System for coherent wind speed measurement using a broad bandwidth light source

A coherent wind speed measurement system, which enables wind speed detection, the system comprising:

• at least one light source emitting light in a broad bandwidth;
• a first optical coupler comprising an input for receiving the light emitted from the light source and at least three outputs for splitting the said light into at least three branches;
• at least two fiber optical delay lines, each of which is connected to a separate output of the first optical coupler and adapted to delay the light from the first optical coupler at different times from each other;
• at least one fiber optic circulator which comprises a first port, a second port and a third port and is intended for routing the light from the said first port that is connected to one of the outputs of the first optical coupler to the second port and the light from the second port to the third port;
• a lens system which is connected to the second port of the fiber optic circulator and intended for transmitting the light from the second port to the external environment and for collecting the light scattered back from the air molecules and transmitting it to the second port;
• a third optical coupler for splitting the light incident on its input into at least two branches and comprising one input connected to the third port of the fiber optic circulator and at least two outputs;
• at least two second optical couplers, each of which comprises two inputs and at least one output, where one of the inputs is connected to one of the outputs of the third optical coupler and the other input connected to the output of one of the fiber optical delay lines, and combines the light from one of the outputs of the third optical coupler with the light from one of the fiber optical delay lines;
• at least two frequency shift detection modules each of which is provided at one of the outputs of the second optical coupler and detects the frequency shift between the lights combined by the second optical coupler to which it is connected;
• a signal processing unit which is connected to the frequency shift detection modules and adapted to perform wind speed detection at different points separately according to the different frequency shift information received from the said modules.