System and method to measure an atmospheric thermodynamic profile with a compact, all-fiber and eye-safe Lidar
View Patent ↗A lidar system and method to enable simultaneous accurate and high spatial and temporal resolution measurements of atmospheric temperature, wind, and water vapor. The technology employs a laser ( 101 ), a telescope ( 110 ), an acousto-optic modulator ( 105 ) or an electro-optic modulator ( 205 ), a Thulium-doped fiber amplifier ( 206 ), and an optical circulator ( 108 ) which projects a laser signal into the atmosphere toward a phenomenon to be studied. The laser is reflected or backscattered by the atmospheric phenomena and retrieved by the telescope ( 110 ), where the laser is processed by a signal sampler and processor ( 114 ) for analysis.
1. A method comprising:
generating at least one pulse train laser signal using a master oscillator;
locking the frequency of the at least one pulse train laser signal using a frequency locking mechanism;
interleaving the at least one pulse train laser to create a single laser beam;
splitting the single laser beam into a laser first portion and a laser second portion;
feeding the laser first portion into a modulator;
routing the laser first portion from the modulator into a Thulium-doped fiber amplifier;
routing the laser first portion from the Thulium-doped fiber amplifier into an optical circulator;
transmitting the laser first portion from a telescope;
reflecting the laser first portion off of atmospheric phenomena;
collecting the reflected laser first portion using a telescope;
mixing the reflected laser first portion with the laser second portion and detecting the result by integrated photodetector;
sampling the mixed reflected laser first portion and laser second portion; and
retrieving at least one parameters of interest from the sampled signal.
2. The method of claim 1 , wherein a coherent Doppler lidar is used with the master oscillators.
3. The method of claim 2 , wherein the coherent Doppler lidar form is all-fiber pulsed heterodyne.
4. The system of claim 1 , wherein the modulator is an acousto-optic modulator.
5. The system of claim 1 , wherein the modulator is an electro-optic modulator.
6. The method of claim 1 , wherein the interleaving uses sequential interleaved pulses.
7. The method of claim 1 , wherein the reflected laser is backscattered.
8. A system comprising:
at least one master oscillator ( 101 ) to generate at least one pulse train laser beam;
a frequency locking mechanism ( 111 ) to measure and lock the at least one pulse train laser beam frequency;
a three by one switch ( 209 ) to sequentially interleave the at least one pulse train laser beam and create a single laser beam;
a beam splitter ( 104 ) to divide the single laser beam into a laser beam first portion and a laser beam second portion;
a modulator ( 105 ) to receive the laser beam first portion;
a Thulium-doped fiber amplifier ( 107 ) to receive the laser beam first portion from the modulator;
an optical circulator ( 108 ) to receive the laser beam first portion from the thulium-doped fiber amplifier ( 107 );
a transceiver telescope ( 110 ) to transmit the laser beam first portion and to receive the reflected laser beam;
at least one photodetector;
a balanced mixer ( 113 ) to receive and combine the reflected laser beam first portion and the laser beam second portion and detect a signal through the at least one photodetector; and
a sampling mechanism ( 114 ) to receive the combined signal from the mixer ( 113 ) and retrieve parameters of interest.
9. The system of claim 8 , further comprising an all-fiber pulsed heterodyne to facilitate Doppler shift sign detection.
10. The system of claim 8 , wherein the modulator is one of an acousto-optic modulator ( 105 ) and an electro-optic modulator ( 205 ).
11. The system of claim 8 , wherein the at least one photodetector further comprises a pair of integrated balanced photodetectors.
12. The system of claim 8 , wherein a coherent Doppler lidar is used with the master oscillator ( 101 ).
13. The method of claim 12 , wherein the coherent Doppler lidar form is all-fiber pulsed heterodyne.
14. A system comprising:
at least one signal generating oscillator ( 101 );
a switch ( 109 ) to combine signals from the at least one signal generating oscillator ( 101 );
a modulator ( 105 ) to receive and modulate the combined signal;
a Thulium-doped fiber amplifier ( 107 ) to amplify the modulated signal;
an optical circulator ( 108 ) to use the amplified and modulated signal;
a transceiver telescope ( 110 ) to transmit and receive the amplified and modulated signal from the optical circulator ( 108 ); and
a sampling mechanism ( 114 ) to sample the received amplified and modulated signal,
wherein a coherent Doppler lidar all-fiber pulsed heterodyne is used with the at least one master oscillator ( 101 ).
15. The system of claim 14 , wherein the modulator is one of an acousto-optic modulator ( 105 ) and an electro-optic modulator ( 205 ).
16. The system of claim 14 , wherein the signal is a laser beam.
17. The system of claim 14 , wherein a photodetector receives the amplified and modulated signal.
18. The system of claim 14 , wherein a mirror ( 104 ) splits the combined signal into a first signal and a second signal and the second signal is combined with the amplified and modulated signal.
19. The system of claim 18 , wherein the second signal is inverted 90 degrees and combined with the amplified and modulated signal.