公开(公告)号：NL1002179C2

公开(公告)日：1997-07-29

申请号：NL1002179

申请日：1996-01-26

Applicant: STICHTING FUND OND MATERIAL

Inventor： HELDEN GERT JOACHIM VON ,  MEIJER GERARDUS JOHANNES MARIA ,  ENGELN RICHARD ANTONIUS HENDRI

IPC: G01J3/433 ,  G01J3/453 ,  G01N21/31

Abstract: The output (17) of a continuous wave He/Ne laser (51) is mixed in an electro-optical modulator (52) with the output of a signal generator (6). This has a range from 10kHz to 1MHz. The modulated signal (53) goes to a resonant cavity (2) containing a gaseous sample (24). The cavity (2) consists of two plain/concave mirrors (13,14) with input (15) and output (16) couplings. The phase difference between input and output is measured by a phase-sensitive detector (4). From this and the optical path length of the cavity the characteristic decay time and absorption coefficient can be calculated.