Robert Hanbury Brown is known for developing the intensity type of this instrument. The Fabry-Perot type uses a pair of parallel half-silvered glass plates, one of which is adjustable, while an acoustic version can be used to measure the velocity and absorption of sound waves in a gas or liquid. Identify this device that splits electromagnetic radiation into two parts, used in radio astronomy and 
Robert Hanbury Brown is known for developing the intensity type of this instrument. The Fabry-Perot type uses a pair of parallel half-silvered glass plates, one of which is adjustable, while an acoustic version can be used to measure the velocity and absorption of sound waves in a gas or liquid. Identify this device that splits electromagnetic radiation into two parts, used in radio astronomy and which was, FTP, essential to the Michelson-Morley experiment.
Robert Hanbury Brown is known for developing the intensity type of this instrument.
interferometer