![motion pulse vibrate ticking optical pictures motion pulse vibrate ticking optical pictures](https://www.frontiersin.org/files/Articles/585363/fbioe-08-585363-HTML/image_m/fbioe-08-585363-g001.jpg)
![motion pulse vibrate ticking optical pictures motion pulse vibrate ticking optical pictures](https://www.thorlabs.com/Images/GuideImages/8451_FiberOpticCouplers_4.jpg)
The process (which de Forest called Phonofilm) recorded sound as parallel lines of variable shades of gray, photographically transcribing the electrical waveforms from a microphone, which were translated back into sound waves when the movie was projected.Ĭase Lab fine-tuned the process with an invention called the 'Aeo-light' for use in sound cameras. Case Lab first converted an old silent-film projector into a recording device in 1922, using the projector's light for exposing a soundtrack onto film. De Forest had been granted general patents for a sound-on-film process in 1919, though it was the Case Research Lab's inventions which made de Forest's systems workable. Sponable collaborated with fellow wireless communications pioneer Lee de Forest, inventor of the Audion tube, to apply their optical sound system to motion pictures. Newspaper ad for a 1925 presentation of De Forest Phonofilms shorts, touting their technological distinction: no phonograph.Īfter the war, Theodore Case and Earl I. A fourth major contender for the sound film market - Warner Brothers' Vitaphone sound-on-disc system which synchronized large-size (16") phonographic records with a film's projector was used on early talkies, such as their' 1927 hit The Jazz Singer (which was marketed as being " all singing" though the talking was sporadic, used in only several isolated sequences), utilised Vitaphone discs, but by 1931, optical sound-on-film would supplant the separate sound-on-disc technology. Three types of optical sound-on-film technology emerged in the 1920s: Phonofilm, Photophone and Movietone. When the light shines through the film, it is read by a photo-sensitive material and fed through a processor which converts the photovoltaic impulse into an electrical signal that is then amplified and converted into analogue sound waves through a speaker. Most of the inventions which led to optical sound-on-film technology employed the use of an electric lamp, called an 'exciter', shining through a translucent waveform printed on the edge of a film strip. The width of the white area is proportional to the amplitude of the audio signal at each instant. The early work by Case, Sponable and Hoxie was instrumental in the development of sound-on-film systems for motion pictures during the 1920s.Įxample of a variable-area sound track on the right side of the frames on this strip of 16mm film. With GE's backing, Hoxie's invention was used in 1922-1923 to record then-Vice-President Calvin Coolidge and others for radio broadcasts. Similar to the Case infrared system used by the Navy, the Pallophotophone was also intended for wireless communications at sea, but was then adapted for recording speech. Hoxie's Pallophotophone (from Greek roots meaning "shaking light sound"), manufactured by General Electric (GE). Ĭontemporary with the work of Case and Sponable was Charles A. Navy used the system during and after World War I. Case and Sponable's system was first tested off the shores of New Jersey in 1917, and attending the test was Thomas Edison, contracted by the Navy to evaluate new technologies. The Thallofide tube was originally used by the United States Navy in a top secret ship-to-ship infrared signaling system developed at Case's lab with his assistant Earl Sponable.
![motion pulse vibrate ticking optical pictures motion pulse vibrate ticking optical pictures](https://m.media-amazon.com/images/I/61+t14KU+NL.jpg)
In 1914, he opened the Case Research Lab to experiment with the photoelectric properties of various materials, leading to the development of the Thallofide (short for thallium oxysulfide) Cell, a light-sensitive vacuum tube. While studying at Yale, Case became interested in using modulated light as a means of transmitting and recording speech. The idea was that sound pulses could be converted into light pulses, beamed out from one ship and picked up by another, where the light pulses would then be re-converted back into sound.Ī pioneer in this technology was American physicist Theodore Case.