Optical air data system suite of sensors
Systems and methods for laser based measurement of air parameters for use, e.g., on aircraft are disclosed. An example system includes a coherent source of radiation, a modulator, a transceiver, an optical mixer, and a measuring system. The coherent source produces a coherent radiation beam, and the modulator is configured to modulate the coherent radiation beam. The transceiver is configured to transmit the modulated radiation beam to, and receive a scattered radiation signal from a target region. The optical mixer is configured to determine a difference between the scattered radiation signal and the reference radiation beam. The measuring system is configured to determine at least one of velocity, air density, pressure, temperature, barometric altitude, angle of attack, angle of side slip, icing and turbulence based on the difference between the scattered radiation signal and the reference radiation beam.
1. A system comprising:
a source configured to produce a radiation beam;
a modulator configured to modulate the radiation beam to produce a modulated radiation beam, said modulator being further configured to periodically interrupt the radiation beam, whereby at least one particular type of representative molecules within air at the target region will be induced to fluoresce and re-emit radiation, the re-emitted fluorescent radiation decaying in intensity following the interruption of the radiation from the laser;
a transceiver configured to receive the modulated radiation beam via a first optical fiber and to transmit the modulated radiation beam to a target region and to receive a scattered radiation signal from the target region, said transceiver being further configured to receive the re-emitted fluorescent radiation;
an optical mixer coupled to the transceiver via a second optical fiber and coupled to the source via a third optical fiber, the optical mixer configured to:
receive the scattered radiation signal from the transceiver,
receive a reference radiation beam from the coherent source, and
determine a difference between the scattered radiation signal and the reference radiation beam; and
a measuring system configured to determine at least one of velocity, air density, pressure, temperature, barometric altitude, angle of attack, angle of side slip, icing and turbulence based on the difference between the scattered radiation signal and the reference radiation beam, the measuring system being further configured to determine an air density of air in the target region based on a time-dependent decay of the re-emitted fluorescent radiation.
2. The system of claim 1 , further comprising:
a temperature measuring system configured to determine the temperature of air in the target region;
wherein the measuring system is further configured to determine the pressure of air in the target region based on the air density and temperature.
3. The system of claim 2 , wherein the measuring system is further configured to determine the barometric altitude based on the pressure.
4. The system of claim 3 , wherein the measuring system is further configured to:
determine relative humidity of air in the target region based on characteristics of the re-emitted fluorescent radiation; and
determine presence of icing conditions based on the air density, temperature, pressure, and relative humidity.
5. A method comprising:
generating a radiation beam;
modulating the radiation beam to produce a modulated radiation beam;
transmitting the modulated radiation beam to a target region and receiving a scattered radiation signal from the target region;
receiving a reference radiation beam from the source;
determining a difference between the scattered radiation signal the reference radiation beam; and
determining at least one of velocity, air density, pressure, temperature, barometric altitude, angle of attack, angle of side slip, icing and turbulence based on the difference between the scattered radiation signal and the reference radiation beam;
periodically interrupting the radiation beam, whereby at least one particular type of representative molecules within air at the target region will be induced to fluoresce and re-emit radiation, the re-emitted fluorescent radiation decaying in intensity following the interruption of the radiation from the coherent source;
receiving the re-emitted fluorescent radiation; and
determining an air density of air in the target region based on a time-dependent decay of the re-emitted fluorescent radiation.
6. The method of claim 5 , further comprising:
determining the temperature of air in the target region;
determining the pressure of air in the target region based on the air density and temperature.
7. The method of claim 6 , further comprising determining the barometric altitude based on the pressure.
8. The method of claim 5 , further comprising:
determining the relative humidity of air in the target region based on the characteristics of the re-emitted fluorescent radiation; and
determining the presence of icing conditions based on the air density, temperature, pressure, and relative humidity.