Sound pressure metrology instrument and determining sound pressure from index of refraction

Sound pressure metrology instrument for determining sound pressure from index of refraction, the sound pressure metrology instrument comprising:

• a light source that produces source light and communicates the source light to an optical cavity;
• the optical cavity in optica al communication with the light source, in acoustic communication with a sound source, and in optical communication a photodetector, such that an acoustic medium is disposed within an optical mode volume of the optical cavity and such that the optical cavity;
• receives an acoustic field from the sound source;
• receives the source light from the light source;
• produces acoustic-modified light from the source light in response to the source light interacting with the acoustic field in the optical cavity, such that the acoustic-modified light encodes modulations in the index of refraction of the acoustic medium inside the optical cavity due to the acoustic field, and optically communicates the acoustic-modified light to the photodetector;
• the photodetector in optical communication with the optical cavity and in electrical communication with an analyzer module and that receives the acoustic-modified light from the optical cavity, produces an acoustic-modified signal from the acoustic-modified light, and communicates the acoustic-modified signal to the analyzer module;
• the analyzer module in electrical communication with the photodetector and that receives the acoustic-modified signal from the photodetector and determines the sound assure of the acoustic field produced by the sound source from the modulations in the index of refraction of the acoustic medium inside the optical cavity encoded in the acoustic-modified light;
• and an acoustic enclosure in which is disposed the optical cavity, the acoustic medium, the sound source, and the acoustic field, wherein the acoustic enclosure comprises an acoustic coupler, wherein the acoustic field has constant acoustic pressure in the acoustic enclosure such that λac<<L/N, wherein N is an integer, and L is a distance of separation of the sound source and a microphone that are disposed on opposing ends of the acoustic enclosure.

A sound pressure metrology instrument for determining sound pressure from index of refraction, the sound pressure metrology instrument comprising:

• a light source that produces source light and communicates the source light to an optical cavity;
• the optical cavity in optical communication with the light source, ac ustic communication with a sound source, and in optical communication a photodetector, such hat an acoustic medium is disposed within an optical mode volume of the optical cavity and such that the optical cavity;
• receives an acoustic field from the sound source;
• receives the source light from the light source;
• produces acoustic-modified light from the source light in response to the source light interacting with the acoustic field in the optical cavity, such that the acoustic-modified Right encodes modulations in the index of refraction of the acoustic medium inside the optical cavity due to the acoustic field;
• and optically communicates the acoustic-modified light to the photodetector;
• the photodetector in optical communication with the optical cavity and in electrical communication with an analyzer module and that receives the acoustic-modified light from the optical cavity, produces an acoustic-modified signal from the acoustic-modified light, and communicates the acoustic-modified signal to the analyzer module;
• the analyzer module in electrical communication with the photodetector and that receives the acoustic-modified signal from the photodetector and determines the sound pressure of the acoustic field produced by the sound source from the modulations in the index of refraction of the acoustic medium inside optical cavity encoded in the acoustic-modified light;
• and a microphone in acoustic communication with the sound source such that the optical cavity is acoustically interposed between the sound source and the microphone, such that the microphone receives the acoustic field that propagates through the optical cavity from the sound source, produces a microphone signal from the acoustic field, and communicates the microphone signal to a microphone receiver.

A process for determining sound pressure from index of refraction, the process comprising:

• receiving, by an optical cavity comprising an acoustic medium disposed within an optical mode volume of the optical cavity, an acoustic field from a sound source;
• receiving, by the optical cavity, source light from a light source;
• interacting source light with the acoustic field in the optical cavity;
• producing an acoustic-modified light from the source light in response to interacting with the acoustic field, such that the acoustic-modified light encodes modulations in the index of refraction of the acoustic medium inside the optical cavity due to the acoustic field;
• communicating the acoustic-modified light signal to a photodetector;
• receiving the acoustic-modified light by the photodetector;
• producing, by the photodetector, an acoustic-modified signal from the acoustic-modified light;
• communicating the acoustic-modified signal from the photodetector to an analyzer module;
• determining, by the analyzer module, the sound pressure of the acoustic field from the modulations in the index of refraction of the acoustic medium encoded inside the optical cavity in the acoustic-modified light and receiving the acoustic field by a microphone and producing a microphone signal from the acoustic field.