Biography provided by the Patrick Montgomery Collection (Archive Farms)
 
While not known as a photographer, French physicist Jean Bernard Léon Foucault (1819-1868) was involved in early efforts to use photography for scientific study. Foucault is best known for his creation of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation. He also made an early measurement of the speed of light, discovered eddy currents, and is credited with naming the gyroscope. He began experimenting with daguerreotypes shortly after their announcement in 1839, and working with bacteriologist Alfred Donné, took some of the first daguerreotype microphotographs. When their attempts to make prints directly from the etched daguerreotype plates failed, the images were published as engravings in 1844. With Hippolyte Fizeau, a friend from his student days, he carried out a series of investigations on the characteristics of light. Together, they also worked on improving the sensitivity of daguerreotype plates and on August 2, 1845, they took the first daguerreotype image of the sun. In 1860 he traveled to Spain on behalf of the Observatory of Paris to photograph a total solar eclipse. This "small" heliostat (from helios, the Greek word meaning Sun, and stat, root of stationary), designed by Foucault and built by the Duboscq workshop, was a device for following the course of the sun and could be used to provide a steady beam of light for indoor photography.
 
Wikipedia
 
Jean Bernard Léon Foucault (UK: , US: ; French: [ʒɑ̃ bɛʁnaʁ leɔ̃ fuko]; 18 September 1819 - 11 February 1868) was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of Earth's rotation. He also made an early measurement of the speed of light, discovered eddy currents, and is credited with naming the gyroscope.