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) IUD and the combined oral contraceptive pill. In 1965, only 10% of U.S. married couples used a diaphragm for contraception. That number has continued to fall, and in 2002 only 0.2% of American women were using a diaphragm as their primary method of contraception. In 2014 Janssen Pharmaceuticals announced the discontinuation of the Ortho-All Flex Diaphragm, making it very difficult for women in the US to have that option as a birth-control method. The single-sized, silicone diaphragm was developed by PATH during the late 2000s. It was licensed to Kessel Marketing & Vertriebs GmbH of Frankfurt, Germany which began to