An optical spectrometer assembly comprising: a light source for providing illuminating light; an optical cuvette extending generally parallel to a first direction and comprising: an inlet for receiving a sample in fluid form; a transparent sidewall defining a cavity in fluid communication with the inlet, for receiving and containing the sample therein, wherein signal light emanates from the sample when the sample is illuminated with the illuminating light; an outlet; and an optical assembly comprising: a first laterally variable bandpass optical filter optically coupled to the transparent sidewall for receiving the signal light; a second laterally variable bandpass optical filter fixed at a first distance from the first laterally variable bandpass optical filter and downstream thereof in an optical path of the signal light; and a photodetector array optically coupled to the second laterally variable bandpass optical filter and comprising photodetectors disposed along the first direction; wherein the first laterally variable bandpass optical filter comprises a two-dimensional array of bandpass optical filter segments (81-84A-B), the two-dimensional array of bandpass optical filter segments including two or more one-dimensional arrays arranged side by side in the first direction; the second laterally variable bandpass optical filter comprises a different two-dimensional array of bandpass optical filter segments, and a circular polarizer, disposed in an optical path between the first and second filters for suppressing light reflected from the second filter in a direction towards the first filter. a light source for providing illuminating light; an optical cuvette extending generally parallel to a first direction and comprising: an inlet for receiving a sample in fluid form; a transparent sidewall defining a cavity in fluid communication with the inlet, for receiving and containing the sample therein, wherein signal light emanates from the sample when the sample is illuminated with the illuminating light; an outlet; and an optical assembly comprising: a first laterally variable bandpass optical filter optically coupled to the transparent sidewall for receiving the signal light; a second laterally variable bandpass optical filter fixed at a first distance from the first laterally variable bandpass optical filter and downstream thereof in an optical path of the signal light; and a photodetector array optically coupled to the second laterally variable bandpass optical filter and comprising photodetectors disposed along the first direction; an inlet for receiving a sample in fluid form; a transparent sidewall defining a cavity in fluid communication with the inlet, for receiving and containing the sample therein, wherein signal light emanates from the sample when the sample is illuminated with the illuminating light; an outlet; and an optical assembly comprising: a first laterally variable bandpass optical filter optically coupled to the transparent sidewall for receiving the signal light; a second laterally variable bandpass optical filter fixed at a first distance from the first laterally variable bandpass optical filter and downstream thereof in an optical path of the signal light; and a photodetector array optically coupled to the second laterally variable bandpass optical filter and comprising photodetectors disposed along the first direction; a first laterally variable bandpass optical filter optically coupled to the transparent sidewall for receiving the signal light; a second laterally variable bandpass optical filter fixed at a first distance from the first laterally variable bandpass optical filter and downstream thereof in an optical path of the signal light; and a photodetector array optically coupled to the second laterally variable bandpass optical filter and comprising photodetectors disposed along the first direction; wherein the first laterally variable bandpass optical filter comprises a two-dimensional array of bandpass optical filter segments (81-84A-B), the two-dimensional array of bandpass optical filter segments including two or more one-dimensional arrays arranged side by side in the first direction; the second laterally variable bandpass optical filter comprises a different two-dimensional array of bandpass optical filter segments, and a circular polarizer, disposed in an optical path between the first and second filters for suppressing light reflected from the second filter in a direction towards the first filter.