Patent ID: 11949208
Assignee: OCEAN UNIVERSITY OF CHINA
Field: Measurement (Instruments)
Classification: CPC H  G | IPC G  H

Claim 8:
9. A degassing-free underwater dissolved carbon dioxide detection method applied to the degassing-free underwater dissolved carbon dioxide detection device according to claim 6, wherein the degassing-free underwater dissolved carbon dioxide detection method comprises:
step I, the computer controlling the laser device driving control module to input a driving signal to the laser device of 2004 nm and driving the 2004 nm laser device to emit laser, and injecting the emitted laser serving as a seed source into a cavity of the thulium-doped fiber vertical-cavity laser device after the laser passes through the photo-isolator;
step II, the HR grating and the LR grating forming the resonator cavity of the thulium-doped fiber vertical-cavity laser device, and the computer inputting the driving signal to the power tuning unit to periodically tune intracavity loss to realize power turning and Q-switched pulse outputting;
step III, the first pump laser device and the second pump laser device performing bidirectional pumping on the thulium-doped fiber through the first wavelength division multiplexer and the second wavelength division multiplexer, and outputting laser from one end of the LR grating;
step IV, performing filtering, pressure relief, flow stabilization and volume fixing on sea water through the filter, the pressure relief valve and the flow valve in sequence, putting the sea water into a cell through a water inlet, and draining the sea water by the pressurized draining pump through a water outlet;
step V, the laser entering the photoacoustic cell system through the fiber collimator, converging the laser to one position through the focusing lens to stimulate the sea water to be measured, and carbon dioxide in the sea water absorbing light energy with a specific wavelength 2004 nm to generate a photoacoustic signal; and
step VI, the microphone generating a current signal after detecting a sound wave signal and sending the current signal to the pre-amplifier circuit for current-voltage conversion, transmitting an output voltage signal to the computer for calculation after the voltage signal passes through the phase-locked amplifier, and performing inversion to obtain a concentration value of dissolved carbon dioxide in the seawater to be measured.