Patent ID: 8881576

Claim:
A device for performing leak detection at a plurality of test sites, said device comprising a plurality of measuring cells for optical detection of a tracer gas, each of said measuring cells including an excitation means for transforming the tracer gas into a metastable state, a radiation source and a radiation receiver, and comprising a host unit, said host unit including a frequency-variable laser and a photodetector and being connected to the measuring cells via light-conducting fibers forming said radiation source and said radiation receiver, and wherein said laser is operated by two-tone frequency modulation (TTFM) by generating side bands (ω 0 −ω 1 )±½Ω and (ω 0 +ω 1 )±½Ω for the emitted laser radiation being guided via the light-conducting fibers ,wherein ω 0 is the laser center frequency ω 1 is a first modulation frequency equal to or above 1 GHz and Ω is a second modulation frequency equal to or below 10 MHz.