Robust, precise, high-resolution Fourier transform Raman spectrometer

A robust, flexible Fourier transform Raman spectrometer (FT-Raman) based on a Michelson interferometer and a self-made photon counter is presented. The proposed inexpensive setup has no complex hardware or control systems for optical path compensation. The mechanical and thermal induced errors are mathematically compensated by extracting the optical path information from the generated interference pattern of a λ = 632.8nm Helium-Neon laser (HeNe laser). This information also permits high frequency precision of the calculated Raman spectrum. This system is flexible and allows the user having complete access to hardware and software. It enables a variety of experimental changes in the system, which are difficult to achieve with commercial devices. Precise, high resolution Raman spectra of cyclohexane with a resolution of 1.66 cm^-1 to 5.0cm^-1 have been measured with this device. Higher resolution values can be achieved since longer scanning distances at the Michelson interferometer are possible and its calculated ´etendue (throughput) does not substantially corrupt the obtained interferograms. Other chemical compounds have been also monitored. Additionally, a detailed spectral analysis of different precision optical components and light sources has been performed.