its aperture is exactly the same diameter as the field of view, then put on the eyepiece to begin observation. Each objective switch requires a sequential coordination operation along with the transition. Some condensers have a scale indicating the opening aperture on the frame of the variable apertures, which can be adjusted according to the scale.
