Photophone Optical communication

the photophone (originally given alternate name, radiophone) communication device allowed transmission of speech on beam of light. invented jointly alexander graham bell , assistant charles sumner tainter on february 19, 1880, @ bell s 1325 l street laboratory in washington, d.c. both later become full associates in volta laboratory association, created , financed bell.

on june 21, 1880, bell s assistant transmitted wireless voice telephone message of considerable distance, roof of franklin school window of bell s laboratory, 213 meters (about 700 ft.) away.

bell believed photophone important invention. of 18 patents granted in bell s name alone, , 12 shared collaborators, 4 photophone, bell referred greatest achievement , telling reporter shortly before death photophone greatest invention [i have] ever made, greater telephone .

the photophone precursor fiber-optic communication systems achieved popular worldwide usage starting in 1980s. master patent photophone (u.s. patent 235,199 apparatus signalling , communicating, called photophone), issued in december 1880, many decades before principles came have practical applications.