Interferometric Raman spectrometry with fiber waveguides.
We present the design and expected performance of a Fourier-transform fiber-optic Raman spectrometer that should be capable of rapidly diagnosing environmental contamination to levels approaching a few parts per thousand. The system design is predicated on fiber arms that are unequal in length initially. A voltage applied to the piezoceramic substrate hosting the shorter fiber strains it through zero path difference to a new length that exceeds the reference arm by its initial length deficiency. This approach permits one to resolve spectral features separated by 0.5 cm(-1) over an electromagnetic bandwidth that exceeds 2000 cm(-1) without using a moving mirror or introducing a second laser to provide the sampling reference. Specific expressions are given for computing the spectral resolution, modulation bandwidth, and modulated signal-to-noise ratio of the device as a function of the system's design parameters.
Heaton
H I
HI
Applied Physics Laboratory, The Johns Hopkins University, MS 8-372A, 11100 Johns Hopkins Road, Laurel, Maryland 20723-6099, USA.