Design and evaluation of spatial heterodyne Raman spectrometer at 785 nm excitation wavelength

Raman spectroscopy has emerged as an essential technique for material composition analysis due to its noncontact, nondestructive, and rapid characteristics. Spatial heterodyne spectroscopy offers the advantages of high stability, high throughput, and ultra-high spectral resolution, making it particularly suitable for Raman spectroscopic detection. The main design parameters of a spatial heterodyne Raman detection system were determined under near-infrared wavelength excitation: a Raman shift detection range of 300 to 2000 cm−1 and a spectral resolution of 5 cm−1 at an excitation wavelength of 785 nm. The optical design of the dispersion module and imaging module was completed. Test results demonstrate that the spectrometer achieves a spectral resolution of 5.33 cm−1 and can detect Raman shifts in the range of 315 to 2131.6 cm−1. Verification tests on cyclohexane and lipstick samples confirm that the system exhibits excellent fluorescence suppression capability, with a signal-to-noise ratio of the cyclohexane Raman peak reaching 1600.8.