Robert Williams Wood was an American physicist and inventor.
Born in Concord, Massachusetts, Wood attended The Roxbury Latin School with the initial intent of becoming a priest. However, he decided to study optics instead when he witnessed a rare glowing aurora one night and believed the effect to be caused by "invisible rays". In his pursuit to find these "invisible rays", Wood studied and earned several degrees in physics from Harvard University, the Massachusetts Institute of Technology, and the University of Chicago. From 1894 to 1896, he worked with Heinrich Rubens at the Berlin University.
Dr. Wood returned to the U.S.A., where he taught briefly at the University of Wisconsin and eventually became a full-time professor of "optical physics" at Johns Hopkins University from 1901 until his death. He worked closely with Alfred Lee Loomis at Tuxedo Park, New York. He wrote many articles on spectroscopy, phosphorescence and diffraction. He is best known for his work in ultraviolet light.
Another of his claims to fame was his debunking of N-rays in 1904. The French physicist Prosper-René Blondlot claimed to have discovered a new form of radiation like X-rays, which he named N-rays. Some physicists reported having successfully reproduced his experiments; others reported that they had failed. Visiting Blondlot's laboratory at the behest of the journal Nature, Wood surreptitiously removed an essential prism from Blondlot's apparatus during a demonstration. The effect did not vanish, showing that N-rays had always been self-deception on Blondlot's part.
Wood identified an area of very low ultraviolet albedo (reflectivity, that is most of the ultraviolet is absorbed) in the Aristarchus Plateau region of the Moon, one that he suggested was due to high sulfur content. The area continues to be called Wood's Spot. In 1909, Wood constructed the first practical liquid mirror astronomical telescope, by spinning mercury to form a paraboloidal shape, and investigated its benefits and limitations. Wood has been described as the "father of both infrared and ultraviolet photography." Though the discovery of electromagnetic radiation beyond the visible spectrum and the development of photographic emulsions capable of recording them predate Dr. Wood, he was the first to intentionally produce photographs with both infrared and ultraviolet radiation. In 1903 he developed a filter, Wood's glass, that was opaque to visible light but transparent to both ultraviolet and infrared, and is used in modern-day black lights. He used it for ultraviolet photography but also suggested its use for secret communication. He was also the first person to photograph ultraviolet fluorescence. He also developed an ultraviolet lamp, which is widely known as the Wood's lamp in medicine. The slightly surreal glowing appearance of foliage in infrared photographs is called the Wood effect.
Dr. Wood also authored nontechnical works. In 1915, Wood co-wrote a science fiction novel, The Man Who Rocked the Earth, along with Arthur Train. Its sequel, The Moon Maker, was published the next year. Wood also wrote and illustrated two books of children's verse, How to Tell the Birds from the Flowers (1907), and Animal Analogues (1908).
Wood also took part in the investigation of several crimes including the Wall Street bombing. Dr. Wood married Gertrude Hooper Ames in 1892 in San Francisco. She was the daughter of Pelham Warren and Augusta Hooper (Wood) Ames, and the granddaughter of William Northey Hooper and the Massachusetts Supreme Court justice Seth Ames. Dr. Wood died in Amityville, New York.