BLODGETT, Katherine née Burr, American physicist, 1898-1979. The first woman research scientist at General Electric in the USA, from 1917. Then the first woman PhD graduating from Cambridge (1926) after studying under Rutherford. At General Electric, Katherine had worked with Langmuir and they developed a thin-film technology now known as Langmuir-Blodgett Films. She became an expert on surface chemistry technology, and held several patents. Katharine also developed a dipping process to put monomolecular layers of fatty acids on metal sheets, then discovered that the reflected colours differed with the thickness of the layer. It became necessary for her to invent a gauge measuring layers to a millionth of an inch. In 1938 she patented non-reflecting glass, an extremely valuable product concept. This glass had a layer of soap only ¼ of the thickness of the wavelength of light, the layer did not refract so there was no reflection from the glass. Such glass is now used in cinematography projector-lenses, her non-reflecting glass reduces glare and so is usable in many related optical products. During WW2 she worked on plane wing de-icers, and invented the system of smokescreens as used in tank warfare. In 1947 she invented a humidity meter for use in high-flying weather balloons. Katherine also devised the first controlled-thickness x-ray diffraction grating for crystallography. The non-reflecting glass patent had great worldwide commercial significance.