condensorlens

A condenser lens is a lens or a group of lenses used to concentrate or distribute light or particle beams onto a target or along a path. The term is used in both optical illumination and electron optics contexts, and it describes a component whose primary function is to shape the illumination before it reaches the subject, sample, or image plane.

In optical illumination, a condenser lens is placed near the light source to collect divergent rays and form a bright, uniform field at the plane to be illuminated. By adjusting the lens position, focal length, or grouping, designers improve illumination efficiency and uniformity and reduce hotspots or shading on the subject or film.

In electron optics, condenser lenses are electromagnetic lenses that set the convergence of the electron beam before it enters the objective lens. In instruments such as scanning and transmission electron microscopes, multiple condenser lenses (often labeled C1, C2) control the probe size, convergence angle, and beam intensity. Changes in lens current or spacing modify the illumination conditions, which in turn affect brightness, resolution, and depth of field in the final image.

Condenser lenses are typically contrasted with the objective lens, which forms the final image or projection. They can be fixed or adjustable components, and their design must balance factors such as aberrations, illumination uniformity, and beam current to achieve the desired optical performance.