A Fourier transform Raman spectrometer with visible laser excitation

Abstract

We present the development and performance of a Fourier transformation (FT) based Raman spectrometer working with visible laser (532 nm) excitation. It is generally thought that FT-Raman spectrometers are not viable in the visible range where shot-noise limits the detector performance and therein they are outperformed by grating based, dispersive ones. We show that contrary to this common belief, the recent advances of high-performance interference filters makes the FT-Raman design a valid alternative to dispersive Raman spectrometers for samples which do not luminesce. We critically compare the performance of our spectrometer to two dispersive ones: a home-built single channel and a state-of-the-art CCD based instruments. We demonstrate a similar or even better sensitivity than the CCD based dispersive spectrometer particularly when the laser power density is considered. The instrument possesses all the known advantages of the FT principle of spectral accuracy, high throughput, and economic design. We also discuss the general considerations which helps the community reassess the utility of the different Raman spectrometer designs.

Recent advances in linear and non‐linear Raman spectroscopy. Part X

“…They show that contrary to the common belief, the recent advances of high‐performance interference filters makes the FT‐Raman design a valid alternative to dispersive Raman spectrometers in the visible region for samples which do not luminesce. The instrument possesses all the known advantages of the FT principle of spectral accuracy, high throughput, and economic design . Harris et al .…”

“…The instrument possesses all the known advantages of the FT principle of spectral accuracy, high throughput, and economic design. [173] Harris et al described how to avoid misidentification of bands in planetary Raman spectra. They presented spectra from a number of Mars analog samples that include a range of molecules, highlighting where such confusion may occur and identifying the most useful bands for differentiation.…”

Raman Spectroscopy for Quantitative Analysis in the Pharmaceutical Industry

“…The diversity of the types of device configurations allows amplifying the sensitivity of the technique and allows a variety of applications, ranging from the quantification of drug substances in tablets and mixtures of powders to multiplex samples (3,(10)(11)(12)(13)(14)(15)(16)(17), samples in low concentrations (18,19), molecular traces (20)(21)(22), samples inside packs (23) and materials in nanometric scale (Table 1) (24,25). Conventional Raman spectroscopy requires high sample concentration and it is affected by fluorescence.…”

“…Conventional Raman spectroscopy requires high sample concentration and it is affected by fluorescence. FT-Raman can resolve such spectral interference (11). Furthermore, fluorescence interference also can be reduced by exciting the near infrared laser sample as Nd-YAG at 1064 nm (5).…”

Raman spectroscopic detection for liquid and solid targets using a spatial heterodyne spectrometer

“…However, the slits limit the optical throughput of the systems, which ultimately affects the detection sensitivity. Conventional step scanning Fourier transform Raman spectrometers can avoid this problem, but because of their moving mirror, they are not compatible with gated detection using pulsed lasers. Many published results have proved that gated detection is very essential for the work conditions with strong ambient light or long‐life fluorescence.…”