A spectrally encoded endoscopy optical device includes a bundle of multi-mode optical fibers that transmits light received from an imaging target to a spectrometer. A far field pattern of light transmitted through a fundamental mode of at least one of the multi-mode optical fibers is nonparallel to an optical axis of the spectrometer for reducing nonuniformity of the far field pattern at an input sensor of the spectrometer. For still further reduction of such nonuniformity, a far field pattern of light transmitted through a fundamental mode of the bundle of multi-mode optical fibers is nonparallel to an optical axis of the spectrometer.