The Collaborative International Dictionary
Photophone \Pho"to*phone\, n. [Photo- + Gr. ? sound.] (Physics)
An apparatus for the production of sound by the action of
rays of light.
--A. G. Bell.
Wiktionary
n. a device that transmitted sound on a beam of light
Wikipedia
The photophone (later given the alternate name radiophone) is a telecommunications device which allowed for the transmission of speech on a beam of light. It was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, at Bell's laboratory at 1325 L Street in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.
On June 3, 1880, Bell's assistant transmitted a wireless voice telephone message from the roof of the Franklin School to the window of Bell's laboratory, some 213 meters (about 700 ft.) away.
Bell believed the photophone was his most important invention. Of the 18 patents granted in Bell's name alone, and the 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone".
The photophone was a precursor to the fiber-optic communication systems which achieved worldwide popular usage starting in the 1980s. The master patent for the photophone ( Apparatus for Signalling and Communicating, called Photophone) was issued in December 1880, many decades before its principles came to have practical applications.
Usage examples of "photophone".
Little Rob McGee was standing with the photophone receiver in his hand.
But there was only the thin voice of Anders in the photophone receiver, sharp and angry now.
The photophone upon its black tapered snout began flickering furiously.
The photophone light continued to flicker at brief intervals with that weirdly semihuman voice.
McGee called into the photophone until his throat was dry, but the only answer was the eternal voiceless whisper of the stars.
Another mounted into the pilothouse and dropped back with the photophone receiver and a length of cut wire.
For the photophone went abruptly dark, and the vessel lurched spaceward in a hurried take-off.
The photophone light went out and the unknown attacker was lost in the black of space.
Hopefully he climbed into the pilothouse to see if the photophone could be repaired.
Anders has got our photophone receiver aboard the wreck, along with our bags of diamonds.
Some information could be transmitted over relatively short distances by photophone, but ordinarily the whole complex traffic of the space lanes depended on radio.
Of course he had a photophone also, but it had been designed for communications over a reasonable distance, not for cheek-to-cheek whispers.
Alexander Graham Bell, inventor of the telephone, had also patented the photophone, a device by which sound waves vibrated a beam of reflected sunlight and the receiver changed the varying light intensity back into sound.
Clarke had built his own photophone transmitter from a bicycle headlight, and also played with audio modulation of sunlight by mechanical means by the time he was 13.
Europe a fully protected and patented transmitting camera as far ahead of the old-fashioned photophone as a Bell telephone is ahead of a tin speaking-tube.