What are the condenser lenses of the microscope?
The condenser is installed under the stage. Small microscopes often do not have a condenser, but must have a condenser when using an objective lens with a numerical aperture above 0.40. The condenser can not only make up for the lack of light and change the properties of the light from the light source, but also focus the light on the object to get the best lighting effect.
There are many structures of the condenser, and the requirements for the condenser are also different according to the numerical aperture of the objective lens.
Abbe condenser
This is designed by Ernst Abbe, a master of the German University of Optics. The Abbe condenser is composed of two lenses and has good light-gathering ability, but when the numerical aperture of the objective lens is higher than 0.60, chromatic aberration and spherical aberration will appear. Therefore, it is mostly used on ordinary microscopes.
Achromatic aplanatic condenser
This kind of condenser is also known as "aplanatic condenser" and "qiming condenser". It is composed of a series of lenses. It has a high degree of correction of chromatic aberration and spherical aberration. The highest type of condenser has an NA value of 1.4. Therefore, such condensers are often equipped in advanced research microscopes. It is not suitable for low magnification objectives below 4X, otherwise the illumination source cannot fill the entire field of view.
Swing out condenser
When using a low magnification objective lens (such as 4X), due to the large field of view, the light cone formed by the light source cannot fill the entire field of view, causing the edge of the field of view to be dark and only the central part to be illuminated. To fill the field of view with illumination, the top lens of the condenser needs to be swung out of the light path.
4. other condensers
In addition to the types of condensers used in the above-mentioned bright field, there are also condensers for special purposes. Such as dark field condenser, phase contrast condenser, polarizing condenser, differential interference condenser, etc., the above condensers are applicable to the corresponding observation methods.
