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 compressor properties and sufficient temperature resistance. A diaphragm compressor is the same as a membrane compressor. In the late 19th century William Burton started a workshop building pumps and air compressors at Nogent-sur-Oise, 60kM north of Paris, France. Henri Corblin, generally recognised as the inventor of the metallic diaphragm compressor, was based nearby in Paris itself and in 1923 he received a US patent for his invention and design work. The photograph included in this section depicts a three-stage diaphragm compressor used to compress hydrogen gas to 6,000 psi (41 MPa) for use in a prototype hydrogen and compressed natural gas