Raman Microspectroscopy with a Card-Based Spectrograph

Abstract

A Raman microprobe employing a card-based spectrograph and a HeNe excitation source was constructed and evaluated. Particular emphasis was placed on the low-cost room-temperature charge-coupled device (CCD) employed in the instrument. This detector exhibited a relatively high fixed pattern noise [198 e⁻/pixel/s, root mean squared (rms)] and read noise (35 e⁻, rms) compared to conventional charge-coupled detectors employed for Raman spectroscopy. However, by compensating for the fixed pattern noise and signal averaging, we obtained Raman spectra of a variety of common materials with reasonable signal-to-noise ratios at room temperature. Spectra having good signal-to-noise characteristics were collected on polystyrene spheres as small as 5 μm in diameter and a nylon fiber 23 μm in diameter. Although the sensitivity of the detector is limited for weak scatterers, the instrument can be used in specific industrial applications and for educational purposes. Suggestions are made for improving the system.