Jacques Babinet (1794-1872), French physicist, astronomer and meteorologist. Babinet was the first to suggest using wavelengths of light to standardise measurements. In 1827 he standardised the Angstrom unit using the wavelength of the red line of cadmium. Babinet also invented a number of instruments for use in polarised light microscopy, studied Mercury's mass, the Earth magnetism and the course of rivers.