An optical assembly comprising: an optical probe for collecting signal light emanating from a sample when the sample is illuminated with illuminating light; an optical fiber having a first end and a second end, wherein the first end is optically coupled to the optical probe for receiving the signal light collected by the optical probe and propagating the signal light to the second end; an optical conduit having a first surface and a second surface, wherein the first surface of the optical conduit is optically coupled to the second end of the optical fiber for receiving the signal light propagated to the second end of the optical fiber, for propagating in the optical conduit; characterized in that the optical assembly comprises a first laterally variable bandpass optical filter optically coupled to the second surface of the optical conduit for receiving the signal light propagated in the optical conduit; and 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, wherein the first laterally variable bandpass optical filter has a first bandpass center wavelength ( λ T), and the second laterally variable bandpass optical filter has a second bandpass center wavelength ( λ T), wherein the first bandpass center wavelength and the second bandpass center wavelength vary in a mutually coordinated fashion along a first direction transversal to the optical path; wherein the first bandpass center wavelength and the second bandpass center wavelength have a substantially identical dependence of the bandpass center wavelength on distance along the first direction, and wherein the optical conduit is a planar slab of homogeneous transparent material having one or more reflective walls for redirecting at least apportion of reflected light back to the first laterally variable bandpass optical filter; and wherein the optical assembly further comprises a photodetector array optically coupled via an air gap or direct physical contact to the second laterally variable bandpass optical filter and comprising photodetectors disposed along the first direction for wavelength selective detection of the signal light propagated through the second laterally variable bandpass optical filter. an optical probe for collecting signal light emanating from a sample when the sample is illuminated with illuminating light; an optical fiber having a first end and a second end, wherein the first end is optically coupled to the optical probe for receiving the signal light collected by the optical probe and propagating the signal light to the second end; an optical conduit having a first surface and a second surface, wherein the first surface of the optical conduit is optically coupled to the second end of the optical fiber for receiving the signal light propagated to the second end of the optical fiber, for propagating in the optical conduit; characterized in that the optical assembly comprises a first laterally variable bandpass optical filter optically coupled to the second surface of the optical conduit for receiving the signal light propagated in the optical conduit; and 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, wherein the first laterally variable bandpass optical filter has a first bandpass center wavelength ( λ T), and the second laterally variable bandpass optical filter has a second bandpass center wavelength ( λ T), wherein the first bandpass center wavelength and the second bandpass center wavelength vary in a mutually coordinated fashion along a first direction transversal to the optical path; wherein the first bandpass center wavelength and the second bandpass center wavelength have a substantially identical dependence of the bandpass center wavelength on distance along the first direction,