An optical spectrometer having a multi-wafer structure. The structure may be fabricated with MEMS technology. The spectrometer may be integrated with a fluid analyzer. A reflective grating such as a diffraction or holographic grating situated on the circumference of a Rowland circle along with a point of light emission and a detector may be a configuration of the spectrometer. Some configurations may use an external light source where the light may be optically conveyed to the point of emission on the circle. There may be a Raman configuration where an interaction of light with a sample or an interactive film of a channel in a fluid analyzer is the point of light emission for the spectrometer. In some configurations of the spectrometer, the grating and/or the film may be reflective or transmissive.