This paper presents a monolithic spectrometer based on a plano-convex glass lens and achieves a resolution better than 0.7 nm in the spectral range of 550-720 nm. In the monolithic instrument, all components were fixed in the machined lens, resulting in a much smaller size and more stable assembly than traditional mini spectrometers. Additionally, a dual-band design was proposed and demonstrated to extend the spectral range from the visible band (550-700 nm) to the near-infrared band (800-900 nm), thus allowing more characteristic spectral fingerprints for improved material identification. The feasibility of compensating the residual aberrations caused by structural limitations with a specifically designed aberration-correcting grating is further detailed.
Keywords: Monolithic spectrometer; aberration-correcting grating; crossed Fastie–Ebert spectrograph; dual-band design; mini-spectrometer.