A system includes an imaging system having a housing with a window, an imaging device within the housing having a field-of-view containing at least a portion of the window, a dark-field illuminator source within the housing directed at that portion of the window within the field-of-view, a control processor in communication with the imaging device and configured to execute instructions that cause the imaging device to acquire a first series of images with the dark-field illuminator source not activated, the control processor configured to control activation of the dark-field illuminator source, the imaging device configured to capture additional images during acquisition of the first series of images, the additional images captured during periods when the dark-field illuminator source is activated. In some implementations, dark-field illuminator can be synched with frame acquisition rate of the first series of images. A method and a non-transitory computer readable medium are also disclosed.