A device images radiation from a scene. The scene can include two materials with spectral characteristics in different radiation wavelength regions. A static filtering arrangement includes two filters with different passbands corresponding to the two wavelength regions. An image forming optic forms an image of the scene on a detector. The radiation from the scene is imaged simultaneously through an f-number of less than 1.5 onto two detector pixel subsets. The imaged radiation on one pixel subset includes radiation in one wavelength region. The imaged radiation on the other pixel subset includes radiation in the other wavelength region. Electronic circuitry produces a pixel signal from each detector pixel. The pixel signals include information associated with absorption or emission of radiation in one of the respective wavelength regions by the two materials. The electronic circuitry determines the presence or absence of each of the two materials based on the pixel signals.