Described herein are a spectrometer system and a spectrometer device, which are suited for investigation or monitoring purposes, in particular, in the infrared (IR) spectral region, and for a detection of heat, flames, fire, or smoke.The spectrometer device allows capturing incident light from an object and transferring the incident light to a length variable filter with a particularly high concentration efficiency. Apart from the spectrometer device, the spectrometer system further includes an evaluation unit designated for determining information related to a spectrum of an object by evaluating the detector signals provided by the spectrometer device.