Diaphragm (optics) curved blades improve the roundness of the iris opening. In a photograph, the number of blades that the iris diaphragm has can be guessed by counting the number of diffraction spikes converging from a light source or bright reflection. For an odd number of blades, there are twice as many spikes as there are blades. In case of an even number of blades, the two spikes per blade will overlap each other, so the number of spikes visible will be the number of blades in the diaphragm used. This is most apparent in pictures taken in the dark with small
Diaphragm (birth control) White. Reflexions also manufactured a flat-spring diaphragm up until 2014. There are a number of variations. The SILCS diaphragm is made of silicone, has an arcing spring, and a finger cup is molded on one end for easy removal. The Duet disposable diaphragm is made of dipped polyurethane, pre-filled with BufferGel (BufferGel is currently in clinical trials as a spermicide and microbicide). Both the SILCS and Duet diaphragms are one-size-fits-all. Diaphragms usually come in different sizes and require a fitting appointment with a health care professional to determine which size a woman should wear. Single size diaphragms that do not