A wide field-of-view infrared optical imaging system with extended spectral coverage into the 1.0 to 2.5 μm wavelength range. In one example, an optical imaging system includes an imaging detector sensitive to light in a wavelength range of at least 1.0 μm to 5.0 μm, and a plurality of lenses optically coupled together and configured to focus incoming light onto the imaging detector, the plurality of lenses each comprised of a material that is transparent to the light in the wavelength range of at least 1.0 μm to 5.0 μm, wherein a pupil of the optical imaging system is located external to the plurality of lenses between the plurality of lenses and the imaging detector.