Abstract: Aspects relate to an optical device providing a large spot size spectrometer. The optical device includes an optical head, an optical window, and a spectrometer. The optical head includes a plastic molded part having an aperture and a plurality of reflectors around the aperture formed therein. Each reflector may include a respective lamp assembled therein. The optical window is configured to receive a sample, to pass input light from the lamps to the sample and to pass scattered light from the sample towards the aperture. The aperture is configured to filter a first portion of scattered light containing unusable sample information and to pass a second portion of the scattered light to the spectrometer.