The spherical aberration experiment employs a large aperture spherical lens following a slide with transparent dots at different radial distances. An expanded, collimated laser beam is incident on the slide and the large-aperture lens to illustrate variation of focal points from light rays emitting from radial positions. 

The second experiment shows a typical coma pattern by imaging an off axis point source through a lens following a slide with concentric transparent rings. 

The third experiment is to illustrate astigmatism of a spherical lens, which allows the measurement of the circle of least confusion between two focused lines formed by the tangential rays and the saggital rays through a rotated lens.