Available Technology

CAVITY RINGDOWN SPECTROSCOPY SYSTEM USING DIFFERENTIAL HETERODYNE DETECTION

A novel AC technique in cavity ringdown spectroscopy that permits IXIO-IO absorption sensitivity with microwatt level light power has been developed. Two cavity modes, one probing the empty cavity and the other probing intracavity absorption, are excited simultaneously, but their intensities are temporally out of phase, with one mode decaying and the other rising. Heterodyne detection between the two modes reveals the dynamic time constants associated with
the empty cavity and the additional intracavity gas absorption. The method offers a quick comparison between the on-resonance and off-resonance information, a prerequisite to reaching the fundamental shot noise limit. This simple and yet important mprovement of cavity ringdown spectroscopy should lead to enhanced performance in a wide range of applications.
Inventors: 
John Hall, Jun Ye
Patent Number: 
6,727,492
Internal Laboratory Ref #: 
00-005US
Phone: 
301-975-2573
Email: 
tpo@nist.gov
Lab Representatives
Share to Facebook Share to Twitter Share to Google Plus Share to Linkedin