a group or mass of distinct or varied things, persons, etc.: an aggregation of complainants. 2. collection into an unorganized whole. 3. the state of being so collected. 4. Biology, Ecology. a group of organisms of the same or different species living closely together but less integrated than a society.
Not to be confused with Pelvic Diaphragm. In optics, a diaphragm is a thin opaque structure with an opening (aperture) at its center.The role of the diaphragm is to stop the passage of light, except for the light passing through the aperture.Thus it is also called a stop (an aperture stop, if it limits the brightness of light reaching the focal plane, or a field stop or flare stop for other uses of diaphragms in lenses).he role of the diaphragm is to stop the passage of light, except for the light passing through the aperture. Thus it is also called a stop (an aperture stop, if it limits the brightness of light reaching the focal plane, or a field stop or flare stop for other uses of diaphragms in lenses).
A lens will most often have an aperture adjustment mechanism, usually an iris diaphragm, to regulate the amount of light that passes. In early camera models a rotating plate or slider with different sized holes was used.