  To more fully take advantage of a low-cost, small footprint hybrid
interferometric/dispersive spectrometer, a mathematical reconstruction
technique was developed to accurately capture the high-resolution and relative
peak intensities from complex spectral patterns. A Fabry-Perot etalon was
coupled to a Czerny-Turner spectrometer, leading to increased spectral
resolution by more than an order of magnitude without the commensurate increase
in spectrometer size. Measurement of the industry standard Hg 313.1555/313.1844
nm doublet yielded a ratio of 0.682, which agreed well with an independent
measurement and literature values. The doublet separation (29 pm) is similar to
the U isotope shift (25 pm) at 424.437 nm that is of interest to monitoring
nuclear nonproliferation activities. Additionally, the technique was applied to
LIBS measurement of the mineral cinnabar (HgS) and resulted in a ratio of
0.682. This reconstruction method could enable significantly smaller, portable
high-resolution instruments with isotopic specificity, benefiting a variety of
spectroscopic applications.
