1. A method for spectrally analyzing an unknown sample, the method comprising: providing a spatially homogeneous region of the unknown sample; directing a plurality of interrogation beams at the spatially homogeneous region with a laser source, each of the interrogation beams being nominally monochromatic and having a different interrogation wavelength that is in the mid-infrared spectral range; acquiring a separate output image of the unknown sample while the unknown sample is illuminated by each of the interrogation beams with an image sensor that senses light in the mid-infrared spectral region; and analyzing less than fifty output images to analyze whether a characteristic is present in the unknown sample with a control system that includes a processor.