ABSTRACT
Stops are used in an optical system to control either the beam width from various points in the object or the size of the field of view. Every operating optical system must contain an aperture stop; otherwise, the beam width from any point in the object field would be infinite. Aperture stops affect the brightness of the image, its depth of field, and the image quality. This entry explains why stops are integral components of optical systems and detail the three types of stops. The application and use of stops will also be discussed.
