How to troubleshoot a microscope having uneven brightness in the observation field?
uneveness of of brightness in the optical field of view (FOV) can be caused by a number of variables, but often times is do to miss alignment of the condenser. Typically when this is the problem there the "hot" (brightess area) will be shifted to one corner or another in the FOV. There are usually some sort of adjustment screw underneath the stage that will allow you to do the alignment. It is easiest if you close down the iris on condenser and adjust the height of the condenser until you can see an octagonal shape appear, then center it in the FOV.
If the uneveness is equally the same throughout the FOV then it may have to do with the position or the height of the condenser. Generally speaking the lower the magnification, the further the condenser should be away from the slide. The condenser narrows or broadens the light allowing you to fill the entire FOV of the objective.
Depending on the quality and the level of the microscope though, you may find that no matter what you do at lower magnifications you can do very little to improve this. I see this a lot with LED models. The dispersion pattern of an LED is much more focused then a halogen, which is GREAT for higher magnification, but often times manufactures will upgrade from halogen to LED an never change the optics of th collector lens and condenser to flatten out the illumination better.
Nov 19, 2010 |