COMPACT AND ATHERMAL VNIR/SWIR SPECTROMETER

A Compact and Athermal VNIR/SWIR Spectrometer utilizes a slit, a Mangin lens, a pupil lens adjacent to the diffraction grating, corrector lenses, a beam splitter, field lenses and SWIR and VNIR FPAs. In examples, two corrector lenses are used. Some examples do not utilize field lenses and beam splitter, some examples utilize only the SWIR radiation spectrum. By balancing the powers of the optical elements and Abbe numbers of glasses as well as usage of aspheric surfaces combinations, a monochromatic and polychromatic aberrational correction is achieved; by balancing optical elements refractive indices change with temperature an athermalization is achieved. The overall length of the spectrometer does not exceed 4 inches, and in some examples it is 2.5 inches. A wide field of view and a low F number are obtained with an operating wavelength range from approximately 400 to 2350 nm. The spectrometer is particularly suited to airborne applications.