Diaphragm (optics) 1889 "Dictionary of Photography" (see figure), but disappeared after Ernst Abbe's theory of stops unified these concepts. According to Rudolf Kingslake, the inventor of the iris diaphragm is unknown. Others credit Joseph Nicéphore Niépce for this device, around 1820. Mr. J. H. Brown, a member of the Royal Microscopical Society, appears to have invented a popular improved iris diaphragm by 1867. Kingslake has more definite histories for some other diaphragm types, such as M. Noton's adjustable "cat eye" diaphragm of two sliding squares in 1856, and the Waterhouse stops of John Waterhouse in 1858. Diaphragm (optics) In optics, a diaphragm
Diaphragm (birth control) the diaphragm. "Contraceptive Technology" reports that the method failure rate of the diaphragm with spermicide is 6% per year. The actual pregnancy rates among diaphragm users vary depending on the population being studied, with yearly rates of 10% to 39% being reported. Unlike some other cervical barriers, the effectiveness of the diaphragm is the same for women who have given birth as for those who have not. The diaphragm does not interfere with a woman's natural cycle, therefore, no reversal or wait time is necessary, if contraception is no longer wanted or needed. The diaphragm only has to be used