Abstract: An optical system measures scene inhomogeneity. The system includes a mirror for receiving radiance of a field-of-view (FOV) of a scene, and reflecting a portion of the radiance to an optical detector. A controller is coupled to the mirror for changing the FOV. The optical detector provides a signal of the reflected portion of radiance of the scene. A processor determines scene inhomogeneity, based on amplitude of the signal provided from the optical detector. The controller is configured to modulate the FOV at a periodic interval, using a sinusoidal waveform, a pulse code modulated waveform, or a pseudo-random waveform.

Abstract: A method for measuring scene inhomogeneity includes the steps of directing radiance of a scene into a dispersive spectrometer, and changing the field-of-view (FOV) of the spectrometer, while directing the radiance of the scene into the spectrometer. The method then processes the radiance of the scene to obtain a signal. The method also includes measuring an amplitude of the signal and determining scene inhomogeneity based on the measured amplitude of the signal. The method may include uniformly oscillating the FOV of the spectrometer and, next, obtaining a sinusoidal signal, based on uniformly oscillating the FOV of the spectrometer.

Abstract: A method for measuring scene inhomogeneity includes directing radiance of a scene into an interferometer; and oscillating a field-of-view (FOV) of the interferometer, while directing the radiance of the scene into the interferometer. A Fourier transform of signals emerging from the interferometer is obtained with magnitude values of the Fourier transform as a function of wavelength. The magnitude values are separated into (1) component values occurring within a predetermined wavelength band of the interferometer and (2) a component value occurring outside the predetermined wavelength band. The component value occurring outside the predetermined wavelength band is used to measure scene inhomogeneity.