One is the local oscillator and the other is sent to the system to be probed.
The scattered light is then mixed with the local oscillator on the detector.
In radio technology, the distinction is not the source of the local oscillator, but the frequency used.
The coherent tone is produced by the local oscillator.
The design suffered from the thermal drift of the local oscillator which changed its frequency over time.
A local oscillator generates a signal at the channel's carrier frequency.
The reference radiation is known as the local oscillator.
The signal and the local oscillator are superimposed at a mixer.
The circuit usually consists of a local oscillator and frequency mixer.
It also eliminated the need for a local tunable oscillator, reducing the price of the system.
