In an embodiment, a dual-etalon cavity-ring-down frequency-comb
spectrometer system is described. A broad band light source is split into
two beams. One beam travels through a first etalon and a sample under
test, while the other beam travels through a second etalon, and the two
beams are recombined onto a single detector. If the free spectral ranges
("FSR") of the two etalons are not identical, the interference pattern at
the detector will consist of a series of beat frequencies. By monitoring
these beat frequencies, optical frequencies where light is absorbed may
be determined.
STATEMENT REGARDING GOVERNMENT RESEARCH AND DEVELOPMENT
This invention was made with Government support under government contract
no. DE-AC04-94AL85000 awarded by the U.S. Department of Energy to Sandia
Corporation. The Government has certain rights in the invention,
including a paid-up license and the right, in limited circumstances, to
require the owner of any patent issuing in this invention to license
others on reasonable terms.