21. The photophone was a precursor to the fiber-optic communication systems which achieved popular worldwide usage in the 1980s. 22. Three brands of optical sound-on-film technology emerged in the 1920s : Photofilm, Photophone and Movietone. 23. Its master patent was issued in December 1880, many decades before the photophone 's principles came into popular use. 24. The photophone was a precursor to the fiber-optic communication systems that achieved worldwide popular usage starting in the 1980s. 25. In its ultimate electronic form, the photophone receiver used a simple selenium cell at the focus of a parabolic mirror. 26. The photophone was a precursor to the fiber-optic communication systems which achieved popular worldwide usage starting in the 1980s. 27. Warner Bros . and First National stopped recording directly to disc and switched to Photophone sound-on-film recording. 28. *the Photophone an optical, wireless telephone, the precursor to fiber-optic communications ( February 1880 ); 29. "This Thing Called Love " was recorded in RCA Photophone and featured a two-tone Technicolor sequence. 30. In 1927 and 1928, Hollywood expanded its use of sound-on-film systems, including Fox Movietone and RCA Photophone .
