Abstract

The performance of an integrated turn-key on-line Raman spectrometer based upon a multiplexed transmission holographic grating, holographic laser rejection filters, and a charge-coupled-device (CCD) detector is described and compared with a laboratory-based research-grade FT-Raman spectrometer. Data for the dispersive system were acquired with a noncontacting, confocal dual-fiber probe of up to 100-m length, with Raman shifts down to 50 cm^-1 and no apparent fiber background features. Despite the fact that the FT-Raman system was directly coupled to the sample (i.e., not through fibers), the sensitivity of the dispersive system was almost three orders of magnitude greater for equivalent incident laser powers and accumulation times. The potential for performing multivariate calibrations with the dispersive equipment was also investigated. With samples of known density, it was possible to produce a partial least-squares calibration for poly(ethylene terephthalate) (PET) density with a precision of 0.002 g cm^-3, with the use of a two-factor model. This precision compared favorably with previous calibrations using FT-Raman data. The effect of changing the <i>f</i>-number of the collection optics of the fiber probe head (to allow variation in the working distance) was also examined. It was found that, for transparent samples, the <i>f</i>-number could be changed by a factor of three without greatly affecting the Raman signal intensity, whereas for an opaque solid increasing the <i>f</i>-number greatly reduced the detected intensity. The reasons for this difference are discussed.

Multicomponent analysis using a confocal Raman microscope

Zhengyuan Tang, Sinead J. Barton, Tomas E. Ward, John P. Lowry, Michelle M. Doran, Hugh J. Byrne, and Bryan M. Hennelly
Appl. Opt. 57(22) E118-E130 (2018)

Long fiber-optic remote Raman probe for detection and identification of weak scatterers

Christian L. Schoen, Thomas F. Cooney, Shiv K. Sharma, and David M. Carey
Appl. Opt. 31(36) 7707-7715 (1992)

Shifted-excitation Raman difference spectroscopy for in vitro and in vivo biological samples analysis

Mário Augusto da Silva Martins, Dayana Gonçalves Ribeiro, Edson Aparecido Pereira dos Santos, Airton Abrahão Martin, Adriana Fontes, and Herculano da Silva Martinho
Biomed. Opt. Express 1(2) 617-626 (2010)

Broadband transmission Raman measurements using a field-widened spatial heterodyne Raman spectrometer with mosaic grating structure

Jun Qiu, Xiangdong Qi, Xiaotian Li, Yuguo Tang, Jiriga Lantu, Xiaotao Mi, and Heshig Bayan
Opt. Express 26(20) 26106-26119 (2018)

Fiber-optic wavelength-division multiplexing and demultiplexing using volume holographic gratings

Behzad Moslehi, Phil Harvey, Joel Ng, and Tomasz Jannson
Opt. Lett. 14(19) 1088-1090 (1989)