US 12,031,903 B2
Detection method and detection device for trace gas
Shuiming Hu, Hefei (CN); Jin Wang, Hefei (CN); and Yu Sun, Hefei (CN)
Assigned to University of Science and Technology of China, Hefei (CN)
Appl. No. 17/614,763
Filed by University of Science and Technology of China, Hefei (CN)
PCT Filed Mar. 30, 2020, PCT No. PCT/CN2020/082019
§ 371(c)(1), (2) Date Nov. 29, 2021,
PCT Pub. No. WO2020/238386, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 201910456370.9 (CN), filed on May 29, 2019.
Prior Publication US 2022/0228977 A1, Jul. 21, 2022
Int. Cl. G01N 21/35 (2014.01); G01N 21/3504 (2014.01); G01N 33/00 (2006.01); G02B 26/08 (2006.01)
CPC G01N 21/3504 (2013.01) [G01N 33/0027 (2013.01); G02B 26/0858 (2013.01); G01N 2201/06113 (2013.01); G01N 2201/0636 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A system for detecting a trace gas, comprising:
a laser light generating device, a resonant cavity, a photoelectric detection device, a feedback control device and a scan control device; wherein
the cavity interior of the resonant cavity is configured to fill with a gas to be tested, wherein the gas to be tested contains a trace gas to be tested; and the cavity of the resonant cavity has retractable degree of freedom in the extension direction of the resonant cavity;
the laser light generating device is configured to provide probe light with different frequencies under control of the feedback control device, wherein the probe light enters into interior of the resonant cavity from one end of the resonant cavity in an extension direction of the resonant cavity, and exits from the other end of the resonant cavity in an extension direction of the resonant cavity, to capture the probe light carrying information of the trace gas to be tested;
the photoelectric detection device is configured to convert the probe light carrying information of the trace gas to be tested into detection information in an electrical signal form;
the scan control device is configured to record the detection information in an electrical signal form, and to control the laser light generating device to adjust frequency of outgoing probe light in a stepping manner; and
the feedback control device is configured to control the frequency of the outgoing probe light from the laser light generating device to match with a frequency of a longitudinal mode of the resonant cavity; wherein
the feedback control device comprises: a radio-frequency signal source, a phase detection device and a PID amplification device; wherein
the radio-frequency signal source is configured to generate a sinusoidal radio-frequency signal;
the phase detection device is configured to convert the detection information in an electrical signal form into an error signal according to the sinusoidal radio-frequency signal; and
the PID amplification device is configured to convert the error signal into a feedback locking signal, so that the frequency of the probe light exiting from the laser light generating device matches with the frequency of the longitudinal mode of the resonant cavity.