A method and device are provided for detecting non-visible content of an object in a non-contact manner. The device includes a light source configured to emit light toward a surface of an object over a period of time. The device also includes an optical sensing component configured to receive a pattern of light from the surface of the object, and to record the received pattern at plural points in time. In addition, the device includes a processing component configured to determine temporal changes in the pattern during the plural points in time, and to detect whether motion is present in the object based on determined temporal changes in the pattern, where the motion represents a frequency source of non-visible content in the object.