EMILIO SEGRE VISUAL ARCHIVES / AMERICAN INSTITUTE OF PHYSICS / SCIENCE PHOTO LIBRARY EMILIO SEGRE VISUAL ARCHIVES / AMERICAN INSTITUTE OF PHYSICS / SCIENCE PHOTO LIBRARY
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George Hale's spectroheliograph. Diagram of the spectroheliograph designed in 1889 under the direction of US astronomer George Ellery Hale (1868-1938). Hale was still an undergraduate at the Massachusetts Institute of Technology (MIT) when he invented this device to aid his studies of the Sun. He described his invention in his graduation thesis. This device is used to capture a monochromatic image of the Sun at a single wavelength of light. The key component is a prism or diffraction grating, combined with a narrow slit (which acts as a monochromator) that allows the passage of a single wavelength of light. This diagram is dated July 1889.
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