An infrared imaging system for the identification of target chemical contents of an object, the imaging system comprising: an optical system including a set of uncooled optical focal plane array units, the optical system having components defining a plurality of optical channels arranged in a two-dimensional array, said plurality of optical channels being spatially and spectrally different from one another, each of the plurality of optical channels positioned to transfer IR radiation incident on the optical system towards the set of optical FPA units, wherein each FPA in the set of optical FPA units comprises an array of uncooled microbolometers, and wherein the optical system further comprises a plurality of spectrally-multiplexed optical filters, each filter positioned to transmit a portion of the IR radiation transmitted through a respective corresponding optical channel, each spectrally-multiplexed optical filter including one of a longpass optical filter or a shortpass optical filter; a first movable shutter configured to be removably positioned to block IR radiation incident onto the optical system from reaching the set of optical FPA units, wherein the first movable shutter is maintained at a first temperature; a second movable shutter configured to be removably positioned to block IR radiation incident onto the optical system from reaching the set of optical FPA units, wherein the second movable shutter is maintained at a second temperature different from the first temperature; and a data-processing unit containing a programmable processor in operable cooperation with a tangible, non-transitory computer-readable storage medium, the storage medium containing a computer-readable program code that, when loaded onto the processor, enables the processor to acquire, in a single occurrence of data acquisition, multispectral optical data representing said target species from the IR radiation received at the set of the optical FPA units. an optical system including a set of uncooled optical focal plane array units, the optical system having components defining a plurality of optical channels arranged in a two-dimensional array, said plurality of optical channels being spatially and spectrally different from one another, each of the plurality of optical channels positioned to transfer IR radiation incident on the optical system towards the set of optical FPA units, wherein each FPA in the set of optical FPA units comprises an array of uncooled microbolometers, and wherein the optical system further comprises a plurality of spectrally-multiplexed optical filters, each filter positioned to transmit a portion of the IR radiation transmitted through a respective corresponding optical channel, each spectrally-multiplexed optical filter including one of a longpass optical filter or a shortpass optical filter; a first movable shutter configured to be removably positioned to block IR radiation incident onto the optical system from reaching the set of optical FPA units, wherein the first movable shutter is maintained at a first temperature; a second movable shutter configured to be removably positioned to block IR radiation incident onto the optical system from reaching the set of optical FPA units, wherein the second movable shutter is maintained at a second temperature different from the first temperature; and a data-processing unit containing a programmable processor in operable cooperation with a tangible, non-transitory computer-readable storage medium, the storage medium containing a computer-readable program code that, when loaded onto the processor, enables the processor to acquire, in a single occurrence of data acquisition, multispectral optical data representing said target species from the IR radiation received at the set of the optical FPA units.