what does a diaphragm do optics
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).