Low-noise optical spectrometer with a high spectral-range-to-resolution ratio

An optical diffraction grating spectrometer is described which achieves a spectral resolution of 1.4<i>c</i><i>m</i>^-1 over a spectral range of 3800<i>c</i><i>m</i>^-1 without moving parts. It offers high detection efficiency (>50<i>%</i> in the green for p-polarized light) and low noise, without requiring thermoelectric cooling. Based on a fast F0.95/50 mm camera lens that is traversed by both input light and grating-dispersed light, it occupies a volume of under 2 L. Such a device is ideally suited for high-resolution low-light spectroscopy needed in portable Raman trace-gas sensing.