公开(公告)号：WO2022258937A1

公开(公告)日：2022-12-15

申请号：PCT/GB2022/050706

申请日：2022-03-21

Applicant: QLM TECHNOLOGY LIMITED

Inventor： AI, Xiao ,  TITCHENER, James

IPC: G01N21/17 ,  G01N21/39 ,  G01N21/3504 ,  G01J3/433

Abstract: A method of gas detection comprises emitting radiation of different wavelengths across the absorption spectrum of a gas towards a target area; and analysing the spectrum of returned laser light from the target area to identify the gas in the target area using the time correlation of the emitted radiation and the returning radiation. The radiation is modulated using respective orthogonal modulation codes for the different wavelengths and the modulation codes are modified by the insertion of a gap between each bit of the modulation code, the gap having a duration of at least n-1 bits where n is the number of different wavelengths.