Many experimenters will ignore many problems when using the optical microscope, such as the selection of the magnification of the microscope, the selection of the brightness intensity, the debugging of the condenser, and so on. I don’t know that such small details affect the imaging quality of the microscope. Let’s talk about the debugging of the condenser of the microscope.
Call out clear polygon: adjust the field aperture and aperture aperture to the minimum state. If the state of the microscope is correct, you should be able to see a polygon with clear edge in the field of vision. If you don’t see a polygon with clear edge, it means that the up and down position of the condenser in the light path is not accurate. At this time, turn the up and down adjustment knob of the condenser (as shown in the figure below) to make the condenser rise or fall slowly, so as to form a polygon with clear edge in the field of view. Note: do not always adjust the height of the condenser. After adjusting the height, don’t move the height again. After the microscope is installed, most of them have adjusted the height, so the next step can be adjusted directly（ Sometimes, if you can’t find a polygon, you can enlarge the field of view aperture a little, and you can find it when it’s a little bright.)
Adjust the polygon to the center: the correct position of the polygon in the field of vision should be in the center of the field of vision. If not, it means that the light path is offset, you need to adjust the centering screw of the concentrator (as shown in the figure below), that is, two Silver knobs, to make the polygon in the center of the field of vision. The visual field during adjustment is shown in the figure below.
Adjust the polygon to be circumscribed: enlarge the field of view aperture slowly. When the polygon is circumscribed to the field of view, it is the best working position of the field of view aperture. In this way, the optical axis of the condenser is aligned with the optical axis of the illumination light path and the imaging light path. After adjustment, do not adjust the centering screw rod in daily use!
Adjustment of aperture: there are engraving and positioning marks on the outer edge of the condenser of the research microscope, which is convenient to adjust the numerical aperture of the condenser and the objective to match. However, there is no number on the outside of some condensing lenses, so the objective lens is focused first, and then an eyepiece is removed. When the eye looks into the lens barrel, it can be seen that the lens behind the objective lens is a bright circle. If the outline image of aperture aperture is not seen, it means that the aperture is too large; If it is only a very small bright contour image, it means that the shrinkage is too small. When the slow increase happens to be a bright circle with the lens behind the objective lens, the numerical aperture of the condenser lens and the objective lens has matched each other.
In order to get the best resolution, the numerical aperture of the condenser is adjusted to match the numerical aperture of the objective. The numerical aperture is closely related to the resolution, so the numerical aperture of the condenser and the objective should match. For example, the objective lens with low numerical aperture should be matched with the condenser lens with low numerical aperture, whereas the oil lens with high numerical aperture should be matched with the condenser lens with high numerical aperture. Only in this way can the resolution of the image be improved